High Compression with Boost question
Thread Starter
Intermediate
Joined: Nov 2019
Posts: 25
Likes: 0
High Compression with Boost question
I am in the process of building a LSX 427 long block and would like some advice on what compression ratio would be best for my setup. I will be running a UPP twin turbo kit expecting to run 20+ lbs of boost. I also have a Haltech 2500T for engine management and flex fuel. My question is what is the best compression ratio to safely make 1000+whp? I have heard that 11.5:1 compression is safe up to 20 lbs of boost with the right fuel.
Race Director
Joined: Mar 2011
Posts: 13,262
Likes: 3,151
From: SW Florida
2021 C6 of the Year Finalist - Modified
There must be a good reason why GM lowered the compression ratio of the supercharged LS9 engine to 9.1:1 (10.5 PSI max boost) while the normally aspirated LS3 is 10.7:1 and the LS7 is 11.0:1
Heel & Toe
Joined: Apr 2019
Posts: 17
Likes: 0
A lot more goes into it than just your static compression ratio of 11.5:1 or whatever you decide; quench, the exact fuel you'll be running, camshaft (determines dynamic compression). Your first step would be to decide exactly which fuel you'll be comfortable with running and sticking to. I'd recommend some sort of ethanol like Ignite 114.
