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Old 12-07-2012 | 04:25 AM
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Originally Posted by HaxbySpeed
It really depends on the application. On 2000+hp stuff I'll run .150 in the hole with a .060 gasket. On stuff where you're gonna run meth injection a little extra will help too. AFR of the intake charge, chamber efficiency, piston design, rod material, pin thickness, target rpm, piston to wall clearance, fuel quality, etc. all effect optimal squish. When the engine is not in boost is the only time detonation may become an issue but can be eliminated through proper tuning.
can you please tell more info on this 2000+hp engine with the piston .150 in the hole and a .060 thick head gasget,things like what fuel was used and compression ratio,also what head was used,i know you think i am a joke,but i assure you,i am for real.im not being a smart azz,i am just curious.
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Old 12-07-2012 | 09:14 AM
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Originally Posted by HaxbySpeed
On a boosted application the squish height is not as critical as an NA deal and can be dangerous if too tight.
Its important in SC apps for cooling the top of the piston (quench) is what I have always understood so I run them close. This is the first I ever heard it could actually be a bad thing with SC. Why might that be? Presuming of course all other design parameters (ie CR) are correct.

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Old 12-07-2012 | 10:57 AM
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Originally Posted by MILD THUNDER
Bad idea with the headgasket imo. Ideally blown you wanna be somewhere in the .040-.060 quench area. A little less is ok, but .100 or more, I wouldnt do it.
+1 usually looking for just a hair under .040 in the quench for optimum combustion, if you dont squeeze it it wont burn right!!! just ask your wife!! lmao!
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Old 12-07-2012 | 11:03 AM
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Originally Posted by HaxbySpeed
It really depends on the application. On 2000+hp stuff I'll run .150 in the hole with a .060 gasket. On stuff where you're gonna run meth injection a little extra will help too. AFR of the intake charge, chamber efficiency, piston design, rod material, pin thickness, target rpm, piston to wall clearance, fuel quality, etc. all effect optimal squish. When the engine is not in boost is the only time detonation may become an issue but can be eliminated through proper tuning.
are we talking BBC or Hemi here hax??? .150 down the hole on a BBC?? plus .060 head gasket? educate me please? cause I've obviously been doing it all wrong for the last 30+ years...
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Old 12-07-2012 | 11:10 AM
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Originally Posted by blue thunder
Its important in SC apps for cooling the top of the piston (quench) is what I have always understood so I run them close. This is the first I ever heard it could actually be a bad thing with SC. Why might that be? Presuming of course all other design parameters (ie CR) are correct.
I think the squish/quench debate is worthy of it's own thread as it is a lot more complicated then a general rule of thumb number that floats around the internet. I will start one later this afternoon when I get time. There is always compromises in engine design/building and there are situations where a tight squish is beneficial and others where it will destroy your engine. In an N/A engine a tight squish clearance is for turbulence, not cooling. Look at a modern true dished BBC blower piston, there is virtually no squish/quench pad. Look at the chamber modifications done to a fast burn type SBC chamber that runs high boost. Anyway, I think it's a very interesting topic and I like to hear what works and what doesn't for others as well. Low boost vs high boost vs N/A, cylinder head temp, octane, intercooler efficiency - It's all a factor.
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Old 12-07-2012 | 11:20 AM
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Originally Posted by HaxbySpeed
I think the squish/quench debate is worthy of it's own thread as it is a lot more complicated then a general rule of thumb number that floats around the internet. I will start one later this afternoon when I get time. There is always compromises in engine design/building and there are situations where a tight squish is beneficial and others where it will destroy your engine. In an N/A engine a tight squish clearance is for turbulence, not cooling. Look at a modern true dished BBC blower piston, there is virtually no squish/quench pad. Look at the chamber modifications done to a fast burn type SBC chamber that runs high boost. Anyway, I think it's a very interesting topic and I like to hear what works and what doesn't for others as well. Low boost vs high boost vs N/A, cylinder head temp, octane, intercooler efficiency - It's all a factor.
agreed... many variables, and yes quench main function is to create the environment (set up for combustion) aka turbulence...
looking forward to the new thread Hax... I may be old school, but if it ain't broke... don't fix it!! lol
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Old 12-07-2012 | 11:42 AM
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Originally Posted by adk61
are we talking BBC or Hemi here hax??? .150 down the hole on a BBC?? plus .060 head gasket? educate me please? cause I've obviously been doing it all wrong for the last 30+ years...
BBC. A little 450" Hemi on alchohol makes 3500+ hp in the 50-60psi range. It's very common to see them at -.250" in the hole.

At a certain level, piston design and sealing becomes a major factor. To run your tight quench of just under .040, at lets say a conservative 1600hp, how far are you sticking the piston out of the bore, and if you're zero decked what head gasket is sealing all that pressure? How do you keep the piston from smashing into the head at 7000+ rpm? None of this pertains to what Dave B is doing by the way but I think this could be an interesting thread. I gotta get some work done though!
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Old 12-11-2012 | 08:09 AM
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Originally Posted by HaxbySpeed
BBC. A little 450" Hemi on alchohol makes 3500+ hp in the 50-60psi range. It's very common to see them at -.250" in the hole.

At a certain level, piston design and sealing becomes a major factor. To run your tight quench of just under .040, at lets say a conservative 1600hp, how far are you sticking the piston out of the bore, and if you're zero decked what head gasket is sealing all that pressure? How do you keep the piston from smashing into the head at 7000+ rpm? None of this pertains to what Dave B is doing by the way but I think this could be an interesting thread. I gotta get some work done though!
Buddy I ran and built the engines for my Alcohol funny car for many years, and on alcohol in a hemi as in Veney or Brad head 525 CID... the lowest compression ratio we ever ran was about 11.5:1 and trust me, that piston was nowhere near 1/4" down the pipe!!!
even when we jumped up to top fuel and ran "NITRO" we never ran a piston that far down the hole and that was @ 6:1 compression... so???? educate me please as I am not sure where your information is coming from... whose head?
what cc chamber? bore size? stroke? I'm dumbfounded by your comments and I'm looking for clarity
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Old 12-11-2012 | 08:15 AM
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Originally Posted by jeff p31
if it aint blowen it just sucks !!!
+1
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Old 12-15-2012 | 02:14 AM
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I stayed with the 509 CID
Took Eddie's advise with the 3.3 Carbed Whipples.
New cams and blower pistons
Chrome valve covers
Stellings headers

Hoping to get 3000HP each with those chromed valve covers
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Last edited by Velocity Vector; 12-15-2012 at 02:26 AM.
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