Ethanol more conducive to knock??

[dsmtuned]

A guy I know wants to convert his turbocharged car to ethanol only. I swear that I read in this forum that ethanol knocks to a greater extent in turbocharged cars. I can't seem to find this though.

Can someone point me to some resources on the properties of ethanol when it comes to knock suppresion?

Thanks for the help, Craig

[SaabTuner]

Ethanol requires a different A/F ratio. So if you just put pure ethanol in your tank, you will run very very lean, and probably knock.

Otherwise I can't explain it.

Here are the octane ratings of a few common chemicals:

Checmical / RON / MON
(The octane number you see in the US is [RON + MON]/2)

Ethanol / 129 / 102

Methanol / 133 / 105

Iso Propyl Alcohol / 118 /98

MTBE / 116 / 103

Toluene / 124 / 112

Meta Xylene / 164 / 124

Dicyclopentadiene / 229 /167

All of these chemicals can be harmful to your engine in excessively high concentrations. Small percentages (30% or less) of Methanol, Ethanol, or Toluene, are generally considered "safe"

Adrian~

[hotrod]

As an injectant for WI / alcohol injection ethanol and methanol are essentially interchangable as far as the engine is concerned. There are some issues of compatibility with different pumps etc, but once its in the air stream its pretty much interchangable. The test Pratt & Whitney did on their R-2800 series air craft engines during WWII ended up using the same injection rates for both methanol and ethanol on their ADI systems.

If he's going to a full alcohol fuel system, I highly recommend high ethanol fuels. I am currently running my WRX on 85% -100% E-85.

E-85 is a mixture of 85% ethanol from corn, and 15% gasoline. There is a small penalty in miles per gallon. Mine dropped from the low 20's to the high teens but the E-85 sells for $1.59/gal vs $2.05/gal for pump premium.
There is also about a 5% gain in power/torque on it when properly tuned.

The Ethanol burns a couple hundred degrees cooler than gasoline, (so cool I need to put a standard thermostat back in during cold weather to get normal engine warm up). Produces slightly more exhaust gas combustion products per pound of fuel than gasoline --- this gives more exhaust to power the turbocharger and slightly better spool.

You can buy the fuel here in the Denver area and much of the mid-west U.S.

For those interested in emissions, since it is 85% renewable fuel (ie the alcohol) its net emissions are much much lower than gasoline. My net emissions of CO2 etc. is approximately what a car that got 120 mpg on gasoline would be. By net emissions I mean the CO2 emissions that are not recaptured in growing the next crop of corn.

For those interested in following my experiment;

http://forums.nasioc.com/forums/showthread.php?t=637920&highlight=E-85

http://www.coloradocorn.com/resources/ethanol/facts.htm
http://www.e85fuel.com/
http://www.ethanolrfa.org/factfic.shtml
http://www.ethanolrfa.org/press.shtml


The last time I ran a data log on my car I had an ignition advance multiplier of 16 which is the highest possible, -- in other words my ECU is very happy with the fuel octane.


Oh by the way the 5 times IHRA funny car champion Mark Thomas runs ethanol fuel!!
http://www.ohiocorn.org/news_2001_0831.htm
http://www.fb.org/views/focus/fo2004/fo0830.html
http://www.ethanolrfa.org/pr040922.html
http://www.mncorn.org/servlet/mcga/news/dailyarticleDir.iml?area_id=42&article_id=7127&display=Y&thispage=news/dailyarticleDir.iml



Larry

[PuntoRex]

How I envy you your option on this!
Here in where I live, the gas price has been going up & up & up :?
While the quality is definitely not :roll:


However, I remember in an article that the ethanol could make different corrosion effects that normal gasoline fueling system can not take.

Did you make any mods for the E85 fuel or experience any problems on your fueling system?

[hotrod]

So far, the stock fuel system is fat dumb and happy with the E-85. No changes and no problems, except some minor nuscience CELs. With the stock system it would take up to about 33% alcohol with no problems. At that concentration it would push the fuel trims to max rich to compensate for the leaning effect of the ethanol. That triggered a "too lean" CEL. After upgrading to an over size injector it will accept 100% E-85 (ie 85% ethanol) without get the "too Lean" cel, but the evaporative emissions system throws a CEL due to the higher vapor pressure of the fuel I believe. It thinks the gas cap is loose, but the car runs great. The only down side is I have to drive 20 miles each way to fuel up, so I bring 2 five gallon gas cans with me and fill them too.


They will eventually add new fuel outlets in my area, I know they are actively negotiating for them with independent fuel outlets (not owned by large petroleum companies). It just takes time for the infrastructure to be built.

Its sort of a "which came first the chicken or the egg" problem. They won't build the fuel outlets until they know there is a good market, and there won't be a good market until fools like me go out of their way to buy the stuff from the stations where it is available.

The good news is the American fuel ethanol producers have had a string of all time record sales over the last few months and there are quite a number of fuel ethanol plants planned for construction in the near term.

The Congress recently passed and President Bush, just signed new legislation that will encourage more investment in E-85 infrastructure.

Larry