Not sure if I'll get much response, since it doesn't seem like too many people around here are running standalone ECUs, but I'll ask anyway.

 

If a non-turbo EA82 is tuned as lean as it will run on the highway, what kind of mileage numbers pop out? I'm considering getting/building a standalone fuel computer for my GL, since I put absurd numbers of miles on it (5000 in the past month, roughly). I'd be running without a cat (though I normally run with a ferret), so I'm not worried about high EGTs. I'll put a wideband in for tuning, and under light load in my normal cruising range (3000-3500 RPM) tune it as lean as I can go without getting surging.

 

There's a side factor for this as well - I'm starting (slowly) on a project RX-7, that will eventually be pushing 400+ HP to the wheels. If I get a standalone & become familiar with it on my Subaru, it will be beneficial for tuning the '7 (rotary engines don't tolerate detonation at all). Plus, if I can get a significant boost in economy (from my 23-27mpg currently), it will literally pay for itsself in short order.

 

Is 70mph economy of 30+mpg doable, or does the stock ECU do a good job? Since the stock ECU will be cycling around 14.7:1 for emissions, I'd think running 16:1 or 16.5:1 would be better for economy, and there shouldn't be any problems under light load with detonation. I might be able to get a bit more power out of it as well.

 

Anyone have input on this? If not, I'll probably go ahead & do it at some point anyway, and provide some feedback.

 

-=Russ=-

since it is a non turbo won't the exhaust be real loud ? since your running no cat ?

Well, right now I basically have a straight pipe that ends under the car, due to exhaust system rust.

 

The plan I have for the exhaust is to put a presilencer (glasspack) where the cat would go, and then back to a normal muffler. It'll be quiet enough.

 

-=Russ=-

you can easily tune 30 mpg into a efi na soob with 9.5 to one. not hard at all