mpg m47 with 3.73 gears
 

Im getting 25-26mpg now with the 3.30 gears with the m47 five speed. I would like to add some lowend to the car. Its a 90 volo 240 the tires (205x55x 16). I have a 3.73 rearend I could bolt in. Just curious if it would kill my milage? Is anybody running this combo to give me some kind of idea. Thanks

I have the zf hp22 in my 262 and 3:73 gears. Got a 91 with alb m47 3:31 gears.installed the alb and used the 3:31 axel.lost some mpg and performance.reinstalled the 3:73 and mpg is back up and drives like it use to. Do it.

I'm actually thinking about going the opposite way. I have a 940 turbo wagon with the stock 3.73 rear end and I have a 3.30 out of a 960 wagon I'd like to switch to improve my mileage. Right now I get exactly what they list 17 mpg in town and 22 highway. You say you get 25-26, is that in town or highway?

That is highway. My engine has no turbo. So its a real dog with 3.30's.

I'm surprised because non turbo 940's are rated at 25-26 mpg with the 3.73 ratio. With a 3.30 I would guess they'd be pushing 30 mpg?

dude I have stock setup and I get 16-17 mpg

these turbos get ****ty mileage, don't think there's much you can do about it.

a lower rear end ratio would mean you'd be turning less RPMs to maintain cruise speed but would need more torque which means you'd be on more boost which likely would neutralize any MPG gain from the RPM difference. it also would make the car accelerate slower in every gear, requiring more throttle and boost to accelerate.

This is rather poor mileage for a 240. I never really liked the mileage that my 240 got - especially around town. On the highway a properly tuned normally aspirated 240 with an automatic should get around 24-26 mpg. Around town it will get less. I usually see 21-23 mpg around town. In the winter it is less for both.

If your getting 16-17, you might want to check a few things. Is your temp coolant sensor functioning properly? If not, the ECU might think it is cold and enrich the mixture. Also, if you have any exhaust leaks upstream of your catalytic convertor, it will allow fresh air in the exhaust stream which is sensed by the O2 sensor making the ECU think that it is running lean and thus enriching the mixture. Any unmetered air getting entering the intake will also hurt your mileage but usually there are other symptoms when this happens.

Actually, I think it might work. Last year I bought some cheap, oversize tires to experiment with changing ratios. Didn't seem to bog down the engine and did improve the mileage, but I only dropped it to 3.5. So, what the hell, I'll try it and see what happens.

know this is old post but
 

did you try it? If so let us know the difference it made. Im thinking about doing the same thing.