Hey guys I'am going to be ordering up a set of those new AFR Eliminator heads in 195cc with straight plugs now just want to get your thoughts on which version of the head the 65cc or the 75cc ones. From what I figured the 65cc ones will give me a 9.0:1 compression and the 75 would be about 8.2:1. Is there any advantage to going with the 75cc head on like a 5.7L motor after I blow this one for rebuild options? Would 8.2:1 compression be a major dog for street driving all though it might be safer with the current stock motor? I'll be changing the cam to a ZZ9 one if that helps at all and will be sticking with the SS runner TPI intake. I'am thinking of going with the 65cc heads myself but let me know what you think.

 

Lower compression and higher boost will make more power than the other way around. Might be a wise choice to go lower than you actually need to, especially with pump gas and a stock bottom end. Slapping on a higher boost pulley set is a lot easier than lowering your compression ratio later. A 1 PSI bump in boost would probably easily make up for the loss in power due to lower compression. And if/when you blow it up, getting compression back up around 9:1 is very easy with a 350 (flattop pistons) and an absolute no-brainer with a larger 383 or 400 (dished pistons).

Yeah, you'll lose some part throttle snappiness, but I doubt it will be a "dog" with a stock cam and a TPI intake helping keep low end torque propped up.

With my roots blower bottom end torque is never a problem and life with a roots blower begins and ends around 8:1 compression, but a roots is not exactly comparable to your setup.

 

Yes not much boost is being made below 3500RPMS unlike your roots blower. Thing to consider still is this is mostly a street car and I'am not totally sure how low compression will affect cruse drivability and I guess gas mileage.

 

Tony,

I could completely light the tires anywhere from a dead stop to about a 35mph roll on dry pavement. Definitely not a dog with 8:1 compression and 12-15 max psi. Don't let the fact that you aren't making that boost down low fool you, because right now with the same engine and my blower completely off the car I can STILL roast the tires from a dead stop using no brakes.

 

Thanks guys the 75cc ones are starting to look more appealing, anyone else have thoughts on this matter cause I'll probably be ordering the heads this next week.