408/360 question

[flyfish]

What do you think is the max compression I could run (keeping in mind I have the aluminum heads) while being able to still run pump gas?

10.8:1 compression is as high as you should go with aluminum heads and pump gas. This is what I run with my storker (no problems).

I have almost 12:1 and I run pump gas most of the time. The issue is, you spend all that money building the motor, you hate to hamstring it with pump gas........

I don't think pump gas "hamstrings" a motor. I built mine specifically to run on pump gas so I didn't have to pay 7+ dollars per gallon for race fuel, and it makes PLENTY of power (530-540hp). Its all about getting a good combination of parts together. In the not so distant future I plan on taking my car from the high to mid 10's, to the low 10's with a cam and carb and cam swap (still on pump gas, probably in the 580hp+ range). You can run fast on pump gas with the right combination. If you had 1 point less compression you could run full timing and pump gas too...but with 11.8:1 and a relatively small cam, you should switch to E85 to fix your "hamstring".

 

[Mopar to ya]

I don't think pump gas "hamstrings" a motor. I built mine specifically to run on pump gas so I didn't have to pay 7+ dollars per gallon for race fuel, and it makes PLENTY of power (530-540hp). Its all about getting a good combination of parts together. In the not so distant future I plan on taking my car from the high to mid 10's, to the low 10's with a cam and carb and cam swap (still on pump gas, probably in the 580hp+ range). You can run fast on pump gas with the right combination. If you had 1 point less compression you could run full timing and pump gas too...but with 11.8:1 and a relatively small cam, you should switch to E85 to fix your "hamstring".

My point is that my car can be tuned up to run on 110 octane and I can add 10 or more degrees of timing, thus more power. When I run 93 octane I have to drop the timing down to 26 or 28 degrees to keep from pinging. Losing 10 degrees of advance is a huge power loss. It is absolutely noticeable when I drive. On my engine, that is pulled hammy.

 

[Mo-Par]

With alum heads you can run 1 point higher on the compression. 10-1 with the right combo on pump gas will run fine.

 

[BrianT]

10:1 with aluminum heads is what we are shooting for on my 408 build.