[Diy_efi] boosted compression ratio

[Matt Porritt]

The turbo specs are pretty close to what we've used before on 2l turbos,
though I'm a little worried about the CR you're stating.
For boost of around 20psi I'd be looking at around 8 to 8.5:1. This would
allow you to run a little more boost if needed, but not see you 400whp
though (@20psi) but with a bit more boost you'd get close.
Now I see you mention 'Street Driving'.. Ever driven a 400whp machine on the
street??? :)))
I'm not that familiar with the Honda range when turbocharged as I am a
Nissan man ;) so i'm not saying that your 10:1 isn't ok in your application,
its just that unless we were building a strip car, then we'd be looking a
little lower in the CR,
-- 
Matt Porritt
RC Race Cars and Supplies
ICQ #22776813


On 22/12/02 3:00 PM Nick Starai wrote

> 
> I'm currently rebuilding my project Honda. Wondering what kinda CR you
> guys would recommend. My engine management system is a modified OEM ECU by
> Hondata. I will have full control of fuel/timing map and boost through an
> electronic boost controller. I also have a knock sensor with individual
> cylinder retard.
> 
> Some specs that may help: 1.95l aluminum head and block. The head has a
> factory port/polish. The engine will run somewhere around 20psi through a
> garrett t3 .63 a/r stage 3 / t04e 57 trim .60 a/r to reach my goal of
> 400whp. Will be run on 93 octane pump gas. My previous build was 8.8:1 as
> I was able to put a shelf pistons in for cheap. I want to choose ideal c/r
> for this next rebuild and will get custom pistons. It sounds like 9:1 (not
> much different then 8.8 )is a reasonable median for street drivability
> while still allowing a decent amount of boost. I've read many many heated
> threads of high compression moderate boost vs. low compression high boost
> merrits and it seems to boil down to around 9. Obviously higher cr will
> make more power all things equal, but there is probably a ratio that is
> more desirable for my street setup. I wouldn't hesitate putting in some
> 10.0:1 or 9.5:1's and running 20psi, I'm just trying to get a feel for
> what everyone else in thinks is reasonable. I know that tuning will be the
> key, but I don't know if 10:1's will be able to run decent timing at
> 15-20psi on 93 octane. I will have access to an inertial w/ wideband
> initially. I'm just wondering what some of the experts on this list would
> recommend for a street boosted custom application. Any advice? Thanks.
> 
> Nick Starai
> 
> 
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