Advanced Engineering Tech - Quence

How low can you go?
Is 0.015 to tight on the Quench?

Thanks

How low can you go?
Is 0.015 to tight on the Quence?

Thanks

Yes. Usually want to shoot for ~ .040"

Yes. Usually want to shoot for ~ .040"

0.040 is the magic number?

Any closer that .40 and you are much more likley to hit the head with the piston

ok I am going to be at 0.035 on my set up.

I'm running .032. I've seen people running even less on this board.

Changed mine bto .032. I put .028 thinking of the wrong gasket thickness.

http://racingarticles.com/article_racing-10.html

http://www.chevyhiperformance.com/tech/engines_drivetrain/shortblock/94138_piston_head_clearance_guide/index.html

Ohhh....quench. I'm not so confused now.

These new-fangled spellings jack me up every time.

Sorry I can't spell. All I know how to do is break stuff.

everything I've heard and read, says optimum quench will typically be somewhere between .040 and .060". alot of people will argue that with nitrous, blower or turbo it doesn't matter, which I think could have some truth to it. it also depends on the specific engine combo i.e. one engine might like .040 better then .060 and another different engine might be the opposite. for a street motor or something you wont be freshening and dyno testing alot, find an easy way to get it somewhere in between 40 and 60, and send it down the road, for a race motor or something that will see excessive dyno testing, try .040 and work your way up to .060 and monitor the tendencies on the dyno then decide from there.

The answer is: As tight as u can get and not hit the head.
No joke, the tighter the better. Here is the thing though, u need to know true deck height, compressed gasket thickness, bore size, and piston to wall clearance hot and cold.

Let take a 346 ls1 (typical), we find the piston is out the hole .006, and we want to use a .041 gasket. Taking the .006 from the .041 we end up w/ .035 clearance. If u used a forged piston u will find it "rocks" in the bore at tdc and u can measure this.If u had a gasket too thin, the piston would hit the head at tdc, because the piston "cocks" in the bore as it changes direction. U will find that u need at least .032 clearance to keep the piston from hitting the head (so the .041 will work but a .031 would not). I used to use .029 gaskets on the sbc and would cut .004 off the edge of the pistons in the bridgeport. Carbon could never build up on the flat portion of the head next to the chamber, cause the piston was so close.

Why do u want this? The engine will be less prone to detonation (even having a higher static comp ratio), will tolerate more timing, and will have higher peak hp/tq #s. I don't care if it runs on 87 octane or 116, the results will show on the dyno everytime. I can get u 12-15hp AT THE REAR WHEELS w/ a head gasket ONLY change on the LS7. Guys are running 12:1+ comp. ratios and 91 octane w/ no issues, proper quench is a major key not to be overlooked.

The answer is: As tight as u can get and not hit the head.
No joke, the tighter the better. Here is the thing though, u need to know true deck height, compressed gasket thickness, bore size, and piston to wall clearance hot and cold.

Let take a 346 ls1 (typical), we find the piston is out the hole .006, and we want to use a .041 gasket. Taking the .006 from the .041 we end up w/ .035 clearance. If u used a forged piston u will find it "rocks" in the bore at tdc and u can measure this.If u had a gasket too thin, the piston would hit the head at tdc, because the piston "cocks" in the bore as it changes direction. U will find that u need at least .032 clearance to keep the piston from hitting the head (so the .041 will work but a .031 would not). I used to use .029 gaskets on the sbc and would cut .004 off the edge of the pistons in the bridgeport. Carbon could never build up on the flat portion of the head next to the chamber, cause the piston was so close.

Why do u want this? The engine will be less prone to detonation (even having a higher static comp ratio), will tolerate more timing, and will have higher peak hp/tq #s. I don't care if it runs on 87 octane or 116, the results will show on the dyno everytime. I can get u 12-15hp AT THE REAR WHEELS w/ a head gasket ONLY change on the LS7. Guys are running 12:1+ comp. ratios and 91 octane w/ no issues, proper quench is a major key not to be overlooked.

Thats what I have been told by multiple people.

And "12:1+ comp. ratios and 91 octane" is that still referring to the LS7? I like those numbers :devil:

The answer is: As tight as u can get and not hit the head.
No joke, the tighter the better. Here is the thing though, u need to know true deck height, compressed gasket thickness, bore size, and piston to wall clearance hot and cold.

Let take a 346 ls1 (typical), we find the piston is out the hole .006, and we want to use a .041 gasket. Taking the .006 from the .041 we end up w/ .035 clearance. If u used a forged piston u will find it "rocks" in the bore at tdc and u can measure this.If u had a gasket too thin, the piston would hit the head at tdc, because the piston "cocks" in the bore as it changes direction. U will find that u need at least .032 clearance to keep the piston from hitting the head (so the .041 will work but a .031 would not). I used to use .029 gaskets on the sbc and would cut .004 off the edge of the pistons in the bridgeport. Carbon could never build up on the flat portion of the head next to the chamber, cause the piston was so close.

Why do u want this? The engine will be less prone to detonation (even having a higher static comp ratio), will tolerate more timing, and will have higher peak hp/tq #s. I don't care if it runs on 87 octane or 116, the results will show on the dyno everytime. I can get u 12-15hp AT THE REAR WHEELS w/ a head gasket ONLY change on the LS7. Guys are running 12:1+ comp. ratios and 91 octane w/ no issues, proper quench is a major key not to be overlooked.

:werd: