I am planning to supercharge another TBI soon. I am looking for better control than a FMU and timing retard can give me. I am going to attempt to use a 2-bar MAP on a $42 code. Will it work or am I better off trying to modify $58B code and put it into a 7730(more common then the 749). I am going roots style Weiand 142 for the curious. Any guidance would be appreciated. Seems everyone has talked about doing it, but nobody has.

 

Except for the satifaction of doing it. A 58 based solution will be so much better.

A simple plate with 8 injector "holes" machined in would be the easiest route. Might check out some 4 cyl rails for spacing. Other wise custom rails would be needed. The machining of the rails & bungs is the major expense.
Then you have to decide what to do for a TB(s).

 

A 730 doesn't have the right injector drivers to run 2 TBI injectors, so you do need a 749, and use the Sunbird wiring.

Roots?, are you going to blow thur, or draw thru?.
Are you going to vacuum reference the regulator?.

 

TBI on a roots, would be a draw thru. No need to vac refrence the regulator, the injectors themself will never see any boost presure.

I assume just to flow enough fuel, you are still planning on running a FMU to add the FP under boost?

 

This is not something i know much about, but what if you connect the MAP sensor to a point between the TB and blower? In this position, won't it behave much like a n/a car and see vacuum when the throttle is closed, atmospheric pressure when open?? It's not gonna see boost in that position..

 

Gee, what an idea, why didn't I think of that....

Personally, I'd vac reference the fuel pressure regulator, ie, to the intake.

Then with the MAP sensor refernced to the manifold (under the blower) rather to the Throttle Body, you could properly run *boost* type code.

 

why would you have to modify the code or hardware for boost? Wouldn't you just divide the actual KPA by 2 before modifying the stock timing and fuel tables that are labeled 0-100?

 

The tables start at 30 K/Pa. Just eyeballing it, so then they'd read 60->200. It's one of them things you'd really want to bench to make sure you have the tables right, and have latitude for overrun, without having to be forced into using DFCO, all the time.

 

forgot about the 30kpa start, makes sense now

 

So you are saying that the TBI sunbird uses a 749 and all I have to do is wire the ECM in sunbird configuration and it will run after some chip work. As in set the cylinder select bit, change the injector constant, load my VE table, and my spark table and run with it in N/A mode. Then stick the blower on and tweak on the boost side of the calibration.

I see one flaw, isn't the $58 code a MPFI code.