ElkySS

iTrader: (6)

I'm trying to plan my next build. I'm currently running about 11.5:1 on 93, I know some guys run some crazy high compression ratios on pump gas and I'm curious what the safe limit is. It will be N/A for now and get a shot of Nitrous down the road. I cant see it being much over a 250 shot though.

HCI2000SS

iTrader: (2)

What kind of motor?

VoyagerCamaro

On my old car, i had 11:7:1 compression with no issues. But I made sure and always kept very, very good quality gasoline (Shell Nitro 93 octane) I was running speed pro pistons (I'll have to check the part number), 0.26 head gaskets, CC503 cam, 160* thermostat, stock heads and many many more mods.

ElkySS

iTrader: (6)

I've heard of guys running around 12.5:1. I'm wondering how feesable that is. I'd like to run about 12:1 but I don't wanna push the envelope too much

hrcslam

I'm at 11.8:1 on 91 octane in the Phoenix heat. No issues. The reverse cooling works as advertised.

But, you HAVE to take into account intake valve closing event timing too.

What cam do you plan on using?

ElkySS

iTrader: (6)

Not sure yet. I'll probably let my head porter decide

bowtienut

iTrader: (1)

I think it all depends on how you plan to use the car.
For drag racing and general driving where the motor doesn't already have a lot of heat in it when you're at full power, 12:1 is manageable on 93 octane. I ran 12.0:1 for 6 years on my heads/cam motor with never a detonation issue. BUT.....for open track sessions where it got very hot, I always mixed half 110 octane race gas.
For the new 383 build, I'll have 11.5:1, a 238 dur SR cam, and will run strictly 93 pump gas, even on the roadcourse.

KW Baraka

iTrader: (7)

I'm running about 12.5:1.....but then, I have a 246* solid roller cam.

I've never had an issue with heat, but I only put about 1500 miles a year on the car. So.....there's that.

Make sure your builder cams the engine appropriately and optimizes your quench (about .030" to .035") and you should make out OK.

Yep......looks good !!!

KW