The Project Pad

Would the knowledgeable out there want to enlighten me on e85 fuel?
What are some advantages and disadvantages of it? What kind of fuel economy does everyone get with respect to their power/driving style?
I know there are power gains from it, but I also know it raises chances of pre-det. In a fairly low performance build(so far) is it worth it?

Interested because for the last 5 years(as long as I've been driving to notice) the nearest location to get e85 was around 25-40 miles away. I noticed Friday filling up that a station <1 mile from my house now carries it for 2.16$/gal.

20VAvant wrote:but I also know it raises chances of pre-det

Huh?

The main benefit of E85 is that it is incredibly resistant to detonation. This allows you to run ideal ignition advance to produce maximum torque. With gasoline, you cannot run anywhere close to this much advance because you are limited by detonation. E85 also burns faster which means MBT occurs at a more retarded ignition time. These primary benefits really only apply to those who have very high boosted or high compression motors though.

There are other benefits like lower MAT, a cooler running engine in general, and more exhaust volume = slightly faster spool.

And yes, it is a lot cheaper, but it contains much less energy per unit than gasoline, so about 30% more fuel is required. Your fuel system will need to be up to the task if you plan to run it.

I was under the impression that E85 burned slower.

EDIGREG wrote:

20VAvant wrote:but I also know it raises chances of pre-det

Huh?

The main benefit of E85 is that it is incredibly resistant to detonation. This allows you to run ideal ignition advance to produce maximum torque. With gasoline, you cannot run anywhere close to this much advance because you are limited by detonation. E85 also burns faster which means MBT occurs at a more retarded ignition time. These primary benefits really only apply to those who have very high boosted or high compression motors though.

This is why I asked.
Thanks for the info!

The only data I can find via Google on fuel burn rate is: Gasoline @ 26cm/s and Ethanol @ 41cm/s. Nothing concrete.

http://dspace.mit.edu/bitstream/handle/ ... 953430.pdf

Pretty interesting and confirms that E85 burns slightly faster (.33 vs .41 at stoich & 1bar). The statement as the end of 5.1 is pretty interesting.

Don't forget that E85 is around 105 RON.

Burning faster is can be a good thing, as long as it doesn't detonate like gasoline tends to do. E85 is like rocket fuel for turbo cars, it is really superior to even it's equivalent octane gasoline for the reasons listed above.

Has anyone else been following the latest developments with the government mandate on ethanol and gasoline? What once was considered an alternative is being attacked by the same environmental groups that pushed the mandate through to begin with. It will interesting to see what happens to ethanol in the short term....enjoy it while you can!

government

Kinda like MTBE, raise the price to put it, have it leak from tanks at gas stations and pollute groundwater then raise prices again to remove and clean up the mess. Great plan guys.

At least E85 has some good upsides

Make sure your fuel system is up to date with Viton o-rings and fittings. Nothing bad will happen but over time the high amount of alcohol will dry out your soft parts in the fuel system.

Ethanol also burns alot cooler vs gasoline. One of the reasons why you can run more timing with more boost. Less heat = less chemical reaction(s). This is also why you have to run more fuel since an ethanol molecule needs less oxygen over gasoline to burn stoich.

If I remember right, ethanol also has a higher specific heat over gasoline which leads to the higher octane (RON technically) rating. Meaning it takes more heat to start a reaction which is why pre-det actually goes down along with knock (if tuned correctly)