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Old 12-28-2015, 03:33 PM   #6 (permalink)
spacemanspif
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Join Date: Jul 2013
Location: Dirty Jersey
Posts: 748

The New Focus - '07 Ford Focus ZX5
90 day: 32.44 mpg (US)
Thanks: 142
Thanked 204 Times in 148 Posts
For 1 year right at the beginning of gas price increases I bought a 2.29:1 rear out of a Malibu and swapped it in to my Monte Carlo (78-88 g-bodies). I didn't have a way to calculate miles travelled other than the math that I think was correct/close to accurate. I drove for a week at the "math'd out" RPM for 65mph (1600ish) and got terrible mileage; even worse than with the stock 3.73:1 rear. Once I brought the RPM up to 2000, I started getting much better MPG to the tune of ~25mpg around ~80mph.

Cruise RPM is super important and should not be over looked. A t56 with its double overdrive might never see 5th with such a tall rear gear. 6th might be totally useless n

I like the idea of a 4cyl cummin in a Malibu wagon.
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-Mike

2007 Ford Focus ZX5 - 91k - SGII, pending upper and lower grill bocks - auto trans
1987 Monte Carlo SS - 5.3/4L80E swap - 13.67 @ 106
2007 Ford Focus Estate - 230k - 33mpg - Retired 4/2018
1995 Saturn SL2 - 256K miles - 44mpg - Retired 9/2014

Cost to Operate Spreadsheet for "The New Focus"

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