[sqwinny]

Copy paste from the 3 series side of the forums to cover more folks looking for info.

Hi Bimmerpost,

Might as well make a post as this is THE longest standing place for information and keeps being referred to. Hopefully this will stop misinformation and make it easier for access to folks searching via internet search engines.

Fueling limits to make power refers to flow limits and overall bandwidth to support power generation. Take note you can only make as much power as the lowest component within the fuel system. Just because one component can flow much more than the other, doesn’t mean you can overpower the rest of the component for more flow.

Please note port injection is available for the N20/N26, but this is something I am NOT discussing within this post.

Fuel System Components

Low Pressure Fuel Pump (LPFP, fuel pump within fuel tank)
High Pressure Fuel Pump (HPFP, fuel pump on top of engine which runs off exhaust camshaft)
Fuel Injectors (fuel injectors, there are 1 injector per cylinder)

What does this mean? When you have decided your power goal, you have to take all 3 components into consideration.

100% F30 n20/n26 stock fuel limits at ideal max flowing possibilities quick discussion

N20/N26 Stock LPFP
450 whp 91/93 octane
430 whp e50 octane
400 whp e85 octane

N20 stock fuel injectors versions EU5 + EU6
91/93 octane 3600 psi 380 whp
E50 octane 3600 psi e50 is approx. 350 whp (fuel trims are a bit leaner than max power possible)
E85 octane 3600 psi e85 320 whp (fuel trims are a bit leaner than max power possible)

N20 stock HPFP (the revised HPFP does NOT bring any more fuel flow)
93 octane - 375 whp
E50 octane – approx 350 whp (fuel trims are a little leaner than max power possible)
E85 octane - 300 whp (fuel trims are a little leaner than max power possible)

[sqwinny]

Let’s apply this knowledge to the stock turbo setup on the n20/n26. Stock turbo at max effort with all parts (FBO, full exhaust [downpipe converted to 3" and full 3" exhaust all the way back to muffler], full intake with turbo inlet, 6" intercooler, Bimmermilvs without cylinder head work) and custom tune is shown to make around 310whp on GOOD Quality 93 octane and 330-340whp on full e85 octane.

LPFP – meets this flow rate
HPFP – right at the edge right at the edge which means you give up some power or cannot support full e85 at this power rating
Fuel injectors – right at the edge which means you give up some power to use this hardware or cannot support full e85 at this power rating

Right at the edge means your tuner will have to lean out the fuel mixture or limit your power generation by the engine and fuel system to support your hardware.

Recommended path forward as of 11/2/24:

Stock turbo stock motor
LPFP – leave stock
HPFP -> upgrade and retrofit to the B58tu HPFP as no tune required
Fuel Injectors – can leave stock

The stock HPFP is known to be weak and gets weaker overtime thus operating right at the limit is a recipe for disaster.

Upgraded hybrid turbo (Pure stage 2, Mambatek, TTE400, MHI turbo and others) stock motor
LPFP – can leave stock as of today 11/2/2024, no off the shelf hybrid turbo can flow this much air to make 400whp on full e85.
HPFP -> Upgrade to B58tu HPFP for support up to 400 whp e85
Fuel Injectors -> upgrade to s63tu injectors. You will need a custom tune for these injectors, however bm3 is working on bringing the “check box” for s63tu injectors to the n20/n26 with a b58tu hpfp check box.
LPFP -> can leave stock however replace due to N20/N26 cars hitting the 10 year old mark

[sqwinny]

Please note these numbers are approx. as it depends on fuel quality + your local elevation which limits these flow limits

F Chassis n20 LPFP fuel limits
Stock LPFP
450 whp 93 octane
400 whp e85 octane

To run these following LPFP pumps, ideally you will need to upgrade your EKP. The only 2 solutions currently to be consistent for upgrading is the following:

ET3 design EKP upgrade - direct website or through amazon
BPM4 ekp upgrade (there are ways to get this but its not easily available through a website)

“Stage 2” walbro 450
91/93 octane 600-700 whp
E85 octane 500-550 whp

“Stage 2.5” walbro 525/535
91/93 octane 700-775 whp
E85 octane 600-650 whp

"Stage 3/4" dual Walbro 450 pumps (can be triggered on with hobbs switch, reflex+ controller, ET3 design stage 4 EKP, BMP4 with dual LPFP harness and "activation point" calibrated within Torqbyte_ software)
91/93 octane 1000 whp
E85 octane 900 whp

F chassis n20/n26 High pressure fuel pump limits
Stock HPFP
91/93 octane 350 whp
E85 octane 300 whp

B58tu HPFP – no tune needed, plug and play
91/93 octane 440 whp
E85 octane 400 whp

Spool FX-150/FX170/Dorch DS1
Not compatible with n20 as this pump does NOT flow enough fuel with upgraded injectors under 3500rpm, thus pulled from market.

Spool FX-180/Dorch DS2 – custom tune needed. BM3 can add to stock maps for you via email
91/93 octane 590 whp
E85 octane 480 whp

Spool FX200/Dorch DS2.5 – custom tune needed. BM3 can add to your maps for you via email
91/93 octane 760 whp
E85 octane 620 whp


N20 fuel injector flow limits and upgrades
N20 stock fuel injectors versions EU5 + EU6
91/93 octane 3600psi 380 whp
E50 octane 3600 psi e50 is approx. 350 whp
E85 octane 3600psi e85 320 whp

M5/M6 S63tu EU5 injectors - custom tune needed. BM3 check mark in beta testing
BMW Part number: 13647599876
Bosch part number
91/93 octane – 600 whp
E85 octane – 500 whp

Nostrum Stage 1 injector s55/n55/n20/n26 compatible - custom tune needed EU5 spray pattern
91/93 octane 630 whp
E85 Octane 580 whp

Nostrum Stage 2 injector s55/n55/n20/n26 compatible - custom tune needed EU5 spray pattern
91/93 octane 760 whp
E85 Octane 590 whp