QUENCH: How important?
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Launching!
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QUENCH: How important? Still mulling over my build setup. If I use Cometic .040 gaskets, my SCR will be 11.53, and DCR will be 8.96. If I retain the stock MLS GM @.060, my SCR will be 10.95, and DCR 8.52, which I think is safer for use with 92 octane pump gas. Will a Quench of .052 lead to added detonation?
The GM gasket should be .054" minus the .008" the piston is out of the hole, should yeild around .046", which I think is great.
One other thing to remember, detonation is all about cylinder pressure, the better the head flows, the more cylinder pressure it makes and the faster you get into detonation.
One other thing to remember, detonation is all about cylinder pressure, the better the head flows, the more cylinder pressure it makes and the faster you get into detonation.
Your DCR is not 8.96:1. We already decided that 2 weeks ago. If you're still talking about the Crane cam on the 112LSA with no advance, your DCR is in the low to mid 8s. You're either using the wrong numbers at .006" or you're using the wrong calculator.
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2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
Thread Starter
Launching!
Joined: Feb 2006
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Originally Posted by Patrick G
Your DCR is not 8.96:1. We already decided that 2 weeks ago. If you're still talking about the Crane cam on the 112LSA with no advance, your DCR is in the low to mid 8s. You're either using the wrong numbers at .006" or you're using the wrong calculator.
Well, I found out the cam is +5 advance built in, and the dur.@ .006 is 281. So the numbers I listed above were what came out in the calcs. And Brian, when I used search, all the posts indicate the '02+ GM MLS gasket compresses to .060. But please correct me if I'm wrong in any of these assumptions. Thanks, Dave.
I had the same question about the GM MLS gasket so I just mic'd my old one and get around .053"-.055" of compressed thickness on the fire ring. It's not the .060" many people claim.
Originally Posted by DavidNJ
I think there are two issues here: quench and compression. You should be adjusting chamber size and valve pockets to get the right compression, not quench.
If the cam spec's out at .050" around 230, then your VEs are good with 2 degrees of advance. If you retard the cam to a 110 ICL and use the .040" Cometics, it comes out to SCR of 11.53:1 and DCR of 8.73.1. That works on 93 octane. The alternative is to install on a 109 ICL and run a .045" Cometic, but the DCR is still 8.69:1, which I think is too high for a quench area of .037". DCR of 8.73:1 and a quench of .032" is going to work much better. The strong DCR is going to make plenty of torque, so even if the IVC is off a few degrees as originally hoped, the cam will become more intake biased and will hold the powerband longer and still make about the same torque numbers, because the VEs will be near optimal for the intake manifolds available.
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Thread Starter
Launching!
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Thanks for all your guidence. I may rethink the cam. When I ordered it they told me it was 0* advance, but the cam card that came with it says differently. What about the same setup using the TQ'r V3? 111 LSA and 0* advance? IMO, it's better to spend a little $$ now and get it right the first time.
And hypothetically, if I stick with the original cam,and use the stock GM gaskets, would that be OK with tuning and 92 oct?
And hypothetically, if I stick with the original cam,and use the stock GM gaskets, would that be OK with tuning and 92 oct?
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Verdad Gallardo It wouldn't be perfect with the GM gaskets. If you don't have an adjustable timing set, they are only $115 or so (Rollmaster LS1, JP LS2). This is a good investment anyway, as you can degree whichever cam you get. You'll have to shim the oil pump, but eh.
Originally Posted by slowride
I had the same question about the GM MLS gasket so I just mic'd my old one and get around .053"-.055" of compressed thickness on the fire ring. It's not the .060" many people claim.
Thread Starter
Launching!
Joined: Feb 2006
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Originally Posted by GuitsBoy
Thats really good news! I feel a lot better about these gaskets now. I was gonna suggest the 6.0L gaskets as they are around that thickness, and even though the bore is larger it would more than make up the difference if the 5.7L gaskets really were .060. Thanks for measuring the gasket though. I already threw out two used pairs and forgot to measure both times.
Originally Posted by exSSer
I wouldn't be too quick to celebrate, because everywhere that sells the '02-newer gaskets insist they're .060 compressed. This may not apply to the ones they make for earlier model years.
Trever at Texas Speed even agreed with my .053"-.055" reading. If I set the mic to .060" it just pulls right off the ring with no friction. I can get a lower reading then .054" if I really clamp down on it, but that seems excessive. If you measure off the fire ring where no sealant is used it is around .052".
TECH Resident
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What I don't understand is why you would use such a large quench with an aluminum block engine. .040-.045 are conservative iron block setting. .028-.030 has been used in more radical, 7k max rpm iron blocks.
Aluminum blocks can use less. Tony Mamo has suggested .033-.038. Others have run down to .025. Just get it warm before revving it!
World uses .060 in their crate engines. But that is a very conservative setting in case a customer really, seriously over revs it.
Why are people using the radical setups on this forum using these relatively large quench dimensions?
Aluminum blocks can use less. Tony Mamo has suggested .033-.038. Others have run down to .025. Just get it warm before revving it!
World uses .060 in their crate engines. But that is a very conservative setting in case a customer really, seriously over revs it.
Why are people using the radical setups on this forum using these relatively large quench dimensions?
