Fuel System

[Polygon]

I plan to be running 25PSI and be around about 350WHP. I plan to buy a Whalbro 255lph, TU fuel rail and regulator. I assume that I will want to get the +40 injectors?

Anything else I should do?

[Turbodave]

Maybe a wideband O2 to tune it. but sounds like good setup to start with.

[turbovanman²]

I think you'll be ok but I think the +40's won't support much more power. Shelgame would know better as he does cals.

[mcsvt]

May want to upgrade your fuel lines. You don't have to, but it wouldn't be a wasted upgrade. Something like run a new feed line and use the old feed line as your return.

[Polygon]

Maybe a wideband O2 to tune it. but sounds like good setup to start with.

I figured that was a given. ;)


I think you'll be ok but I think the +40's won't support much more power. Shelgame would know better as he does cals.

Hmm, do you know the celing for the +40 is? What would be the next step up from them?


May want to upgrade your fuel lines. You don't have to, but it wouldn't be a wasted upgrade. Something like run a new feed line and use the old feed line as your return.

Are you talking braided fuel line with A/N fittings or just new OEM line?

[turbovanman²]

Hmm, do you know the celing for the +40 is? What would be the next step up from them?


No but Rob will.

I don't know if you need to change the fuel lines, 350 whp has been done numerous times on the stockers with no issues.

[John B]

I had rich idle with +40s until I upgraded to 3/8" and used the old 5/16" feed for return. I used aluminum tubing for my new feed line.

[Stratman]

I have been running 352 HP to the wheels with an A-413 and I was just starting to watch it try to go more lean in the upper RPMs. With the stall and everything it maybe 400 or more HP at the crank. I believe the rating on the injectors will supply around 400 HP with four +40 injectors. I am not sure at this point if it is both the injectors and the fuel supply causing it, but I am working on getting some 72 PPH inj since I need them this year.

[turbovanman²]

I had rich idle with +40s until I upgraded to 3/8" and used the old 5/16" feed for return. I used aluminum tubing for my new feed line.

That seems to be the minority, :eyebrows:

I also run +40's and had to turn UP the fuel pressure, lol!

[johnshaft53]

need WALBRO P/N 4495057 Fuel pump motor, or diagram so I can open sealed motor to attempt repair.

[johnshaft53]

:lol::thumb:
need WALBRO P/N 4495057 Fuel pump motor, or diagram so I can open sealed motor to attempt repair.

[badandy]

That seems to be the minority, :eyebrows:

I also run +40's and had to turn UP the fuel pressure, lol!
No, not the minority actually. Most can get away with not doing it but they are running rich at idle. I bet most are either not worried about it or simply don't realize it. I have had to upgrade the fuel return on the past two cars (running +40's) I have owned.

[cordes]

The injector DC is pretty scary on the +40s for most of our motors at anything above 22-24PSI. Not only that, but you are really maxing out your FP while running that much boost. As I have stated in other threads the 43PSI static rating on the 72s, and most other larger injectors is a real bonus in that it frees up so much head room for higher boost pressure while not maxing out the FP.

I have seen injectors from 72pph to as much as any of us could dream of needing for $65 each on the net, so I really don't see a reason not to upgrade if you are going to be pushing really high boost, or are making big power with a hybrid headed motor etc.

I know that many have run 30+ PSI with a little alky on +40s and that it works well, but you can only go to the well so many times. If purchasing new or upgrading I see no reason to handicap ones self.

[badandy]

The injector DC is pretty scary on the +40s for most of our motors at anything above 22-24PSI. Not only that, but you are really maxing out your FP while running that much boost. As I have stated in other threads the 43PSI static rating on the 72s, and most other larger injectors is a real bonus in that it frees up so much head room for higher boost pressure while not maxing out the FP.

I have seen injectors from 72pph to as much as any of us could dream of needing for $65 each on the net, so I really don't see a reason not to upgrade if you are going to be pushing really high boost, or are making big power with a hybrid headed motor etc.

I know that many have run 30+ PSI with a little alky on +40s and that it works well, but you can only go to the well so many times. If purchasing new or upgrading I see no reason to handicap ones self.

The question I have is for an application that is mostly stock (cylinder head and intake) will the larger injectors behave at idle and cruise once the computer is recalibrated? Lower fuel pressure and a larger orrifice at the pintle usually is not a good thing for driveablilty.

[Stratman]

I ran the 52 pph injectors on a stock intake and a head which probably flowed less than stock. Economy was decreased by 2 to 3 MPH over the 42 pph injectors which were installed previously. Idle was fine with calibration, but after the good head work idle was much better. The 72 pph may give you a little trouble with gas mileage and rich conditions.
This will be the first time with the 72 pph but I have a feeling calibrating for anything other WOT is going to take a good amount of time to get it right.

[cordes]

The question I have is for an application that is mostly stock (cylinder head and intake) will the larger injectors behave at idle and cruise once the computer is recalibrated? Lower fuel pressure and a larger orrifice at the pintle usually is not a good thing for driveablilty.

I honestly wouldn't know how it would be with an essentially stock intake and head. From what I have seen, I would think that the stock ECU would be able to handle it well once scaled and adjusted. I think that even the LM would be able to do it, but I don't know that you would have 100% stock characteristics.

At the same time, I probably wouldn't recommend going with the 72s if you have a stock head and intake. I think that the rate of dimenishing returns would be in full effect with a stock head etc. by the time the 72s were really needed.