Im lookong for a very basic rule if thumb. Or maybe clarification.
Do you generally want higher compression ratio like 10.5 and up when running NA and nitrous vs. Lower compression ratio running FI?
Forgive my ignorance. Im still learning.

 

No, lower compression ratio for all power adders such as Turbo and Nitrous, you can often add a supercharger with stock compression ratios

 

Any type of forced air injection only needs low compression.

 

Thanks i was apparently way confused. Ha. Thanks yall.

 

Generally speaking, an engine build centered around N20 as a power adder you can build something with higher compression, such as 10.5:1 as mentioned in your first post. F/I, you want a lower c/r to avoid detonation.

Of course with either there are several other considerations such spark timing, getting that right in the tuning process will get the most out of your build and keep it "safe". Spark timing can be retarded to some extent as a means of combating detonation; that said, most would not want to build a high compression engine for f/i and then just dial back the spark timing as it would probably end up making less power than an engine with lower compression that allowed for more advance in the timing, given equal amounts of boost.

I remember a few years ago when the Coyote engines were introduced how everybody thought that due to the stock compression ratio (think they come in at around 10:1, iirc) that those engines wouldn't be boost friendly. Now look, people are bolting on s/c kits to stock engines and pushing 600+ rwhp on stock internals and didn't have to swap to dished pistons to drop c/r. I don't have a wealth of knowledge on those particular engines but I'm guessing the trick to it is somewhere in the tuning.

 

Lower compression if you wanna boost.