i will turbocharged my 2.4 car using the achieva head, pistons will b forged 9:1 comp ratio, and i was told that if i used the head my comp could go up to 10:5 or 11:1 is this right??? and can i still use it and make something out of it???
What year is the head from? If its before 96 its a 2.3 head it will net you a compression of 10.5-1 with those 9-1 pistons. If so I recommend the thicker cometic head gasket to knock that compression down some.
yeah its a head before 96, thicker comp??? i haven't thought about that thanks Zs Z
You don't want to use a thicker head gasket, it should be a last resort only. It does lower the compression ratio, but it increases the quench distance (distance between head and piston). This lowers turbulence around top dead center, and can cause bad spark knock on the boundary edge. It will hurt power and can decrease the longevity of the engine bigtime if you are knocking. You want to get dished pistons or a larger combustion chamber when lowering the compression ratio.
you can boost on 11:1 you just can't have as much its a trade off. if you do a tune and proper suporting mods then your fine
JBO since July 30, 2001
If you are buying pistons, you might as well get some lower compression ones. As mentioned you CAN run 11:1, but you will end up having to run very low boost. Lower compression (8-8.8:1) is better for the higher boost builds. Unless you plan on running race gas all the time.
well i bought the 9:1 compression ratio and .20 overbore what would be a reasonable boost????? how much boost???? because im planing to use direct port to make it spool faster....
You'll spool faster on high compression, AND you'll have more power out of boost. If done right (aka with the properly sized turbo) you can make the same peak power on high compression, on the same gas, with better low end power, with the same longevity/relability.
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You will not make the same max power on 11:1 as 8.5 or 9:1 on pump gas, no question. Doesn't matter what the size of the turbo is, 11:1 is waaay too high for moderate levels of boost. If you were only planning on running like 8-12 PSI, then 11:1 would probably be okay. If you are trying to get maximum power out of a given setup, the lower compression will make better top end power and be faster overall (maybe not as much torque or as fast of spool).
Which is why big HP turbo drag engines run 11:1 or more...
1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by:
Kronos Performance
WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer
Leafy wrote:Which is why big HP turbo drag engines run 11:1 or more...
Oh yea, those drag cars run on pump gas... oh wait...
Missed the pump gas comment. But I still stand to say that you can make the same peak power on pump gas with higher compression, you wont be using the same turbo, the same cams, or the same head as the low comp guy though.
1994 Saturn SL2 Home Coming Edition: backup car
2002 Chevy Cavalier LS Sport Coupe: In a Junk Yard
1995 Mazda Miata R-package Class=STR
Sponsored by:
Kronos Performance
WPI Class of '12 Mechanical Engineering
WPI SAE Risk and Sustainability Management Officer
if you are using a 2.3 head, make sure you have a manifold for a 2.3 and not a 2.4
yup i have the manifold and the exhaust manifold i match the bolt patterns but now i am not sure if i should use it or no, people are saying not to use it.
Why does the compression goes up when I used the 87 achieva head??????
Use 2.3 manifolds on a2.3 head. There are no bolt patterns to match up. Only other option for an intake manifold is a custom one. Turbo exhaust manifolds for a2.3 can be hard to come by, but if you already have one I guess you have that covered.
