I have a supercharged big block in my '89 Firebird and I would like to use the Holley Projection 4Di that I have laying around. It's a 900 cfm unit with 85 lb/hr injectors at 15 psi, 400 lb/hr fuel pump, and limited to 500 Hp. Here's the challenge:

My idea was to upgrade the fuel pump with an Aeromotive 1300 Hp pump (which I already have), bypass the 15 psi TBI regulator, and use an external regulator to increase fuel pressure until it feeds my motor. The catch is that Holley says the injectors are inefficient after 20 psi. I'm not sure what pressure I'll need yet but I need to support 600 Hp with a decent factor of safety. What can be done?

 

Qwk,

I hate to put a hose to your fire, but 900 SCFM might be a little light for a blown BBC. You REALLY don't want to go lean...

------------------
Later,
Vader
------------------
"Let the bodies hit the floor!"
Adobe Acrobat Reader

 

Looks like you aren't gonna have enough fuel. To close for comfort I think.

Even at 18.5-19psi you will just bearly have enough fuel for a 600hp engine with a BSFC of .55

You need bigger injectors or ones that will tolerate higher fuel pressure.

 

That's the conclusion I was also coming to. Thanks for your advice. Looks like I'm using a carb.

 

you could try to switch to delco injectors, by taking a gm pod, and cutting off the front feet, and then modifying the holley, and facing the pods at eachother, you would need to do some real fuel line modification.

there are also adapters to run the oring style injectors on tbi, and you can get 4 GIANT 90 pph or higher tpi injectors like that but they are hella expensive.

tell me how much you have to spend, i could tell you how you could to it.
i know you want to use as many a parts as you can though.

get me a pic and dimensions of the top of the holley and i might be able to figure something out with a few pods I have.

ive got a design for a 4bbl but no $ to build it, just like my 2bbl.