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Thread: Twin inline walbro 255 set up

  1. #1
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    Default Twin inline walbro 255 set up

    I have some questions on setting this up hopefully from someone who has ran the set up. I have a sumped fuel cell that has two outputs -6an. I ordered 2 GSL392 fuel pumps. I am thinking running 2 individual lines out of the cell then having a Y shortly after the 2 pumps. The only thing I see a problem with is what if one of the pumps fails. The fuel pressure would back feed through the bad pump possibly on a WOT pull that could cause a lean condition engine failure. I would need 2 check valves, one for each pump, to safely run this or would I know fast enough to not need the extra hardware in the set up.

    I can also run it physically set up the same way but wired so that one pump runs the car while the other pump only turns on when triggered with a single check valve on that pump. This way one pump doesn't have to work most of the time and if the pump that is most active failed I would most likely catch it before a problem arose. Any good ideas on wiring and making the configuration the safest and most efficient(both financially and performance based)

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    If you are going full tilt and one pump failed, you will know it. The car will start bucking and knocking pretty badly, or you will go straight to having a hole in the side of the block. I would plumb them both without any checkvalves.
    www.atdsm.com

  3. #3
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    It will be the easiest way, I believe, to run them both on all the time. I have researched some people having problems with the second pump kicking on and off. It does seem hard to tune and depending on how hard it kicked on would cause a spike in fuel pressure and possibly when turning off have a spike in the opposite direction.

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    Is the title of this post correct, or should it be parallel rather than in line?

    If it should be dual parallel, then you will not see fuel running back through the turned off or failed unit with or without an extra check valve. The Walbro's have this built in.

    You didn't mention what size return line you are using. If you run both at the same time, you will over run the stock return line and see a minimum fuel pressure of about 50-55 PSI. I turn my second pump on with a Hobbs switch at about 23 PSI of boost to eliminate over pressure problem caused by my stock return line.

    Search is your friend. This has been covered before. Oh, I forgot you probably do not have access to search.

    Terry
    Terry,
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    I unfortunatly don't have access but your information is greatly appreciated. My current setup is a sumped fuel cell with dual -6an out. I am running two 255 inline pumps in parallel and soon after Y them into one -6an(should I go bigger) line to the rail. I also have -8an line that was ran previously back to the tank. Will the -6an be enough to keep the flow up or should I run the -8an to the rail and use the -6an I was going to use as the return. E85 is the fuel of choice so thats why I went with the over kill fuel system. I bought this car with this cell in it and the feed and return lines. So before I order all my fitting to finish it up what would be more beneficial. If my logic is correct the -6an would be better to use as the feed and the -8an as the return. The-6an would keep the pressure up and I think I would have plenty of flow.

  6. #6
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    You should be fine with the two -6 y'd into a -8, then a -6 return. That is similar to the setup here on the 1g. Two -8 with parallel Bosch 044's y'd into a -10, with a -8 return.

    The fuel pressure build up Terry mentioned is generally only at idle and low speed cruising.
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  7. #7
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    Quote Originally Posted by John Whalen View Post
    I unfortunatly don't have access but your information is greatly appreciated. My current setup is a sumped fuel cell with dual -6an out. I am running two 255 inline pumps in parallel and soon after Y them into one -6an(should I go bigger) line to the rail. I also have -8an line that was ran previously back to the tank. Will the -6an be enough to keep the flow up or should I run the -8an to the rail and use the -6an I was going to use as the return. E85 is the fuel of choice so thats why I went with the over kill fuel system. I bought this car with this cell in it and the feed and return lines. So before I order all my fitting to finish it up what would be more beneficial. If my logic is correct the -6an would be better to use as the feed and the -8an as the return. The-6an would keep the pressure up and I think I would have plenty of flow.
    Just as a heads up, avoid using any 90* fittings. If you have the option of going with a 45* do it. I have seen many similar setups which have enough fuel for the power, not have the fuel needed. All due to the 90*s which add a dramatic amount of restriction. A single 90* fitting is like adding 5 feet of line to your system. It adds up quick as well.
    Jason, 96 Talon TSi auto FWD.

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    Thanks for the help. I will keep you posted on the progress. Next subject I will open up in a few weeks and it requires cutting from the strut towers forward.

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    Quote Originally Posted by John Whalen View Post
    I unfortunatly don't have access but your information is greatly appreciated. My current setup is a sumped fuel cell with dual -6an out. I am running two 255 inline pumps in parallel and soon after Y them into one -6an(should I go bigger) line to the rail. I also have -8an line that was ran previously back to the tank. Will the -6an be enough to keep the flow up or should I run the -8an to the rail and use the -6an I was going to use as the return. E85 is the fuel of choice so thats why I went with the over kill fuel system. I bought this car with this cell in it and the feed and return lines. So before I order all my fitting to finish it up what would be more beneficial. If my logic is correct the -6an would be better to use as the feed and the -8an as the return. The-6an would keep the pressure up and I think I would have plenty of flow.
    John,

    To give you another data point, I am running stock input and return lines, which I believe is 5/16" = 5AN. I have measured flow and at 85 total PSI of boost it will flow about 380 Liters per hour. On E85 my calculator thinks this is enough to support 850 WHP. This would support more HP if your total boost is less.

    I don't even come close to having that much power. I agree with Jason and Bender.

    Terry
    Terry,
    91 AWD

  10. #10
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    Do you mind posting that calculator? It seems to be reading a little high. I was running out of fuel at 29 pounds of boost with a 50psi base fuel pressure with -8 lines and an 044 intank with an 044 inline. That was at about 710hp. The 1600's were also off the charts in duty cycle. I was able to squeeze a little bit more out of the setup by switching to FIC 2150's, but again saw the limit at 35 pounds of boost.

    Granted, an 044 can only flow 300lph freely and 200lph at 72.5psi, but with two inline, you are going to be closer to the 300lph mark under load since the intank pump is just freeflowing. I'm not sure I can see that extra 80lph being able to accommodate an extra 150hp.

    I'm not trying to knock you, I'm just curious is all.

    Here's one I rushed together in 15 minutes about 8 months ago. I haven't looked at it since, but it seemed to be pretty accurate when I checked it at the time.

    http://www-personal.umich.edu/~maben...alculator.xlsx
    www.atdsm.com

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    Quote Originally Posted by bender View Post
    Do you mind posting that calculator? It seems to be reading a little high. I was running out of fuel at 29 pounds of boost with a 50psi base fuel pressure with -8 lines and an 044 intank with an 044 inline. That was at about 710hp. The 1600's were also off the charts in duty cycle. I was able to squeeze a little bit more out of the setup by switching to FIC 2150's, but again saw the limit at 35 pounds of boost.

    Granted, an 044 can only flow 300lph freely and 200lph at 72.5psi, but with two inline, you are going to be closer to the 300lph mark under load since the intank pump is just freeflowing. I'm not sure I can see that extra 80lph being able to accommodate an extra 150hp.

    I'm not trying to knock you, I'm just curious is all.

    Here's one I rushed together in 15 minutes about 8 months ago. I haven't looked at it since, but it seemed to be pretty accurate when I checked it at the time.

    http://www-personal.umich.edu/~mabender/FuelCalculator.xlsx

    Bender,

    I am not sure why you are saying that you feel my calculator is reading high. when according to your math, you feel your calculator is getting 710/300= 2.37 HP/LPH, while mine is only getting 850/380=2.24 HP/LPH. Don't forget that I am running 2 in parallel and know how much fuel I can pump because I have measured it, not calculated it. Although, my HP numbers are calculations, not measurements.
    Terry,
    91 AWD

  12. #12
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    I guess I just didn't put enough thought into it. At first glance, it seemed like that extra 80lph wasn't going to do much. That is a little bit more than the difference between a Walbro 255 and Walbro 190 though, so I can see now why it would.
    www.atdsm.com

  13. #13
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    Quote Originally Posted by Jason L View Post
    Just as a heads up, avoid using any 90* fittings. If you have the option of going with a 45* do it. I have seen many similar setups which have enough fuel for the power, not have the fuel needed. All due to the 90*s which add a dramatic amount of restriction. A single 90* fitting is like adding 5 feet of line to your system. It adds up quick as well.
    Thanks for that info. I have a couple 90* fittings on my feed line, I will consider revising my feed line.
    www.forcedfour.com
    10.9@138.9 (2009)

  14. #14
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    Well made some progress. I just need some ideas on how to mount the pumps. Right now I am thinking of welding a plate to the side of my cage built around the cell and cutting some thin holes in it to feed a worm clamp through the cuts to hold the pumps to the plate. I will use some rubber to assist with the vibrations. I am thinking about building a little rock shield as well. I wish they made the mounts for the bigger fuel pumps in this size. Also I am going to run seperate power to the pumps with a LED. I figured this will be the best way. I went with 8an out of the cell and then reduced to 6an right before the pumps and am going to continue with 6an to the rail. I pipe tapped the stock rail and ordered the an- fittings to thread right in.

    http://i552.photobucket.com/albums/j..._2578087_o.jpg

    http://i552.photobucket.com/albums/j..._2578087_o.jpg

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