AIC

[Robert Gallant]

Hi Tony;

> I done a couple of projects. What do you need extra injectors for -
> boost????


I've got an '86 Rx7 that I put on a positive displacement supercharger. 
currently I'm running 8.5 psi of boost, but will be increasing it to 12
psi.

I wasted a lot of time playing with a holley digital projection.  I
ended up adapting the stock fuel injection system to work with the
supercharger.

The stock system uses staged injection.  One injector fires directly
into the engine, and another fires into an intake runner.

Since the supercharger replaced the intake runners, I installed a
throttle body (similar to an accel) that can hold up to four injectors.

I increased the primary injector from 41 lb/hr to 49 lb/hr, and the
secondary injectors are increased to 62 lb/hr (rotaries under boost like
lots of fuel!).

I've been doing minor fuel adjustments by placing resistors on the water
temp and air temp sensors.

At full throttle/full boost, the mixture is fine up to about 5500 rpm. 
Above 5500 it starts to lean out in a hurry.  I'm using a redline of
8000 rpm and the power doesn't drop off till well above 8000.

I attached a wire to monitor the MAF sensor (remember its a stock
injection system) and found that the MAF is wide open at 5500 rpm/full
throttle.

What I'm guessing is that the computer doesn't sense an increase in flow
from 5500 to 8000 rpm, since the sensor is already wide open, so it
doesn't increase the fuel.

I'm going to try and tighten up the adjusting spring inside the MAF
(flapper door type) so that it doesn't fully open till past my redline
at max boost.  After doing that, the whole fuel curve will be shifted
down.  I'll need to shift it back up by an additional injector (or two).

Ideally, I'd like to pick the cut in boost, slope increase with rpm, and
slope increase with boost.

I'd love to see what you put together.

BTW:  I'm using peak-hold injectors.

Thanks
-- 
Rob
MailTo:gallant at oasys.dt.navy.mil