Factory ring gaps on a forged motor
02-15-2018, 02:06 PM
#1
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Factory ring gaps on a forged motor Trying to get a general idea of how much boost factory ring gaps can tolerate on a forged motor?
Motor Spec:
347 - 3.905 bore
9.5:1
228-332 cam
D-1SC
Motor Spec:
347 - 3.905 bore
9.5:1
228-332 cam
D-1SC
02-15-2018, 09:31 PM
#2
I wouldn't go over say 6-8psi with factory ring gaps
I know I'll get crucified for saying that on here but why destroy good parts if you don't have to
probably open them up to 0.026" top and 0.024" second
that would probably give you enough leeway for 15psi
I know I'll get crucified for saying that on here but why destroy good parts if you don't have to
probably open them up to 0.026" top and 0.024" second
that would probably give you enough leeway for 15psi
02-16-2018, 08:00 AM
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My motor's ring gaps are .0195" top and .0215" bottom. This is per Weiscos recommendation for "street moderate boost" however this is pretty close to the GM factory LS1 gaps (top ring 0.009-0.017 and 2nd ring 0.017-0.027). After speaking with a few engine builders, I'm being told that my gaps are too tight for boost but I see alot of folks boosting stock bottom ends without issue. Here's an apples to oranges comparison but the LS9 factory gaps are the same as the factory LS1 gaps and that seems to be tolerable for the forged pistons in the LS9 @ 10.5lbs of boost. Different beast I know... oil squirters probably aid in keeping piston temps lower.
02-16-2018, 02:20 PM
#6
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And you can bet GM did the R&D to see if it was ok...and have very competent people building and tuning them
Clearly the engine is not built yet...only a fool risks too tight a gap unless they've tested to know for sure it will work, or they are doing the testing.
And all rings are not the same, and all pistons are not the same...so you cannot really compare one against another even if the number variances are very small anyway
Clearly the engine is not built yet...only a fool risks too tight a gap unless they've tested to know for sure it will work, or they are doing the testing.
And all rings are not the same, and all pistons are not the same...so you cannot really compare one against another even if the number variances are very small anyway
02-16-2018, 02:51 PM
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And you can bet GM did the R&D to see if it was ok...and have very competent people building and tuning them
Clearly the engine is not built yet...only a fool risks too tight a gap unless they've tested to know for sure it will work, or they are doing the testing.
And all rings are not the same, and all pistons are not the same...so you cannot really compare one against another even if the number variances are very small anyway
Clearly the engine is not built yet...only a fool risks too tight a gap unless they've tested to know for sure it will work, or they are doing the testing.
And all rings are not the same, and all pistons are not the same...so you cannot really compare one against another even if the number variances are very small anyway
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02-16-2018, 06:58 PM
#9
02-16-2018, 07:25 PM
#10
My motor's ring gaps are .0195" top and .0215" bottom. This is per Weiscos recommendation for "street moderate boost" however this is pretty close to the GM factory LS1 gaps (top ring 0.009-0.017 and 2nd ring 0.017-0.027). After speaking with a few engine builders, I'm being told that my gaps are too tight for boost but I see alot of folks boosting stock bottom ends without issue. Here's an apples to oranges comparison but the LS9 factory gaps are the same as the factory LS1 gaps and that seems to be tolerable for the forged pistons in the LS9 @ 10.5lbs of boost. Different beast I know... oil squirters probably aid in keeping piston temps lower.
I don't know why you think that, but that is not true. If it were, you would have to replace the bearings after torquing them up to check the clearance.
02-17-2018, 05:19 AM
#11
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02-17-2018, 07:05 AM
#12
02-17-2018, 08:08 AM
#14
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02-17-2018, 10:10 AM
#15
02-17-2018, 11:27 AM
#17
welp, that escalated quickly.
OP, my suggestion to open the gaps up are based on my own personal experiences. minimum factory gaps work great when everything goes perfect.
my experience has been murphy's law. a flaw in the tune. a bad tank of gas.
the extra ring gap is just a safe bet with little downside, and I think most experienced FI guys would agree with me.
good luck with your rig. a forged 347 with a blower will be all sorts of awesome!
OP, my suggestion to open the gaps up are based on my own personal experiences. minimum factory gaps work great when everything goes perfect.
my experience has been murphy's law. a flaw in the tune. a bad tank of gas.
the extra ring gap is just a safe bet with little downside, and I think most experienced FI guys would agree with me.
good luck with your rig. a forged 347 with a blower will be all sorts of awesome!
02-17-2018, 01:03 PM
#18
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I could have sworn is was the little retainer tabs in the bearing. Hence the name "retainer tab".
Looks like you've done it wrong 600 times over 20 years.
Just because that's the way you've always done it doesn't make it right.
Looks like you've done it wrong 600 times over 20 years.
Just because that's the way you've always done it doesn't make it right.
02-17-2018, 01:31 PM
#20
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But in no way whatsoever does installing and torquing the bearings up render them unusable. That is just nonsense.