So just like the heading says, anyone have any Idea what the max HP you can get with a 5.4 3v with 39# injectors? My truck is getting dyno tuned tomorrow. I have the STS turbo kit with a 62mm turbo. Just installed new rods pistons and crank and the dual fuel pump set up from JDM. I want to run about 18lb's of boost, but I'm thinking that my injectors are going to be the defining factor on that. BTW gt500 injectors wont work with a 3v

 

I am thinking they are good up to 500rwhp after that then you will need 60lb injectors.

 

I'd say a bit more than 500rwhp. I ran around 535rwhp with 42s on a 4.6 cobra motor with a vortech and twin pumps. Since you are turbo'd, I'd say you can run even more because the motor is not wasting hp spinning the blower on top of its own power. I'd try the 39's because they are OEM before I jump to 60's. Big injectors don't always run as smooth as OEM injectors. The bigger injectors have really improved over the years though.

 

Sweet thanks guys. When I started this project I was aiming for between 500-550 rwhp. Next step is to free up some HP with some e-fans and anything else I can think of. I'll post a dyno graph tomorrow.

 

624fwhp.... 475rwhp give or take the rule of thumb is .5lbs per hour to make 1 hp. so how many hp can one 39lb injector make? 78 multiply that by the total number of injectors and u get 624hp.

 

What are you figuring for the parasitic loss in your function? (I'm not talking about the drive train here.)

 

Saleen's S302E car runs 600+ hp with 39# injectors. And it's supercharged. I don't know if the fuel pump is being overdriven under boost or not though.

 

So, do you mean 24% drivetrain loss and 78% duty cycle?

 

You're going to run out of fuel pump before you run out of injector, unless you're running dual pumps.

 

Hey Im curious on ur Fuel pump set up that you got from JDM, do you have more info on it?

Also why wont the GT500 injectors work?

 

The gt500 injectors were too short. Thats what my mechanic told me when he tried to install them. The fuel pump setup from JDM are (and this is what my mechanic with a 700 hp twin turbo 4.6 3v said) is basically just the gt500 setup with a different fuel hat and relays. And its about $1,300. Pretty damned over priced if you ask me. But hey, they have the monopoly, and they developed it for the saleen f-150's. Supposedly its good for about 800 ponies.

Right now everything is installed, and the truck runs fine (We even managed a jury rigged cmc delete). Just waiting on the dyno guy to tune it. He's had my truck for about a week and a half now. I'm about to go on a murderous rampage. I haven't had my truck since February, and I'm going to sit in my apartment and pout until I get it back. I have my nitrous express kit and my HID's sitting in my room waiting to get installed too. I'm pretty pissed.

 

Oh **** lol, well I ordered some 47lb injectors that fit the GT500, maybe Ill have to modify the fuel rail (how it mounts to the intake) to adapt for the height.

800RWHP or Crank?

 

If you have a 04 truck, you don't even need to get the fuel pump set up I have. You can get one of the butt loads of lightning upgrade system that are out there. I think they run about 600 bucks if I'm not mistaken. The 05-08's have a return less fuel system.

I don't remember if it was crank or rwhp for the system.

 

Oh I have a new body style like you.

Damn now I'm kinda worried bout injectors....

 

oh ok. I was just looking at your sig where it says you have an 04. I wish I could tell you how much HP I'm getting with the 39# ones. But I have no clue. I'm really tempted to flip this guy the bird and find a place in Atlanta to do my tuning. But its a biotch trying to find someone who well work on these trucks, or even knows what they are doing.