Tuning for SC on 165 5.7L (long)

Dave Z dzug at mail.delanet.com
Fri Mar 19 22:21:29 GMT 1999


I'm going to pull both triggers here.. potentially exposing my 
ignorance in the hopes of learning something. Contribute thoughts to 
the thread, maybe it'll make a good archive.

>From what I gather.. when boosting a NA engine, there are a few 
issues that stick out. One is that you need to back off the spark 
advance to get higher boost levels at a given octane rating. for 
selfish purposes, I'm talking a SC not a turbo, so the advance 
reduction increases (advanced reduced) LINEARLY as RPM increases.. 
assuming the SC increases boost linearly with RPM. What I'm looking 
for here is a guideline for just HOW MUCH to back off... I'm guessing 
0-3 degrees as boost goes from 0 to say 5 psi. Oh, the SC manufacturer 
states "use the stock chip".. whats with that? I want to be emissions 
legal, but skweeze out the power too.

the second issue that sticks out is ESC rates. I'm thinking they'll 
need to be more aggressive (more reduction faster) as there is more 
stress on the components and the stock parts can't take the beating.

the third issue that stands out to me is Idle power. the SC takes 
7-10 HP to just TURN at idle.. how's that going to affect idle and 
coast-down performance? might the IAC be able to handle it or need I 
adjust the base throttle plate opening so the IAC doesn't sit at 100% all 
the time?

the fourth issue is MAF level. my 165 apparently tables up to 208 on 
the LV8 scale for spark.. what about 255? I know that IF THERE WERE ROOM I 
could re-index the LV8 spark table to include a 13th and 14th column, 
and use 2 more steps in resolution but the 16k is FULL, and I'm sure 
its not as simple as re-scaling the original 12 columns.. I'll 
probably mess something else up. has anyone dealt with the 208 
thing or the problem of a FULLLY OCCUPIED 16k space?

I'll stop here.

Dave Z - 87 GN 12.74 @ 105 w/1.84 60'
               13.02 @ 103 on 94 octane
       - 89 IROC 5.7 
       - 89 Turbocharged GP (retired itself) 



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