Lean Burn

[niterydr]

Best fuel economy isn't at 16:1, sorry...you are just creating excessive strain and heat. Try to stick to STOIC for gasoline vehicles.

[iceminion]

niterydr, thx for the advice, but please read up on leanburn

"The newer Honda stratified charge (lean burn engines) will operate on air-fuel ratios as high as 22:1. The amount of fuel drawn into the engine is much lower than a typical gasoline engine which operates at 14.7:1, the chemical stoichiometric ideal for complete combustion when averaging gasoline to be the petrochemical industries' accepted standard of C6H8."

everyone on the Megasquirt and DSMAP forums also has conflicting information to what you just said

yes, running lean while under boost creates lots of heat and melted parts, but while idling away on the freeway, running lean cannot damage the engine because there is not enough fuel.

As a matter of fact, you were telling me about how you could lean tune your DSM to 36MPG, I didnt believe you at the time, I have no idea why you have reversed your stance

[iceminion]

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

[niterydr]

I try for 15.5ish max for "lean" anything else is just creating heat. I am sure people aren't mearly driving differently to help them achieve results....

90% of your fuel economy gains are with tuning decel fuel and throttle tip in fueling, not cruise fueling.

[Kracka]

I created this thread since its something I've been thinking about recently and it was being discussed in another thread. The above posts have been taken from the DD Civic thread in "Projects" section.

"Lean Burn" is a popular mod on the Evo's as it can be done very easily within the stock ECU. I figured it creates more heat therefore more wear on the engine (as backed up by Swanny), but am sure but how much. I used to run mine at ~15.6:1 (I've set many other local Evo's to the same) but am now back at 14.7:1 since installing my 850cc injectors; I know Scheides is at 16.0:1. I've been contemplating adding it back on my car to see if I can save a bit of gas. Swanny, could you please elaborate more on why you have chosen 15.5:1 and what made you come to that conclusion? Anyone else have any experience or insights?

[Speedfreak]

My understanding from the EFI 101 class is that when not under load, it's OK to lean out as far as your car will go. They said to find that point you lean it out until the car just doesn't behave correctly(bucking etc) and add fuel until it's all smooth. **This is NOT under load and is in the cruising area of the map.** This is a very simplistic post about how to do it, but you get the idea.

The basic thought is this.. When not under load, leaning it out does not create extra heat. The less fuel, the less burn, the less heat is the way EFI 101 put it. I can pull out my notes from the class to quote exactly if needed, as I was very interested in this exact topic, and we went over it extensively..

[Kracka]

When I setup lean-burn on the Evo's I do it in the 2000-4000rpm and load value 30-70 range. A load value of 30-70 is only seen during steady throttle cruising.

[turbotalon1g]

It seems to be a popular mod, i have been thinking about this and i cannot wait until V3 to implement it on my car, but I am skeptical about what AFR to do it too as well.
I know that some domestic tuners, more than one shop. Tunes cars past 16.0 cruising, my friends mustang is set to 16.8-17.0ish for cruise.
Thats a little too lean for me, but there is some more info, car is on E85. I don't think it is tuned for lean burn on gasoline.

[Goat Blower]

Don't do it on an E85 mix, it's definitely different. On the Duluth cruise I had to add some regular 92 octane piss to get me to an E85 station and was running at about 16.5:1. It bucked under any load at all and really got hot under the hood. I'll stick to stoich.

[turbotalon1g]

I would think the cooling effect of E85 would help to keep temps down even more so compared to reg. gasoline.