N55 Power options 2025

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Hi all! I have been lurking here for about a year now that I’ve had my 135i n55. I have read lots of informative posts that have dictated how I’ve gone about improving my car. However, a lot of the info I have found regarding what the next step from bolt ons is from a few years ago, and and I’d like to hear from the experts here what they think the best option for me would be in 2025. I am looking for somewhere in the ballpark of 450-500 hp, while retaining as much of the stock power band curve as possible. My next step regardless of what turbo I end up going for will be to upgrade my HPFP, and LPFP. Have looked a lot at the Pure500, for pricing and being very oem+. But I have recently discovered the N55+ from shuenk and it’s made me wonder what other options are out there that I am unaware of. If at all possible I’d like to avoid meth injection and PI, but understand if it’s necessary for my power goals. And if it’s at all relevant, I have a DCT running MHD and XHP OTS tunes. Thank you for reading.

[wheela]

Welcome to the forum!

The power you can hit will vary pretty substantially depending on what kind of fuel you run (straight 91, 93, or ethanol blends up to e85) and your turbo selection.

I see you're a 2012, so you should have the newer style hpfp vs. the older n54 style hpfp. Depending how high of ethanol content you run, you may be able to get by just upgrading your hpfp and keeping the lpfp stock.

I don't have alot of analysis to share on e-blends, but here's a link to a summary I put together summarizing peoples' dyno results on 93 only (no meth or added e-blend) on some of the newer turbo options for n55, maybe you'll find it useful:

https://www.e90post.com/forums/showthread.php?t=2216956

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Woah, that is insanely in depth thank you for sharing that. As of now I’m running 93 so that graph is extremely relevant for me. However- and I don’t know how many other people are aware of this, but I reached out to MHD to ask about a flex fueling kit that works with the e chassis n55. They linked me one that works that I think I’m gonna jump on soon so I can start running blends. A little scary because I can’t really find any documentation of anyone using it for e chassis n55s, but I’d imagine installation should be fairly similar to an n54. Being in Florida I do get access to E85, I’m just too lazy to use a calculator to see how much I’d need for E30- so I’ll let the sensor do its job ��. And if I could get by without a LPFP upgrade that would definitely be nice. Leaning towards that P500 as of now especially since I can still use my MHD OTS maps until I can get a custom tune.

[wheela]

No problem, glad it was helpful!

Yeah, flex fuel would be great, but like you said, I haven't seen any first-hand details in the n55 forums yet. I'd feel more comfortable with it if there were more first hand accounts to go on. I can't really be bothered with mixing fuels at the pumps, so unless I go flex fuel I'll probably be sticking with 93.

Pure 500 should be good for your goals, 450 on 93, and 500 on high e-blends.

[mySlow1]

Originally Posted by wheela

No problem, glad it was helpful!

Yeah, flex fuel would be great, but like you said, I haven't seen any first-hand details in the n55 forums yet. I'd feel more comfortable with it if there were more first hand accounts to go on. I can't really be bothered with mixing fuels at the pumps, so unless I go flex fuel I'll probably be sticking with 93.

Pure 500 should be good for your goals, 450 on 93, and 500 on high e-blends.

MHD integrates with Motiv Reflex+ to support flex fuel now! I run a port injection kit (bracket type) and Walbro 535 for fueling. HPFP isn't giving me trouble so far but I have the older N55 which has the N54 style pump.

Recommend a custom tune though MHD has off the shelf flex fuel maps.

[wheela]

Originally Posted by mySlow1

MHD integrates with Motiv Reflex+ to support flex fuel now! I run a port injection kit (bracket type) and Walbro 535 for fueling. HPFP isn't giving me trouble so far but I have the older N55 which has the N54 style pump.

Recommend a custom tune though MHD has off the shelf flex fuel maps.

Sweet! So you're running flex fuel through MHD with Reflex integration? Can you add additional sensors to the Reflex and log them through MHD? I didn't know MHD implemented Reflex integration for n55e yet.

[mySlow1]

Originally Posted by wheela

Sweet! So you're running flex fuel through MHD with Reflex integration? Can you add additional sensors to the Reflex and log them through MHD? I didn't know MHD implemented Reflex integration for n55e yet.

Exactly, I don't think it is widely known / discussed on the forums. I have ethanol content and low pressure sensors integrated. Those are loggable through MHD. There's a handful of additional reflex parameters for the port injection duty cycle, errors, aux 1/2, etc.