(before telling me to search, I have already gone through the archives)

Ok, I will be getting a different motor pretty soon. Setup as follows:

GSR JG Pro Series Head
GEM 83mm b18c1
JE 10:1 pistons
Eagles
Hondata 2b, delphi 550's, walbro 255lph intank
t3/to4e .57, .63

91 OCTANE

QUESTION:

Is my compression too high for california 91 octane gas? I do not plan to use race gas. My goal is 350+ whp and I will be tuning on a dyno. Obviously I will make more power than a 9:1 at lower boost BUT I want to make sure my turbo actually boosts high enough to get its efficency point. What is the efficiency point on my turbo>

I like the higher compression for faster turbo spool. I am just worried that my margin of error is low. Is 10:1 considered high? I hear mixed opinions on this specific compression. Thanks


MAIN POINTS I AM LOOKING AT:
-91 octane gas limits?
-Boost level to hit the highest efficiency?
-Will the 83mm bore have anything to do with my questions?

I have searched and found nothing to satisfy my setup specific question.





Modified by intekragsr at 1:25 PM 5/7/2003

 

well I personally am a fan of higher compression + boost.
I would IM hybridKoop...since he is the one who is a big fan of higher compression with turbo applications (11.1 in his B16)

HTH

 

You'll be able to make your 350whp with lower compression on 91 octane. Essentially lowering the compression makes the turbocharger do the work instead of the engine. I would rather turn up the boost, then stress the bearings, rods, etc with higher compression.

The 83mm bore really has no bearing upon the compression factor. The greater displacement coming from the increase in bore size will allow you to spool up the turbo quicker, and therefore make the turbo more efficient at lower psi levels since the engine will be able to flow more cfm into the turbo (more energy).

The 57 trim is a great compressor since it is efficient at 8psi, as well as 20psi. The greatest efficiency range (most power to be made) is going to be in the 12-16psi range for the 57 trim.

 

Thank you. Hit my question right on the spot.

 

hmm sounds good.. anybody have anymore input on this? i'm thinking of going from 8.8:1 to 10:1

 

8.8:1 to 10:1 is damn good change 10:1 is mostly run on race motor for the longest time i prefer the high compression as well its just more chance of detoantion if untuned. but otherwise its perfect.

 

oooo the spool time is gonna be lovely =D