Metro taller transmission swap thread: +5% efficiency gain (taller final drive)

[MetroMPG]

Feeding the aero/rr web tool my car's stats, and varying just the ambient temperature, I get the following:

Temp: ... 15C/59F ... 25C/77F ... mpg change (from lower temp)
45 MPH ... 74.48 mpg ... 76.28 ... 2.36%
50 MPH ... 63.9 mpg ... 65.54 ... 2.57%
55 MPH ... 55.22 mpg ... 56.71 ... 2.63%

Avg difference: 2.52%

[disrespected3cyl]

thanks for thw work you've done!
I too have been toying with the idea of a trans swap, but it may be too much. I love the look of my new wheels, but they are a bit too tall and def wider. going from the factory 145R12 to 175/65R14 I figure my gearing from a stock 4.1(91 metro) to be a 3.78. At home I have 2 trannies because I want to get another metro and have one for fun(this one now is for fun and econo, so i'm stuck in a cross-hair). I have a 3.52 and a 3.79.
If I'm right, the 3.79 would give me a 3.49, and the 3.52 would give me an overall 3.24....which could be unbearable with such big wide tires on. Oh, what to do......
Just filled up yesterday, so I'll see what my mpg is and go from there. Maybe I'll wear down these tires for the next 2yrs, then go thinner again and to 13" with steelies before I do a swap. putting rear disc on and front vented rotors probably added weigth, along with a neon center console, so maybe this will be the fun car then, since I still have sway bars I want to install.

[MetroMPG]

Without the XFi cam (more low end torque), I'd be reluctant to go with the 3.52 final drive with taller tires on the car. But with it, I'd probably do it. Then you'd have bragging rights for the tallest effective gearing in a Metro that I know of.

That help?

[disrespected3cyl]

Metro-I thought you remembered-I do have that cam
I can't seem to get my distributor to go past 5* though.....

Tranny would be nice, but do have atleast one big hill home in either 3 directions.....I may get the urge to atleast throw in the 3.79 to start.

[badappleny]

I getting ready to test these 3.52's in a '96. I am starting out with a rebuilt engine (.020 over, around 10.25-1 compression,1.3 flywheel). There is a new cam out from Crower that has a 181 duration (very high torque/low rpm cam that works better then the xfi cam. I can't post links yet but you can see the test for yourself. Go to youtube and you can find it under ... Geo Metro XFi Camshaft vs Custom Grind.

[cosmick]

Only reading the original post, I'd assume the discrepancy would be speedometer calibration, possibly from incorrectly using loaded tire radius rather than correctly using unloaded. But that will save you from speeding tickets, using loaded.
Anyway, the solution for taller gearing hurting acceleration is a turbo, plus turbos like tall gearing to pull against.

[MetroMPG]

What discrepancy are you referring to?