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Hi everyone,

I have a few technical questions on my 3800 Supercharged build:

L32 Bottom End

L36 Polished UMI and LMI

Powerdyne Supercharger

Intense Stage 2 Performance Package

Walbro 225 In Tank Pump

B&M Torque Converter

Glo Shift Gauges and Pod


(A/F Wideband)

(Fuel Pressure)

On the Car is already:

Pacesetter Headers

3" Magnaflow Catback

Cat Delete (Straight Pipe)

3.42 Rear End with Upgraded Disc Brakes all around.

My questions are:

1) Since this Performance Package comes with a Custom PCM Tune, will I need to install an FMU???

The words I'm hearing out there is Yes, No, and No, Stay away from FMU's if possible...

YES: The FMU is needed because I will need to be able to adjust the Fuel Pressure and Return Line flow here and there, a tune is set in stone.

NO: Once dialed in the Tune has the A/F mixture set all that is needed is a strong enough Fuel Pump to respond to the higher demands of the Powerdyne, any fluctuations in Lean to Rich would be a mechanical issue in need of fuel pump, pressure regulator, or filter repair/replace.

NO, STAY AWAY FROM FMU'S IF POSSIBLE: Aftermarket FMU's are prone to failure, and when they do you either soak your rings or burn your pistons, or at best leave you stranded until a replacement arrives.

Everybody I have talked to in the area seems to argue a good point, but none are 3800 owners... so they don't know for sure.

2) What size Injectors should I go with, can I pull and use the injectors from the 2004 Plus Grand Prix GTP donor car (I believe its either 32lb or 36lb), or do I really need to go 42lb?

I am planning on running under 10 PSI of boost. I am leaning towards just keeping the L32 Series 3 Bottom end intact without going forged pistons (this mainly is a budget and time issue... the decision could change with other deciding factors). I know that the stock L32 specs are running 5-7 PSI stock on the Grand Prix and there are owners who have upped the boost up from 9-10lbs with light mods, and up to 15 with a tune and some more involved mods without going forged... don't know if the 15 psi unforged range is safe or smart tough.

My mode of thinking is that I can grab the GTP Injectors when I'm pulling the L32 block and be just fine. I'm not going very far off the Supercharged Grand Prix platform specs, the Walbro should be able to to keep the fuel flowing and maintain Stoichiometric output.

3) I have removed the catalytic converter, and had the After-Cat O2 Sensor programmed out of my PCM. With the A/F Wideband Gauge install, will I run into problems with my current O2 Sensor configuration?

I want to be able to monitor my A/F mixture like a hawk, so I want an accurate reading, I'm putting a lot of time, money, and effort into this build... so I don't want a simple thing like a OBDII code removal of O2 Sensor to destroy all my work.

Anybody's 2 cents is appreciated, I have not run across any concrete answers yet. Besides a 9 year old how to article of now out of business Powerdyne Install (Which was intended to be home garage installed, and not professionally tuned), there is no real conversation about building up and boosting a real nice V6 the smart way. Everybody just gets overwhelmed and discouraged and just buys a V8... I was in that category last year, but the thought of a 300-325HP V6 that is still DD capable is really appealing to me.

I'm past the planning phase and no into the compiling parts and watching the junkyard for the L32 phase... Pretty Exciting.
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