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Discussion Starter · #1 ·
Got a question.
Slugmobile needs an in-tank fuel pump, but she also uses a second fuel pump in the engine bay to gain the required flow for high boost.
As long as I need to put a pump in the tank, I may go with one that can handle things on its own, and eliminate the secondary pump.

What's the difference between the walbro 255 (and the walbro 255 high pressure) and the Ed Peter's Viper Pump. I have the Viper pump in my Dodge, but I don't know what flow rating it was. It could handle 400hp in the Viper and has silver windings, but other than that I don't know much about it.
Any suggestions? I did just finish removing the broken one, so I'd like to get something ordered so I can put it all back togther Friday.

Who are the Big Daddy fuel Guru's on the board these days?
Cheers!
Wayne
 

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i think the viper pump is rated at 225lph and the walbro is 255lph, walbro also makes a 190lph.

i think you want the walbo 255.
 

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Discussion Starter · #4 ·
If using the 255lph, Can the existing return line provide enough flow when the engine is idling or in high vaccuum to maintain lowered fuel pressure, such as 25-30 psi over manifold press.
Slug uses 53# inj and a 25-30# reg.

If I remember right, my Dodge has a minimum pressure that no matter how much vaccuum you have on the fp reg, it won't go below. I'm not sure if it is from the Viper pump, or the added bent tubing for the Car Tech reg.
So that is what would concern me with Slug. I don't want to be chugging black smoke at idle, or have overly rich starts.
 

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the size of the return line is what restricts the flow and wont let you bring the FP down, I dont remember exactly what the cut off was with the stock line and a walbro 255, I want to say ~25psi is as low as it will go. This is just from my head(from reading many many posts in the last couple years) as I never ran a stockish setup, except for when my car was basically stock
 

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Some people have a problem getting the fuel down low enough. Their solution is to use the factory 5/16 as a return and run a new 3/8 feed to help things. the 255 is good to
500hp. Let me know how the install goes I am going to do mine soon- I have a 255 walbro intank for mine.
 

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Discussion Starter · #7 ·
I'm not sure which route I'll go yet.
In keeping with Slugmobile's primary theme "low-buck HP" I'll go with the cheapest and easiest route. I'd rather not have to run new 3/8" supply line.
But if the 255 would work with the current fuel lines S & R, then I would do it. Pump is about $89 on ebay.
 

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I guarantee that the eBay pump is a knock off and not a real walbro. Plenty of people have had problems with them, enough that I would shy away. Get one from the vendors, like FWDPerformance.

And if you do want to risk it with the fake one, be SURE to replace the rubber fuel hose with good quality high pressure injector hose. The other stuff isn't rated for the pressure of for fuel use or something because they do deteriorate and fall apart.
 

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Have a 255HP on my van, no pressure issues. Pressure issues will only come around at the lowest flow point, which would be idle or even when the car is off, after that point the injectors are flowing enough to make up for the lack of the return line size. That is to say, just because you're running good while driving around, does not mean you're not over running.
 

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Discussion Starter · #11 ·
tkelly27:
What injectors are you using on your van?
What fuel pressure do you run?
Do you use a rising rate of gain secondary regulator?
Supply and return lines are stock?

Thanks!
Wayne
 

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I'm using a custom computer, 83 lbs injectors, stock fuel pressure regulator and stock pressure, stock size fuel feed and return lines, and walbro 255 pump. Wideband says I have no a/f problems.
 

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Big second on not buying the ebay stuff. With a vendor you will get support and be sure that you don't get a knock off.
 

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Discussion Starter · #14 ·
and if you have vaccuum signal on your stock fuel pressure regulator you can get down to 40 psi fp? (29.92 " Hg on the stock 55# regulator)?

Thanks for the help, I just want to make sure I have all the info to make my decision. I certainly don't want to have to lower the tank again!

Wayne
 

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Discussion Starter · #15 ·
one of the vender was posting on ebay.
I am familiar with some of the crap out there. That's why I'll stay away from Advance Auto for this item.
Although, they have the Holley Pump which is the same as Walbro from what I've heard/read.
 

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On my '88 Shelby Z I had to upgrade to 5/16" return line. I couldn't get my pressure below something like 60#'s even with a vac source to the reg.

I'm running a 255HP pump, +40 injectors, Accfab reg, FWD S5 cal.
 

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Discussion Starter · #17 ·
Thanks for all the input.
I was leaning towards just replacing it with a stock unit. I'd like to keep the set-up how Gus designed it, and you helped me make up my mind.

I've had a new pump to replace the secondary in the engine bay also, just need to get the right fittings to install.
 

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Nice to see you keeping Slug stuff going.

I personally like the two pump setup. I believe 2 stock pumps will outflow a Wallbro 255 (no testing, just gut feel). Having said that, the only drawback is that there is now an extra point of failure.

BTW, I use two very large pumps in my Neon because I was dropping fuel pressure at 22 psi.
 

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^^do you run them in parrallel or series?

Also, so you know the +'s and -'s of each of those set-ups. This is something I've been pondering about for a while now...
 

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^^do you run them in parrallel or series?

Also, so you know the +'s and -'s of each of those set-ups. This is something I've been pondering about for a while now...
Series. These pumps have a hard time with high volume at high pressure. The series configuration helps them maintain the volume at the higher pressure. 55 base + 30 psi of boost = 85psi. Very few single pumps can maintain high flow when you need it most.

With paralell, both pumps are pushing against each other. Both working very hard.
With series, they help each other, both under less load.
 
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