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Old 08-29-2006, 12:30 AM   #6
bboy
Scooby Specialist
 
Member#: 56468
Join Date: Mar 2004
Chapter/Region: NWIC
Location: Seattle, WA
Vehicle:
04 Improved STI
Dirty White

Default

I can't help but ramble....too many variables.

I can believe that the JDM stuff is more aggressive, but I wonder if there is much difference in the shape of the map---sort of a amplitude difference even though the frequency is unchanged.

Scotty...4 or 5 degrees is a lot!!!

The "spool up" region, for lack of a better word, is the region of most interest of me. What I've found is that more AVCS advance just above atmospheric pressure, around 2800-3500 seems to help get the turbo going. Below atmospheric (vacuum) it's very hard to tell. At first I added advance to these load sites (2500-3000, 85-10 mm Hg) and it seemed more slugglish, but the fueling was off, too rich. Now that I lowered the AFR it seems about the same as it was before.

There are a ton of variables: cam advance, spark advance, fueling, plus everything is changing so quickly in those load sites on the road it's hard to know what is "best".

Dyno time is expensive so people don't tune this stuff very often. It would be nice to have a vendor, preferably one that has a load varying dyno, look into general principles. Even then, I know each car will be different. Torque though would seem to be the baseline measurement to optimize. If torque is optimized, then so should the exhaust volume and heat.

Intuatively my larger turbo should have a different AVCS map than the stock turbo, but that may not be true. If one were to look at RPM vs MAP maybe it would be exactly the same for a given set of cams.

I think what I'm going to try a few different maps in the "spool up" region with the fueling adjusted, then switch between them and log the output.

At high boost (let's say 15-20 psi), mid RPM, Phil's map is just about maximized (as much advance as you can run without "flutter"), and that is what I've tried to maintain. After about 4800, AVCS is tapered down and off by around 6000. I'm willing to throw out a little fuel (west-minist) at mid-RPM to get quicker spool or less lag (if that is occuring....anybody know when injectors begin fueling?....it may be after the AVCS-advanced intake valve opening).
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