Supercharging ?
12-07-2012, 09:14 AM
#31
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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.
Last edited by blue thunder; 12-07-2012 at 09:48 AM.
12-07-2012, 11:03 AM
#33
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.
12-07-2012, 11:10 AM
#34
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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.
12-07-2012, 11:20 AM
#35
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.
looking forward to the new thread Hax... I may be old school, but if it ain't broke... don't fix it!! lol
12-07-2012, 11:42 AM
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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!
12-11-2012, 08:09 AM
#37
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!
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!
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
12-15-2012, 02:14 AM
#39
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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
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
Last edited by Velocity Vector; 12-15-2012 at 02:26 AM.
12-15-2012, 06:40 AM
#40
Why not use a carburated Whipple if you want to stay carb. They love some compression and 9.3 is not out of the ordinary. I have done them up to 10.2:1 and 9.5-10:1 is not uncommon.
I did a set about 1 1/2 years ago. They were a pair of my 750 NA's. They are 598, 10:1 with a 1050 dom. We just removed the intake and bolted on the Whipple and went to the dyno. They made 942 hp and 1070 ft lbs at 5.5 psi on 93 octane and 1020 hp and 1190 ft lbs at 8 psi on 100 octane
I did a set about 1 1/2 years ago. They were a pair of my 750 NA's. They are 598, 10:1 with a 1050 dom. We just removed the intake and bolted on the Whipple and went to the dyno. They made 942 hp and 1070 ft lbs at 5.5 psi on 93 octane and 1020 hp and 1190 ft lbs at 8 psi on 100 octane
