LPFP/HPFP needed after turbos upgrade?
Senior Member
Joined: Apr 2010
Posts: 394
Likes: 155
2013 E63 P30, 2010 GL550
As you know, Ethanol is key to your question simply because it takes more alcohol by volume to produce optimal AFR. Turbos are secondary. Search through any related threads for your answer. There was great Ethanol interest in this forum 2 years ago, where some aftermarket HPFP/rail options were discussed. Stock M157 holds very well before flow becomes an issue.
Perhaps, a more timely question is where you are in the M157 performance quest. What is your objective? Turbo/HPFP/rail upgrades imply a packaged deal with custom tuning (and possibly internals build). Yes, benefits are substantial, but so is cost. There is a very reasonable M157 upgrade roadmap without going all out.
Anecdotally, OEM HPFP (Bosch HDP5) flow is good until around E50 on stock turbos. OEM injectors are adequate for E85, but needs upgraded mechanical HPFP such as XDI or Spool. I wonder about Bosch HDP5 Rev B, C, D. Upgraded electric LPFP and HP fuel lines are needed for E85 + turbos.
Perhaps, a more timely question is where you are in the M157 performance quest. What is your objective? Turbo/HPFP/rail upgrades imply a packaged deal with custom tuning (and possibly internals build). Yes, benefits are substantial, but so is cost. There is a very reasonable M157 upgrade roadmap without going all out.
Anecdotally, OEM HPFP (Bosch HDP5) flow is good until around E50 on stock turbos. OEM injectors are adequate for E85, but needs upgraded mechanical HPFP such as XDI or Spool. I wonder about Bosch HDP5 Rev B, C, D. Upgraded electric LPFP and HP fuel lines are needed for E85 + turbos.
Last edited by maxusa; Sep 7, 2022 at 02:03 AM.
Thread Starter
Joined: Jan 2009
Posts: 1,106
Likes: 85
From: Lebanon
Cls63 & C32
Thanks for your reply, not many threads, some have done it with fuel upgrades some without, as you said upgraded turbos with ethanol should need fuel pumps upgrades, now does upgraded turbos needs fuel pumps with only pump gas?
i am looking to do the turbos but if need LPFP and HPFP i will not go this route i will stay stage 2 (downpipes/bridge, methanol, bov, cooling, plugs).
i am looking to do the turbos but if need LPFP and HPFP i will not go this route i will stay stage 2 (downpipes/bridge, methanol, bov, cooling, plugs).
Senior Member
Joined: Feb 2020
Posts: 352
Likes: 128
From: Northern Va
2014 E63s
Thanks for your reply, not many threads, some have done it with fuel upgrades some without, as you said upgraded turbos with ethanol should need fuel pumps upgrades, now does upgraded turbos needs fuel pumps with only pump gas?
i am looking to do the turbos but if need LPFP and HPFP i will not go this route i will stay stage 2 (downpipes/bridge, methanol, bov, cooling, plugs).
i am looking to do the turbos but if need LPFP and HPFP i will not go this route i will stay stage 2 (downpipes/bridge, methanol, bov, cooling, plugs).
