alright so i am putting together a motor and i need some advice on fuel pump options.

s4 turbo motor+mild streetport+750cc pri. and 850cc sec.+rtek 1.8 =

A:stock pump
B:fd pump
C:something bigger

 

supra tt pump?

prob wont need to upgrade for a long while

 

How much boost? Remember FD pumps usually sell for ~35 shipped.

 

im not sure what boost i am going to run yet, i just dont know if the stock pump will be alright to push those injectors.

 

if your going to change the pump get the supra TT pump for sure

 

What about the Walbro Pump or the performance fuel pump from rx7.com?

 

Best thing to do is add up your injectors - (750*2)+(850*2) = 3200cc/min

So, you need a pump that will flow 3200cc/min or whatever that is in lbs/hr (onlineconversion.com is a great place to get that info) at your base pressure + boost. 60psi would be a good place to start. 43.5 PSI base, which is high, + boost, 16.5 PSI is high.

Get the pump that you know will flow that.

On the other hand, FD's ran what for injectors? 850*4? If that's the case, the FD pump will work.

 

the walbro is garbage bro dont ever by one. i had one fail and blow my motor. and when i took it to the shop the rotary mechanic of 20 years told me he has many people come in with a failed walbro pump and a blown motor...he recomended the OEM quality supra twin turbo pump. he said he has never seen one fail. and it pumps 255+ lph which is just as much or more then the walbro

 

thanks, that helps alot. ans iirc fd's had 550 pri and 850cc sec.

 

No worries. If the FD runs 550/850 (which I think you're correct btw) I would hop over to rx7.com as I believe they had a flow chart of the stock pump. I would not jump to conclusions that the FD pump will work and be safe just because other people have run it. Best thing to do, in my eyes, is to match the pump to the worst case scenario that your injectors will see, 100% duty cylce at a high base pressure plus more boost than you plan to run. This way you're certain that the pump will suffice even if the injectors won't. I believe you can view injector duty cylce with the Rtek, no?

 

I didn't find the flow chart for the fd pump. Does anyone know what the max flow of the fd pump is?

 

here is a little tid bit of info i found
http://fc3spro.com/TECH/MODS/FUEL/fpump.htm

 

Please correct mean if I am wrong but according to that chart the fd pump can pump 72gallons per hour. What does that brake down into cc per min?

 

4542cc per min

 

At what pressure though? I plan on using the RP pump that I have, that was an upgrade for the FD as my LIFT pump. Meaning virtually 0 pressure.

 

I am having trouble understanding this fuel flow deal. That chart says 72 gal per hour and 0 psi. How does that work? 4542cc per min is quite a bit of flow. Is that right, or can someone explain this flow chart to me?

 

it means at rail pressures the FD fuel pump will flow ~45 gallons/hr. The less resistance, the more a pump will flow. The better pumps have a more linear predictable drop off rate of flow. There's nothing magical about that chart. Look at what your rail pressures are going to be, and then intersect that with what the pump will flow. Pretty easy low grade math.

FWIW a gallon is ~ 3785cc's or the pump flows 170344ccs/hour or /60 = 2839 ccs/min @ rail pressure. (750*2)+(850*2) = 3200ccs /min. Or I wouldn't use the FD pump.

Let me correct that, I wouldn't use an FD pump for a pressure pump. I would use it for a lift pump though becuase it flows 72 gal/hr @ 0psi and 69 gal/hr @ 10psi. And my injectors can't eat that up (750/1000) regardless of how big my pressure pump is.

Why do people not do simple math and just follow the flock?

 

Oh for eff's sake - I just went to RP and they have thier **** listed in lbs/hour just to make things more mathematical......

what does a gallon of gas weigh? 7lbs iirc? so that pump is supposedly flowing - 57g/hr or ~3600cc's/min. Just barely enough for my fuel system...... assuming a gallon weighs 7 lbs.