02-04-2019, 12:10 AM | #45 |
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F87source , Raymondo and TTFS are correct.
DME responds a little differently car by car, even the same platform. In early 2017, Wang my friend, the then N55 1/4 mile record setter (I have a thread dynoing his car), see zero gain from E40. My abuse M2 (installed everything except for big turbo) struggles above E50, but the gain above 30 is very marginal. Ethanol improves octane no doubt about it, but it also messes up with AFR which in a way can affect power. It's complicated, there is no definitive theory on it. For example, outside of BMW, GTR is known for being happy with E85 but it is not happy with E95-100.
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02-04-2019, 12:32 AM | #46 | |
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Also when you tune a car you're not looking at how the DME responds, that's just looking at stock fuel adaptations which shouldn't matter if you tune the car to match your fuel requirements. If all you cared about was how the DME responds then your tuner isn't making any meaningful adjustments to make your car run right. I couldn't push anywhere near the limits of the PS2 on my m235i on anything less than E55. Of course your AFR's will be leaner on E85 because of the oxygen content in the fuel, a tuner can adjust for this based on E content used. There are a bunch of tuning documents online elaborating this. The only way you affect power negatively using E85 is on a garbage tune, if you correct for the AFR's you'll be fine. I've used E85 all the way to E98 on all of my previous cars with protunes and zero issues. Albeit anything over 85% ethanol from what I have heard is not optimal because ethanol lacks the lubricity of gasoline.
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02-04-2019, 12:35 AM | #47 |
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@F87source
I don't use ethanol whatsoever with my GP500. I have two M2s. One is GP500. The other one is the abuse car (FBO, meth, ethanol, PI, stock turbo, bm3+jb4). Other cars I mentioned, not my cars. More ethanol = more octane, but =\ more boost. I'm sure Raymondo can agree in his case as well. The 11.11s N55 does 25psi maxing out PS2 with E40 and meth. More ethanol does nothing in his case.
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02-04-2019, 12:40 AM | #48 | |
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The reason why it can make 25PSI on E40 is because he has meth to supplement octane, that's essentially the same thing as running more ethanol content, but it is easier on the fuel system if he doesn't have the setup to flow more fuel for the higher E content.
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02-04-2019, 12:44 AM | #49 | |
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All i'm saying is I'm glad BM3, TTFS and XDI are making these hpfp solutions of us N55 guys to solve our fuelling issues. And sorry to PTF for kind of cluttering this thread.
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02-04-2019, 12:47 AM | #50 | ||
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My MHD tunes have actually lowered the boost and applied more timing, and the car feels more linear. I'm more concerned about the transfer case if I push it any further as this is unchartered territory on the xdrive, and as said it's my daily. I will be doing 1/4 miles when the weather improves, and that's the only time I will use the e30 tune. |
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02-04-2019, 12:58 AM | #51 | |
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Wow I didn't know it was an Xdrive lol, yeah you better becareful then. Maybe have a high boost map with Xdelete to convert it to RWD when you are pushing hard. Then have a low boost map with Xdrive back on for daily use. (Xdelete said they were covering the F series later this year) The old technical documents I have read explaining that was preflash tuning and fuel upgrades, and the reason why going over E30 was bad is because it crashed the HPFP and made it misfire. I also have yet to see anyone max out PS2 on sub E50, maybe E45, without the help of meth injection.
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02-04-2019, 10:30 AM | #52 | |
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02-04-2019, 11:05 AM | #53 | ||
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02-04-2019, 12:52 PM | #54 |
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Thanks Sean, once I’ve gone as far as I can on oem fuel system I’ll be looking into either meth or xdi plus e30 to max out the oem setup.
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02-04-2019, 11:18 PM | #55 | |
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I'd upgrade turbo first. These days the hybrid turbo is really just a bolt on affair and is a better value for money. If I had access to 100RON like Euro guys, I'd add XDI pump as well. STG2 turbo + XDI pump + FBO + 100RON =450whp (when cool of course) with some headroom, is the ultimate package for M2 OG in my opinion.
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02-05-2019, 01:21 PM | #56 | |
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From the dragy results I’ve seen posted ethanol seems much more effective from a performance point of view with on the road performance. The quickest meth cars are over 1 second slower over 100-200 on n55 stock turbo variants. BM3 xdi support is great and increasing fuel flow capacity with full dme control is a massive bonus in my opinion. |
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