I know Terry was talking like it could be a limit of the HPFP now, but I don't agree. I think FFTEC has the answer, but time will tell. I personally don't know all the details, but my car did very well running 100% e85 and my stock pump couldn't hang before.
Originally Posted by Mike@N54Tuning.com
They are tuning E85 for RB turbos. Tuning for 520+whp is a bit different than stock turbos. I know they have made 500rw on E60 no meth but over that the high pressure fuel drop came back. I think they were running a richer AFR also for testing. So leaning it out would probably allow more power but their goal was to find the next limit so they could whittle away at it. The Walbro in tank pump is holding it's full 72psi to redline now where the OEM would fall below 50psi so it's a move in the right direction. They suspect there is some new limiting factor in the high pressure pump that needs to be addressed.