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Raise or Lower?

3042 Views 4 Replies 5 Participants Last post by  ali.zahiroleslam
Alright well I've been talking to my auto tech instructor, and been reading on here for quite some time. I'm kinda getting mixed signals. I'm getting the impression that if I plan to have a turbo in order to have higher boost, I need to run lower compression. So...

Lower Compression allows more boost?
Higher Compression allows more HP on an N/A motor?

I plan to turbo, but it probably won't happen for a year. I only want to run around 10psi. So would I be better going for higher... 9:1 compression, or staying somewhere around stock... 8.5:1, or lower... 8:1 compresion? thanks
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You can run 10psi on stock compression. Which is 9.5:1 for KA24DE. Just make sure you have enough fuel.

Edit.. and yes, lower compression allows more boost on pump gas. higher compression you get more hp either way you go, NA or forced induction.
it's just that lowering compression is ideal for turbo and you do lose some power but it's made up, up top with the extra boost you can run.
i have a 97 240 ka24det and run 8psi and have dynoed at 156 whp my freind has a 240 and has a sr20det with mods and runs 14psi and dynoed at 152 whp and he cant figure out how im making the same power at only 8psi and its becuase im at 9.5:1 comp so my ka doesnt need 14 psi to put out big hp numbers his comp is 8.5: big difference when adding boost!!
Honestly, with the technology that is available today, a compression b/w 9:1 and 10:1 will be better for street driven turbo cars up to 15psi or so. A higher compression motor will do way better out of the hole, and spool the turbo up way faster. High boost applications is another story tho.
I used just 3psi and i have 188whp using 9.2:1 in my KA24DE
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