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  1. #1
    RXP 260 X Short Course Veteran RXP244's Avatar
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    Walbro 255lph High Pressure Pumps

    I keep being told that if I want to run a base pressure of say 58psi and then run a boost level of 20-25psi (turbo) even the high pressure walbro upgrade pump won't handle the extra pressure. Who can tell me otherwise. The expert I have that is telling me this is actually is in the fuel pump business, can sell me any pump and regulator I want, but keeps advising that the smaller body walbro's would just not do the business at the higher pressures once at full boost? He says I should be looking at something like the larger body bosch pumps that have a higher boost threshold.

    Advice please.


  2. #2
    eb87's Avatar
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    Walbro makes 2 different versions of the 255 lph fuel pump, a "regular" one meant to run at the automotive standard of around 30-40 psi and a "high pressure" for boosted applications. The biggest difference is the ability to maintain higher flow as the pressure increases (as the pressure goes up volume goes down). Look at this websitehttp://www.autoperformanceengineerin...l/fpspecs.html, there is a chart showing the relation between pressure and volume for each of the pumps.

    When you say baseline pressure, you mean at idle (high vacuum)? seems a little high to me. Hopefully the more knowledgeable members will add information.

  3. #3
    Eric Ocman's Avatar
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    Quote Originally Posted by RXP244 View Post
    I keep being told that if I want to run a base pressure of say 58psi and then run a boost level of 20-25psi (turbo) even the high pressure walbro upgrade pump won't handle the extra pressure. Who can tell me otherwise. The expert I have that is telling me this is actually is in the fuel pump business, can sell me any pump and regulator I want, but keeps advising that the smaller body walbro's would just not do the business at the higher pressures once at full boost? He says I should be looking at something like the larger body bosch pumps that have a higher boost threshold.

    Advice please.
    If you are running that much bost your probably should be running around 80LB Injectors. That way your base will be in the 20-30lb range and the pump will not get stressed hard bro.

  4. #4
    The pump will handle the pressure. If we assume you would need around 195 #/hr, or approx. 32 gallons/hr, of fuel flow to support that level of hp you can see based on the attached graphs that the Walbro high output pump will do what you need. You would be at the limit of the non-HO Walbro pump. Attached are the data for the various Walbro pumps along with a spreadsheet I made to easily compare stock vs. Walbro 255 and 255HO.

    Mark
    Attached Files Attached Files

  5. #5
    RXP 260 X Short Course Veteran RXP244's Avatar
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    Quote Originally Posted by eb87 View Post
    When you say baseline pressure, you mean at idle (high vacuum)? seems a little high to me. Hopefully the more knowledgeable members will add information.
    58psi being the standard "key on engine not running" setting just to set an example. With the engine running of course that will drop a bit to provide a lower starting point once the boost starts coming in.

    Injectors will be at least 60lb at this stage. Will be be used with Riva ECU and a fuel controller to add or remove fuel where required. We have done it before with great results. However it was done with a much bigger fuel pump, hence the qusetion about the Walbro. I have been using the HO Walbro for 4 years on my RXP with great results, but only SC Boost at 16lb.

  6. #6
    RXP 260 X Short Course Veteran RXP244's Avatar
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    HO 255 Pump

    How do I identify the HO 255 pump from normal 255 pump?

  7. #7
    Eric Ocman's Avatar
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    Quote Originally Posted by RXP244 View Post
    How do I identify the HO 255 pump from normal 255 pump?
    THe one you want is the GSS342

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