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Username Post: 454 guys - what is your mpg?        (Topic#184528)
Senior Moderator
Posts: 8497
Loc: Cleveland, OH
Reg: 01-30-00
03-13-08 02:40 PM - Post#1387240    

specifically i am looking for what someone with a 454 TBI dually is getting with either the 5 speed overdrive manual (91-95) or the 4L80-E.

my mileage sucks with the SM465 non overdrive manual, and i need to see what i would be comparing to for gas savings to decide if it would be worth it or not to sink the cash into a tranny swap.

Low priced Genuine GM Auto Parts
Marv D 
Posts: 218
Marv D
Loc: Arizona
Reg: 05-29-07
03-13-08 06:17 PM - Post#1387379    
    In response to patgizz

Pat, you want me to tell you how to 'fix' the mileage <grin>

Sorry, really have nothing for you. I know my fuel vendor runs a 70's 1-ton 454 carb'd motor with 4.10 gears ,, he is lucky to get 8-10 with a couple of drums of fuel and a liftgate on the back. He hates the truck with fuel at $3.25 here.

BTW, pulled the trigger on a new motor for my 94, anbd have it at the body shop getting prettied up. One of these days I'm going to have to get all this junk I own in one picture,,, WIDE angle lense no doubt. (I'm almost to catch up with you!)<grin>

1966 C-10 street toy 12.06@107
1964 chevyII 9.14@145
all the junk in one place

Posts: 103

Age: 25
Loc: Austin, TX
Reg: 05-19-06
03-13-08 08:53 PM - Post#1387474    
    In response to Marv D

I know a kid who can get as good as 12-14MPG if he keeps his foot out of it. But in spirited driving, he says he can get as bad as 6-8MPG.

Boosted 1 
Posts: 179

Loc: Downey,Ca.
Reg: 10-25-06
03-13-08 09:52 PM - Post#1387492    
    In response to patgizz

I have a 92 3500 dually 454,TBI,4L80E,and mileage sucks about 8 mpg on a good day ! Its almost how many gallons to the mile

92 3500 toy hauler, 63,70,Nova,83 Shovel, Blown with N2o 90 step side

Very Senior Member
Posts: 2401

Loc: Minden, NV.
Reg: 09-14-00
03-14-08 04:13 PM - Post#1388118    
    In response to patgizz

My '91 454SS with 4L80E, 4:10 & TBI got just under 14mpg on a 1K trip through the mountains (March 3). It usually gets around 13mpg on the open road regardless of conditions, bed full of junk or empty.
It does have a Comp Cams 302 and slightly cleaned up heads & intake.
Best thing I ever did for mileage is change to a heated O2 sensor. Oh, I also changed it over to a Vette knock sensor. The original knock sensor is too sensitive.

IMO, there is nothing much you can do to justify the swap based on mileage. Although the 4L80E is a great tranny. You'll need a matching ECU for the swap - so keep an eye out. The trannys are not hard to find.

Every Government Interference In The Economy Consists Of Giving Unearned Benefit, Extorted By Force, To Some People At The Expense Of Others - Ayn Rand

Low priced Genuine GM Auto Parts
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