Going from KB boost a pump to GT 500s

[flounderlipps]

I have a Kenne Bell 2.6L
I'm Going from KB boost a pump to the GT 500 pumps.
Does anyone know if I have to get the car retuned?
Thanks

 

[3c673cxao7l9o7u80ag8as1g2]

The Ford installation manual for the GT dual fuel pump makes no mention of a need to retune/recalibrate the vehicle.

 

[MSgt46270]

When I went from the stock fuel pump to the GT500 fuel pump, I did need to get the car re-tune. After the GT500 fuel pump I was running rich then.

 

[3c673cxao7l9o7u80ag8as1g2]

I would call and ask Ford Racing this question. You're going to have both a YES and NO response to your question.

 

[MikeVistaBlue06]

Actually I would ask that question to a good tuner rather than Ford Racing.

Mike

 

[Dread53]

I'll be paying attention to this as I have a set of GT supercar pumps sitting at home waitng for install.

 

[rog06gt]

If I'm not mistaken, not matter how much pressure you push on the injectors the PCM will always try to maintained a 40psi differential pressure across the injectors...
Somebody correct me if I'm wrong...

 

[ZmanM3]

I too have heard it both ways, some people have had to retune and some have not retuned with on problems.

 

[ChevyKiller]

If I'm not mistaken, not matter how much pressure you push on the injectors the PCM will always try to maintained a 40psi differential pressure across the injectors...
Somebody correct me if I'm wrong...

Unless you tell it otherwise in the tune. I see about 60 psi at WOT.

I have -8 lines, #60 injectors, GT500 pumps, KB dual 40 amp BAP, and Adam didn't have to change the tune during these upgrades. (they were done at different times)

I think you may run a little more rich if you are getting more fuel but I don't think you 'have' to have a new tune. I think a new tune will capitolize on the upgrade though.

I think if you plan on spinning the car higher now that's it's got more fuel available, then you will need to retune and for your a/f accordingly.

 

[cekim]

I think a new tune will capitolize on the upgrade though.

The PCM should "trim" (learn) the amount of pump duty cycle needed to get the desired rail pressure. There is a coefficient in the tune which basically gives the PCM a ballpark figure on what to expect from the fuel pump and then it "learns" from what it sees while running and adjusts on top of that...

So, particularly when you first put it in, it will be a little "surprised" by how much pressure it gets from a given command (compared to the old pump), but it is a feedback system so it should adjust. Not a terrible idea to get the tune adjusted though, so it does not have to "learn" and does not lose this info in the future when things get reset.

 

[US-1]

Actually I would ask that question to a good tuner rather than Ford Racing.

X54000000000000000000000000

 

[Kevin@PMP]

Unless you tell it otherwise in the tune. I see about 60 psi at WOT.

At WOT the fuel pressure drop across the injectors is still the commanded fuel pressure (DeltaP) in the tune and for most tunes will remain static across the RPM range.

Fuel pressure drop across the injectors = DeltaP + Manifold Pressure so if running a DeltaP of 39.5psi (stock) with 20psi of boost you will see 59.5psi on a gauge but the pressure drop across the injectors is still 39.5psi. The FRPS adds 1psi of fuel pressure for ever 1psi of boost unless the car is tuned otherwise. That is why at idle if you data log fuel pressure drop across the injectors it will read 39.5psi but on a gauge it is around 30psi or so. 30psi = 39.5 - 9.8. The 9.8psi is a conversion from 20in-hg (vac at idle) to psi.

The PCM should "trim" (learn) the amount of pump duty cycle needed to get the desired rail pressure. There is a coefficient in the tune which basically gives the PCM a ballpark figure on what to expect from the fuel pump and then it "learns" from what it sees while running and adjusts on top of that...

So, particularly when you first put it in, it will be a little "surprised" by how much pressure it gets from a given command (compared to the old pump), but it is a feedback system so it should adjust. Not a terrible idea to get the tune adjusted though, so it does not have to "learn" and does not lose this info in the future when things get reset.

Exactly it may take a little bit of driving but the PCM will learn the fuel pump voltage tables to compensate for the new pumps. It will run rich until it relearns the pumps and will run lean anytime the tune is reset.

 

[cobra4548]

So if you have the GT500 duel pumps or the Ford GT Duel pumps, do you need the KB dual boost-a-pump or can you not use it?

 

[Kevin@PMP]

So if you have the GT500 duel pumps or the Ford GT Duel pumps, do you need the KB dual boost-a-pump or can you not use it?

For 99% of people it isn't needed any more with twin pumps. If you want to run a BAP with the full GT500 pump setup with twin FPDMs or any twin FPDM setup you will need 2 BAPs or the new BAP from KB for the GT500 which is just 2 BAPs in one big enclosure. Without 2 BAPs you are only increasing the output of one pump. If running twin pumps with a single BAP then you would only run a single standard BAP.

 

[ChevyKiller]

Ditto. I didn't have a need for the dual BAP until I breached the 650 rwhp mark. Now this is on my trans. On a manual, I wouldn't have needed the BAP's on top of the GT500 pumps until I breached around the 700 rwhp mark.

Up until there, the dual pumps were plenty enough.

 

[ChevyKiller]

At WOT the fuel pressure drop across the injectors is still the commanded fuel pressure (DeltaP) in the tune and for most tunes will remain static across the RPM range.

Fuel pressure drop across the injectors = DeltaP + Manifold Pressure so if running a DeltaP of 39.5psi (stock) with 20psi of boost you will see 59.5psi on a gauge but the pressure drop across the injectors is still 39.5psi. The FRPS adds 1psi of fuel pressure for ever 1psi of boost unless the car is tuned otherwise. That is why at idle if you data log fuel pressure drop across the injectors it will read 39.5psi but on a gauge it is around 30psi or so. 30psi = 39.5 - 9.8. The 9.8psi is a conversion from 20in-hg (vac at idle) to psi.

Thanks. Great info.

 

[cobra4548]

Thanks for the clarification!

 

[Slofoot]

My car was pig rich after swapping from the BAP to the GT500 pumps even after driving with them for a month or so. You don't have to retune but you may be leaving HP on the table. I was.

 

[flounderlipps]

Thanks for all the feedback
The reason I'm changing over to the GT 500s is I have the recalled fuel pump (hesitation after a long cruise).
I feel the car hesitate some times when I just stomp on it, if I don't punch it hard or punch it with the rpm's up, no problem.
But I'll probally go for the retune.
Thanks again everyone.