Sonicyeller

So does the SS/TC use an actual fuel pump or just a lift pump?

Here's my thinking, and correct me if I'm wrong...

Can you compound liquid pressure like you can air pressure? If so, would it be possible to increase the output of the in-tank pump and use that to increase fuel pressure going into the HPFP which would result in higher output pressure, ie more fuel overhead?

Iam Broke

iTrader: (10)

BYT has rn a Walbro upgrade with some success but the HPFP is positive displacement, so increasing the inlet pressure has little effect IMO unless it just starves out.

BYT*SS*TURBO

iTrader: (6)

They sell these boost pump kits where you can increase the voltage to the in-tank pump, they also sell a Aeromotive Digital FMU with secondary pump where you can add another pump inline, have full adjustment of it and also increase pressure in the line before the HPFP. Haven't tried it to see if that will help but it seems like no matter what, the HPFP will be the limiter regardless.

jphugel11

If this is correct, and I only say if because I have no idea, then the HPFP proves to be the limiter and there really won't be a difference. When it comes to positive displacement pumps, increasing inlet pressure won't increase output, not significantly at least.

silverbullet08

I have a walbro 255 in my car. It does help slightly.... The HPFP is still the limiting factor though. I run a 22-23psi spike on full E85 and you can see the pressure drop off pretty good to about 1400-1500psi sometimes lower, With the walbro FRP falls a little later now. It seems to hold the pressure a little longer then falls just as hard as on the stock pump but seems to recover to normal pressure a lot faster.. im guessing cause the motor is further revved out and boost is starting to taper by then..