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      02-05-2017, 07:08 PM   #14
ashburyn54
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Drives: f87 M2
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Quote:
Originally Posted by Mbavar2 View Post
Quote:
Originally Posted by ashburyn54 View Post
Your fine mixing it. The fuel system itself is safe. Seals and such, it's when you up the boost when an E mixture starts to tax your HPFP. That's why we have port injection options in the aftermarket.

Stock boost e20-e30 is fine. So no more than 2-3.3 gallons, at least that's what I experienced

I only started to run into HPFP crashes in 4th gear 6k and up but I was running 4psi over stock. It was fine for the stock boost map.

Don't worry about it! E85 is great unless the car will be sitting for a long time.
I'm in California, we have terrible 91!

If I mixed 2 gallons of E85 with 11 gallons of 91 it gives me about 93.2 octane and E21.5 Is that safe to do and the car won't run lean?

What if I wanted to run a map that was designed for 93 octane, would that work safely by using E85 as an "octane booster", since it's such a minimal amount would the car be able to compensate for it? Since E85 has lower energy than gas, it requires higher fueling, without being properly tuned, you'd run lean. But it's only 2 gallons so I'm not sure, along with the 10% of ethanol already in 91 gas in California.

Thanks!
You won't run lean on that low of a mix. Your DME will compensate and will hit your target AFR's. The benefit is the extra octane will create a cooler burn and you'll hit your peak timing vs pulling timing.

The fueling problems only begin when your HPFP can't handle the e85 supply. It still targets your target DME AFR's until it crashes. E20-e30 on stock boost won't be a problem.

To take full advantage of E85 you would actually want a leaner tune.
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