TP690.45
.E44
1987x
United States Environmental
Protection Agency

Office of Mobile Sources
Washington, DC 20460
United States Department
of Agriculture

Office of Energy
Washington, DC 20250
        EPA
      I USDA
        A Joint Report
          April 1987
Effects of Using Unleaded
and Low-lead Gasoline, and
Non-lead Additives on
Agricultural Engines
Designed for Leaded Gasoline
                                          OOOR87900

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      Effects  of Using Unleaded and

Low-lead Gasoline,  and Non-Lead Additives

   on Agricultural  Engines  Designed for

             Leaded Gasoline


                 April 1987
   U.S. Environmental Protection Agency


      U.S.  Department of Agriculture


              Washington, D.C.
                            U.S. Environmental Protection Agency
                            Region 5, Library (5PL-16)
                            2oO S. Dearborn Street, Room 1670
                            Chicago, IL   60604

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                                Table of Contents

                                                                        Page

I.    Background	1


II.   Scope of Study	3

      A.  Dynamometer Testing	  4

      B.  Farm Engine-Use Survey 	  .....  5

      C.  Cylinder Head Survey	  6


III.  Agricultural Machinery Testing on Engine Dynamometers  	  7

      A.  Test Design	, ,	7

      B.  Engines Tested	,	10

      C.  Dynamometer Testing Limitations  	 11


IV.   Results of Dynamometer Testing 	 13

      A.  Tests of Leaded Gasoline	13

      B.  Tests of Unleaded Gasoline 	 16

      C.  Tests of Low-lead Gasoline	24

      D.  Tests of Non-lead Additives  	 26


V.    Results of the Farm Use Survey and Survey of Valve Seats	31

                                 Appendices

      Appendix 1    Exhaust Valve Seat Recession by Cylinder 	 38

      Appendix 2    Consultants Evaluations of Engine Testing Performed
                      by NIPER	64

      Appendix 3    Duty Cycles Used in Engine Tests	 72

      Appendix 4    Engines Tested 	 75

      Appendix 5    Farm Engine-Use Survey Form	77

      Appendix 6    How to Obtain Documents Referred to in this Report . 79

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I.  Background



     Due to health concerns from public exposure to lead in



automotive exhaust, the Environmental Protection Agency (EPA)



undertook a lead phasedown program in the early 1970's to



remove lead from gasoline.  At that time, refiners used



approximately 2.5 grams per leaded gallon (gplg).   In 1982



the amount of lead permitted in leaded gasoline was reduced



to 1.10 gplg.  On March 7, 1985, EPA further reduced the



allowable level to 0.50 gplg, effective July 1, 1985 and



0.10 gplg on January 1, 1986.  A complete ban on leaded



gasoline has been considered for as early as 1988.  The



Agency has not proceeded with a total ban because of a concern



that older engines designed for leaded gasoline may suffer



premature valve seat wear if required to use unleaded gasoline



exclusively, and a maior health effect study of lead exposure



required further review.



     The Agency determined that 0.10 gplg would be satifactory



to protect those older engines, based on testing that had



been done in the early 1970's.  Results of those tests are



summarized in Costs and Benefits of Reducing Lead  in Gasoline--



Final Regulatory Impact Analysis (EPA-230-05-85-006,



February, 1985).  Generally,  these tests showed that certain



engines when operated on unleaded fuel for continuous high



speeds, experienced valve seat recession.  However, at lower



speeds, valve seat recession was greatly reduced.   One study



showed that between 0.04 and 0.07 gplg would be satisfactory

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                            - 2 -






to protect valve seats.   Based on this and other studies,



EPA concluded that 0.10 gplg would be sufficient to protect



exhaust valve seats from recession in engines  designed for



leaded gasoline.



     The farming community expressed a concern that older



farm engines designed to operate on leaded gasoline may



experience engine damage if operated on low-lead or unleaded



gasoline.  In response to that concern, Congress required  a



study to be conducted under Section 1765 of the Food Security



Act of 1985 (P.L. 99-198) (Act).



     The Act required the Administrator of EPA and the



Secretary of Agriculture (USDA) to "jointly conduct a study



of the use of fuels containing lead additives  and alternative



lubricating additives," on gasoline-powered agricultural



machinery.  The study was to analyze the potential for



mechanical problems (including but not limited to valve seat



recession) that may occur with the use of other fuels in farm



machinery.  The Secretary of Agriculture was to specify the



types and items of agricultural machinery to be included in



the study and all testing of engines was to reflect actual



agricultural conditions, including revolutions per minute



and loads placed on the engines.

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                            - 3 -






II.   Scope of study



     The study's overall goals are to determine the risk to



engines if gasoline is limited to either low-lead or unleaded



and to evaluate alternative additives to lead.  The study



has a complex design hecause the relationship between gasoline



type and engine durability is a function of both engine



design and usage patterns.  The primary engine component at



risk with a fuel change is the exhaust valve seat.  This



wears by receding into the cylinder head.  If wear is severe



enough, the exhaust valve eventually will not seat properly



and engine failure will follow.  Factors influencing the



risk of wear include engine speed (rpm), load, temperature



and cylinder head design.  Information is needed on all of



these factors to assess the risk of engine failure.



     Little information was available about rpm and load



levels for agricultural equipment under actual use conditions.



Further, concern arose that since most of the equipment is



not new, the valve seats could have been modified during



overhauls so that original equipment specifications would no



longer accurately reflect the type of valve seats in use.



     The study was divided into three areas:   Agricultural



machinery testing on engine dynamometers; farm use survey of



gasoline-powered equipment; and field measurement of the type



of valve seat material in exhaust valve seats in gasoline-



powered tractors.

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                            - 4 -






  A.  Dynamometer Testing



     The design of the testing portion of this study was



initiated with a letter from EPA on December 6,  1985 to 25



potential commenters from EPA, USDA, the American Farm Bureau



Federation (AFBF),  tractor manufacturers, university professors,



and independent consultants.  The letter forwarded a statement



of work suggested for the study.  Comments were  received from



most of the recipients of the letter and suggested a wide



variety of changes.  A meeting was held on January 27, 1986



with all commenters who wished to attend to discuss the



program and reach a consensus on engines to test, duty cycles



and other details of the test program.  Twenty-one commenters



attended the meeting.  Based on discussions at this session,



EPA revised the statement of work and sent it back to the



commenters for a final review.  Through this procedure and



further contacts with engine manufacturers and others, EPA



and USDA representatives agreed on a test procedure for



tractors, combines, and farm trucks, including the selection



of engines and duty cycles.



      In addition, EPA decided to incliide a recreational



vehicle (RV) engine in the study because of a concern expressed



by RV owners related to potential engine damage while operating



these engines on low-lead or unleaded gasoline.   EPA developed



a duty cycle to be used on the RV engine, after discussions



with consultants and original-equipment manufacturers.

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                            - 5 -






     Engine testing was performed by the National Institute



for Petroleum and Energy Research (NIPER), an independent



research laboratory located at Bartlesville, Oklahoma.   (See



Appendix 6 for information on how to obtain a copy of their



report.)  Technical advice and oversight were provided by two



consultants, Dr. Louis I. Leviticus of the Nebraska Tractor



Testing Laboratory, Lincoln, Nebraska and Dr. Ralph Fleming



of Energy, Fuels and Engine Consulting Services, Accokeek,



Maryland.  The consultants commented on the original program



design, visited the test facility on several occasions and



consulted on major program decisions throughout the study.



Their evaluation of the test program is in Appendix 2.






  B.  Farm Engine-Use Survey



     The second area of this study was a survey of the number



and use of selected gasoline-powered farm equipment (tractors,



combines and trucks).  Questions were added to a Farm Labor



Survey conducted in July 1986 by the National Agricultural



Statistics Service, USDA.  (See Appendix 5 for a copy of the



survey form and see Appendix 6 for information on how to obtain



a copy of the manual that accompanied the questionnaire.)



Survey results were related to the results of the dynamometer



tests in order to characterize the degree of risk encountered



by farm equipment.  Highlights of that analysis are included



in this report.  More extensive analysis of the data may



reveal additional information about the use of these engines.

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                            - 6 -






  C.  Cylinder Head Survey



     Valve seat recession is affected by the type and hard-



ness of the material used in valve seats.  A field survey of



cylinder heads was performed to determine what material



(cast iron, soft steel, hard steel or stellite) is in the



exhaust valve seats of tractors.  Due to overhauls, engines



may no longer have valve seats meeting original equipment



specificat ions.



     The survey, conducted by the Radian Corporation,



Sacramento, California, involved sending an engineer to test



cylinder heads removed by eight tractor dismantling and



salvage firms located throughout the United States.  (See



Appendix 6 for additional information on how to obtain a copy



of the protocol and quality assurance plan for this survey.)

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III.  Agricultural Machinery Testing on Engine Dynamometers

  A.  Test Design

     Lead combustion products serve as solid lubricants for

some parts of the engine--primarily the exhaust valve seats.

Engines designed for leaded gasoline typically have a valve

seat geometry designed to prevent excessive accumulation o£

lead compounds.  They may also use valve rotators for this

purpose.  Valve seat wear appears to be related primarily

to engine speed and load.

     A tractor duty cycle was designed to reflect a full range

of tractor use conditions.  The duty cycle had two parts.

The first part consisted of 144 hours (16 hours/day) at

governed engine speed and loads varying from no load to full

power.  This cycle was adopted from the cycle used by the

Nebraska Tractor Testing Laboratory (SAE JVOS).^/  The

second part consisted of a 56-hour continuous test at governed

engine speed and 75% of maximum available power.  This segment

represents the maximum continuous load that is likely to be

placed on these engines, such as pumping irrigation viator.

The combine engine was tested using the same duty cycle.

(See Appendix 3 for a description of the duty cycles.)

      The farm truck engine was operated throughout the 200

hours at varying engine speeds (2000-3600 rpm)  and loads

(25% to 85% of maximum power)  representing normal conditions
I/This cycle has a long history of use in testing the perfor-
mance of new tractors.

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                            - 8 -





for farm trucks larger than one-ton capacity.   The RV engine



was operated for 144 hours at varying engine speeds (2000-3600



rpm) and loads (45% to 85% of maximum power) followed by a



56-hour hour steady state cycle (100 HP,  which is 52% of



maximum power, at 3000 rpm).  The farm truck and RV engines



were operated for 16 hours on and 8 hours off  throughout the



tests.  (See Appendix 3 for a description of the duty cycles.)



     Before each test, the cylinder heads were changed and



broken in on the next fuel being tested.   Testing was conducted



on leaded (1.2 gplg), unleaded, and low-lead (0.1 gplg)  gasoline,



and gasoline containing non-lead additives.£/   The principal



focus of the testing was to record wear of exhaust valve seats.



Valve clearance was set to manufacturers' specifications each



time a measurement was taken.  In addition,  the contractor



measured intake valve seat recession, valve stem length, valve



guide and stem wear, valve tulip diameter and  valve seat angle,



valve spring force and height, and other measures of engine



wear.  Engine performance was monitored and emissions tests were



performed on the exhaust gases.  After each fuel test, engines



were carefully examined for deposits and other conditions that



may have resulted from the test.  Elemental analyses of the



lubricating oils were conducted.  Cylinder heads and valve seat



inserts were carefully selected to control the hardness of



exhaust valve seats.
2/Leaded gasoline in this study contains tetraethyl lead,

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                            - 9 -






     Tractor and combine engines usually have solid valve



lifters.  A valve adjustment is needed in the engines after



about every 15 thousandths of an inch of wear and new valve



seats are needed after about 125 to 200 thousandths of an inch



of wear.  While repeated valve adjustments theoretically make



it possible to continue operating an engine as valve seat



recession occurs, as a practical matter, an engine operator



is likely to burn a valve and, thus, require an overhaul of




the valve assembly before all of the potential adjustments



can be made.  This is because valve seat wear gives an operator




few clues to the problem until significant damage occurs.



There is no increase in engine noise and misfiring and loss



of power often are not noticed until after valves or valve



seats have burned.  Automotive-type engines usually have



hydraulic valve lifters so regular valve adjustments are not



needed.  New valve seats are needed in these engines after



about 75 thousandths of an inch of valve seat wear.  New



valve seats may be obtained by replacing the cylinder head



or by machining out the valve seats and installing valve



seat inserts.



     Proper clearance also must be maintained between valve



stems and valve guides.  Worn valve stems and guides result



in increased oil usage and may cause excessive valve and valve



seat wear because the valve does not seat properly.  When valve



guide clearance increases by more than 2 thousandths of an inch,



many manufacturers recommend that the valve guides be replaced



or that the valves be replaced by ones with oversize stems.

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                            - 10 -






     See Appendix 6 for information on how to obtain a copy of



the statement of work used in the study and a detailed descrip-



tion of the engine tests,  including fuel  and oil  specifications,



engine rebuilding procedures, recession measurement guidelines,



and other test parameters  which NIPER was required to follow.






  B.  Engines Tested




     The five farm equipment engines initially selected by



USDA were:  John Deere "B", Farmall "H" and International



Harvester 240 tractors, John Deere 303 cubic inch displacement



(CID) combine engine, and  a pre-1974 General Motors 292 CID



(GM 292) truck engine.  The engines, described in Appendix 4,



represent a broad range of engine sizes and characteristics.



EPA selected the pre-1984 General Motors  454 CID V-8 engine



(GM 454) to represent engines used in RVs.



     Plans called for purchase of a duplicate of the engine



that experienced the most  valve seat recession on unleaded



gasoline, in order to focus more attention on tests of this



engine.  The GM 292 truck  engine proved most vulnerable and



a duplicate was purchased.  At the request of the USDA and



the American Farm Bureau Federation, a Ford 8N tractor engine



also was procured for the study after it  was learned that



one of the other tractor engines selected did not need to be



tested on low-lead gasoline and non-lead  additives.  Manufac-



turers' specifications for the John Deere "B", International



240, John Deere 303, and GM 292 engines called for ordinary



cast iron cylinder heads without valve seat inserts.  Hardness

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                             -11-


of these valve seats typically ranges from 9 to 25 on the

Rockwell C scale._3/  The Farmall "H" was originally equipped

with "gray iron" valve seat inserts (Rockwell C scale values

of 26-36); the Ford 8N was originally equipped with harder

exhaust valve seat inserts (Rockwell C scale 39-43); and the

General Motors 454 CID engine was originally equipped with

induction-hardened cast iron valve seats (no inserts) with a

Rockwell C scale hardness of: about 55 specified by the manu-

facturer.^/  The General Motors 454 and 292 engines are

currently being manufactured with induction-hardened cast

iron valve seats.  All engines were tested with valve seats

meeting original equipment specifications except the Farmall

"H" and Ford 8N.  Since the latter engines may have been

rebuilt with different valve seat material, they were tested

with ordinary cast iron valve seat inserts (Rockwell C scale

value of 17).


  C.  Dynamometer Testing Limitations

     The dynamometer testing portion of this study has a

number of limitations.  First, budget limitations did not

permit testing enough engines to assure statistical reliabil-

ity.  Only one or at most two engines of any given type

could be tested.  Second, dynamometer tests typically show
3/Lower numbers indicate softer materials.

4/Hardness of induction-hardened cast iron valve seats typically
ranges from 40 to 60 on the Rockwell C scale.

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                             -12-






raore wear than is found during actual in-use operation of



engines.  Every attempt was made to make the tests represen-



tative of actual in-use conditions, but this was difficult



because data on how the engines are used did not exist.



Third, because of time and cost restrictions, valve design



factors which could affect valve seat wear,  such as the



presence of valve rotators, were not examined fully.  Finally,



unforseen engine characteristics such as air/fuel ratios and



mechanical problems, which appear to have an effect on valve



seat wear rates, were not controlled in the study design.

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                             -13-






IV.  Results of Dynamometer Testing



  A.  Tests of Leaded Gasoline (1.2 gplg)



     Baseline tests were run on the six original engines



using gasoline containing 1.2 grams per leaded gallon (gplg).



The duplicate truck engine (GM 292-B) and the additional



tractor engine (Ford 8N) were not tested on gasoline containing



1.2 gplg because none of the original engines showed appreciable



wear with this fuel.



     Table 1 summarizes the maximum rates of valve seat



recession (in thousandths of an inch per 100 hours) found



while operating the engines on leaded,  low-lead, and unleaded



gasoline.  Except for the GM 454 engine, essentially no valve



seat recession was found and no unusual wear occurred on



other engine components when leaded gasoline was used.   It



should be noted that the GM 292-A exhaust valve guide diameter



increased by 1.8 thousandths of an inch and that the International



Harvester 240 intake valve guide diameter increased by 14.3



thousandths of an inch (probably due to an oil line blockage



that was corrected early in the test) which are substantially



more than were observed in the other engines.  Exhaust  valve



seat recession is not a problem with gasoline containing 1.2



grams per leaded gallon.

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-14-




















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                             -15-
     Table 1--Maximum exhaust valve seat recession rates*--continued
4/  Recession may have heen influenced by improper alignment
of rocker arm assembly.  _5/  Operated 244 hours.   j3/  Operated
300 hours.  _7/  Results are for two tests.  During the first
test (the larger recession rate),  the cylinder head gasket
failed and may have generated additional heat which contributed
to the recession.  ^/  Engine could complete only 71 of the
scheduled 200 hours due to recession.  _9/  Engine was run
without the 3600 rpm part of the duty cycle.  1O/  Engine was
stopped after 88 hours of operation due to recession.

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                            - 16 -






  B.  Tests of Unleaded Gasoline



     All engines procured for this test program were evaluated



on unleaded gasoline.   Recession data are summarized in



Table 1  and Appendix 1, Figures 1-13.  Principal findings



are as follows.



     1.   The John Deere "B" tractor engine was  tested twice



on unleaded gasoline (Appendix t,  Figures T and 2).   The



first test found that  one cylinder had 11 thousandths of an



inch of  recession after 200 hours  of operation, all  of



which occurred during  the steady state portion  of the test.



Examination of the engine after the test showed that the



rocker arm was not striking the valve stem tip  properly and



it was believed that recession was due to this  mechanical



problem instead of the fuel.  This may have caused valve



guide diameter wear to increase from 1.0 thousandths of inch



for the leaded fuel test to 3.2 thousandths of  an inch during



the first unleaded test.  After properly aligning the rocker



assembly, the unleaded test was repeated with a new cylinder



head.  Both exhaust valve seats experienced some recession



after 80 hours, but no additional  recession through 200



hours.  The test was continued on the intermittent portion



of the duty cycle for  100 more hours and no additional reces-



sion occurred.  Valve  guide diameter wear was consistent



with the rate observed for leaded gasoline.  Valve stem



wear increased from 0.2 thousandths of an inch  for leaded  gas-



oline to 0.8 thousands of an inch for unleaded  gasoline.  No

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                            - 17 -






other unusual wear was observed.  The John Deere "B" tractor



engine may experience a small amount of valve seat recession



but should not have problems operating on unleaded gasoline.



     2.  The Farmall "H" tractor engine did not experience



valve seat recession or any other unusual wear while operating



on unleaded gasoline and was not tested any further (Appendix 1,




Figure 3).



     3.  The John Deere 303 CID combine engine experienced



substantial valve seat recession while operating on unleaded



gasoline (Appendix 1, Figure 4).  At 144 hours, all cylinders



showed recession ranging from 10 to 24 thousandths of an



inch.  After the steady state portion of the test, total



recession ranged from 41 to 63 thousandths of an inch.



Valve guide wear increased from a maximum of 0.2 thousandths



of an inch on leaded fuel to 1 .5 thousandths of an inch on



unleaded fuel.



     4.  The International Harvester 240 tractor engine was



tested three times on unleaded gasoline.  The first test



showed no valve seat recession (Appendix 1, Figure 5).   We



subsequently found that the cylinder head used was among the



hardest of the heads purchased for the tests.  It was decided



to test the engine a second time using a cylinder head  at



the softer end of the hardness range of heads available.



Substantial valve seat recession (43-49 thousandths of  an



inch) occurred on two of the valve seats (Appendix 1,  Figure 6).



About one-half of the recession occurred during the 56-hour



steady state portion of the test cycle.

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                            - 18 -






     Further investigation of the cy]inder heads  after the



tests were completed revealed that the hardness of the metal



in the seat area was essentially the same for hoth heads.



Differences in wear in the International  240, therefore,  were



not due to differences in hardness of the valve seats.



Evaluation of the data revealed that the  air/fuel ratio was



much higher during the test that exhibited valve  seat recession



even though the engine was set to the manufacturer's  specifica-



tions (Tahle 2).  The higher air/fuel ratio may have  contributed



to the valve seat recession since a leaner mixture would



cause higher exhaust temperatures.  After the test was completed,



the carburetor was cleaned and the air/fuel ratio returned



to its original level.



     A third unleaded test was performed  on the engine using



exhaust valve seat inserts.  The inserts  were of  about the



same hardness as the valve seats in the first two unleaded



tests on this engine.  Appendix 1, Figure 7 shows that no reces-



sion occurred during the first 80 hours but then occurred very



rapidly.  After 144 hours of variable loads, recession ranged



from 16 to 47 thousandths of an inch and  then rose to 63 to 94



thousandths of an inch during the final 56 hours  of steady



state operation.  The air-fuel ratio did  not rise during this



test.  This test suggests that engines with valve seat inserts



are more susceptible to recession than engines without inserts



when the valve seats are of equal hardness.

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                                  -19-
       Table 2--Average emissions and air-fuel  ratios by  engine
                             and test fuel
   Engine and fuel
00 1/
HC 2/
NOx 3/
Air-
fuel
ratio
                            Percent      ppm         gpm

John Deere B
  1.2 gplg	      5.3       3,303        679
  Unleaded
    Run 1   	      9.3       3,202        202
    Run 2	      6.0       3,605        847

Farmall H
  1.2 gplg	      5.1        3,544       1,008
  Unleaded	      4.2       2,187       1,116

International 240
  1.2 gplg	      5.1        3,133        817
  Unleaded
    Run 1   	      5.7       2,358        925
    Run 2	      2.1        1,338       1,380
    Inserts	      4.6       2,022         NA
  0.1 gplg
    No inserts	      6.3       2,606        868
    Inserts	      5.6       2,104         NA

John Deere 303 CID
  1.2 gplg	      4.9       3,610       1,212
  Unleaded                    4.6       1,951        1,305
  0.1 gplg	      6.3       2,612        738
  DuPont additive 4/ .  .      5.2       2,033         NA
  Standard "PowerShield"
   additive _5/	      7.3       2,482         NA

Ford 8N
  Unleaded	      5.5       2,933         NA

GM 454 CID
  1.2 gplg	      2.0       1,726       1,950
  Unleaded
    No inserts	      2.5         930       1,802
    Steel  inserts  ...      3.4        813         NA
  0.1 gplg	      2.5        1,090       1,868
  Standard "PowerShield"
    additive 5/  .  . .  .      3.0         891          NA
                                    13.0

                                    10.9
                                    12.2
                                    13.0
                                    13.4
                                    12.7

                                    12.5
                                    14.3
                                    12.9

                                    12.3
                                    12.5
                                    12.7
                                    13.0
                                    12.2
                                    12.7

                                    11.8
                                    12.5
                                    14.0

                                    13.8
                                    13.4
                                    13.9

                                    13.6
                                                           Continued--

-------
                                   -20-
         Table 2--Average anmissions and air-fuel ratios by engine
                         and test fuel—continued
   Engine and fuel
00 1/
HC 21
NOx 3/
Air-
fuel
ratio
                               Percent      ppm

GM 292 CID, engine A
  1.2 gplg	       3.8       2,356
  Unleaded	       4.3       1 ,006
  0.1 gplg
    Run 1   	       3.0       1,597
    Run 2	       3.9       1,182
  aiPont additive 4/             3.8       1,054
  Standard "PowerShield"
    additive 5_/	       2.7       1,205

GM 292 CID, engine B
  Unleaded
    IHCI 6/	       3.9       1,436
    Lighter load 7/  ...       3.9       1,222
  0.1 gplg	       5.2       1,416
  Concentrated "PowerShield"
    additive 8/	       4.9       2,865
                       1,339
                       1,119

                       1,696
                          NA
                          NA

                       1,924
                       1,398
                          NA
                          NA

                          NA
                        13.4
                        13.1

                        13.7
                        13.2
                        13.3

                        13.6
                        13.1
                        13.2
                        12.7

                        12.7
  J_/  Carbon monoxide.
  2/  Hydrocarbons.
  7/  Nitrogen oxides.
  4_/  200 pounds of additive per 1,000 barrels of gasoline.
  5/  250 pounds of additive per 1,000 barrels of gasoline.
  ][/  Induction-hardened cast iron exhaust valve seats.
  7J  Engine was run without the 3,600 rpm part of the duty cycle.
  EV  1 ,000 pounds of additive per 1 ,000 barrels of gasoline.

-------
                            - 21 -






     Valve train inspection data show that exhaust valve



guide wear was up to 2.2 thousandths of an inch without



inserts and up to 3.7 thousandths of an inch with inserts



compared to a maximum of 0.9 thousandths of an inch with



leaded fuel and no inserts.



     5.  Tested with ordinary cast iron valve seat inserts,



the Ford 8N had up to 17 thousandths of an inch of valve seat



recession after 144 hours, and 17 to 29 thousandths of an inch



of recession after 200 hours, a significant amount of wear



(Appendix 1, Figure 8).



     Two cylinders may have had ahove-normal valve guide wear



based on comparisons with the leaded fuel  tests on the other



engines (the Ford 8N does not have a leaded-fuel baseline test



since none of the original engines tested  showed appreciable



wear with this fuel).



     6.  The GM 292-A CID truck engine, when tested on unleaded



fuel with ordinary cast iron valve seats,  experienced the



highest rate of recession (Table 1  and Appendix 1, Figure 9).



In fact, the test had to be terminated after 71 hours due to



fear that the engine would be severely damaged by excessive



valve seat recession.  Exhaust valve guide wear increased



but not substantially more than found in the leaded test.



     A duplicate engine, GM 292-B,  was tested with the harshest



portion of the duty cyclo (3600 rpm) deleted.  The wear rate



was reduced by 40 percent, but the test still had to be



terminated after 88 hours due to excessive valve seat recession

-------
                            - 22 -






(Appendix 1,  Figure 10).   Subsequently,  the GM 292-B engine



was tested with induction-hardened cast  iron exhaust valve



seats, and experienced 11  thousandths of an inch of recession



after 200 hours (Appendix 1,  Figure 11).  However,  there was



a greater change in exhaust valve guide  diameter (a maximum



of 4 thousandths of an inch versus 1.8 thousandths  of an



inch for leaded fuel)  during this test.   Valve length was



reduced by up to 8 thousandths of an inch compared  to increases



of up to 4 thousandths of an inch for leaded fuel.



     7.  The GM 454 recreational vehicle engine was tested



with induction-hardened cast iron valve  seats.  All cylinders



showed significant recession, ranging from 14 to 30 thousandths



of an inch after 144 hours.  Total recession increased slightly



to a maximum of 34 thousandths of an inch after the steady



state portion of the test (Appendix 1, Figure 12).   The



induction hardening process for the GM 454 affects  the valve



seats to a depth of about 50 thousandths of an inch.  Rapid



wear would be expected after the induction-hardened portion



of the valve seat is worn away.  Exhaust valve guide wear



increased from a maximum of 1 thousandths of an inch using



leaded fuel to 4.6 thousandths of an inch while operating



on unleaded fuel.



     A second test on unleaded fuel was conducted using soft



steel "XB" valve seat inserts (Rockwell  C scale value of 42)



designed for moderate-duty use.  This test also showed valve



seat recession but it was much less; 17 thousandths of an inch

-------
                            -  23  -





after 144 hours with little recession during the final steady



state portion of the test (Appendix 1, Figure 13).  Maximum



exhaust valve guide wear of 1.7 thousandths of an inch occurred



compared to 1 thousandths of an inch on leaded fuel.



     8.  Summary of Results on Unleaded Gasoline.



     Engines operated at low speeds (e.g., John Deere B,




rated at 1250 rpm; and Farmall H, rated at 1650 rpm) should



have little or no problem operating on unleaded gasoline,



regardless of the type of valve seat material.  Engines



which operate at medium rpm (e.g.,  International 240 and



Ford 8N rated at 2000 rpm) are likely to experience significant



valve seat recession unless they are used only for light-duty



tasks or have hard steel valve seat inserts.  Engines operated



under heavy-duty steady state conditions may experience 2-4



times more recession than engines operated under a wider range



of load conditions.



     Farm equipment engines operating at higher speeds (e.g.,



John Deere 303 CID, rated at 2500 rpm) which have ordinary



cast iron valve seats probably will experience considerable



valve seat recession.  Based on the tests of the GM 292 and



GM 454 CID engines, we concluded that automotive-type engines



of the type tested, when operated under conditions represented



by the duty cycles used in these tests, are extremely suscept-



ible to valve seat recession when they have ordinary cast



iron valve seats.  Furthermore, the tests on the GM 454



showed that engines could experience considerable recession

-------
                            - 24 -






even if they are equipped with induction-hardened cast iron



valve seats which are still being installed in new vehicles.



Based on tests of the GM 454, soft steel inserts also are



vulnerable with unleaded fuel although wear rates appear to



be lower than for induction-hardened cast iron seats.  Unleaded



gasoline also increases valve guide wear and may increase



valve stem wear.



     Factors other than the lead content of fuel also affect



valve seat recession, probably because of heat differences.



Higher air/fuel ratios appear to increase valve seat recession.



Engines with valve seat inserts appear to be more susceptible



to valve seat recession than engines with equally hard integral



cylinder head seats.  The use of valve rotators also may



increase recession.






  C.  Tests of Low-lead Gasoline (0.1 gplg)



     Four of the original six engines showed significant



recession on unleaded gasoline and, therefore, were tested



on gasoline containing 0.1 gplg.  The John Deere 303, the



International 240 (with and without valve seat inserts) and



the GM 454 engines all operated satisfactorily on 0.1 gplg



(Table 1 and Appendix 1, Figures 14, 15, 16, and 17).



     Other parameters measured showed no changes for the



International 240.   Compared to leaded fuel, maximum valve



guide wear increased from 1.0 thousandths of an inch to 2.0



thousandths of an inch in the GM 454 and from 0.2 thousandths



on an inch to 1.2 thousandths of an inch in the John Deere 303.

-------
                            - 25 -


     The GM 292-A experienced significant recession after

91 hours (Appendix 1, Figure 18).  Since the head gasket failed

at about that time, and may have contributed to the valve

seat recession, it was decided to retest the GM 292-A engine

and the duplicate GM 292-B, engine on this fuel.£/ One of

the engines showed no increase in wear compared to the leaded

test.  The other engine showed slightly more recession in

one cylinder.  Overall, little recession occurred in these

subsequent tests (Appendix 1, Figures 19 and 20).  Under

good operating conditions, most farm engines probably will

experience little or no valve seat wear using 0.1 gplg gasoline.

     However, 0.1  gplg appears to be at or near the minimum

level needed by most of these engines when they are properly

maintained and operated under conditions similar to the duty

cycles tested, unless other forms of valve seat protection

are used (such as  non-lead additives or more wear-resistant

seat materials).

     The technical specialists who worked on this study

believe that excessive heat may contribute significantly to

valve seat recession.  The head gasket failure and differences

in air/fuel ratios observed in this study are two of many
     £/The exact time that the gasket failure started to
occur is not known because it did not cause an abrupt change
in the engine's behavior or in the performance measures being
monitored, such as power,  engine temperature and emissions.
One of the consultants on  the project (Dr.  Ralph Fleming)
examined the test data and engine characteristics to determine
if the gasket failure caused the recession, and reported that
a conclusive determination could not be made.

-------
                            - 26 -


factors that could cause excessive heat that may not  be

detected by operators in everyday engine operations.   An

improperly maintained engine might experience excessive

valve seat recession even when high concentrations of lead

are in the gasoline, but good engine maintenance is especially

important when using gasoline containing only 0.1  gplg or less

of lead.


  D.  Tests of Non-lead Additives^/

     Two proprietary additives were evaluated in the  test

program.jV  An additive manufactured by Lubrizol Corporation

(Lubrizol) was tested on the John Deere 303, GM 454 and GM

292 A and B engines.  The second additive,  produced by E.I.

duPont de Nemours and Company (DuPont), was evaluated on the

GM 292-A and the John Deere 303 engines.

     Table 3 and Appendix 1, Figures 21-25, summarize the

rates of exhaust valve seat recession found while operating

the engines on the Lubrizol and DuPont  additives.

  1.  Test Results Using the Lubrizol Additive

     Three formulations of the Lubrizol additive were tested.
     ^/Products containing tetraethyl lead to be added by the
consumers were not evaluated because we would expect the same
results as with the leaded-fuel tests that were conducted.

     ^/Additives were selected for testing in this program if
the manufacturers indicated to EPA a desire to have their pro-
ducts tested and they provided data to EPA which showed that
their products had the potential for reducing valve seat
recession when used with unleaded gasoline.

-------
-27-









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-------
The first, a modified version of a product Lubrizol  sells



under the trade name "PowerShield" had little effect on valve



seat recession.  Lubrizol, subsequently,  notified NIPER that



the product had not been properly formulated and asked that



"PowerShield" be tested.  "PowerShield" was tested at the manu-



facturer's recommended concentration of 250 pounds per 1,000



barrels of gasoline*  For the GM 454, recession was  about



comparable to that found using 1.2 gplg and 0.1 gplg.  However,



compared to unleaded gasoline, "PowerShield" slightly reduced



but did not stop wear in the other two engines tested



(John Deere 303 and GM 292-A) (Table 3 and Appendix 1, Figures



21, 22, and 23).  Valve guide wear was above normal  with



"PowerShield" (based on the test using 1 ..2 gplg gasoline) in



the John Deere 303 (3.3 thousandths of an inch compared to



0.2 thousandths of an inch with leaded).



     "PowerShield" was tested in one engine (GM 292-B) at a



concentration of 1,000 pounds of additive per 1,000 barrels



of gasoline (four times the level normally recommended for



the product).  Valve seat recession was stopped (Appendix 1,



Figure 24).  Valve stem wear was slightly greater than was



observed for both leaded and unleaded gasolines.



     The "PowerShield" additive caused deposits to form in



the combustion chamber of the engines.  Engine deposits



increased when the "PowerShield" concentration was quadrupled.



Combustion chamber deposits can increase an engine's octane



requirement, but it is not clear from this testing whether

-------
                            - 29 -


the deposits seen would significantly alter octane requirements

or have any other effects on the engines.

     "PowerShield" at the 250 pounds of additive per 1,000
                          y
barrels of gasoline also caused oily black deposits to form

on intake runners, but the implications, if any, are not

known.  This occurred in both the GM 292-A and John Deero 303

engines and to a lesser extent in the GM 454.

     Examination of lubricating oils revealed substantially

higher levels of sodium in the oil after running the engines

on "PowerShield."  Two of the engines also had elevated

levels of phosphorus and the engine that ran on "PowerShield"

at 1,000 pounds of additive per 1,000 barrels of gasoline had

much larger quantities of sulfur in the oil.


  2.  Test Results Using the DuPont Additive

     Two engines (John Deere 303 and GM 292-A) were tested on

the DuPont additive at about twice the concentration normally

recommended by the manufacturer.  The test on the John Deere

303 was terminated after only 48 hours due to a problem with

the engine's cooling system.  At that point, essentially no

valve seat recession was occurring.  However, 48 hours was

not long enough to yield meaningful results.

     The DuPont additive reduced valve seat recession in the

GM 292-A engine, although,  at 22 thousandths of: an inch per

100 hours, wear was st 11 excessive (Table 3, and Appendix 1,

Figure 25).   The additive caused deposits to form in the

ongine.   A large amount  of  hard,  sticky deposits was found on

-------
                             -30-






th e intake valves.  One intake valve was unable to close



completely and was beginning to burn.  Inside the combustion



chamber, a glaze deposit had formed on valve surfaces.   The



full implications of these deposits, including the potential



for eliminating them,  are not known.



     Examination of the lubricating oils revealed substantially



higher levels of phosphorus after running engines on the



DuPont additive.






  3.  Summary of Additive Testing



     The DuPont additive, at about twice the concentraton



normally recommended by the manufacturer, provided some degree



of protection against  valve seat recession.  At the manufac-



turers recommended concentration, Lubrizol's "PowerShield"



reduced recession.  At four times the concentration normally



recommended by the manufacturer, Lubrizol's "PowerShield"



stopped recession in the one engine tested.  Both additives



produced engine deposits which raised unanswered questions.



The DuPont additive increased the amount of phosphorus  in the



lubricating oil.  "PowerShield" also increased the amount



of sodium, sulfur, and phosphorus found in the lubricating



oils.  Nevertheless, although further product development



work is essential, the additives may have potential as  sub-



stitutes for lead.

-------
                             -31-






V.  Results of the Farm Engine-Use Survey and Cylinder Head Survey



     The National Agricultural Statistics Service, USDA



conducted a survey of farmers to learn how many gasoline-



powered tractors, combines, and large trucks are in use on



farms and how much they are used.  The survey was conducted



in July 1986.  The questionnaire is in Appendix 5.  (See



Appendix 6 for information on how to obtain a copy of the



manual that accompanied the questionnaire.)



     At that time, farmers operated a total of 4.4 million



tractors, of which 1.8 million were gasoline powered and 2.6



million were diesel powered.  The gasoline-powered tractors,



which average 26 years of age, were used an average of 250



hours in 1985.  The amount of use varies with the size of



the tractor (Table 4).  Further, tractors with low annual



hours of operation tend to see more light duty use (Table 5)



than tractors that are used more.



     About 42 percent of gasoline-powered farm tractors are



used exclusively in light duty tasks and, therefore, have



little risk of valve seat recession if operated on unleaded



gasoline.  The other 58 percent of tractors see some medium



and heavy uses which potentially make them vulnerable to



excessive valve seat wear if fueled with unleaded gasoline,



unless they are low-rpm engines, have hardened exhaust valve



seats, or are protected by a fuel additive.

-------
                     -32-
Table 4--Distribution of gasoline-powered



 tractors by size and hours of use,  1985
Annual
hours of use
20-49
50-99
1 00-149
150-249
250-499
500-749
750-1499
1 ,500 or more
All tractors
Number of tractors
213,784
324,146
321 ,520
350,372
303,857
141 ,992
84,884
33,160
1 ,773,715
Average horsepower
31
34
38
43
46
49
49
54
40

-------
                          -33-
Table 5--Annual  use of gasoline-powered  tractors,  1985
Annual
hours
of use
20-49
50-99
100-149
150-249
250-499
500-749
750-1 ,499
1 ,500 or more
All tractors
Percentage distribution of use
Irrigation
pumping
0.35
0.05
0.44
0.42
0.17
0.41
0.27
0.16
0.29
Hard
use
8.61
9.15
9.99
12.26
14.37
16.80
18.72
23.00
12.08
Medium
use
25.48
30.08
33.92
34.29
36.77
40.45
43.22
43.54
33.91
Light
use
65.55
60.71
55.64
53.03
48.68
42.34
37.79
33.31
53.72

-------
                             -34-






     Farmers operate 271,000 gasoline-powered combines that




average 19 years of age.   On average, each combine harvested




220 acres of grain in 1985.  Combines, like tractors, see a




skewed use distribution (Table 6).  All combine engines




receive hard use and are  likely to experience excessive




valve seat recession if they have cast iron valve seats and




are operated on unleaded  gasoline.




     About 750,000 gasoline-powered trucks larger than 1-ton




capacity are used on tarms.  They average 19 years of age




and were driven an average of 3,800 miles in 1985.  Over




half of the trucks were driven less than 2,000 miles (Table 7).




Trucks receive a range of light to hard uses.  Data are not




available that would more precisely characterize this use




although, on average, it  is thought to be represented by




the duty cycle specified  for the tests conducted by NIPER.




      The Radian Corporation conducted a survey of tractor




dismantling operations to determine the type of material  in




tractors' valve seats.  (See Appendix 6 for information on how




to obtain a copy of the protocol and quality assurance plan




for this survey.)  An eddy-current test *ias used to identify




stellite valve seats and  steel/cast iron seats.  A chemical




test (for the presence of chromium) was then used to distin-




guish between valve seats made of steel and cast iron.  Data




were obtained from eight  establishments located throughout




the United States.  This survey is subject to large sampling




and measurement errors and the data have not been fully

-------
                           -35-
   Table 6--Distribution of number of gasoline-powered



       combines by number of acres harvested,  1985
Number of acres harvested
Number of combines
        1-99



      100-199



      200-299



      300-399



      400-499



      500-999



    1,000 or more



    All combines
     101,641



      69,159



      32,418



      24,446



      13,793



      22,594



       6,294



     270,345

-------
          Table 7--Annual  miles  of  farm  trucks

         larger than 1  ton rated capacity,  1985
   Total annual
   miles driven
Number of trucks
     0-1,000

 1,001-2,000

 2,001-3,000

 3,001-4,000

 4,001-5,000

 5,001-10,000

10,001-20,000

20,001 or more

All trucks
     254,805

     145,783

      81,896

      42,568

      74,053

      96,361

      32,341

       5,955

     733,762

-------
                             -37-





examined at this time.  A preliminary analysis suggests that



33 percent of all gasoline-powered tractors may have hard



valve seat inserts.  These would not be vulnerable to valve



seat recession with unleaded gasoline.  The remaining 67



percent of the tractors have cast iron inserts or have seats



that were machined into the cast iron heads.  These tractors



are potentially vulnerable to valve seat recession with



unleaded fuel if the engines are operated under medium-duty



and/or heavy-duty conditions.



     While hundreds of thousands gasoline-powered engines on



tractors, combines, trucks and other large farm equipment



face no risk of damage if fueled with unleaded gasoline,



hundreds of thousands of others need lead or an effective



substitute if they are to continue in their present uses



without needing an engine overhaul.

-------
                  -38-
               Appendix 1



Exhaust Valve Seat Recession by Cylinder

-------
                                  -39-
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               -64-
            Appendix 2



    Consultants Evaluations of



Engine Testing Performed by NIPER

-------
                                   -65-
          Ralph D. Fleming
          Consultant
           17506 Clinton Driye
          Accokeek,  Maryland 2O6O7
          (301) 283-6520
                                          Energy. Fuels and Engine Consulting Services
                                                                 March 2, 1987
Mr. Richard G. Kozlowski
Director, Field Operations and Support Division
EN-397F
U. S. Environmental Protection Agency
Washington, DC 20460

Dear Mr. Kozlowski:

     The purpose  of  this letter  is  to provide  comments on  the  testing  program
involving agricultural  engines  that  was  conducted by the  National  Institute for
Petroleum  and Energy Research (NIPER) at Bartlesville, Oklahoma.  The final report
resulting from that study is entitled "Effect of  Low Levels of  Lead and Alternative
Additives to Lead on Engines Designed to Operate on Leaded Gasoline".  In order to put
my comments into perspective, some background  information on the overall study will
be given.
Background
     During the latter part of Calendar Year 1985, a proposed test plan was developed
by  the  Environmental  Protection Agency  (EPA)  in  cooperation  with the  U. S.
Department of Agriculture (USDA). That test plan was reviewed and commented on in
December  1985  by representatives from various engine manufacturers, universities,
government agencies, organizations  representing the farmers  and  other  interested
parties. An EPA/USDA meeting was held in January 1986 with members of the various
reviewing groups  to discuss the development of the testing program.  The contractor
was under contract to do the work by early summer of 1986 and actual engine testing
was begun  in June 1986.  The draft  final  report was delivered to EPA for review in
January 1987.
     Because of  a variety of  different equipment configurations ranging from two to
eight cylinder engines, laboratory modifications  were necessary to accommodate the
various  engines.    Some engines required  pressurized cooling systems, while others
operated at atmospheric pressure.  Some older engines used in the study had carburetor
systems  that  were inherent y poor in their ability  to control  air—fuel ratios.
Procedures for determining valve seat hardness and  recession during the accumulations
had to be developed by the contractor.

-------
                                    -66-
     Severai  factors unrelated to the fuels being tested, resulted  in setbacks of the
experimental  schedule.    They  included:   failures  of  dynamometer  equipment-
mechanical failures of  engines; and an unusual amount of rainfall in the vicinity of the
contractor site which flooded the laboratory-
Performance of Contractor
     The contractor has done an excellent job in conducting the testing program and
executing th« various tasks on a  reasonable time schedule, considering  the short lead
time for setting up the experiments and the many setbacks that were beyond the
contractor's  control.   The  quality of the  data is as good  as could be  expected,
considering the limitations on the  budget  and  the  number  of eng>nes available for
testing.   The methods developed for  determining valve seat  hardness and recession
dunng the accumulation of hours were adequate for the purposes  of the study.   The
valve seat recession  measurements taken during the accumulation  of  hours were
backed-up by bench inspections of the cylinder heads.  The bench measurements were
mads beforp  the start of the accumulation  of hours on the engines  and  after  the
completion of each test by an independent certified automotive mechanic.  This was an
excellent method tor  confirming the accuracy of valve seat recession measurements
because  the  two separate  measurements were  made  totally  independent from  each
other.

     The testing program  was well conceived with  a  representative cross section of
engine types  being  incorporated into the testing.  The chosen engine duty cycles were
good in that they served to show valve seat recession as a function of fuel type for some
engines, while other engines  showed no valve seat recession with any of the fuels.  !n
general, the  contractor performed  well  in executing the experimental  testing in a
timely fashion and produced a technical report that provides useful data on the effect of
gasoline lead levels and alternative additives to  lead on valve seat recession in engines
that  were originally  designed  for  leaded  gasoline.  However, at no fault of  the
contractor, EPA or USDA (because of budget constraints), it would have been helpful to
have had more engines in the testing program.  This aspect will be discussed further in
the following section.
Adequacy of the Test Data
     The data from the program are adequate for the purposes of  the study with the
exception of  two areas. One area relates to the question of whether or not lead at 0.10
gram per gallon in gasoline  is adequate to prevent  valve seat recession in all of the
engines tested. The Ford  8N engine was not tested on 0.10 gram per gallon leaded
gasoline, therefore, no data are available to determine if 0.10 gram per gallon leaded
gasoline would prevent valve seat recession in this engine.  The GM 292 engine showed
significant valve seat recession in one cylinder  with 0.10 gram per gallon leaded
gasoline. Because a head gasket failure occurred mid-way through the accumulation of
hours on this first test, the engine was rebuilt and retested and 10 thousands of an inch
recession was noted for one valve seat. A duplicate GM 292 engjne was tested later in
the program with no observed valve seat recession.  Although a head gasket failure
occurred In  the  first test,  the  engine was repaired  at 120 hours and the test was
continued to  200  hours.    Valve seat recession continued after the  head  gasket
replacement at 120 hours. Although the rate of valve seat recession was lower after

-------
                                    -67-

the head gasket replacement  than that just prior to the head gasket failure, there
appears to be no basis for throwing out  this test result.  The overall results from the
GM 292 engine tests for 0.10 gram per gallon leaded gasoline are mixed.   Further
engine testing  is required to determine whether or not 0.10 gram per gallon leaded
gasoline will provide adequate protection against valve seat recession  in the GM 292
engine.
     The second area which needs further study is alternative additives.  One additive
(additive "D")  tested in the current program showed good results when blended at a
concentration of 1,000 pounds of additive to 1,000 barrels of gasoline. However, the
lubricating  oil wear metals analyses  for  the additive "D" test  showed increased
concentrations of iron,  chrome, sodium  and molybdenum when compared to other fuel
tests  with the  same GM 292 engine.  These results indicate the need for longer term
engine durability testing with the additive to determine any adverse effects on the
engine such  as  deposit formation in the engine or  increased wear. Since the additive
contains sodium and possibly other metallic elements, an assessment should be made to
determine if the use of the additive might result in potential degradation of air quality.
Recommendations for Future Work
     Should additional  engine testing  be  considered  in  the future,  I suggest  that
additional studies be done on alternative  additives as a method for preventing valve seat
recession.   In  addition to  identifying additives that  successfully prevent valve seat
recession, once an  additive  has  been shown to be  effective, further  work would be
needed to determine any detrimental effects the additives might have on the engine.
      If further testing  is done, I  recommend that a larger number of engines be tested
to account  for engine-to-engine, test-to-test, and day-to-day variability.   In
addition, changes in uncontrolled engine  variables such as air-fuel ratio may influence
valve seat recession.  The  experimental tests just completed indicate that a larger
number of engines is required to give conclusive results.
     An  example  illustrating  the need  for  a  larger number of  engines  is  the
International  Harvester 240 engine  used in the current study.  The first test with
unleaded gasoline showed no valve seat recession.  A repeat test with a slightly softer
cylinder head showed exhaust valve seat  recession in two cylinders. At this point,  one
might conclude that the softer  cylinder head was responsible for the   valve seat
recession in the repeat test.   However,  subsequent inspections to  determine  the
hardness of  the cylinder head material near  the individual valve seats indicated that the
observed valve seat recession in the repeat test probably was  not due to differences in
hardness between the two cylinder heads. It was also noted that the engine's air-fuel
ratio (uncontrolled variable) was significantly leaner for the repeat  test which could
have contributed to increased valve recession. A third test was run on this engine using
unleaded gasoline with cast  iron valve seat inserts which resulted in exhaust valve seat
recession in all of the cylinders.  In the third test, the average daily air—fuel ratio was
similar to the  first test. The variation  in test results for a given system suggests  the
need for replicate testing for each engine/fuel combination in the testing program.
      It is recognized that  it is  impractical to run every engine type in the overall
population.  However,  once a given  set of  engines is selected for testing, replicate
testing of each engine setup  and fuel is highly desirable.  In many cases, it is impractical
to run enough engines and tests to provide statistically significant results.  However, a

-------
                                   -68-

compromise situation may be appropriate for  providing a basis for good engineering
judgments.  For a test program such as the one just completed,  three tests is the
minimum number  of replicates  which would give reasonable confidence in the data.
This could be done in two different ways. One  way would be to repeat the same test
three times on the same engine.  The second way would be to run three identical engines
simultaneously.   Should  further  testing  be  considered in  the  future,  I  strongly
recommend that replicate testing be done to increase confidence in the resulting data.
     One way to reduce test-to-test and day-to-day variability, and possibly reduce
the number of engine tests required to provide conclusive results, is to control air-fuel
ratio.  First,  one would have to determine the normal operating air-fuel ratio for each
operating mode and the variation  of air-fuel ratio within each mode for  each given
engine.  Then the air—fuel ratio  would be controlled (by means of a special  laboratory
apparatus) at  its "average" value throughout the accumulation of hours on each test.
The air-fuel ratio would be controlled at a different value for each operating mode
corresponding to the normal air—fuel ratio characteristics of the engine.
     Since most of the engines tested showed a problem with valve seat recession  on
unleaded fuel  an assessment  should be made to compare the  relative cost and
practicality  of  retrofitting  cylinder heads  with hardened  valve  seats to  using
alternative additives or using D.10 gram per gallon gasoline.  This assessment should
take into account the total number of engines in the field, the number of engines that
have potential for a valve seat recession problem, etc.
Summary
     In  summary,  the  contractor  has  done  an  excellent  job  in  conducting the
experimental  work and completing the project  in a reasonable time frame. The data
from this program are of significant value and should be published in a form such that
anyone in the public domain can obtain a copy of the report. In addition, the contractor
should be encouraged to  publish the  results of the study in an engineering society
technical paper.   Should any future testing  be contemplated, I recommend that
additional work be done on alternative additives to lead. An assessment should be done
to determine the  cost and practicality of retrofitting cylinder heads with hardened
valve seats.  Also, replicate engine tests should be considered to better account for
test-to-test variability.
Should there  be any questions about these comments, please do not hesitate to give me
a call.
                                              Sincerely,
                                              Ralp'h D.Fleming          '
                                              Consultant
 CC:
 Jerry Allsup, NIPtR
 John Garbak, EPA
 Gerald Grinnell, USDA

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                           -69-

                             REPORT

Assess.ment of the testing p_ro.gram conducted  by  NJ,PER on selected
                       gasp]. ine engines...

                       Louis I. Leviticus
                Nebraska Tractor Testing Laboratory.
March 25, 1987.

1.  1 want to compliment NIPER,  and  in  particular  Mr.  All sup and
his staff, for a job well done under  severe  time  constraints.  The
work  was  carried out with competence and   integrity.   The  only
criticism  I  have  is  the fact that the oil   analysis  was  not
carried out exactly as in the original plan  of  work.

2. One of the great limitations of this  project has been the fact
that  not enough engines of each type could  be  evaluated.   It.  is
guite  clear  from the hardness  measurements   that  considerable
variation exists between heads.  This variation may be  the result
of manufacturing processes or may be  due to  different sources for
the  heads  or  inserts used.  Hence,  tests of  the statistical
significance cannot be applied in this study.

3.  Although  the  results  obtained  may  be   debatable  from  a
statistical significance viewpoint,   they nevertheless  provide  a
good  insight  into  the problems encountered when   operating  an
engine,  designed for leaded fuel use,   on unleaded fuel  and with
addi t i ves.

4.  In  general,  the  results tend to show  that  the  combustion
chamber temperature may be a major contributor  to the  phenomenon
of  recession  of valve seats below a certain   critical   hardness
value.  Higher combustion chamber temperatures  can  occur due to a
variety of reasons:
  a.  High loads.
  b.  Inadequate cooling  (dirty radiator, si i piping  belts,  blocked
      passageways in the engine etc.).
  c: .  Lean fuel mixtures  (High A/F ratio).
  d.  Ignition problems  (Timing, Fouled  spark plugs).
  e.  Carbon or other deposits in the combustion  chamber.

5.  It cannot be determined with certainty from the data what the
critical seat  hardness is.  This would  seem to  depend   upon, the
engine  characteristics and,  possibly,  on  the way the  engine is
used and maintained.
6.  Engine speed may not be a factor by  i tsel-f-p-bu^-f coupled  with
a high load and/or a 'Jean mixture an increase  in  engine  speed may
lead to earlier recession.  This is a  judgement call.  The  study
was  designed  to simulate the operation  of engines  under   normal
conditions.    It  accomplishes  that   purpose.  However,  several
guest ions  remain  unanswered  concerning  what   exactly    causes
recessi on .

-------
                            -70-

7.   The results tend to show that  ai  0,1  gplg none of the engines
s u f i e r • e d  f r o m e x c: e B s r e c e s s i o n .   A  d e f i n i t e c o n c:: 11.i s :i c1) n c: a n n o t b t?
reached  however  since  one of  the  engines  did  show  excessive
recess:! on  after  head gasket failure.   Si nee the  test  did  not
examine  the harshest possible  operating  conditions,  one  cannot
conclude  that  0.1  qp] g   will  protect.   all  engines  under  all
operating conditions.

8.  The data from the additive tests,  limited as they were, do not
warrant their recommendation,at  this stage,  as a replacement for
lead. This conclusion is based  on  the following reasons:*
  a.  It  appears that there is,   as yet,  uncertainty about the
      correct cocentration  of some of the additives.  I may point
      out  that.  it  is possible  that   different  engines  might
      reguire different concentrations  of an additive.
  b.  The recommended concentrations, for the additives tes-
      ted, showed that, the  engines were not completely protected
      against recession.
  c,,  An examination of the effect of the additives on emissions
      was inconclusive.
  d«  The oil analysis showed that when additives were used, the
      Sodium content usually increased  drastically.  The sodium is
      apparently  introduced  to the oil   through  the  additive.
      Since  the formulation of  the  additives is proprietary  the
      composition of the compound  in which sodium occurs is not
      known.
  e.  The  oil and exhaust  gas  analysis did not include checking
      for  sulphur compounds.   Sulphur  in the exhaust  qases  can
      cause damage1 +o the engine and exhaust parts since they are
      mixed with Hydrocarbons and  water  vapor and may form acids;
      the  sulphur  compounds   in  the  0.1 3  cart  cause  damage  in
      certain engines since they attack  certain metal compounds,,
       It  is very difficult to  determine which engines  would  be
      affected, since this  depends upon;
      .» Engine combustion characteristics, which can vary with
        engine design and operating  conditions.
      .„ Different  oils  contain different additives  which  may
        react differently with  sulphur  compounds.
      .. Metal alloys used in the engine.  There are examples of
        manufacturers warning the  users against certain oils,
        c o n t. aim n g  a  m o 1 y b d e n u m  c o m p o u n d ,   w h i c h  release s  a
        sulphur compound in the oil.  This compound then combines
        wit h  w a t e r  to  c r • e a t e a n a c id,   w h i c h  a 11 a c k s  c. e r't a i n
        alloys used.
   f „   The  nature  of   the  deposit;;::   found  and  their  long-term
       influence on the engine were not  determined.
   g.   The only fuel additive combination, which did not cause re-
       cession was tested on one engine  only,

 9.  Re c o m m e n d a t i o n s f o r  f u t u r e t e s t .1 n g ,
 The  additives should be tested  and evaluated -further in order to:
   a,,   Determine the correct concentrat. i on (s> to be used.
   b.   Investigate whether the concentrations should differ for
       different engine  makes.
   c.   Determine  the composition of  the exhaust gases and  their

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                         -71-

    influence, i -f  any, on the various engine components.
d.   Determine the influence on the composition of engine oils
    and the influence of- i he compounds on the oil quality  and
    on alloys used in various engines.
                                LouiB I.
                                Nebraska
Testinq Lab

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                             -72-


                          Appendix 3

               Duty Cycles Used in Engine Tests


Duty cycles were developed to represent conditions

normally encountered by farm tractors,  combines and large

trucks, and by recreational vehicles.   Each engine  was  operated

on its specified duty cycle until 200  hours were accumulated

on each test fuel.

                    Tractors and Combines

The duty cycle for  tractor and combine engines consisted of

two parts — an intermittent portion covering 144 hours of

operation and a steady-state portion covering 56 hours.  The

intermittent part is consistent with the duty cycle (SAE J708)

used for many years by the Nebraska Tractor Testing Laboratory

to test the performance of new tractors.  The steady-state

part was selected to represent the maximum continuous load

that is likely to be placed on these engines, such  as pumping

irrigation water.

Intermittent Part--Each engine was run through six  power

settings with the engine speed controlled by the governor per

manufacturers' specifications as follows until 144  hours

were accumulated (16 hours on 8 hours  off per day):

    a.  85% of dynamometer torque obtained at maximum
        power--40 minutes

    b.  Zero dynamometer torque at rated rpm--40 minutes

    c.  42.5% of dynamometer torque obtained at maximum
        power--40 minutes

    d.  Dynamometer torque at maximum power--40 minutes

-------
                             -73-
    e.  21.25% of dynamometer torque obtained at  maximum
        power--40 minutes

    f.  63.75% of dynamometer torque obtained at  maximum
        power--40 minutes

Steady-State Part—Each engine was run at governed speed and

75 percent  of maximum torque around the clock until 56 hours

were accumulated.  After 24 hours, the engines were shut off

for 2 hours for valve seat recession measurements and service

checks.

                         Farm Trucks

The engines were to be operated 16 hours on and 8 hours off

per day on the following duty cycle until 200 hours were

accumulated for each fuel.

    a.  85% of maximum power (available at 3,000  rpm) at
        3,000 rpm--40 minutes

    b.  45% of maximum power (available at 3,000  rpm) at
        3,000 rpm--40 minutes

    c.  45% of maximum power (available at 2,500  rpm) at
        2,500 rpm--40 minutes

    d.  25% of maximum power (available at 2,000  rpm) at
        2,000 rpm--40 minutes

    e.  85% of maximum power (available at 3,600  rpm) at
        3,600 rpm--40 minutes

                    Recreational Vehicles

The recreational vehicle test called for the engine to be on

16 hours and off 8 hours per day until 200 hours  were

accumulated for each fuel.  The engine was operated in both

intermittent and steady-state modes.

-------
                             -74-


Intermittent Part--The engine was  operated  in  six  speed  and

power settings as follows until  144 hours were accumulated:

    a.  85% of maximum power (available at  3,000 rpm)  at
        3,000 rpm--40 minutes

    b.  45% of maximum power (available at  2,000 rpm)  at
        2,000 rpm--40 minutes

    c.  85% of maximum power (available at  3,600 rpm)  at
        3,600 rpm--40 minutes

    d.  45% of maximum power (available at  2,500 rpm)  at
        2,500 rpm--40 minutes

    e.  45% of maximum power (available at  3,000 rpm)  at
        3,000 rpm--40 minutes

    f.  85% of maximum power (available at  2,500 rpm)  at
        2,500 rpm--40 minutes

Steady-State Part — During the steady-state  part of the cycle,

the engine was run at a setting  that produced  100  horsepower

(52 percent of maximum power) at 3,000 rpm  until 56 hours

were accumulated.

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                             -75-






                          Appendix 4



                        Engines Tested



1.  John Deere "B" tractor;  2-cylinder I-head  engine;  rated



    at 24 horsepower at 1,250 revolutions  per  minute (rpm);



    4 11/16" x 5 1/2"  bore and stroke, 190.4 cubic  inch



    displacement (CID).  The engine was originally  equipped



    with ordinary cast iron  cylinder heads with  a hardness of



    9-25 on the Rockwell C scale.  The tractor was  manufactured



    between the 1930s  and 1952.  Similar tractors were manufac-



    tured until about  1960.



2.  Farmall "H" tractor; 4 cylinder I-head engine;  rated  at



    24 horsepower at 1,650 rpm; 3 3/8 x 4  1/4" bore and stroke.



    The engine was originally equipped with "special gray iron"



    valve seat inserts having a hardness of 26-36 on the  Rockwell



    C scale.  The tractor was manufactured between  the 1930s



    and 1953.   Similar tractors were built until  about 1958.



3.  For "8N" tractor;  4-cylinder L-head engine;  rated  at  23



    horesepower at 2,000 rpm; 3 3/16" x 3  3/4" bore and stroke,



    119.7 CID.  The engine was originally  equipped  with valve



    seat inserts having a hardness of 39-43 on the  Rockwell  C



    scale.  The tractor was  manufactured between  1947  and 1952.



4.  International Harvester  240 tractor;  4 cylinders;  rated  at



    27 horsepower at 2,000 rpm; 3 1/8" x 4" bore  and strokes,



    122.7 CID.  The engine was originally  equipped  with an



    ordinary cast iron cylinder head with  a hardness of 12-23



    on the Rockwell C scale.   The tractor  was  manufactured

-------
                             -76-






    between 1958 and 1962.   Similar  tractors  were built  until



    1978.



5.  John Deere 95 303 CID 6-cylinder combine  engine;  rated



    at 80 horsepower at 2,500 rpm.   The engine was originally



    equipped with ordinary cast iron cylinder heads with a



    hardness of 9-25 on the Rockwell C scale.  The engine



    was manufactured between about  1960 and 1974.  A 4-cylinder




    version of this engine also was  used in combines  and



    tractors, and a 3-cylinder version was  used in tractors.



6.  Pre-1974 Chevrolet 292 CID 6-cylinder truck engine;  rated



    at 115 horsepower at 4,000 rpm.   Prior  to 1974, the  engine



    was equipped with ordinary cast  iron cylinder heads. The



    engine is still in production  but now has induction-hardened



    cast iron exhaust valve seats.   The engine also has  been



    used in combines and other agricultural equipment.



7.  Pre-1984 General Motors 454 CID 8-cylinder recreational



    vehicle engine; rated at 210 horsepower at 4,000 rpm.



    The engine has always been manufactured with induction-



    hardened exhaust valve seats.

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            -77-
         Appendix 5



Farm Engine-Use Survey Form

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-------
                             -79-





                          Appendix 6



 How to Order Additional Documents Referred to in this Report





The following documents, referred to in this report,  are



available in EPA docket Number EN-87-03.   Copies may be



obtained by writing to Control Docket Section (LE-131A),



Environmental Protection Agency Gallery 1,  West Tower, 401  M



Street, S.W., Washington,  D.C. 20460.  Telephone (202)



382-7548.  The docket may be inspected between 8 a.m. and



4 p.m. on weekdays.  As provided in 40 CFR  Part 2,  a reason-



able fee may be charged for photocopying.



1.  Effects of Low Levels of Lead and Alternative Additives



    to Lead on Engines Designed to Operate  on Leaded  Gasoline,



    Final Report.  Report by the National  Institute for



    Petroleum and Energy Research (NIPER) on results  of engine



    tests performed for this study (193+ pages).



2.  Statements of work covering work performed by NIPER.



    A.  Effects of Low Levels of Lead and Alternative Additives



        to Lead on Engines Designed to Operate on Leaded Gasoline,



        Covers tests of leaded and unleaded gasoline  performed



        during fiscal year 1986 (10 pages).



    B.  Study of the Effects on Leaded Engines of Alternative



        Additives to Lead.  Covers tests  of non-lead  additives



        performed during fiscal year 1987  (12 pages).



3.  Quality Assurance Project Plan for Engine Testing Work



    Performed by NIPER (23 pages).

-------
                              -80-


4.  Interviewers  Manual  for Gasoline-Powered  Farm Equipment

    Survey.   Survey conducted by the National  Agricultural

    Statistics  Service,  USDA during July  1986  (7 pages).

5.  Survey Protocol and  Quality Assurance Plan for Field

    Measurement of Exhaust Valve Seats  in Gasoline-Powered

    Tractors.   Survey conducted by the  Radian Corporation

    during September 1986 (84 pages).
                  U.S. Environmental Protection Agency
                  Region 5,  Library (5PL-16)
                  230 S. Dearborn Street, fioom 1670
                  Chicago. IL   60604

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