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Hi all-

I'm looking at running 137mm h-beam rods and vitaras in a d16a6 with an ebay turbo (AR .63 on the hot side, .5 on the cold). Aiming to make 300hp on this build (all specs below). The car is for competition only, 1/4 mile drag and autoX for the GRM $2k challenge, so I'm VERY budget limited.

The zeal calculator says that my CR will be 7.3 as opposed the stock 9.1. How big of a problem is the low CR? I've read that for every full point of CR you drop you'll lose between 3-4% power. That's a 8% power loss until the turbo kicks in, but the car should launch at 3k in the drags, and I don't think he revs would go lower than that in the autoX.

Am I missing anything, or will I be fine with that CR?

Specs:
1991 CRX HF, gutted
225/45/15 A7 Hoosiers
DX cable transmission
d16a6, 137mm H beams and Vitaras
LS throttle body, z6 intake
Felpro mls HG (.028)
ARP head studs
ebay turbo kit .63/.5
3" side exit
225 walbro
450cc DSMs currently, probably evo 560cc soon
OBD0 Tuner Express currently, hopefully OBD1 on HTS soon
 

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You can retard the timing under boost a bit to help spool it up.

You can always shave the head a bit to bring some compression back, but honestly, as much as I HATE low compression, it will help keep the motor alive.


If you only have DSM 450s right now, I have a set of ID600's I need to get rid of. I think they have capability of OBD0/1/2 with the included adapters. See my for sale post if it is still available
 
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