hi i'm rebuilding my engine and i whant to know what is the best compression ratio for my combo to feed good my heads and headers because they are little big for my combo so what i have is 306 forged pistons, AFR 185's, 1 3/4 LT headers, 2.5 pipes til mufflers and 3" tail pipes, typhoom intake ported, 70mm TB, comp cams XE274HR, 30 pounds injectors and how many HP's can i expect from this at the wheel and at the flywheel....
what CR for a 306
- Thread starter aleborjas
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jgfiveoh
New Member
What pistons do you have? Flat tops?
350rwhp is easily do-able but that cam isn't the right cam. Your heads and headers are nothing "too big". Keep what you have and work from there. If you have a good flat top piston and a zero deck block, just mill the heads as needed to get 10.5-11:1. Just keep in mind that if you mill a lot the manifold may not line up 100%.
350rwhp is easily do-able but that cam isn't the right cam. Your heads and headers are nothing "too big". Keep what you have and work from there. If you have a good flat top piston and a zero deck block, just mill the heads as needed to get 10.5-11:1. Just keep in mind that if you mill a lot the manifold may not line up 100%.
Those heads are "to big" for a daily driver that sees different scenarios.
For what he wants, they aren't to big, since he appears to be going for track times.
350rwhp is easy if you want to take off a couple accessories and have a high revver (more than 6k) with high compression...
350rwhp is not easy at all if you want to keep your accessories and streetabilities...
Also vacuum from the cam effects your brakes...in general, the bigger the cam, the less vaccum...
With the "flat tops"...obviously p-v clearance might be close if you are going to start cutting on those heads...
Good Luck!
For what he wants, they aren't to big, since he appears to be going for track times.
350rwhp is easy if you want to take off a couple accessories and have a high revver (more than 6k) with high compression...
350rwhp is not easy at all if you want to keep your accessories and streetabilities...
Also vacuum from the cam effects your brakes...in general, the bigger the cam, the less vaccum...
With the "flat tops"...obviously p-v clearance might be close if you are going to start cutting on those heads...
Good Luck!
my pistons are 4.040 they are SRP flat tops and the heads are 58cc's and i dont whant to change the cam because i whant to keep the A/C i whant to get the most HP's with what i have and some persons tells me that i have big injector and some tells me that those are ok so what do i do?i have stock rails and holley 190GPH fuel pump... should i look for 10.5 CR?Grn92LX said:
I think you'll be happy with the combo. I'd like to see a little more gear but it'll make decent power for sure.
Not sure what changing the cam has to do with deleting your AC?
Do you know the specs on those pistons? I'm sure you'll be in the 10:1 + range. What you have is fine, just get it running and enjoy.
Not sure what changing the cam has to do with deleting your AC?
Do you know the specs on those pistons? I'm sure you'll be in the 10:1 + range. What you have is fine, just get it running and enjoy.
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