Originally Posted by
gomba hmm, that's good to hear! How much fuel/whp can a walbro 255lph support on e85?We had the S13 running 414 RWHP on the Walbro 255 lb/hr HP fuel pump with E85 running 3-bar fuel pressure and 22 psi. It was using Nismo 750cc injectors I believe. We switched to gasoline and water/meth after that and upped to 25 psi. The fuel pump was hitting it's limit with E85. You might be able to get a tiny bit more out of it using a higher base pressure.
This was with slightly leaner mixtures than you seem you're comfortable with. Also at times the mixture was close to soteciometric under boost likely because the pump wasn't keeping up. On inspection the turbo's exhaust wheel was bleached white which indicates very lean conditions for long periods of time. When the engine eventually threw a rocker arm and was torn down, there were no signs of detotation anywhere to be found.
I would say 400 WHP on E85 is the safe upper limit for the Walbro 255 lb/hr hp pump.