HPFP upgrade
- Thread starter jdeprato
- Start date
05yellowgt
New member
Does anyone know which Bosch HPFP's are used in the Traverse and Longitudinal 3.5 Ecoboosts?
05yellowgt
New member
I'm trying to do some math here to understand how much fuel the stock high pressure fuel system should be capable of flowing, assuming that the low pressure pump is keeping up on its end. All the Bosch HPFP data I can find lists that the pumps flow 1.1cm^3 per rotation. As you can see in the picture below, the Cam lobe that drives the HPFP is 4 sided. This means that each full RPM flows 4.4cm^3 of fuel.
The max pressure that the stock ECU commands the fuel system to deliver is 2150psi (~150 bar) according to Ford's specs I have found online. If I can assume that the HPFP can deliver the quoted 1.1cm^3 at 150 bar then I can put together a simple table that shows the maximum flow at a given RPM(.
rpm flow cm^3 liter/hr
1500 6600 396
2000 8800 528
2500 11000 660
3000 13200 792
3500 15400 924
4000 17600 1056
4500 19800 1188
5000 22000 1320
5500 24200 1452
6000 26400 1584
6500 28600 1716
7000 30800 1848
IF (and this is a big if in my mind) the math is correct, there should be MORE than enough fuel on the HPFP side, so long as the ECU cam command it and the pump can flow the advertised 1.1cm^3 of fuel per stroke. It is totally possible that the pump can't keep up those flow numbers at high pressure, in which case there would definitely be a limitation. IF (again big assumption) these numbers are right, we just need to increase the low pressure fuel pump flow and the next limit would be the injectors themselves.
The max pressure that the stock ECU commands the fuel system to deliver is 2150psi (~150 bar) according to Ford's specs I have found online. If I can assume that the HPFP can deliver the quoted 1.1cm^3 at 150 bar then I can put together a simple table that shows the maximum flow at a given RPM(.
rpm flow cm^3 liter/hr
1500 6600 396
2000 8800 528
2500 11000 660
3000 13200 792
3500 15400 924
4000 17600 1056
4500 19800 1188
5000 22000 1320
5500 24200 1452
6000 26400 1584
6500 28600 1716
7000 30800 1848
IF (and this is a big if in my mind) the math is correct, there should be MORE than enough fuel on the HPFP side, so long as the ECU cam command it and the pump can flow the advertised 1.1cm^3 of fuel per stroke. It is totally possible that the pump can't keep up those flow numbers at high pressure, in which case there would definitely be a limitation. IF (again big assumption) these numbers are right, we just need to increase the low pressure fuel pump flow and the next limit would be the injectors themselves.
05yellowgt
New member
Was that due to the fuel pump running out of capacity, or due to the direct injectors running out of capacity? Some more math assuming a 0.95 BSFC for E85 on this motor you need about 790L/hr to produce 700bhp. That should be supportable by the stock HPFP if my previous math is right. I'm pretty sure the ECU would be able to command that without scaling several tables (This had to be done with my returnless fuel tables on my Mustang when I kept with the returnless fuel system but it worked afterwords).
I really need to see some of these fuel tables and see what they look like compared to what I am used to.
I really need to see some of these fuel tables and see what they look like compared to what I am used to.
05yellowgt
New member
We're all anxious to see how your build progresses, as always!
Are the in take pumps supplying your aux system too? I can't remember. Looking at them, they flow right at 300L/hr at the pressures that the supply pumps run at.
Are the in take pumps supplying your aux system too? I can't remember. Looking at them, they flow right at 300L/hr at the pressures that the supply pumps run at.
05yellowgt
New member
The dual pumps are probably near their limits then. The stock system runs around 65psi I think, which would mean around 300L/h per pump. Take a look at the Walbro 400lph E85 compatible pumps. They shouldn't be too much of a difference dimensional wise vs what you have now.
05yellowgt
New member
Peak of 85PSI looks to flow a little below 250L/hr per pump. Round that up to 500 total and the math isn't making sense to me. Given that the BFSC of just about ever E85 boosted motor I have seen has been between .85-.95 the math tells me you would need 625-700L/hr of fuel to hit 550rwhp. If we were to assume the pumps are giving their all the BFSC would calculate out to around .68. It would add up if you were running gasoline, but not while running E85 unless the ecoboost is the most efficient motor I've ever heard of (which it is impressive, but not THAT impressive).
Sorry I keep dragging this on out, I'm just a numbers guy that can't help but try to do the math. The 10.9 AFR means you had plenty of fuel so I guess it means I must have made an error along the way somewhere.
Sorry I keep dragging this on out, I'm just a numbers guy that can't help but try to do the math. The 10.9 AFR means you had plenty of fuel so I guess it means I must have made an error along the way somewhere.
