If you read the description it says not for use in all motor applications or builds making less than 400HP due to flow. We have return style systems though so is that part in the description a load of bull? Or does it really flow that much where a stock return couldn't keep up and it would pressurize? My plan was to use that pump at 60PSI which only flows 287.86LPH at 12 volts and 346.57 at 13.5 volts using a -6AN feed and if not a -4AN return then a -6AN return. That and ID1000cc injectors.

 

If it says don't do it...don't do it. I don't think they would NOT reccomend their own product unless there was a good reason behind it. Bigger is not always better.

 

When we start talking about E85 though you need a good 30% more fuel. The bigger pump, less heating, and quieter operation of the 400LPH vs 255LPH is why I am so attracted to it. I am just curious as to why it is not recommended? It will be a -6AN into the Aeromotive regulator and a -6AN return line out. I can't imagine why it would be a downside to running a larger/more efficient pump.

 

I can see your angle but it still comes down to the gross overall amount of fuel your motor will be using, not what it is capable of using. The ID1000's are going to be at around 45-50% duty cycle which is good, but they are not going to need the added fuel pressure to fuel your car correctly so the pump is going to still be running agains some resistance. Im assuming your FPR is going to be set at 45-50psi because you're not going to need more fuel than that. You would be bottlenecking it... In a way trying to be more efficient in this aspect seems to be less efficient if you see what im trying to say.

 

I haven't ready anything from Walbro on that note, however the only basis for that recommendation would be due to a stock pressure relief valve not being able to handle the extra bypass volume. In which case, you'd experience fuel pressure creep at idle.

I've sold Weldon 2025's for all-motor applications - you have to pump whatever the engine requires. If it requires a 1000 lb/hr system, you have to make sure you can bypass 1000 lb/hr through your p.r. valve & return line. If you need two p.r. valves to accomplish that - so be it.

I'm presuming that Walbro is stating that to prevent someone from going from a stock 190 lph pump to their 400 lph pump without upgrading the p.r. or return line, which may cause pressure creep issues depending on how restrictive the stock p.r. & return is.

 

I'd really like to run 60psi though due to the much better spray pattern at that pressure. Would 725cc be a smarter choice in this aspect?