[N55SFH]

I'm finding it difficult to navigate the discussion on fuelling upgrades and options.
At what power do stock N55 injectors start to become a bottleneck for power, and what brands are people running as upgrades?
Same for both LPFP and HPFP, when do they need upgraded and what with?
Are there other supporting mods required to get the most out of them?

Thanks in advance.

[whyzee125]

You'll run out of air long before you'll run out of fuel on a stock turbo N55.

Stock turbo on pump gas will get you up to about 320whp. E85 mix will get you slightly higher in the mid range at which point you'll need an upgraded LPFP. If you're running high ethanol content or full E85 most run port injection but since you're 2013, you have an upgradable HPFP. The injectors would be the last thing in the fuel system to bottleneck.

[N55SFH]

Originally Posted by whyzee125

You'll run out of air long before you'll run out of fuel on a stock turbo N55.

I forgot to add that this is a concern for after I’ve done basically everything else. I plan on getting a stage 2 pure turbo with all the expected supporting mods

[whyzee125]

I don't see you maxing out the stock injectors as you'll max out the N55's internals before you run out of fuel

[wheela]

For what it's worth, the new style hpfp (not the n54 style) though not flowing as much as the n54 style, seems to be much less dependent on an upgraded low pressure fuel pump.

For reference, here's what one of the f30 guys could do with his Speedtech kit with EFR 8374 turbo, and different combinations of stock hpfp and stage 2 hpfp. Granted he's f-chassis, but it's the same hpfp, so this should be a good reference for max you can get from the stock hpfp. And somebody please correct me if I'm wrong, but I assume (hope?) the f-chassis lpfp is the same capability as e-chassis lpfp? I'll be putting this same turbo on my car, and an only planning on Dorch stage 2 hpfp for fuel system upgrades (Dorch now makes a stage 2.5, but I bought my stage 2 right before they released the 2.5).

[wheela]

Here's that thread the screenshot is from:


https://f30.bimmerpost.com/forums/sh....php?t=1723999

He was on stock lpfp.

[N55SFH]

Much appreciated. I'll give it a read and make a plan