Anyone know how many horsepower the walbro pump is good to?? Can I push a Garrett GT30 to 30 psi with a ported head on 720cc injectors on a single walbro??

 

I would say around 450whp.

 

I would think you should be OK as long as your running pump. You might want to consider going to a larger injector size though. I think a 255lph is good for around 500hp.

 

In my experience 520whp on a dynojet was the limit with 1 walboro that I saw....with 1,000cc injectors and a really high duty cylce.

 

Here is AEM's answer by the numbers for fuel pumps:

(Estimated HP x BSFC) x (1 + Safety Margin) = pounds/hour
pounds/hour / 7.25 = gallons/hour
gallons/hour * 3.785 = lph

BSFC refers to the efficiency of the engine. They suggest .65 to .68 for forced induction.
The recommended safety margin is .30 to give you a comfortable net to work with.
The 7.25 is the estimated weight of a gallon of fuel (gasoline) for conversion. If you are using something else (Meth, E85, Water, Nitrous, etc), this will change.

Let's assume your end goal is 500hp.
500hp x .65 x 1.3 / 7.25 = 58gal/hr * 3.785 = 220.6lph

This leaves a pretty big cushion for you to work with.

Or we could work it backwards, knowing that the Walbro outputs 255lph...

255/3.785 = 67.37gal/hr * 7.25 = 488.44lbs/hr / (1.3 x .65) = 578.04hp

So this would mean that the 255lph Walbro is good up to 578hp on gasoline with a .3 margin of safety.

 

Gas the 255 is OK, injectors are too small though - 880's would be better, and at that point go BIG anyway.

E85 the single pump won't work, and you need some 1200 or bigger injectors.