Sorry to bring this back up. But I'm thinking about running a Walbro 525 as my secondary pump that will be hooked up to a hobbs switch. I have seen this pump need to be hooked up to a relay. But with a secondary pump being hooked up to a hobbs I wouldn't have to hook up a relay right? Would I just run a 8 gauge power and ground wire. But I see the wire that is on the pump its self isn't that big. I know it's no 8 gauge. Would cause any prob running an 8 gauge wire to that smaller wire on the fuel pump? I see STM doing it on there triple pumper set up. Mine would be somewhat the same way. But not 2 pumps wired to a 8 gauge wire just one pump.

 

Here's a photo that I just took. F90000274 on the left, Hellcat pump (F90000285) on the right. Definitely 100% the same size.

As someone else noted, the Hellcat pump requires a lot of electrical current to achieve its 8% higher flow rate. This means that the voltage available at the pump will be more sensitive to any electrical resistance in the wiring for the pump (such as from the wiring itself and any relays). Probably need extra beefy wiring (8 ga probably sufficient), high quality connections, and a very low electrical resistance on/off relay to maximize voltage at the pump.

I'll just comment that this pump or the F90000274 are only helpful/needed for people making 475+ whp on E85 or possibly for people making 600+ whp on pump gas. A single Walbro 255HP should be fine for most other lower whp scenarios.

 

Figured I would bump this for some data.

I replace my walbro 450 with a walbro 525 this weekend. It installs identically to the 450. Just have trim the top barb off the outlet, just like a 450. I ran it on the same hi/lo voltage rewire I had with the 450, and the siphon drill to 9/64's. I still run a stock FPR and return line, with a 6an feed line and AEM fuel rail. Idle and cruise fueling did not need to be changed, so the stock parts are still keeping up. Where the walbro 450 was out of flow out the top, 12.5 AFR and fudging the fuel map, the 525 brought AFR down to a 10.80-11.0 so we brought it back to an 11.30 afr where it seemed happy and it left there. This was with FIC 1650 hi-z injectors. They were at 88% duty cycle at 8500rpm.

 

Wanted to bump this to say there is a new pump out, F90000295, that draws much less current than the F90000285 but also outflows it!

One thing to note is that it does not have an internal check valve, if that matters to you.

http://www.radiumauto.com/Blog/Post/...-Pump-Test-100

 

Too bad that Walbro BKS1000 is so big.

 

I've had my 285 installed for about 3 months, and my experience has been largely the same as yours - the 285 is a huge step up from the 274. One area of difference for me though is that I was seeing substantial overrun at moderate loads in full voltage mode. I had to max out the low/full change over table to 165 load for rpms below perhaps 5000 rpm. That just barely stopped the overrun. If you are not monitoring fuel pressure, you may be in a similar situation but not know it.

Impressive, and I'm glad its out there. Unfortunately, I don't see how the factory return system could ever handle that pump. Some kind of custom low/med/full pump voltage scheme would be needed to use it with the stock return line, even with a drilled out siphon.

 

Regarding the F90000295 what is the downside to not having a check valve? Fuel pressure dropping to 0 as soon as the car is turned off? Do you think that you could overcome the problem regarding the factory return system by going with a 6AN (3/8") fuel line for the return and using an adjustable FPR?

 

Fortunately, I have a mappable fuel pump controller.

 

Interesting that there is no check valve. It must be removed to further enable high flow. Without a check valve, startup might take a little longer. The idea is that it could take additional time to build fuel pressure or perhaps fuel in the supply line might drain back into the tank. The first notion is a non-issue from my experience. These pumps build pressure instantly. Drainback into the tank seems unlikely as well because it would require a means for air to get into the system as the fuel drained back. As long as the pump inlet is submerged, that can't happen.

I think its always been hoped that these monster flow single pumps would represent a low cost solution to support moderately high hp. In retrospect, after all the fiddling around I've done to make a single pump solution work well, I probably could have done a double-pumper for less money. Now that I have a recipe that works well, it would be cheaper to do the single, but still...

lgtd, one other comment for you - The Evo ECU sends full voltage to the fuel pump during cranking and for a period of time after cranking has ended. Its a necessary requirement to contend with the possibility of a low battery, but for a healthy battery, full voltage causes massive overrun during cranking and in the few seconds after startup. You might want to limit the length of time the pump remains at full voltage after startup. I think stock is something like 1.5 seconds, and I think I lowered mine to 0.5 seconds. I have the table posted somewhere in the ECUFlash section.

 

Interestingly enough, on the topic of drain back.. lots of new cars prime the fuel system for a few seconds when you first open the drivers door.. (could be a EU thing, I dont know..) I always thought it was to eliminate fuel vapor pockets in the system..

 

Maybe associated with high pressure fuel systems? Or maybe fuel systems in newer cars are allowed to get much hotter? Or maybe just a cute thing that can be done when door status is integrated into the ECU.

Evo 10 supposedly activates the pump as soon as the key is set to "On". Evo 8/9 waits for cranking.

 

My theory is that it has to do with hydrocarbon emissions... you want that car to fire up right away and not spew out unburnt fuel..

 

Betcha a single F90000295 would flow enough to break 850+ whp with the right turbo and lines.

 

Is this with the pump hard wired? Because i was told not to use the deatschwerks kit even though I have it already and have used them before. It's just not installed obviously. My current pump is a 450lph and I'm at 27psi right now hitting 13.2 afr at 8000 rpm. Around 7500 it starts going above 12.5. Increasing duty cycle did nothing. I'm currently on 1700 ID's. I'm debating on whether to get the 525 hellcat or hard wire my pump? I have aem rail, fuel lap fpr with -6 an return to factory hard line. Fuel feed is completely stock from pump to rail except an added in line filter. I'm wondering if yall are getting these type of numbers from your 450lph maybe I need the -6 rail to pump and hardwire the pump?

 

Yes, I have a digital programmable fuel pump controller with 10AWG wire.

I would hard wire or add a controller. I still have OEM feed line, rail and FPR.