I have been talking with some friends here in Oklahoma, I know the crossfire has a 3.2l supercharged engine and have been toying with the Idea of trying adapt it to the 3.7. B&G performance will custom program my ECM to work with the changes. but have yet put pen to paper on the idea to figure cost and not to mention weather this motor will handle such an upgrade. any one want to chime in on this
I think it's going to take a little bit more than ECU programming to compensate for the boost pressure, depending on the amount of boost involved.
A while ago I had a pipe dream of fitting a turbocharger to my Nitro, but I thought it would be too expensive, so never really looked into too much.
For the purposes of your supercharger, I'll assume a modest 7psi of boost (1.5 bar). I also assume, without knowing, that the 4.0L has a volumetric efficiency (VE) of 92% and a air to fuel ratio (AFR) of 14:1
The stock system consumes 390 cubic feet of air per minute. That translates roughly into 30 lbs of air per minute. An AFR of 14:1, yields 7.1% fuel to 92.9% air every stroke. That means the stock injectors, including the standard 20% extra are a minimum of 25lb/hr injectors. The stock fuel pump is a minimum of 150lb/hr @ 41psi. I'm pretty sure the bean counters prevented the factory from putting higher rated injectors/fuel pumps into the vehicles stock.
7 lbs of boost:
The boosted system is moving 48lbs of air. Since the charge air is hotter due to compression, the mixture must be increased to 13:1 to produce a knock resistant mixture. This moves the percentage up to 7.6% fuel to 92.4% air. This new setup will require 31lb/hr injectors with a fuel pump capable of 185lb/hr @ 48psi.
I don't think the stock fuel system will handle 7lbs of boost. You might be able to get by with 2 or 3 lbs of boost, with some timing retardation, but I'm not sure if the expense is going to be worth it.
P.S. I estimate 400 bhp, minus the "cost" of the supercharger with 7lbs of boost.
P.S. -- O.k., last time I tried to post this stuff I didn't have any of my books or reference materials and I came close, but screwed up a few points. This is take 2. The Fuel/Air ratio of 13:1 was just fine, it was the method I was using to calculate the percentage weight of the fuel that was way off. No wonder my other post so was way off 13:1 != 13% in anyone's book.