317 HEADS for boost?
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317 HEADS for boost? I have some 317 heads i wanted to use on my turbo build i was wondering if there is anything wrong with using these besides the deck height, will the valves be okay and everything ?
I run 317 on my twin turbo 408 using E85 and have regularly hit 18 pounds of boost with stock valves. Using LS9 head gaskets. No problems at all. I would highly suggest stainless valves to be safe though. I'm installing some now before I break a valve.
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thats what i keep getting on them. they seem to be the go to heads for affordable heads for boost. im 90% sure i want to go with 317 heads. I read really good things about them from mild setups to pretty crazy HP numbers. Im going to stick to about 10psi myself.
what i found odd is that if i go with 317 heads, according to the CR calculators, using even .040 cometics gaskets, the CR isnt that much lower on a stock LS1.
heres some calculations i got
with 317 heads 71cc, stock gasket .058, 9.6:1 CR
with 317 heads 71cc, LS9 gasket .051, 9.7:1 CR
wtih 317 heads 71cc, Cometic .040, 10:1 CR (thats 10 even. not 10.1:1)
so with that added in there, im probably going with 317 heads. also gonna do a cam with them to make up any possible low end lose. not sure if i should go with the LS9 gasket or go .040 for more optimum quench.
still wondering if anyone has expreienced boost numbers on these heads. perferably without meth in the mix. or E85 lol
what i found odd is that if i go with 317 heads, according to the CR calculators, using even .040 cometics gaskets, the CR isnt that much lower on a stock LS1.
heres some calculations i got
with 317 heads 71cc, stock gasket .058, 9.6:1 CR
with 317 heads 71cc, LS9 gasket .051, 9.7:1 CR
wtih 317 heads 71cc, Cometic .040, 10:1 CR (thats 10 even. not 10.1:1)
so with that added in there, im probably going with 317 heads. also gonna do a cam with them to make up any possible low end lose. not sure if i should go with the LS9 gasket or go .040 for more optimum quench.
still wondering if anyone has expreienced boost numbers on these heads. perferably without meth in the mix. or E85 lol
Just remember that boost pressure is not 100% relevant to cylinder pressure and does not directly correlate to the amount of power being made. Boost pressure is just a measurement of how much residual pressure is left over in the intake manifold where it's measured. Boost pressure is a measurement of the pressurized air mass that the motor cannot consume because it does not have enough volumetric efficiency to take into the cylinder all of the air mass that is available. Thus leaving what is "left over" in the manifold to be measured by the map sensor.
So if someone says, "I run 25psi of boost on 317 heads", that doesn't necessarily mean that the next guy can go out and crank 25psi on his boost controller and expect his heads not to lift.
So if someone says, "I run 25psi of boost on 317 heads", that doesn't necessarily mean that the next guy can go out and crank 25psi on his boost controller and expect his heads not to lift.
Last edited by Sales@Tick; Jun 20, 2013 at 10:58 AM.
I do understand that part. plus I don't plan on boosting past 15psi. im limited to 2 bar map and a 98 PCM. so 14.7ish psi is the most id put down the engine.
I just want to make sure moving from my stock 98 ls1 heads to 317 heads on 12ish psi would be worth the trouble? with a larger cam I understand the flow characteristic's would be better especially up top, but id lose some low end torque but not much with proper gaskets and a good tune.
I just want to make sure moving from my stock 98 ls1 heads to 317 heads on 12ish psi would be worth the trouble? with a larger cam I understand the flow characteristic's would be better especially up top, but id lose some low end torque but not much with proper gaskets and a good tune.
