The handful of super/turbo tunes I've seen use the stock values for the basic and extended "Volumetric Efficiency vs rpm vs map" tables. I thought super/turbo chargers always improved VE. Why aren't these tables modified? If they should be changed is there a "rule of thumb" as to % change per psig of boost?

 

If the cars are using the maf then they are not referenced AT ALL period. So it doesn't really matter what it says in there unless the maf fails. The cars you're looking at are also probably not running major boost either I would hope if they are tuned the way I am thinking.

If the cars were running a 2bar map sensor I would expect to see extensive changes in the timing and ve tables. Imo that is the only suitable way to tune a forced induction lt1 car. The problem being, it takes one hell of a lot of time to get it all 100% where it should be and you have to do a lot of 'tricks' due to the way the ecm is constrained. Due to the time involved an lsx pcm swap with a 2 or 3 bar os is my preferred route on a FI car.

 

WS6T3RROR:
Sounds as though the VE tables are an artifact from the 1993 speed density cars ECMs. I looked further and found what was tagged as a 383 8psig Speed Density tune and there were changes, which confirms your info. Interestingly though those changes were reductions from stock. Thanks for your reply.

 

Poor hot rods don't run as good at low speeds as stock.

 

"Poor hot rods" ... yes, the differences were greatest at low rpm and/or low MAP pressures.

 

Numbers in the ve table are not everything. If you have a much greater than 100% ve number you can screw with the injector constants so you can get enough room to richen the car up. Again it all depends on exactly what methods you're using.