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Is there a rule of thumb on how much lowering your quench will let you run higher static? Example... will going from .040 quench to .035 will let you run .5 more CR without getting to streetability issues? My reason for asking is I've decided on TFS 220 as cast heads with the bigger bore/valve (LS2) and can have them milled for the cc I need. BTR says highest is 65cc, but I thought TEA said they could do 66cc. I've tried getting hold of TEA all week to confirm, but no one is answering their phones
So, assuming 65cc is the largest I'll get I have a few options, but dropping the quench is getting my static high. Running a .040 gasket gets my quench to .034 and 11.48 CR. Will that low of a quench be enough to keep knock down on 93 with high CR in the southern summers? Or I could run .045 gasket which puts quench at .039 and 11.30 CR.
This is all assuming I can run 4.060 bore gasket. BTR couldn't confirm bore size for that head and told me they'd just run 4.100 to be sure. Not crazy about that idea leaving so much dead space in the chamber though.
Heads are going on a 4.030 6.0l. Flat top pistons with a pistion to deck height of .006, out of the hole. Its a daily street truck, 6500 rpm max, and far from anything considered max effort. Reliability and ease of use are most important. I'm not chasing some high CR number for power. I'd be comfortable running 10.9-11.0:1 but that doesnt seem to be an option without getting .046 quench. And maybe I'm over thinking this and .046 is just fine
It's not as important as you think, stock head gaskets or blue felpro head gaskets are what I always recommend. Many of us are running close to 12:1 or greater on pump gas with felpro head gaskets we didn't bother or worry about quench at all. The stock are always and the good aftermarket pistons are out of the hole slightly anyway, Giving a good enough quench with the stock thickness head gasket. Any gain in quench with a thinner head gasket gives you less PTV and the The stock head gaskets and felpro are far more reliable than many of the thinner aftermarket stuff. The static compression number only matters when compared to the dynamic compression calculation based on your intake valve closure event both of which can be pushed more than you think. The LS engine ignition system is far more accurate than older cam driven distributor stuff. This is why we can run higher compression ratios because our ignition timing is so much more accurate and kept in safe check by the computer. Having your tune spot on is way more important than quench on these engines. Just use the head gasket that doesn't leak. look at my hack of a combo. I'm at 11.8 to 1 with a stock LS3 piston and a O.O48" felpro head gasket with a stock unported 61.15cc 706 head. It's never pinged once, not even on 89 octane and still running the stock timing table before I finished tuning it
You won’t notice a huge difference going from .046 quench to say .040, if it’s not a max effort build, which you say it’s not. .035-.040 quench is important only if your chasing max compression and ignition timing numbers. I’d stay at .046 and look to find the absolute best tuner you can find to get you the most power you can squeeze out of it. I’m absolutely blown away by how many guys won’t chase down the best tuner around to find extra power. Tune is everything with the LS platform, no matter how much has been spent on the latest and greatest builds.
Thanks everyone. Definitely not worried about making a ton of power. Just want to make sure I'm getting the right cc chamber the first time to save headaches down the road. .046 lets me run a stock gasket, so thats is nice.
Truck is being tuned by PCM of NC remotely right now. They are about 5 hrs away, and once all the kinks are worked out, I'll take it to them to finish with an in person street tune.
You won’t notice a huge difference going from .046 quench to say .040, if it’s not a max effort build, which you say it’s not. .035-.040 quench is important only if your chasing max compression and ignition timing numbers. I’d stay at .046 and look to find the absolute best tuner you can find to get you the most power you can squeeze out of it. I’m absolutely blown away by how many guys won’t chase down the best tuner around to find extra power. Tune is everything with the LS platform, no matter how much has been spent on the latest and greatest builds.
I agree. There comes a time when you reach a point where more compression from reducing quench will not help with spark knock. So much depends on combustion chamber shape, and piston crown design. Which, btw, I'm totally in favor of flat top pistons, with no raised domes. Also with no more valve reliefs than there are valves. Meaning if you have a 2 valve head, why have 2 reliefs on each side of the piston, making 4 total? My opinion.....
You won’t notice a huge difference going from .046 quench to say .040, if it’s not a max effort build, which you say it’s not. .035-.040 quench is important only if your chasing max compression and ignition timing numbers. I’d stay at .046 and look to find the absolute best tuner you can find to get you the most power you can squeeze out of it. I’m absolutely blown away by how many guys won’t chase down the best tuner around to find extra power. Tune is everything with the LS platform, no matter how much has been spent on the latest and greatest builds.
So the tune is less important on other engine platforms?
It seems like you're referring to the terms "quench" and "static," but the context is not clear. These terms are often used in various fields and can have different meanings depending on the context. Without more specific information, it's challenging to provide a meaningful answer.
If you could provide more details or clarify the context in which you are using these terms, I'd be happy to help you understand their meaning and how they relate to each other.
The terms are pretty common, but I understand that they also have generic meanings as well. Its the same as calling a spark plug a plug. There are may types of plugs, but when speaking about an ignition system "plug" generally refers to a spark plug.
Static - static compression ratio (SCR or CR). Cylinder volume to combustion chamber
Quench - the distance from the head to the piston at TDC. Some also call this "squish".
I agree. There comes a time when you reach a point where more compression from reducing quench will not help with spark knock. So much depends on combustion chamber shape, and piston crown design. Which, btw, I'm totally in favor of flat top pistons, with no raised domes. Also with no more valve reliefs than there are valves. Meaning if you have a 2 valve head, why have 2 reliefs on each side of the piston, making 4 total? My opinion.....
I agree flat top always if possible and I would have to guess that for OEMs and stock rebuilders it's simplicity's sake then the piston can go on either bank anywhere also, that bit of material weighs something and it would have to come off of the other side somewhere to keep the piston balanced over the pin If you want it to last a really long time right? Oh wait look We already have this machine to cut a chunk out on this side that weighs this much. Just cut a chunk out on the other side and it will weigh even? Pistons supposed to be balanced that way right? I mean people fly cut all the time too. We should start another thread, " How many miles do you have on your home fly cut combo and does it burn any oil?"
Is there a rule of thumb on how much lowering your quench will let you run higher static? Example... will going from .040 quench to .035 will let you run .5 more CR without getting to streetability issues? My reason for asking is I've decided on TFS 220 as cast heads with the bigger bore/valve (LS2) and can have them milled for the cc I need. BTR says highest is 65cc, but I thought TEA said they could do 66cc. I've tried getting hold of TEA all week to confirm, but no one is answering their phones
So, assuming 65cc is the largest I'll get I have a few options, but dropping the quench is getting my static high. Running a .040 gasket gets my quench to .034 and 11.48 CR. Will that low of a quench be enough to keep knock down on 93 with high CR in the southern summers? Or I could run .045 gasket which puts quench at .039 and 11.30 CR.
This is all assuming I can run 4.060 bore gasket. BTR couldn't confirm bore size for that head and told me they'd just run 4.100 to be sure. Not crazy about that idea leaving so much dead space in the chamber though.
Heads are going on a 4.030 6.0l. Flat top pistons with a pistion to deck height of .006, out of the hole. Its a daily street truck, 6500 rpm max, and far from anything considered max effort. Reliability and ease of use are most important. I'm not chasing some high CR number for power. I'd be comfortable running 10.9-11.0:1 but that doesnt seem to be an option without getting .046 quench. And maybe I'm over thinking this and .046 is just fine
.046 is perfectly fine, that's OEM numbers
Your 4.030 with 65 cc and a .052 gasket nets 11.1:1 compression. Send it
you could also do a .040 gasket for .034 quench and 11.5:1 compression but the 11.5:1 may be pushing it depending on usage
Your 4.030 with 65 cc and a .052 gasket nets 11.1:1 compression. Send it
you could also do a .040 gasket for .034 quench and 11.5:1 compression but the 11.5:1 may be pushing it depending on usage
Yeah, the stock HG and 65cc sounds like what I'm looking for. I definitely dont want to be running the limits of anything. I was thinking the thinnest I'd go was .045 gasket. That would put me at 11.3:1 and .039 quench. BUT...If the difference between the .045 and stock HG is negligible, I see no reason to go cometic, given the reliability and price of stock.
Yeah, the stock HG and 65cc sounds like what I'm looking for. I definitely dont want to be running the limits of anything. I was thinking the thinnest I'd go was .045 gasket. That would put me at 11.3:1 and .039 quench. BUT...If the difference between the .045 and stock HG is negligible, I see no reason to go cometic, given the reliability and price of stock.
I agree and love OEM for that reason
I mentioned .040 because ws6 store makes MLS in .040 for 69.95, and that's a pair
Actually .045-.046, but yeah, it's a good deal regardless.
Get both gaskets for about the same as a single GM, thats pretty tempting. I'd get better quench and save some coin but is it worth risking gasket failure and tuning headaches?
Get both gaskets for about the same as a single GM, thats pretty tempting. I'd get better quench and save some coin but is it worth risking gasket failure and tuning headaches?
Ive used a few sets of the WS6Store headgaskets and they are still going fine to this day. Tuning with optimized quench is actually easier on a tuner, if he/she is a competent tuner.
Ive used a few sets of the WS6Store headgaskets and they are still going fine to this day. Tuning with optimized quench is actually easier on a tuner, if he/she is a competent tuner.
For what it's worth I'm not knocking anybody or their parts. Just trying to let you understand how much leeway there is with this stuff I used the ws6 head gaskets when I first put my 6.2 l together, a radiator hose popped off on me after breaking it in and I got it a bit hot like over to the red. Blew the passenger side head gasket. I swapped out the 853 heads with 706 heads and used parts store felpro gaskets so less quench and more compression, It was a bit stinky until I returned it but it turned out just fine I was even running it wot in the scanner with the old tune so I could see how the changes affected the tune
Well things took a turn for the worst today. I pulled the heads off to prep for the new heads and found some concerning stuff. Not sure if the cam should have that much wear for such low miles. With a fingernail I can feel a difference where the lifter rides but I'm not sure if its because its smoother there. Thats not as concerning as what looks like pitting on one lobe. Pics dont to show the "pitting" very well. I'm going to try to upload a video. Then theres the lifters. Some of them do have spots I can feel with a fingernail. Cam has about 1000 miles, lifters and short block about 500 miles.
Does anyone know if I can send the lifters in to Johnson to have them inspected, possibly replace the wheels? I really dont want to drop another $900 on lifters. Also, does anyone know if TEA will inspect cams? I am sending them my valve springs for the new heads and it would be easy to send them the cam too to get a professional opinion. I checked on both websites and couldnt find an answer. I planning on calling them both tomorrow to ask but I might sleep better tonight knowing I dont have to buy brand new lifters.
Everything will come down to your dynamic compression ratio.
For example I'm building a ls6 with 11.55 to 1 static compression ratio with 6.3 inch rods 67cc chamber and an 0.40 gasket. I will be decking the block to achieve a .008 out the hole. Bringing the quench down to .032 clod start up. Dynamic compression ratio will be 8.73 to 1 with inlet valve closing at 69.44ABDC.
This is when engine is cold. So when the engine is at operating temperature the deck height will be zero or as close as possible +- .001.
This will then lower my static compression ratio to 11.31 to 1.
My dynamic compression ratio will then lower due to aluminium block expansion to be 8.63 to 1.
perfect for pump gas 93 octane USA and equivalent 98 octane Australia.
I personally would like to know the USA fuel octane AKI of E10 fuel to see if it would be suitable for that dynamic compression ratio.
For a side note the optimum quench for pump gas is .038 to .045 from everything I've found online and talking to people in the know.
Last edited by Shtstr; 01-01-2024 at 06:32 AM.
Reason: Wrong word used
10-08-2023, 07:29 AM
Quench vs Static. How much will get you how much? 
