Generation IV Internal Engine - 11.3 compress OK with 91 Octane?

Hey guys, I sourcing the part for my 418 stroker LS3. Looks like I will end up with 11.3 compression. I live in Cali where all we have is 91 octane. Am I going to be OK with the compression I'm running?

I appreciate any info you guys can provide.

Nate

I hear there a few variables, such as cam duration, what are the spec on the cam you are going to run? A cam with higher duration will bleed off some of the compression and allow you to run a higher compression ratio.

Our stroker is running a 11.8:1 on CA 91. Our cam is a Cam Motion 257/266 .646/.646 114 +4 in a LSX 454 ci stroker.

Will be fine I have run much higher than that with out issues even with the CA shit fuels.

11.3:1 on 91 would be fine with a good tune!

Thanks guys, my tuner also said the same thing. He mention if it were him, he'd supplement the fuel with added octane booster to get to 94 and tune the car to for 94. He mention cases are available on Amazon for $6 per bottle vs 410 at the store and one case could last me a year. He can also tune for a little more power. I think I'm going to go that route.

Our stroker is running a 11.8:1 on CA 91. Our cam is a Cam Motion 257/266 .646/.646 114 +4 in a LSX 454 ci stroker.

Yeah and Im sure it passes emissions too! :hump:

You could calculate the dynamic compression ratio (DCR) to get an idea. The intake closure angle will determine DCR. The answer to your question depends a lot on what cam you use.

I am running 12.3-1 compression on 93 pump gas..

My new set up will be 11.89cr and I am moving back to Cali in a few months. Worst case is that I will just mix a little race rule if needed.

Hey guys, I sourcing the part for my 418 stroker LS3. Looks like I will end up with 11.3 compression. I live in Cali where all we have is 91 octane. Am I going to be OK with the compression I'm running?

I appreciate any info you guys can provide.

Nate

Just curious what parts you have in mind to get there? I'm new to stroker motors and am wondering if my .030 milled LS3 heads from my 6.0 are going to be usable or not. (Also in Cali)

Depends on the cam being used.

12-1 here with the cam in my sig, also I wouldn't run an additive. I think that's bad advise, ok on your tune you'll be "supposedly at 94 octane"(if it really works) what if you don't have a bottle to add after using up that gas? Why not just get a 91 oct tune and leave it at that? Your not going to gain much IMHO. Keep us posted on those numbers though, nice build regardless.

Although you can go higher on pump gas, we will typically recommend something closer to 11:1-11.5:1 for street cars for that "just in case" scenario.

i have 12:1 and run 93

Dynamic compression will be the great equalizer. The bigger the intake duration and the less advanced the ICL is the lower the DCR will be, and vice versa.