[Deadwrong]

FTW

[biz77]

Originally Posted by vasillalov

Well not exactly. Resistance to detonation = AKI -> Anti-knock index. So that's your unit of measurement.

Yes, E85 has additional benefits when it comes to cooling the combustion chamber, but technically, that's different than anti-knock index.

Plain and simple:

USA 91 fuel = 91 AKI
USA 93 fuel = 93 AKI
USA E85 = 94-96 AKI
PURE ETHANOL = 99.15 AKI

Source: http://en.wikipedia.org/wiki/Octane_rating

Do not confuse E85 and pure ethanol. Totally different things.


EDIT:

Take a look here:

http://en.wikipedia.org/wiki/E85

Second paragraph in Octane and Performance Section:


So guys, stop propagating a lie! E85 does NOT have such a high octane rating as you think it does.

There is no lie being propogated. I don't care what the AKI rating is, E85 tunes more like C16 race gas. 100 octane AKI unleaded gasoline cannot come close to what E85 does. Spend some time outside of the BMW forums where people have been tuning on this stuff for the last 5-7 years and you can see multiple examples of how E85 performs similarly to something like C16 or Q16.

[MDORPHN]

Originally Posted by biz77

There is no lie being propogated. I don't care what the AKI rating is, E85 tunes more like C116 race gas. 100 octane AKI unleaded gasoline cannot come close to what E85 does. Spend some time outside of the BMW forums where people have been tuning on this stuff for the last 5-7 years and you can see multiple examples of how E85 performs similarly to something like C116 or Q116.

+1.

And the articles for which I provided links explain why this is the case.

Neil

[packinDSS]

awesome!

[enrita]

no shit look at the timing table



versus Stage 2plus

[RnmEvo9]

Originally Posted by dfv2

Looking at the mapping, there's NO way in hell...

I take back what I said. The car responded much differently today than last night. I am happy.

[spool twice]

whoa, that's an aggressive mid-range timing bump, more aggressive than the OE timing curve even

[Bleep]

Originally Posted by spool twice

whoa, that's an aggressive mid-range timing bump, more aggressive than the OE timing curve even

No doubt, damn. Good job Cobb.

[Myaddiction]

Originally Posted by MDORPHN

Accusing folks of "propagating a lie" does not encourage informed discussion of any topic, but.... the subject of ethanol's "effective octane" (which is far higher than you suggest), at least in a direct injection motor, is far more complicated.

Take a look at these articles:

http://web.mit.edu/mitei/lfee/progra...2008-01-rp.pdf

http://web.mit.edu/mitei/lfee/progra...2008-01-rp.pdf

dspace.mit.edu/bitstream/handle/1721.1/69496/775670245.pdf

Neil

Lol, Whatever, I'll take Wikipedia over some MIT engineering papers. Wiki has way more pictures in it! It's painful to read some of the things posted on here when a more through search then a wiki search provides volumes of data.

Thank you for taking the time to post some real data. I kinda gave up on it a while ago.

[3-Serious]

So all my logs so far have look clean as hell! Only one log had a one cylinder with a slight timing correction. But when I logged a 2nd-3rd gear log the car seemed to have 4 different timing corrections as soon as I got into 3rd gear and then the corrections slowly disappear as the rpms raise? Is this bad?

[blisstik]

If I put 10 gallons of 91 octane, how many gallons of E85 do I need to put for this map? It didn't say it supported 91 octane, only 93.

I'm doing a custom tune anyway but just wondering...

[Ænema]

Originally Posted by nickkg37s

So all my logs so far have look clean as hell! Only one log had a one cylinder with a slight timing correction. But when I logged a 2nd-3rd gear log the car seemed to have 4 different timing corrections as soon as I got into 3rd gear and then the corrections slowly disappear as the rpms raise? Is this bad?

If you have several clean logs and the just one log where a couple corrections occur during a shift then I wouldn't too much.

[drewmeyer87]

How is there 4 pages on this post and nobody has asked if these new maps are called "Corn on the COBB"???

[sdstatestud88]

Originally Posted by blisstik

If I put 10 gallons of 91 octane, how many gallons of E85 do I need to put for this map? It didn't say it supported 91 octane, only 93.

I'm doing a custom tune anyway but just wondering...

about 5 gallons...There is an equation on page 3 I believe

[bceagle1991]

Originally Posted by drewmeyer87

How is there 4 pages on this post and nobody has asked if these new maps are called "Corn on the COBB"???

LOL

[vasillalov]

Originally Posted by MDORPHN

Accusing folks of "propagating a lie" does not encourage informed discussion of any topic, but.... the subject of ethanol's "effective octane" (which is far higher than you suggest), at least in a direct injection motor, is far more complicated.

Take a look at these articles:

http://web.mit.edu/mitei/lfee/progra...2008-01-rp.pdf

http://web.mit.edu/mitei/lfee/progra...2008-01-rp.pdf

dspace.mit.edu/bitstream/handle/1721.1/69496/775670245.pdf

Neil

Neil,

Read those articles carefully! They are talking about pure ethanol, not E85. Like I said before, there is a big difference between pure ethanol and E85 fuels! They ARE NOT the same.

From your MIT PDFs:

IV. Effective Octane Number Of Ethanol
Table IV shows the results for direct injection of ethanol. The calculations are performed
for a given ethanol fraction addition, defined as the fraction of the fuel energy that is
provided by the ethanol or a high concentration ethanol blend such as E85. This fraction
was 20%. For the present calculations, neat ethanol (E100) was used.

So yes, you are still propagating a lie!

[spool twice]

IMHO, given the variances of "E85" from pump to pump, you should run at least 7 gallons of E70-E85 to 9 gallons of 91-93 octane (with or without 10% ethanol content) which should give you anywhere from 30-43% ethanol content, more than what our stock fuel system has been able to handle, even without a re-flashed fuel table.

[spool twice]

Originally Posted by Jason@Cobb

While there is no "Safe mode", the DME has some ability to compensate. A short (gentle) drive home to reflash will likely be OK, however WOT runs over and over might lead to undesirable results.

This is correct to a point. The DME will pull ignition timing when needed, but during part-throttle situation's, I would imaging running this aggressive map to drive home, would be more than safe. But why would anyone have COBB and not keep other maps loaded in the AP in the car to prevent this scenario in the first place ? Plus anyone who drives flat out in this map with just 91-93 octane and having then complaining about engine performance shouldn't be modifying cars in the first place.

[Tranic335i]

Wow very very impressive! This is nuts specially for a base map, I wonder how much HP you can squeeze out with a pro tune.

[JC335xi]

Originally Posted by vasillalov

...

Plain and simple:

USA 91 fuel = 91 AKI
USA 93 fuel = 93 AKI
USA E85 = 94-96 AKI
PURE ETHANOL = 99.15 AKI

Source: http://en.wikipedia.org/wiki/Octane_rating

Do not confuse E85 and pure ethanol. Totally different things.

...

Originally Posted by vasillalov

Neil,

Read those articles carefully! They are talking about pure ethanol, not E85. Like I said before, there is a big difference between pure ethanol and E85 fuels! They ARE NOT the same.
.
.
.
.
So yes, you are still propagating a lie!

Those MIT articles indicate that in a direct injection application the effective octane of pure Ethanol (R+M/2) is 160. That is a pretty big difference from the 99 you cite from Wikipedia but don't forget though that according to the standards used those values were NOT determined for a direct injection configuration. For example ASTM standard D2700 - 12 (for measuring MON) as well as ASTM D2699 - 12 (for measuring RON) calls for a carbureted engine to be used in the testing!


From that same MIT article,

It should be noted that direct injection of gasoline also increases the effective octane of the gasoline, but to a much lower degree than for ethanol or methanol.

Ford claims that even just direct injecting E85 as a supplement to regular gas port injection can raise the effective octane to over 150. The numbers are probably a little optimistic given this is a new technology they are trying to develop but it is good information none the less... http://news.pickuptrucks.com/2009/06...el-engine.html

So if we assume that,
1) The gasoline the ethanol is blended with is 87 octane
2) We can ignore that the gas will see an increase in effective octane from DI
3) We are getting the lowest allowed concentration of ethanol in E85 (68% per the DoE Handbook for Handling, Storing, and Dispensing E85)
Then using MIT's numbers, in a DI setup, we should still get an effective octane of about 136.

So perhaps the difference between E85 and E100 is not as great as you think.

[Myaddiction]

Originally Posted by spool twice

IMHO, given the variances of "E85" from pump to pump, you should run at least 7 gallons of E70-E85 to 9 gallons of 91-93 octane (with or without 10% ethanol content) which should give you anywhere from 30-43% ethanol content, more than what our stock fuel system has been able to handle, even without a re-flashed fuel table.

I'm not trying to knock you Spool Twice as I'm guessing you are going off what has been posted here on this forum numerous times about the variation. Has any one (besides someone that has a lot to gain by perpetuating this idea) tested the E85 they purchase? I have been running E85 for years in various platforms (It's been popular since 2006 with other groups) and have not seen anything lower then 82%.

You can test it with a simple graduated test tube that costs 5 bucks. I'm not saying there isn't a "bad batch" out there somewhere it's just that it's not nearly as bad as some may lead you to believe.

The standards for E85 do allow some variance that changes from state to state. Here in Washington state it has to be between 85-75% or it's illegal to sell. However like I said I have yet to see it below 82%.

http://agr.wa.gov/bioenergy/docs/E85...Guidelines.pdf

[Myaddiction]

Originally Posted by vasillalov

Enrita,

EDIT:
To get 14 gallons of E30, one needs to blend 4 gallons of E85 and 10 gallons of AKI 93 fuel. This will end up achieving 14 gallons of E31 and the AKI rating would be 93.3 which is just 0.3 bump in AKI from what you normally get out of the pump

If you ignore all the data and just look at the real word results, do you think COBB would get a 40+hp delta by adding an .3 in effective octane or close to 80+hp running straight E85? (using Procede FBO car 380rwhp VS. Procede Flexfuel set up 453rwhp as the example) Clearly there is more to it.