so, tuning to try and get a bit better gas mileage... what is a decent A/F to strive for while cruising.

i've been tuning at 65, 70, and 75mph. would like to improve my MPG (i work really far away).

i've seen someone posted "15.3". 16s. i've heard some cars (not evos) hit 17:1.


anyone?

 

One of my EFI books says that Max fuel economy is @ 15.4 AFR.

Another one of my books, says you may be able to get away with 16:1

I havent tested either of these, as I have never worried about MPG with the EVO.

If I was to, I would try 15.4

 

noted. will do. i guess a heavier, AWD car isn't gonna get all that great mileage. eeeeh. well. just curious. gracias.

 

risky in a turbo car, but if your not boosting you should be alright.

 

When you start getting too lean driveablity starts suffering. Depending on the load and rpm it could be 20:1 or 13:1. "normal" cruising upper 14's to low 15's os so. When you are under higher than idle vacuum and under decel you can easily go 20:1.

 

my 8 seats about 15-15.5 when on the hwy

 

Lean misfire limit in an Evo is around 17.5:1 AFR and/or 47* of timing (while cruising).

The thing about EGT and lean out of boost is it doesnt hurt anything. There isnt enough heat energy to do damage out of boost. As far as that goes, you run into a point of diminishing returns if you take too much fuel out since it cant create enough hp to cruise efficiently.

That being said I usually target around 16.2-16.6:1 for cruise.