Thoughts,opinions wanted gas porting pistons

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madmax/6

madmax/6

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Thoughts,opinions wanted on gas porting my pistons.My engine is due for a freshen up,over 400 runs on it.I want to try to get anouther 10-15 hp out of it.Will bee bumping compression from 12.3 to about 13.5,other than that my combo is pretty maxed out.This is a slant six that holds six national records that I would like to lower.Cars best is a 11.43 and I shift at 6200.Will gas porting help any on a low hp motor only beeing spun to 6500 tru the traps?Please,,NO drop a sb or bb in it suggestions.Guzzi Mark
 
I believe a properly honed block, high quality Total Seal Ring face, and a good valve job make 10 times the power then a gas ported piston will do.
I would also think with that compression that ring flutter would not happen till 6800 rpm and up.
But what do I know,I definitely never had a national record...
Martin
 
From what I have read,I agree.I personally think its useless for my car,but have a racer friend that thinks I am stupid not to do it.He is very sharp and has a couple Bonneville records but that is a whole different game.Mark
 
use the thinnest low tension ring set you can get and gas port them. open up all the bearing clearances to the max or a tad more. use the longest collect that fits. back cut the valves to have the thinnest face and cut the seats to the thinnest. use the light hollow push-rods you can. use the lightest valve spring that will keep the lightset lifters following the cam. if you have the option of using light weight rods use them or if not pick out the lightest stock ones you can find. light weight wrist pins are good too.
 
I'm assuming these are custom pistons.. I like CP in terms of "top of the heap". I do believe it will help you too. Be vey specific on the hone and cylinder finish too. I've seen the same engine (V8 5.9L modified tour) gain 40hp just by playing with cylinder finish with the same ring, same gap, same piston. The only differences were gaskets (replaced with same pcs) and the finish. Also, have you centered the head over the bores? I've seen some V8s that really seemed to wake up by centering the heads properly. What have you done with it in terms of dyno work? Cam phasing? BSFCs? Valvetrain dynamics? You're not looking for much, but the record holders I was mentored by had to really fight for those "last few". Also, is it an auto trans? There are tricks to lighten and tighten there that are worth some ET.
 
madmax/6 said:
Thoughts,opinions wanted on gas porting my pistons.My engine is due for a freshen up,over 400 runs on it.I want to try to get anouther 10-15 hp out of it.Will bee bumping compression from 12.3 to about 13.5,other than that my combo is pretty maxed out.This is a slant six that holds six national records that I would like to lower.Cars best is a 11.43 and I shift at 6200.Will gas porting help any on a low hp motor only beeing spun to 6500 tru the traps?Please,,NO drop a sb or bb in it suggestions.Guzzi Mark
Click to expand...

If you go to a .043 3mm combo, and backcut the ring then it will be beneficial even at 3000rpm if it's WOT.
I'd also run a 600 or 800 grit ball hone down the cylinders for 5-6 strokes. Also if you can lighten the pistons up at least 20g's that will pick up power.
Brian
 
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