Discussion in 'The Garage' started by bigblock454, Oct 23, 2003.
Someone with 3.73 or 3.53s, what mileage do you get with a th400?
I do with 3.73's but I have the 5 speed manual. I get about 13 on the freeway and around 9 to 10 in town.
My buddy has a dually too with the TH400 and 4:11 gears and he gets 8 all the time.
my 89 3 + 3 crew dually 454tbi gets 10 around town.. 12 freeway driven easily... 4.10 ratio/turbo 400
8 is about what I get city/highway average with 4.10s. I wonder what 3.54s would get me?
I have a '95 C3500 454/4L80HD 14BFF/3.73s 215/85R16 tires. 8-9 mpg around town 11-12 on the freeway. Best I've ever got was 14 mpg on the freeway at 55 mph.
You guys aren't doin so bad. My 1 ton 2wd '87 with TBI and TH 400 and 4.10s gets 14 empty and about 8-9 pulling and it's a total dog.
454's with TH400's and 3.73 seem to get right at 10 local and 12 hwy with STOCK SIZED TIRES. Thats what my 454 burb does. Best I have seen was 11.55 hwy at 70-75 mph. Weight doesn't seem to matter much. I pulled a 79 K5 on a heavy trailer and it pulled 9.5mpg
Driver can always effect. Dogging rices at stop lights seems to have a negative effect on MPG /forums/images/graemlins/laugh.gif
My odometer is correct and has been checked over a 100 miles of travel against a GPS.
WHo ever said their 87 TBI is a dog...is that a 350 or a 454. My bone stock 88 heavy burb will plant you in the seat. Last night in the rain I could spin the tires at will even rolling from about 15mph......Sounds like you have something wrong. If it's a 454 check the gasket where the heater meets the intake. Very prone to failing and it will screw up the mix but not throw a code. Mine had that problem and it made a huge difference fixing that.
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