Was there power loss?

 

As I understand e85 tuning, there aren't major gains in power if any going from 11.0-12.5. Running the mixture "fatter" does allow for more timing and therefore increased tq.

Just my .02.

 

In practice, there is less knock with E85 for AFRs leaner than about 11.8:1. Most people are finding that the sweet spot for greatest knock resistance while staying in the maximum power AFR range is about 11.8-12.0:1.

 

From my experience MBT can be hit on E85 before any knock, even at leaner mixtures. I'd say 9 out of 10 times I can hit MBT on a E85 evo before any significant knock counts.

 

Ethanol will make more power and run a lot smoother at a richer AFR most of the time. No real need to run it lean.

 

What AFR is "richer" to you? I've run E85 at 10.8 to 12.8 and it seems to like it the best in the 11.8 to 12.4 range. All on a gasoline wideband

In the low 11's and high 10's it has a tendency to break up alot.

Of course, my word is not gospel, just sharing my experiences.

 

Just from the limited testing locally, it seems on our blend the cars seem to make best power around 11.3-11.8 on high boost (30-45PSI). Supposedly, we only get E70 year round because of our elevation.

However, I will mention, there is a lot of suspicion that we have recently been switched to something like E60/E50. Everybody that was running it previously recently found the cars to be running about 1.0-1.5 AFR point richer across the board then originally tuned. The cars have also been considerably easier to run into detonation as well. It seems to have lined up with the most recent refilling of the station tanks. We only have 2 E85 stations in my area and they both get the fuel from the same place.

As of the last couple months, higher compression guys are having a hard time running over 30 PSI now, regardless of AFR or timing advance. The low compression guys have still been able to run up around 40 PSI though they did have to retune for the change in AFR.

 

Are those that are running north of 11.8 on non-MIVEC cars changing timing any?

 

bumping an old thread.

question, doesn't a richer mix result in a faster flame speed? if it's burning faster, wouldn't we have to retard timing?

also, i'm sure folks have put more miles on their cars, new experience, etc. what's the current target afr?

 

I'm still happy with about 12.1:1 gasoline scale. Via my job, I have access to many scientific journals, and maybe 6-9 months ago, I spent a few afternoons trying to find info on combustion properties of ethanol fuel blends in ICEs. I found an interesting article on combustion properties as a function of ethanol/gasoline ratio, but nothing vs ethanol AFR. Perhaps its time to look again to see if any new articles have hit the journals.

 

You should be able to find MBT with E85 with 11.0 just as easy as if you where at 12.5

Don't go beyond MBT, that is when you bend rods or vent blocks. For safety I almost always find MBT and then dial it back a bit.

I'm in 0xDEAD's camp of not running leaner then 12.5, my personal sweet spot is usually 11.9-12.2 on street cars and 11.6-11.9 on track cars. You won't really find power differences between those AFR's. I've tested it many times. Like 0xDEAD said, E85 gives you the option of those ranges depending on the use of the car.

- Bryan

 

I have not found a holy HP grail hiding beyond 12.5-1 A/F on any DSM or Evo I have ever tuned.

Cars will just continue to get flatter, hotter and either break up - or break something the farther you go beyond 12.5-1.

I've pushed into the 13.0-1 range with meth with my own car and, again - there is no magic hiding there. If there is, I sure didn't find it. Not on gasoline, toluene, xylene, methanol... and everything in between.

*Although I don't and haven't used E85* Given the nature of it - I can't see it being likely that is going to be any different.

 

are the timing maps appreciably different for 11.6 to 12.2?

 

For those with issues over the blend, just so you know it is quite easy to test. Ethanol mixes with water and gas doesn't, so all you need is a graduated cylinder and a little water. If I remember right (I tested it every time I got fuel for my racecar since it was carbureted), you use 5cc of water and 20cc of fuel. The gas goes to the top and the ethanol-water mix to the bottom. Depending on the fuel, it may separate right out, or you may have to stir it and let it sit for a few minutes; I think what makes the difference is what they denature it with. This is how the tech inspectors tested our fuel at the track as well.

 

No that was my whole point to my post, you should have no problem finding MBT in that AFR range.

- Bryan