1 is enough. Rewired of course

1 or 2 will support 500hp. Make sure you rewire it too.

I did 452hp on a mustang dyno on e85 and 1 walbro 255 intank.

of course 2 would, but I was wondering what the limits ofa single was. And yes they are both rewired as of now and wouldnt change if I went single. Idk how you would be able to tell if it is maxed out or not, but Gamble did it seem to suffice enough for an additional 50-100 hp? (just estimating a lil more than I want just incase I get a wild hair. )

If you have two already installed why bother removing one? I would leave both of them in even if you are using a 14b on a stock engine. The parts have been purchased and the work is done.

I have to back in that access area anyway and might as well since I will be in there and ahve the chance, and I am pretty sure they are touching the bottom as well, cause it was a lil bitt longer than the stock assembly. And it was cause of the y peice for the pumps, so I elimnate that piece with a single pump then it hangs in the right place. THen get 50 or so from the other pump help put towards other parts.

I found this thread.
I think It might help you find your answer.
It has really good information.

http://www.dsmtuners.com/forums/bolt-tech/290215-walbro-255hp-max-hp.html

You could sell both the 255's and get the FP 340. That'll be more than enough for your goals.

If $50 is going to make or break your build then you have bigger problems than needing to know if a single 255 intank will supply 500whp. With fuel supply it is always best to have more than you need.

Tyeler18 said:

You could sell both the 255's and get the FP 340. That'll be more than enough for your goals.

Click to expand...

The wally 255 (number 34*) flows the same as the FP 34* Rated at the same power and everything. So he could sell one of his current walbro pumps and have the same flow as the fp 342. The difference in price between the wally and the no-name fp model is a wopping $10.

. . .So yea. One of his walbros is enough for his goal. But like mentioned, why bother downgrading? There's been no legitimate reason given by the OP so far. Hanging slightly lower or getting an extra $50 in cash doesn't seam like a collection of good reasons to me. Take the time you would spend pulling the pumps and putting it up for sale and having net dialog with potential buyers; add all that time up and instead work the same time as overtime.

arturorz said:

I found this thread.
I think It might help you find your answer.
It has really good information.

http://www.dsmtuners.com/forums/bolt-tech/290215-walbro-255hp-max-hp.html

Click to expand...

Thank you, read that seems to be good info.

dsm-onster said:

The wally 255 (number 34*) flows the same as the FP 34* Rated at the same power and everything. So he could sell one of his current walbro pumps and have the same flow as the fp 342. The difference in price between the wally and the no-name fp model is a wopping $10.

. . .So yea. One of his walbros is enough for his goal. But like mentioned, why bother downgrading? There's been no legitimate reason given by the OP so far. Hanging slightly lower or getting an extra $50 in cash doesn't seam like a collection of good reasons to me. Take the time you would spend pulling the pumps and putting it up for sale and having net dialog with potential buyers; add all that time up and instead work the same time as overtime.

Click to expand...

No ligitimate reason, and 50 isnt goign to make or break my build, I am jsut relitavely saying, for my power now it is unnecassary, and would rather have 50 in hand to put toward something else bigger. And the fact that the overall length of the way my pumps are set up is longer than stock and I am sure it is riding on the bottom of the tank, which is not that good for the pumps. So wanting to decrease length I can tank one pump out, leave out the Y-piece and then it would be right at stock length and keep it from grabbing nastys at the bottom.

DSM_munky_man said:

of course 2 would, but I was wondering what the limits ofa single was. And yes they are both rewired as of now and wouldnt change if I went single. Idk how you would be able to tell if it is maxed out or not, but Gamble did it seem to suffice enough for an additional 50-100 hp? (just estimating a lil more than I want just incase I get a wild hair. )

Click to expand...

You can tell 1 way by seeing if the afr goes lean in the upper rpm range.

I also use two walboro fuel pumps, they are both HP, one is "in-tank" and the other is "in-line", I noticed that before I changed to dual, the single pump had the loud whine. I think it was straining, with the e85 fuel and the 950cc injectors, I couldn't run over 22lbs with the stock fuel lines, after changing to larger lines, the single setup allowed over 28lbs, so I can imagine that the addition of the "in-line" will allow me to lift my head if I want to do that.

Hmm, cause at this piont I am no where near 500 at all, I say probably bout 250 being generous. Nothing really crazing going on yet till I get it tuned on 85, I mean I am up to date on mods in profile, and only thing going to be different here in a month or so is FMIC, SD setup and then getting it tuned. So far at 16 psi, but will bump up to 20+ with the fmic and e85

If you have really large injectors, and an afpr, you can make a good deal more power by lowering your base fuel pressure.

Why lowering it? And it is on stock press. right now, but on e85 it should be set to 43.5 correct? So why would I want to lower it?

DSM_munky_man said:

Hmm, cause at this piont I am no where near 500 at all, I say probably bout 250 being generous. Nothing really crazing going on yet till I get it tuned on 85, I mean I am up to date on mods in profile, and only thing going to be different here in a month or so is FMIC, SD setup and then getting it tuned. So far at 16 psi, but will bump up to 20+ with the fmic and e85

Click to expand...

Which new turbo are you planning to switch to? In order to achive 500Hp.
I'm just curious.

I'm going to be tunning for E85 soon. I can hardly wait !!!
Let us know how you liked it once you make the switch.

DSM_munky_man said:

Why lowering it? And it is on stock press. right now, but on e85 it should be set to 43.5 correct? So why would I want to lower it?

Click to expand...

Lowering your base fuel pressure effectively reduces the size of your injectors, it also allows your fuel pump to flow more, because of the reduced load on the pump. So, if you have injector to spare, you can lower the base pressure to stretch a single pump a lot further. Look at flow charts for fuel pumps, after 70-80 psi, they fall off hard.

That's why people mod there wally by pinching the relief valve so it won't bleed out at higher boost.

arturorz said:

Which new turbo are you planning to switch to? In order to achive 500Hp.
I'm just curious.

I'm going to be tunning for E85 soon. I can hardly wait !!!
Let us know how you liked it once you make the switch.

Click to expand...

Unsure of turbo atm, I am going to max out my e3 first, then decide. Still up in there are for a holset or an FP green or red.

donniekak said:

Lowering your base fuel pressure effectively reduces the size of your injectors, it also allows your fuel pump to flow more, because of the reduced load on the pump. So, if you have injector to spare, you can lower the base pressure to stretch a single pump a lot further. Look at flow charts for fuel pumps, after 70-80 psi, they fall off hard.

Click to expand...

Ic, well right now I am running 1250s, how much psi is seen at the top ends of our motors really?

DSM_munky_man said:

Unsure of turbo atm, I am going to max out my e3 first, then decide. Still up in there are for a holset or an FP green or red.



Ic, well right now I am running 1250s, how much psi is seen at the top ends of our motors really?

Click to expand...

Base pressure + boost pressure + pressure loss through the fuel lines = pressure at the pump.

DSM_munky_man said:

Unsure of turbo atm, I am going to max out my e3 first, then decide. Still up in there are for a holset or an FP green or red.

Click to expand...

Smaller turbos like those need boost to make power. You need more pump if you want to make power with more boost. . . You are wasting your time and infact handicapping your setup you ALREADY HAVE IN PLACE.

Imback said:

That's why people mod there wally by pinching the relief valve so it won't bleed out at higher boost.

Click to expand...

What relief valve? Is it on the wally itself? I must of missed this post when I was replying.

dsm-onster said:

Smaller turbos like those need boost to make power. You need more pump if you want to make power with more boost. . . You are wasting your time and infact handicapping your setup you ALREADY HAVE IN PLACE.

Click to expand...

Are you saying I am handicapping my current set up because of the low boost? I am planning on turning boost up again, I am currently eliminating knock right now on my current level. And am Waiting on a few other parts to turn it up as well.

DSM_munky_man said:

What relief valve? Is it on the wally itself? I must of missed this post when I was replying.



Are you saying I am handicapping my current set up because of the low boost? I am planning on turning boost up again, I am currently eliminating knock right now on my current level. And am Waiting on a few other parts to turn it up as well.

Click to expand...

Are you running e85 already? If so, getting knock at low boost is next to impossible.

For the money you have wrapped up in your setup, you could already be running low 12's. The formula is out there. 16g, e85, injectors, 1 wally, clutch, and a 3" exhaust. My car trapped 107 with the only mods being a walbro, 16g, 750cc injectors, and i burned a chip. Full stock exhaust, and intake.

Ok but he wants to do it easily. Without the lengthy seat time and many more busted trannys as a consequence So he should stick with the fuel pump setup he has and know that he will have plenty of fuel if he wants to up the boost with a healthy enough turbo to actually see his goal realistically. He did mention 500whp here. And he IS running a 16g.

The single wally setup would be enough for that. But it's plus $50 to you and minus the time taking the pump out AND minus the time money put into installing it that way in the first place. . . I don't see why this is a big discussion. If you're going to do it, you can see your goal with one intank. But you're doing away with all the work you already put into a dual pump setup. . . So I tend to keep my work IN my setup, instead of taking it out by doing more work for $50.