I had heard the same thing as Rorik, and had always thought so to. I thought optimal E85 afr's under boost were like 8.5:1. "Stoich" being somewhere around 9:1.

Also, I had heard some of the same stuff as Rorik about afr's and lean tuning as well. But it does make sense that e85 would be more tolerable to lean tuning as it does contain less btu's which should translate to less (heat) sensitivity to a/f changes.

I'd love to play with some e85 on my next turbo build, unfortunately theres no place around here that sells it. Maybe someday...

Oh yeah, nice "Hellement", btw.

 

here ya go. Not my vid but good enough....

http://video.google.com/videop...dex=2

 

here ya go. Not my vid but good enough....

http://video.google.com/videop...dex=2

here is the orig video:

http://videos.streetfire.net/v...5.htm

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rorik &raquo;</TD></TR><TR><TD CLASS="quote">Well, the o.p. got into it, so maybe a few more exchanges won't be considered thread jacking..

Let us know what you think about this..
A diesel has a really high dynamic compression for 2 reasons, high static (mechanical) compression and no throttle. That dynamic compression is mostly what makes the diesel so efficient. Not so much the btu content of the fuel. So the more air you let into a gas motor, the more like a diesel it becomes, as far as efficiency..to a point. Same thing with egr, actually, that is probably better, since the exhaust is basically inert. I created a thread on another forum on the subject of tuning for mpg, and some of the things people posted up amazed me. For instance, aircraft motors running open throttle above 5k feet, with enough fuel taken out to drop the egts getting the best mpg. (start taking out fuel, egts rise, keep taking it out, they drop, now you're at the power level needed for cruise, they call it "wide open throttle/lean of peak") (I don't know what that a/f ratio actually is, they don't have widebands..)
So I don't have any numbers here at all as far as what ratios, what % efficiency increases, etc, for what motors. Those air cooled aircraft motors are old as hell, and not designed for that type of operation, yet it works.. All I'm saying is that it might be worth it to experiment. I remember reading in an old book from the 60s about carburetors that some of their cruise mixtures were as high as 18:1, I was like, "wtf??" But that won't work with a catalyst, so..not anymore.</TD></TR></TABLE>

Well, high compression vs a throttle plate (TB) restriction does really wierd things to a gas engine's efficiency, and the reason why super high CR engines died with the 70's emissions crunch was the inability to deal with lack of idle emissions resulting from high CR and the engine fighting itself below it's optimum powerband.

All in all sounds like I should maybe have another think on the lean burn subject... my only experience with it is tuning my beater's D15B7 for 15.8:1 at cruise, and I picked up zero mpg while requiring higher MAP pressure to cruise and increased throttle angle. Actual/dynamic CR, camshaft profile, and operating rpm band @ cruise are all going to have an effect on ideal operating parameters so my one dabbling likely doesn't mean anything and there could be a window of opportunity here.

I've not dealt with any of the lean burn stuff, but the engineering texts show combustion temps (as well as chamber pressures!) fall way the hell off after 17:1 AFR. liveforphysics/Luke (wtf has he gotten to in the last few years? A real internal combustion engineer is a rare bird to have floating around) was telling me at one point about super efficient lean burn (20+:1 AFR) setups requiring funky ignition setups to correctly start the burn under those conditions.

BTW, in this mpg thread you speak of... did anyone mention fully opening EGR and adding a lot of ignition timing giving a nice bump in fuel efficiency?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by rorik &raquo;</TD></TR><TR><TD CLASS="quote">Same thing with egr, actually, that is probably better, since the exhaust is basically inert. </TD></TR></TABLE>

Most of what I wrote in y other thread was above the other people's heads, but yes, I have thought of using egr for fuel efficiency enhancement. Makes me feel dumb to know that I've always disabled/removed it in the past..

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by FULLTHROTTLE &raquo;</TD></TR><TR><TD CLASS="quote">G it is more than 100% efficient. </TD></TR></TABLE>

you should patent that.

 

thats one of the best burnout vids i've ever seen.

 

turbo SUV's FTW