Max power from fuel system with and without PI

Reaper0995

Specialist
Jan 10, 2017
69
20
0
Pretty simple question, but I can't find a definitive answer. I have a stage two fuel it lpfp, would I be able to make more power with PI or would it be the same as just the DI by itself? In a nutshell, it looks like there are various power levels for DI only with the stage two pump, but if I have PI and the stage two, does hat open up more headroom..? Or do I need to upgrade the lpfp along with PI?
 
Nov 3, 2016
121
102
0
IL
There are a fair amount of factors that need to be considered, which is why you are getting multiple, and different answers.

Regarding fueling hardware, our standard stage 2 LPFP supports ~550 whp on 100% e85. The HPFP however only supports ~420-430ish whp on full e85. If you wish to achieve the most power, and utilize full e85, the HPFP needs to be supplemented. It is this very reason some choose to run blends, e30, e40, e50 and so on. PI will open up more power potential, that being said feeding the 6 additional injectors in the PI rail, does put some added strain on the LPFP (it's really a give & take relationship here). To answer your question, yes, PI + stage 2 will open up more headroom. The limiting factor in your fueling will no longer be the High pressure side, but now the LPFP.

It really comes down to a few things, power goals, and budget.
 
Last edited:

doublespaces

Administrator
Oct 18, 2016
9,127
4,166
0
AZ
Ride
2009 E93 335i
Max power is likely to happen on race gas or pump gas and meth or a wet nitrous setup of some type. If you're talking ethanol then what Dave said.
 

Snelson3003

Sergeant
Nov 7, 2016
325
199
0
Denver
www.nelsonracingwheel.com
Ride
2010 BMW 135i
On E85 i would say you are limited to 490WHP running the Stage 2 LPFP and a lean AFR target of 12.9.

Outside of that the HPFP wont handle anything more. Ive tried it with 3 new ones and the results are the same on a OEM pump build.
 

[email protected]

Lieutenant
Nov 14, 2016
655
261
0
North Wilkesboro
To be fair from some results I've seen just because of less strain in the HPFP side e60-e70 would be preferable in some aspects.

But, overall just adding a little e85 will go further than you'd think. E30-E40 on a rather stock car with stage 2 lpfp, the car seems to love it.