Justin@VMP
June 24th, 2007, 10:01 PM
Today I did a quick wiring upgrade on a 7.5psi (3.825" pulley) intercooled whipple 06 Mustang GT. GT500 pumps are going in tomorrow, but figured I would try this first.
Before the wiring upgrade FPDC (Fuel Pump Duty Cycle) was at 95% at 6500rpm. After the wiring upgrade it dropped to 85%, the fuel pump required almost one volt less at peak fuel flow (about 4.6lb/min). This car was making 420rwhp with a 11.5:1 A/F. I then tried a smaller 8.5psi pulley, still had plenty of fuel (about 91% DC). With the 3.325 (10.5psi) whipple pulley the stock pump is finally on the edge.
I did this mod a while back on the wife's 06 4.0L with a 15psi Vortech making 395RWHP. At the track it dropped the FPDC by 8-10%, I never put it back on the dyno so I was hesitant to post results. After seeing it work on this GT I definitely think its a good way for some guys on the edge to get a little more head room.
The saleen SC cars with the 3.6"/8.5psi pulley pretty much peg the fuel pump by 6300-6500rpm, so this mod would be really good for them.
It would be interesting to try the Ford GT pump + wiring upgrade, if it results in 20% more fuel flow overall then it would be an inexpensive way to safely support 450-475rwhp.
Whenever I do this type of testing on blown cars I tune the fuel pump tables so the car runs a constant 39psi deltaP, if you don't tune the pump then fuel pressure will drop off at high RPMs and fuel flows. The more pressure required the harder a pump has to work. The V6 is a perfect example, it pegs the pump much sooner than a V8 because so much more boost is required to make the same power. The point is, your FPDC may look fine, but if your fuel pressure is low from the pump tables not being tuned then your pump is getting away with less work. When properly tuned the pump would most likely be pegged.
Before the wiring upgrade FPDC (Fuel Pump Duty Cycle) was at 95% at 6500rpm. After the wiring upgrade it dropped to 85%, the fuel pump required almost one volt less at peak fuel flow (about 4.6lb/min). This car was making 420rwhp with a 11.5:1 A/F. I then tried a smaller 8.5psi pulley, still had plenty of fuel (about 91% DC). With the 3.325 (10.5psi) whipple pulley the stock pump is finally on the edge.
I did this mod a while back on the wife's 06 4.0L with a 15psi Vortech making 395RWHP. At the track it dropped the FPDC by 8-10%, I never put it back on the dyno so I was hesitant to post results. After seeing it work on this GT I definitely think its a good way for some guys on the edge to get a little more head room.
The saleen SC cars with the 3.6"/8.5psi pulley pretty much peg the fuel pump by 6300-6500rpm, so this mod would be really good for them.
It would be interesting to try the Ford GT pump + wiring upgrade, if it results in 20% more fuel flow overall then it would be an inexpensive way to safely support 450-475rwhp.
Whenever I do this type of testing on blown cars I tune the fuel pump tables so the car runs a constant 39psi deltaP, if you don't tune the pump then fuel pressure will drop off at high RPMs and fuel flows. The more pressure required the harder a pump has to work. The V6 is a perfect example, it pegs the pump much sooner than a V8 because so much more boost is required to make the same power. The point is, your FPDC may look fine, but if your fuel pressure is low from the pump tables not being tuned then your pump is getting away with less work. When properly tuned the pump would most likely be pegged.