Low compression?
 

Sorry for the possibly noob question but what's the point of a low compression built motor? Are they any good NA or only FI?

Thanks!!!

The higher the compression the more HP you'll get out of it NA (in theory, there are limits). In NA builds sometimes youll see custom pistons increasing the CR along with other things like cams, headwork, sleeves, blah blah blah.

Lower compression for FI means you can push more boost safely. Lower compression from stock will result in a smaller gain in HP per PSI of boost as compared to stock 12.5:1 CR. On the flip side youll be able to run more PSI.

My $.02 is that if you want to run more than 12ish PSI then you can lower the compression to ~ 10.5:1. If you plan on pushing more than 20 PSI then >10:1

This is on pump gas ofcourse. E85 is a different story.

So lower compression means more safe boost but less hp per psi. So the only reason to lower CR is push lots more boost?

In a nutshell, yes.

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Essentially what your dealing with is octane limitations when your talking about amount of boost vs. static compression.