Need some recommendations on a fuel pump

3ponyshow

Founding Member
Jun 26, 2002
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Las Vegas
So I'm at the dyno and my A/F is crapping out at about 5800 rpm making it very dangerous to put into boost. My Tuner says the duel Steeda pumps (came with my mongoose setup) aren't getting the job done. He also said I'm pushing my 30 lb injectors and really should upgrade to 42 #'s.

My question is, since my basket was modified to accept the dual pumps, would it be better for me to get a Focus or Lightning pump (and buy a new basket?) or stay with a dual setup and go with something like the dual Cobra pumps?

What other options do I have that I don't know about?

'Preciate any tips. :flag:
 
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I'm making about 360 rwhp and only looking for +/- 400.

As for BAP's, that a good question. From what I know of BAP's, (which isn't much) they're: 1. for more aggressive applications. 2. if the pump's duty cycle is maxed out, the BAP won't help.
 
Hopefully others with more experience will chime in.

However the KB site says that the stock GT pump with BAP can handle 475 HP.

Dual Cobra pumps with BAP is good for 650 HP.

See "Fuel System" on page 6

http://www.kennebell.net/techinfo/ford-techinfo/46gtTechTips_26L.pdf

There is a whole section on Fuel tech at:

Ford Technical Info

It is very interesting. Sounds like it may save a bunch of $$ as the current pumps should be good for the current HP level. With the BAP, they would be good for a lot more.

My vote is look at the bigger injectors first.

OBTW, how much boost are your making? Could you be chasing boost at the expense of HP? Consider that as boost goes up, then the Delta fuel presure has to go up. Greater absolute pressure reduces the capacity of the fuel pump.

Consider that in some cases, less boost and more timing could make more total HP. Isn't that really the goal?
 
I'm making ~400rwHP with 36# injectors and the stock GT pump with a KB BAP. I agree with wmburns: the pumps are probably not your problem. You can verify this with a fuel pressure gauge.

How did your car come to have 30# injectors? I thought the Mongoose kit came with 42# units...

According to the formula for "safe horsepower" as a function of injector size:

SHP = (Inj# x N x DC) / BSFC

where:
  • Inj# = size of injectors (in pounds)
  • N = num cylinders
  • DC = max desired injector duty cycle
  • BSFC = brake specific fuel consumption

and using a BSFC of 0.6 for a supercharged engine, the safe horsepower limit for 30# injectors at an 80% duty cycle is theoretically:

SHP = (30 x 8 x 0.80) / 0.6

or 320HP. Even the 36#s I have come in at "only" around 384HP. 42# injectors would bump that to 448.
 
wmburns said:
My vote is look at the bigger injectors first.
First, thanks for the reading. I was on the KB site, but didn't see that. I'm going to go back over there after I send this. As for the bigger injectors, We didn't max out their duty cycle yet when the pumps gave out, so we know the pumps are the weakest link. He suggested the injecters because 30# injector are not rated to make that much hp, 42's are.

wmburns said:
Could you be chasing boost at the expense of HP?
No. But he did say that 400 rwhp was not obtainable with my 6# of boost. I would definately have to reduce the pulley. Unfortunately, as you've already outlined, that creates other problems and is not a solution in and of itself.

wmburns said:
Consider that as boost goes up, then the Delta fuel presure has to go up. Greater absolute pressure reduces the capacity of the fuel pump...Consider that in some cases, less boost and more timing could make more total HP. Isn't that really the goal?

That makes sense and if I'm underfstanding it correctly, it does line up with what he's saying.
When I brought the car in, I had 5.58# boost , 19 deg timing and produced 360 rwhp. The A/F was already dangerously high and he backed off the timing right away. Long story short with the setup the way it is, I can't reach my 400 rwhp goal.

trinity_gt said:
...the pumps are probably not your problem. You can verify this with a fuel pressure gauge.
Wow! that's great stuff! Thank you!
The gauge on the dyno is what confirmed that they are the problem. At 5800rpm WOT the A/F meter went straight up. That said, the fact that you're setup provides you with what I'm looking for in results indicates my understanding of BAP's is incorrect. Time to reconsider them as a viable solution.

trinity_gt said:
Do you know what the boost and/or HP rating of those kits was when sold with the 30# parts?

I believe the base Vortech mongoose with the 3.60" pulley was supposed to deliver 6# and produced 325rwhp when first installed.

Keep in mind, I'm very much out of my league with this stuff and can't competently repeat half of what he told me but, he has a great reputation, more equipment than any shop I've ever seen and explained in detail the relationships of all the working parts.
 
Wow! that's great stuff! Thank you!
The gauge on the dyno is what confirmed that they are the problem. At 5800rpm WOT the A/F meter went straight up. That said, the fact that you're setup provides you with what I'm looking for in results indicates my understanding of BAP's is incorrect. Time to reconsider them as a viable solution.

Just to clarify, I said fuel pressure gauge, not AFR. The AFR simply tells you you're lean but it doesn't pinpoint why.

You'd need to hook a fuel pressure gauge to the fuel rail and/or log the fuel pressure from the sensor on the rail via a scan tool to know if the pressure is dropping.

If the pumps have the capacity, you'd see the AFR showing lean but the fuel pressure still as expected (e.g. if you read the sensor on the rail via a scan tool you'd always see somewhere around 40psi.)

BTW, I just re-read your OP and note you're running dual Steeda pumps. Is that pump setup compatible with the original FPDM (fuel pump driver module) in terms of current demand?

I believe the base Vortech mongoose with the 3.60" pulley was supposed to deliver 6# and produced 325rwhp when first installed.

If that's what the system was originally rated for the 30# injectors make much more sense. If you want an additional 75rwHP you're going to need bigger injectors.

Keep in mind that for a daily driver, especially one in a smog-region, you want to run the smallest injector that you can that meets the fuel demands of the engine. As you move up to larger and larger injectors low-RPM, low-load drivability and emissions can suffer because it becomes tougher to accurately control the fuel shot: it's easier for the PCM to give a small injector a bit more duty cycle than to dial back the duty to a minimum value and still have the injector shoot a large wad, so to speak.

42s would be a good choice for your goals. But double check the fuel pressure and FPDM compatibility too.
 
You're never going to make 400 rwhp at only 6psi. You'll need a smaller pulley to achieve that.

As for your fuel issue, I think the injectors are the weak link, not the pumps.

FYI, I'm selling my 42 lb injectors and my entire GT fuel tank with SVT Focus pump that has successfully made 400 rwhp. PM me if you're interested.
 
Just to clarify, I said fuel pressure gauge, not AFR. The AFR simply tells you you're lean but it doesn't pinpoint why.

You'd need to hook a fuel pressure gauge to the fuel rail and/or log the fuel pressure from the sensor on the rail via a scan tool to know if the pressure is dropping.
Yes, I understood you and he was connected to the fuel rail and was monitoring both AF and AP.

fightmstr1 said:
I'm selling my 42 lb injectors and my entire GT fuel tank with SVT Focus pump that has successfully made 400 rwhp. PM me if you're interested.
Interested? Hell yea, PM'd.
 
Do you know what the boost and/or HP rating of those kits was when sold with the 30# parts?

most I saw were non intercooled 8lbs kits were 360-380 rwhp , few pulleyed more and got near 400rwhp but they were close to maxing out , and Tim never raised rev limiter on stock engines , I think he used to raise the fuel pressure 10lbs in the tune to get more fuel as well