Need tech help

[EKelley]

I am rebuilding an '89 GT convertible that my wife inherited from her brother who was killed in '02.

'89 GT conv. 5.0,T-5, Mac short tube 1 5/8" headers,2.5 off road pipe, flowmaster mufflers,sub frame connectors.

The car came with a Paxton 5-7 psi supergharger NIB. He had never installed on the car.

I am in the process of rebuilding the engine with several new components to strengthen it for the supercharger.

.030 over hyperutectic pistins. flat tops, eagle rods.
I purched a set of FRPP y303 GT-40 aluminum heads from Racer Walsh.
F303 roller,FRPP aluminum roller pedistal rockers,
Intake is the new BBK,70 MM throttle body
I purched the MASS air kit with 24 lbhr injectors and 76MM MASS air sensor with calibrated ECM.

My question is: Is this enough injector for my combination using the supercharger?
I can return the MASS air kit before I install on the engine.

Any help will be greatly appreciated.

Thanks
Edwin Kelley
Longview TX

[Hozer 88GTConv]

You would need at least 30lb injectors and a bigger (i.e. 90mm-ish MAF) to optimize your setup. The bigger injectors would be mandatory though, IMO.
The trick is with injectors, you never calculate their output at 100 percent of their duty cycle, because they would wear out too quickly. The Mustang Handbook recommends calculating your fuel requirements based on an estimated horsepower output of your combo using only 80 percent of the duty cycle of a given injector. This leads to a much more uniformly reliable spray pattern over a greater time frame, i.e. reliability over time for a daily driver.
Eddie Miller or Mike Lynch at Racer Walsh here in Jax would be great help for you. 904-291-2289
I'm not too sure about those pistons either, maybe for lower boost psi, but forged pistons would be better.
Good Luck...

[EKelley]

Hello Hozer,

I rellay appreciate the tech help. I was told locally that the 24 lb inj would work but after reading articles and write ups on other engine with comparable compopnents I figured I would need larger ones. Are you running the stock ECM? If not what and where did you get the new chip? Is the FMU the same thing as the ECM?

Thanks
EKelley

[Hozer 88GTConv]

There are a myriad of personal preferences to optimize a blower setup.
Some like to go way big on injectors to ensure that a lean condition under boost never occurs, and it's easier on the injectors.
My example: 8 Psi blower with 42lb injectors and a 90mm MAF and a chip (a programmed flash card plug-in for your EEC that readapts fuel and timing curves for a given combo). Why 42's? Because the injector only has to work at 70 percent of its duty cycle. The chip gave it more predictable and finely tuned response across the RPM spectrum than could be achieved with the FMU alone.
Some have had good luck with an FMU, but it is not what I recommend.
Again, I recommend talking to several people with expert knowledge to form your own idea of what you want.
I got my chip from Johnson Motorsports via Racer Walsh. Eddie or Mike will give you all the help you need.
Good luck.