6.9 vs 7.3 IDI fuel economy - Diesel Truck Forum - TheDieselGarage.com
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post #1 of 3 (permalink) Old 02-06-2011, 05:14 PM Thread Starter
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6.9 vs 7.3 IDI fuel economy

I have a '91 E350 (8 pass) w/7.3 IDI that as the family truckster usually averages 20 mpg (and as high as 22)

One of my buddies told me the 6.9 IDI did much better then the 7.3, can anyone confirm this ? Mostly, Ive owned 7.3 P'Strokes.

Im looking for a beater daily driver 6.9 or 7.3 that can do about the same as the van
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post #2 of 3 (permalink) Old 02-06-2011, 07:40 PM
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Our '93 F250 7.3L IDI gets about 20+ at 70 MPH, 5 speed w/OD and 3.73 gears.

'93 F-250 HD, 7.3L IDI, 5spd - FARM TRUCK
I Support: Trailer brakes an every axle over the towing vehicle's GVW; CDLs for RVers; Safety inspections for ALL vehicles and 6 axle trucks (97K GVW proposal).

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post #3 of 3 (permalink) Old 03-02-2011, 03:36 PM
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I have owned both a 6.9 and a 7.3 idi. The 6.9 had a C6 and 3.55 gears. The best I ever got on it was 18mpg. The 7.3 is a 5sp with 3.55 gears and I may have gotten 20mpg a few times. 18mpg is more realistic and on short runs about 15-16mpg. Both of my trucks have been 4wd which makes them a bit heavier. I drive conservatively. No jack rabbit starts and maintain the posted speed limits. Some guys claim to get in the mid 20's on these engines but I don't honestly see how. Still 18mpg is close to double what the gas models get.
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