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Old 05-12-2011, 02:20 PM   #86 (permalink)
Diesel Addict/No Cure
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Originally Posted by Rusty Marina View Post
Area near my house is notorious for water over the roads. I miss that old F250.
I'm needing a pickup again and I'm wondering how well a old 6.9 diesel Ford can do on fuel as they pop up for cheap.
The old IDI 6.9/7.3 in that chassis will do in the 14-16 mpg range all natural, will do better if turbocharged with either the factory ( nee ATS ) or a Hypermax system. The biggest problem with these engines is simply gearing.
From the factory, these engines are geared too low, and if the gearing were changed to lower the speed to 1600-1800 in top gear at cruise, the mileage goes up substantially.

I used to frequent an IDI site, and one of the founders took a stock 6.9 IDI and a 5 speed OD transmission and put it in a F150 pickup with 3.08 gears in the back. Got 30 mpg out of it.

If there was a gearset in the 2.73 to 3.08 range for the 3/4 to 1 ton rear axle that was readily available, buying an IDI truck would be an mpg dream
Volvo WIA42 VED-12 / 335 hp / 1300 ft/lbs / 9 mpg

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Last edited by cleanspeed1; 05-12-2011 at 02:28 PM..
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Rusty Marina (05-13-2011)