Chris Edwards

I'm shocked you made 540rwhp on E85 out of a Walbro 255 lol. Generally the MAX MAX for a gasoline setup for a Walbro 255 is 525-550. Do you have a fuel pressure gauge on the car to see if the pump is losing pressure at high rpm ?

On my turbo truck I only made 550rwhp on a Walbro 450 and a BAP (E85) before I needed dual pumps.

SmoothFRC

I have a 255 lpe and Hotwire kit with stock 97/8 return line. No bap. At 625 at wheels with 80lb injectors.

I was was struggling with the same pump and stock 00' return less setup at 500 wheel power.

The returnless is horrible.

blackdak318

There seems to be a lot of wrong assumptions about this pump. Keep in mind this is not a stock walbro 255, this is the unit from Racetronix. I honestly am too lazy to see what exactly that means, but I believe they modify it for more flow. I did my research by talking with others who have similar motor set ups to mine and this fuel system and they all said no issues at all at 600RWHP + on E85 on N/A motors. See post #20 from hellbents-10. He is who I talked to, made way more HP than me, same fuel set up, no issues at all.

Chris Edwards

Racetronix doesn't modify anything. They just sell out of the box Walbro GRJ420P pumps and mark up the price and then offer nice wiring harnesses to go along with them. Im still curious if your pressure is dropping off at high rpm's. To make 580rwhp on E85 on a 255lph pump in a returnless system would have to be some sort of record. That's Walbro 450 territory. Very impressive nonetheless!

C5 Pete

For another reference...

I have a Walbro 255 with a hotwire kit and boost-a-pump. Returnless system. I log fuel pressure and it is solid the entire pass turning 7600 rpm.

I'm NA on E85 and have gone 141 in the 1/4. I have not had it on a dyno. My car weighs 3050 with me in it.

Chris Edwards

Boost-a-pump is a completely different story. We're talking out of the box Walbro GRJ420P 255 pump.

blackdak318

Rather than argue back and forth about the 255, can anyone post up info on how to do a walbro 450 in stock C5 bucket? Any modifications required? Anyone make a kit?

Lots of people saying Walbro 450 but not much info on how.

Racetronix

We use our own RXP255J pump which flows more, is quieter, has a higher pressure capability and handles Ethanol better than the GRJ420 pump. We bundle this pump with a new lower bucket assembly and upgraded Teflon in-tank wiring.

blackdak318

Any plans to replicate this but with a Walbro 450? There seems to be a lot of demand for a plug and play kit like what you offer with the 255. Make it happen! I'll be the first order.

Chris Edwards

The issue becomes sucking the C5 canister dry. The "jet pump" design of the C5 canister, similar to the Neon SRT-4's, uses that little black tube at the base of the pump to keep the canister full at all times. Meanwhile the fuel pump motor also draws fuel from the 2 inlets (1 inlet draws fuel from inside the canister, the other inlet draws from outside the canister). You cannot adapt a Walbro 450 inside the factory canister without completely eliminating the jet pump system.

The "solution" is to cut the bottom of the canister out, turning it into a "bracket" for the Walbro 450. You eliminate the jet pump functionality completely, and in doing so need you'll need to keep the fuel level as high as possible to ensure the pump motor doesn't suck air during acceleration or cornering (since it's no longer constantly surrounded by fuel inside the canister).