[Daleb]

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Hi guys,

Looking for some feedback from anyone who has run some form of supplementary fuelling, ideally still on the oem turbo.

The 2 options I’ve considered are the XDI HPFP upgrade or the BMS meth kit. The cheaper option would be the meth kit as I already have a jb4 however it has its drawbacks. The XDI pump works like oem with the DME controlling it. The only draw back I can see is the price, being 4x that of the meth kit.

I’d continue to use bm3 and would obviously need a map specific to what ever route I go.

[cookiesowns]

I really don't like relying on meth for fueling. Maybe a bit of 50/50 to buffer IAT and buffer HPFP.

For stock turbo however either is fine. Your limits will be the turbo with 98RON and just a bit of supplemental fueling.

Anything above 16psi past 5K is just spinning the tiny turbo hard, and this is with catless DP's. And you can get by without fueling upgrades at that boost levels if you have strong octane and run the car a teeny bit lean.

[Daleb]

Originally Posted by cookiesowns

I really don't like relying on meth for fueling. Maybe a bit of 50/50 to buffer IAT and buffer HPFP.

For stock turbo however either is fine. Your limits will be the turbo with 98RON and just a bit of supplemental fueling.

Anything above 16psi past 5K is just spinning the tiny turbo hard, and this is with catless DP's. And you can get by without fueling upgrades at that boost levels if you have strong octane and run the car a teeny bit lean.

Just seen your response now Joseph, thanks.

Have you done a ‘maxed’ out tune on the oem M2 turbo where octane and fuel supply isn’t an issue?

For me dyno numbers isn’t the goal, the on road performance is where I’m looking to see a healthy gain in.

From my previous n55 car when I ran supplementary fuelling using TBI, the gain I seen on my Vbox was substantial. It was very basic as it was stock flash+Jb4 but I managed to run quite a bit more boost from the 3000-6000 rpm range without upsetting the HPFP.

I still have the TBI kit but I haven’t really considered running it due to it’s on/off nature.

[SeanWRT]

Daleb, just read your message and post here.

Believe it or not, with stock turbo and pump gas, fueling upgrade is NOT helping much, if any at all. Unless you always have extremely cool IAT, which just means more octane.

Octane is always always by FAR the first and biggest restriction of most platform, especially N55.

You experienced "substantial" improvement from supplemental fueling with previous N55, only because your previous N55s do NOT make top end power at all unlike M2. You were short shifting all the time staying 4~6k where hpfp is the weakest.

With M2 stock turbo, you probably should use 5k~6k5 a bit more. After 5k5, it is all about octane with stock turbo. So will you benefit from more boost (3~5k) that's only possible with more fueling? Yes, you will, but WOT acceleration will benefit at a much narrower power band (4K5~5k). Above 5k, you'll be trading timing for boost. Above 6k, you can don't even get close to stock fueling limit given the octane. Again, unless you always have extremely cool IAT (below 70F).

The map you have is as strong as a pump gas map gets. Do not be obsessed with hpfp slightly dip here and there. Doesn't matter at all. And you will NOT want to have more boost any more.

Do proper pulls and I think you'll be in low 9s. Don't believe these high 8s result. Ambient Condition differs.

If you really want to be faster with M2, upgrade turbo. Or trade in for a competition.

[DrKevM5]

Fuel-It Stage 3 and CSF upgrades with Dinan Stage 4 https://f87.bimmerpost.com/forums/sh....php?t=1537671

[Daleb]

Originally Posted by SeanWRT

Daleb, just read your message and post here.

Believe it or not, with stock turbo and pump gas, fueling upgrade is NOT helping much, if any at all. Unless you always have extremely cool IAT, which just means more octane.

Octane is always always by FAR the first and biggest restriction of most platform, especially N55.

You experienced "substantial" improvement from supplemental fueling with previous N55, only because your previous N55s do NOT make top end power at all unlike M2. You were short shifting all the time staying 4~6k where hpfp is the weakest.

With M2 stock turbo, you probably should use 5k~6k5 a bit more. After 5k5, it is all about octane with stock turbo. So will you benefit from more boost (3~5k) that's only possible with more fueling? Yes, you will, but WOT acceleration will benefit at a much narrower power band (4K5~5k). Above 5k, you'll be trading timing for boost. Above 6k, you can don't even get close to stock fueling limit given the octane. Again, unless you always have extremely cool IAT (below 70F).

The map you have is as strong as a pump gas map gets. Do not be obsessed with hpfp slightly dip here and there. Doesn't matter at all. And you will NOT want to have more boost any more.

Do proper pulls and I think you'll be in low 9s. Don't believe these high 8s result. Ambient Condition differs.

If you really want to be faster with M2, upgrade turbo. Or trade in for a competition.

Hi Sean,

My previous n55 (m135i) did mid 8s with stock fuel system and an e25 mix. Once the suplimentary fuelling was added, more boost (jb4) and I used an e50 mix these times dropped to 7.8-8.0. For me thats was a substantial gain, I have the graphs available if you are interested.

Yes I agree regarding pump fuel (99 ron) and hpfp won’t yield much at all due too octane limits. However I would be open to running a small ethanol mix to help raise octane to it’s required amount.

The U.K. distributor has seen a 30-40bhp gain with the hpfp upgrade and a e20 mix with 99 ron fuel over their stage 2 map. I have requested some Vbox times for this setup which he will hopefully get round to when time allows.

This latest map feels the best so I am looking forward to seeing the 100-200 results once I can test. I can let you know the results once done.

Cheers.

[SeanWRT]

Mid 8s is impressive with stock turbo. Octane from E25 definite takes the credit. I don't really see the possibility of breaking into 8s with pump gas alone, at least in my country where I think octane actually lives up to its rating (RON98) unlike ACN of USA.

My very best RON98 run (on STG1 turbo last year) was 8.5s on a freezing cold day, using a map that's maxing out fueling and cold day octane. Normally it was just 8.7~9.0s. If it's hotter, low to mid 9s. This is how you're vulnerable and inconsistent with N55 that's lacking the octane.

If you're sure octane holds up whatever you throw at it, go XDI pump. Clean and simple. Easier to tune. And actually not that much more expensive than PI solution all in.

Originally Posted by Daleb

Hi Sean,

My previous n55 (m135i) did mid 8s with stock fuel system and an e25 mix. Once the suplimentary fuelling was added, more boost (jb4) and I used an e50 mix these times dropped to 7.8-8.0. For me thats was a substantial gain, I have the graphs available if you are interested.

Yes I agree regarding pump fuel (99 ron) and hpfp won’t yield much at all due too octane limits. However I would be open to running a small ethanol mix to help raise octane to it’s required amount.

The U.K. distributor has seen a 30-40bhp gain with the hpfp upgrade and a e20 mix with 99 ron fuel over their stage 2 map. I have requested some Vbox times for this setup which he will hopefully get round to when time allows.

This latest map feels the best so I am looking forward to seeing the 100-200 results once I can test. I can let you know the results once done.

Cheers.