Quote:
Originally Posted by mhayes
The Ford 5 liter can be made to get exceptional mileage. The figures you are shooting for are close to what the factory window sticker said back in the 80s when these cars were new.
I see no problem with this little combo pumping out mpgs in the low 30s.
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My most fuel efficient combo on my 1988 Thunderbird was mostly factory parts.This was early 2009. (edit: had 4r70w transmission swap in 2008, so I wasn't on the AOD during this testing)
60mph average speed, stock 2.73 gears, 0.7 overdrive, rebuilt motor with 1989 Mustang cam, mass air, 1993 Cobra intake and heads, stock timing, around 9:1 compression ratio, 87 octane, electric fan, 3G alternator - 34mpg on 300 mile highway round trips. With a new mechanical fan clutch, I couldn't break 32mpg. Completely factory, I'd see about 31mpg.
I found that with mechanical fan, I saw the same fuel economy on a slight incline. Saw a 3mpg increase on the return trip/slight elevation decrease. This was A-B-A-B-A back-to-back testing highway trips to compare directly.
Now I can't break 25mpg - usually see 24. Much of that car has changed. I'd like to eventually add under-body panels and try some air diverters in front of the front wheels. I'm sure a T56 with 0.50 6th gear would drastically bring my economy back up, and could require even lower gearing in the rear since 3.55s with 0.5 OD would be lower than stock with 2.73s and 0.67.
Besides that, my around-town back then was 20mpg. Useless to compare "city" driving as heavy traffic commuting would return some pathetic 14mpg. Takes 45 minutes to go 6 miles around here.