N54 Stock DME Flex Fuel

Jake@MHD

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That's bad ass!

Okay, I have a stock fuel system with a Warblo 450 fuel pump. Anyone know about how much E85 this can handle?
Asking for a friend :p

It's pointless to run above E50 on the OTS map as boost will start to taper back towards pump gas levels above it. If you plan on regularly running above E50 and want more power, I suggest a pro-tune.
 
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Hill'n'toe

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Here's an E36 log : https://datazap.me/u/hillntoe/e36?log=0&data=3-5-20

It's pointless to run above E50 on the OTS map as boost will start to taper back towards pump gas levels above it. If you plan on regularly running above E50 and want more power, I suggest a pro-tune.

Why will the boost tapper back ? I tought E85 had higher octane rate than pump gas, so what's the technical reason to not go over E50 ? I'm learning :)
 

works

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Why will the boost tapper back ? I tought E85 had higher octane rate than pump gas, so what's the technical reason to not go over E50 ? I'm learning :)

It does indeed, but the stock fuel system of the N54, or even Stage 2 LPFP upgraded, can't keep AFR's on safe levels with pure E85 as it's energy content is lower than pump gas -> you need more of E85 than 93 to get the same amount of energy out of them and the stock HPFP can't provide enough of it to take advantage of using only E85 AND extract more power from it as you could if your fuel system could keep up.

Therefore E50ish has the best octane/energy density/volume for a Stage 2 LPFP and stock HPFP fuel system to get the best power output with these restrictions in mind.
 

Hill'n'toe

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It does indeed, but the stock fuel system of the N54, or even Stage 2 LPFP upgraded, can't keep AFR's on safe levels with pure E85 as it's energy content is lower than pump gas -> you need more of E85 than 93 to get the same amount of energy out of them and the stock HPFP can't provide enough of it to take advantage of using only E85 AND extract more power from it as you could if your fuel system could keep up.

Therefore E50ish has the best octane/energy density/volume for a Stage 2 LPFP and stock HPFP fuel system to get the best power output with these restrictions in mind.

Ok now that's totaly clear, thanks for this great explanation. So E85 is possible with stock HPFP and stage 2 LPFP but I'll get less power than E50.
 

NoGuru

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Nice looking log!
I noticed the boost was not smooth upon spoolup. Had you done a few pulls prior to this one?
Yeah, this is after about 1/4 tank burnt through.

I think it had to do with throttle position. This is merging on the expressway off another expressway and it can be a little hard to get going so I never really went WOT in this pull.
 

Jake@MHD

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Here's an E36 log : https://datazap.me/u/hillntoe/e36?log=0&data=3-5-20



Why will the boost tapper back ? I tought E85 had higher octane rate than pump gas, so what's the technical reason to not go over E50 ? I'm learning :)

Log looks good. The reduced power / taper for full E85 is due to these being OTS maps. They are designed to suit a wide spread of cars and modifications (even at a certain "stage"). Full E85 has high mass fuel flow requirements that are beyond that of most "OTS" cars. So if you wish to benefit from the increase in power full E85 can bring to your setup, you should get in touch with a pro-tuner who can evaluate your fuel system, guide you in the direction of getting the needed parts, and tune your car appropriately.
 

works

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Ok now that's totaly clear, thanks for this great explanation. So E85 is possible with stock HPFP and stage 2 LPFP but I'll get less power than E50.

That's right, especially so on OTS maps as Jake above mentions.
 

NoQuarter

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I am tuned for 100% E85. (Turns out to be E80 out of my local pump)

I have an upgraded LPFP and lines but otherwise stock fuel system. So, I am tuned for 100% E85 based on what my fuel system will support, not based on trying to get maximum power.
 
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Hill'n'toe

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I am tuned for 100% E85. (Turns out to be E80 out of my local pump)

I have an upgraded LPFP and lines but otherwise stock fuel system. So, I am tuned for 100% E85 based on what my fuel system will support, not based on trying to get maximum power.

That's exactly what I'm going to do.