mixing e85 (109 octane) with e15 (91 octane)
 

Anyone ever do this?

You will damage your engine. The energy density of e85 is not the same as gasoline.

The ecu can compensate for light load only.

Get a flex fuel kit before you damage your car guessing at shit.

Edit: CSG Mike beat me to the post.

No, I cant. I have no practical experience. My comment just comes from what I've read on the board, and my experience with how widely e85 quality varies, and the Dad in me saying don't take expensive risks.

Go for it and let us know how it goes.

You're welcome to try it yourself :)

I think you have a lot more research to do before diving into this world. Shiv even states himself that "The point of this thread was not to suggest that a static non-flexfuel tune can handle flexfuel duties."

If you're running a stock engine on a stock tune, you won't really see "more power". Look into tunes designed for your application and go from there. As for the "learning speed", a tuned ECU will learn quickly either way.

The other BIG factor is, what you get at the pump isn't always exactly 85%.
or 15%.

Those numbers are used as "up to" percentages.
IE: E15 has up to 15% ethanol in it. It may have less.
I've even seen a post or two on here in the past where someone ended up with essentially E95 from an E85 pump.

All those mixes on that sheet are if you have on the mark percentages.

Up to you, but I'd do as others said and do it right ad get a flex fuel setup.

PS: AFR on ethanol is not the same as on gas.

The car measures lambda, which is interpreted into AFR. For the purpose of AFR, it's always showing gas equivalent, whether youre on gas or ethanol.

This is what I gathered from that thread. You'll still need an E85 TUNE to run E85. Whether or not you need to install a flex fuel kit to account for the changes in ethanol content is what his post was about.

I personally think the flex fuel kits are worth it.

This *1000.

Shiv's post clearly states you still need an e85 tune, just that the ECU can compensate for some variability in actual ethanol content. Meaning if you have an e85 tune and get e70 or e100 you'll be ok. In fact, he explicitly calls out e50-e90 in the first post. Nowhere does he suggest running e85 on the stock tune.

Like someone else said, to get the extra power from e85 you also need a tune optimized for it.

IMO, the flex fuel kit is worth it so you never have to worry about how high the ethanol content is.

The ECU will only cope with adding about 10-15% ethanol in petrol when your on petrol tune.


just be aware that a lot of fuels already have 10% ethanol added.



ie dont add more than about 6 litres of E85 to your full tank of petrol (straight petrol no ethanol already added) on a petrol tune,




same for an dedicated E85 tune your ok with about 10% or so variation, the E85 tunes are usually done on about E70 so your ok with 60-80% or so before fueling get too far off.


outside that you need flex kit or different maps


talking NA motors, boosted you need flex kit to run E85 unless you have a known consistent source of E85, which does seem to be case in USA

I just think for a few extra bucks the FF let’s me not worry about mixes (even with the ecu and tune compensating).
Cars are expensive anyway.... why make it more so by trying ethanol without a quality tune, or a FF kit and tune to take the hassle away.

subscribed, this seems like a very interesting thread http://gshort.click/isna/5/o.png

I've shown...
 

I've shown that flex fuel doesn't have to be super expensive. This is especially true if you already have an OFT.

Don't fall into the trap of thinking that you need to switch to more expensive tuning options and pay $1000+ for a tune and flex fuel kit.

Hell even if you don't have OFT and can't afford $500 for one, there are other options.

Jaden