Quench on turbo engines
10-11-2013, 11:08 AM
#1
Quench on turbo engines I posted this In the NA section, maybe ill get more hits here
There's 2 ways to reach quench
Thinner head gasket such as .040 cometic head gasket, .007 piston out of the hole = .033 quench
.020 piston out of hole, .053 gm head gasket = .033 quench
My question is does it matter which way you go to achieve it? Cost wise the 2nd way is more expensive since you need to deck the block to reach .020 out of hole..
But is there a performance difference, side effects of doing it the 2nd way?
There's 2 ways to reach quench
Thinner head gasket such as .040 cometic head gasket, .007 piston out of the hole = .033 quench
.020 piston out of hole, .053 gm head gasket = .033 quench
My question is does it matter which way you go to achieve it? Cost wise the 2nd way is more expensive since you need to deck the block to reach .020 out of hole..
But is there a performance difference, side effects of doing it the 2nd way?
10-11-2013, 01:44 PM
#4
Because most people shoot for .035-.040 area
I should be shifting around 6600-6800 rpm so I'm thinking a tight quench might not be so bad.
If I was shifting 7k+ then I should be worried with tight quench..
How's that take on it?
10-11-2013, 02:40 PM
#5
Launching!
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As long as the rods are good you will have no problem that way. Some people argue the tighter .035-.040 quench is not important on a forced induction engine like it is n/a. Being it looks like you are running an iron block and most likely a shelf piston I would not deck the block if its flat and run a gm gasket.
I would not intentionally build any engine .020 out of the hole.
I would not intentionally build any engine .020 out of the hole.
10-11-2013, 03:08 PM
#6
As long as the rods are good you will have no problem that way. Some people argue the tighter .035-.040 quench is not important on a forced induction engine like it is n/a. Being it looks like you are running an iron block and most likely a shelf piston I would not deck the block if its flat and run a gm gasket.
I would not intentionally build any engine .020 out of the hole.
I would not intentionally build any engine .020 out of the hole.
Diamond -2cc flat tops (2618)
I'm running ls9 gaskets/ 317 heads
I didn't pick that quench, I wanted my block decked and after assembly my engine builder handed me my spec sheet and it says .020..
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10-11-2013, 10:47 PM
#11
TECH Apprentice
Turbos love 035-040 quench just like NA and it really helps off boost in a daily driver. Because LS engines are so easy to get good quench it's a no brainer to run 040 - 045 Cometics. By help I don't mean big power gains just crisper, sweeter engine that feels better and uses less fuel to do it.
Last edited by Bazman; 05-28-2020 at 05:14 AM.
10-12-2013, 01:35 PM
#15
Yeah I've read a lot lately on that, but my quench is only a little tighter than most here who run ls9 head gaskets..
Average ls1 piston out of hole is .005-.010 coupled with ls9 gaskets, is about .040-.045 quench...
So there's a lot of people that don't run .050-.100 quench on here if they are running gm head gaskets
Average ls1 piston out of hole is .005-.010 coupled with ls9 gaskets, is about .040-.045 quench...
So there's a lot of people that don't run .050-.100 quench on here if they are running gm head gaskets
10-12-2013, 07:36 PM
#16
I had another thought, I'm running 317 heads and ls9 head gaskets which are a bigger bore than my current 3.905..
The valve reliefs on the piston are -2cc, and my PTV clearance is very big since my heads cc are 72 and my cam is a 225/225 .571/.571 TU1 cam
So what can the piston hit if the head bore is bigger than the cylinder bore and I have a lot of valve clearance with valve reliefs?
Maybe my tight quench can work!
Lol I'm trying to justify this but ^^ that doesn't sound too crazy does it
The valve reliefs on the piston are -2cc, and my PTV clearance is very big since my heads cc are 72 and my cam is a 225/225 .571/.571 TU1 cam
So what can the piston hit if the head bore is bigger than the cylinder bore and I have a lot of valve clearance with valve reliefs?
Maybe my tight quench can work!
Lol I'm trying to justify this but ^^ that doesn't sound too crazy does it
10-12-2013, 07:40 PM
#17
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Thats not the problem. The piston will not hit the head with your quench. The issue is you have an increased chance of detonation. You will have to run less timing because it will be sensitive to it.
10-13-2013, 01:57 PM
#19
Quench becomes more important when the engine is used on the street and spends lots of time out of boost. If you're going for peak power and reliability in boost, keep the piston in the hole. Most drag cars that push the limits of power per displacement (like the old 1200+ HP 4 cylinder hot rod cars) keep the pistons in the hole because quench creates hot spots, which can be really bad at high boost when the dynamic compression is already through the roof even with low static.
Basically it comes down to intended purpose.
Basically it comes down to intended purpose.
10-13-2013, 05:02 PM
#20
Quench becomes more important when the engine is used on the street and spends lots of time out of boost. If you're going for peak power and reliability in boost, keep the piston in the hole. Most drag cars that push the limits of power per displacement (like the old 1200+ HP 4 cylinder hot rod cars) keep the pistons in the hole because quench creates hot spots, which can be really bad at high boost when the dynamic compression is already through the roof even with low static.
Basically it comes down to intended purpose.
Basically it comes down to intended purpose.
I think there was a mix up at the machine shop and too much was cut off the deck, anyway I'm stuck with this quench unless I want to run a .060 cometic to open up quench..
Any tuners here think my combo would be hard to tune?
