forged piston OIL consumption
11-04-2002, 02:41 PM
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forged piston OIL consumption
Originally posted by rjcardinal
One thing to remember is that the 502 will use more oil than the 7.4 because it has forged pistons. The cast pistons in the 7.4 dont expand as much as the forged pistons of the 502 do. Because of this the piston clearances on a 7.4 is smaller because you dont have to leave room for expansion.
If you think you are having a lean condition with the reprogrammed ecu borrow a stock one and run it. The stock ecu is fairly rich and should be good enough to give you a baseline.
Good luck and post what you find.
Ron
One thing to remember is that the 502 will use more oil than the 7.4 because it has forged pistons. The cast pistons in the 7.4 dont expand as much as the forged pistons of the 502 do. Because of this the piston clearances on a 7.4 is smaller because you dont have to leave room for expansion.
If you think you are having a lean condition with the reprogrammed ecu borrow a stock one and run it. The stock ecu is fairly rich and should be good enough to give you a baseline.
Good luck and post what you find.
Ron
you guys with forged pistons what kind of oil/hr usage are you seeing?
hopefully, i will have forged pistons by spring, so just looking for what i should be expecting come boat’n time.
11-04-2002, 03:48 PM
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I run TRW forged (454 +.030)and my clearances are a little tighter than most recommend (.003-.0035). According to my machine shop, the TRW's dont swell as much as other forged. Ive never hurt one but I dont ask for more than 450hp or so at 5400. I file fit my rings to .021 gap and I dont burn any oil at all.
11-04-2002, 07:19 PM
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I would not expect to see a lot of oil consumption if an engine is built properly with forged pistons. The GM 502's use a low tension oil ring which tends to allow a little more oil by. I usually use a standard tension oil ring and haven't had any oil consumption problems. My personal 555/600hp engine uses at the most a quart in 30 hrs.
11-04-2002, 07:41 PM
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bobl is correct. It's not because they are forged pistons. the 502 Actually use metric rings and thats why they use more oil. on the average it's about 1 quart every 10 hrs, but that can change depending how hard you run.
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11-05-2002, 08:20 AM
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about a quart in the 1st 5 hours during breakin,,
now basically I use a totl of about 1/2 - 3/4 of a one quart bottle to top it up between 25 hour oil changes. They can be built to use oil or not depending on rings/clearances,,my builder reco'ed not unless you were 500++hp and said it was more common to do drag engines that way, less friction=more hp and they don't care about consumption on the<10sec runs
now basically I use a totl of about 1/2 - 3/4 of a one quart bottle to top it up between 25 hour oil changes. They can be built to use oil or not depending on rings/clearances,,my builder reco'ed not unless you were 500++hp and said it was more common to do drag engines that way, less friction=more hp and they don't care about consumption on the<10sec runs
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11-05-2002, 01:44 PM
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1999 502 mag mpi. Not running hard can go 10-15 hrs before using a quart. Run it wide open a couple of times(only for about 45 seconds each time) will usually drop half quart in that one day...
