How much do L98 pistons weigh????
02-27-2004, 03:37 PM
#1
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Car: 1988 GTA Notchback
Engine: 5.7 TPI
Transmission: TH-700R4
How much do L98 pistons weigh????
Can anyone tell me how much the -12cc L98 dish pistons weigh including rings and wrist pin???
If anyone has an old one lying around and could weight it, I would REALLY appreciate it.
LOL
If anyone has an old one lying around and could weight it, I would REALLY appreciate it.
LOL
02-28-2004, 07:42 AM
#2
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Car: 1988 GTA Notchback
Engine: 5.7 TPI
Transmission: TH-700R4
Just to clarify......how much do the STOCK L98 -12cc dish pistons weight including rings and pin????
thanx
thanx
02-29-2004, 12:01 AM
#3
After going through some of my balance spreadsheets it appears that average 350 stock cast pistons are about 498 grams. Stock pins are about 218 grams, and stock (new) ring sets are about 14g. Rod/cap assemblies (without bolts) are around 586g. Average entire assemblies go about 1,315g with cap bolts. I apparently remove an average of about 10-12g from the assemblies in the balancing process. Usually, pistons don't require a lot of balance work, and can be mixed and matched with pins to get fairly close "sets". Most of the mass removal is from rod caps and rods.
BTW - I thought L98 pistons were flat tops with four valve reliefs, not dished.
BTW - I thought L98 pistons were flat tops with four valve reliefs, not dished.
02-29-2004, 08:40 AM
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Car: 1988 GTA Notchback
Engine: 5.7 TPI
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Vader,
Thanx for the info.......L98 F-Body pistons have 4 valve reliefs and a circular dish. Total....-12cc (approx).
If you calculate 4.00 bore, 3.48 stroke, .021 shim head gasket, 64cc chambers, -12cc pistons and -.025 deck height you wind up with 9.36:1 compression which is what the factory specs are.
L98 Corvette pistons are also flat top with 4 valve reliefs and have higher compression, but, do not have the dish.
Thanx for the info.......L98 F-Body pistons have 4 valve reliefs and a circular dish. Total....-12cc (approx).
If you calculate 4.00 bore, 3.48 stroke, .021 shim head gasket, 64cc chambers, -12cc pistons and -.025 deck height you wind up with 9.36:1 compression which is what the factory specs are.
L98 Corvette pistons are also flat top with 4 valve reliefs and have higher compression, but, do not have the dish.
02-29-2004, 11:00 AM
#6
Well. After re-reading my first post, the quoted "14g" for a ring set just didn't seem quite right. I went back and looked at my spreadsheets, and apparently was looking at the wrong rows. The "14g" was for the oil ring set ONLY. Stock 4" compression rings are about 19g each, and the total set of new rings (minus the envelope) is 55g. Those are for standard cast 5/64" compression rings and SS 3/16" oil ring set.
The piston mass should be correct, however.
I didn't want to leave any misinformation posted without a correction, just in case anyone ever uses the SEARCH feature.
EDIT: For further reference, stock bearing shells (un-grooved) are 45g and cap bolt/nut sets are 77g.
The piston mass should be correct, however.
I didn't want to leave any misinformation posted without a correction, just in case anyone ever uses the SEARCH feature.
EDIT: For further reference, stock bearing shells (un-grooved) are 45g and cap bolt/nut sets are 77g.
Last edited by Vader; 02-29-2004 at 11:26 AM.
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