Thread: 350 vs 454 in mileage

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If you have gone from a 350 to a 454 big block.

Was there a big difference in gas mileage?

Could the Big block go 80% as far on the same tank of fuel?

Originally posted by POWER2BURN
If you have gone from a 350 to a 454 big block.

Was there a big difference in gas mileage?

Could the Big block go 80% as far on the same tank of fuel?

I had a 72 Chevy 3/4 Ton truck that got 10 miles to the gal. made little or no difference if you drove with the wind, - against the wind - empty or loaded.
I'll bet there are 454's out there that would do as good or better.

my truck has no load in it or behind it. 95% of the time.

I get as good as 13mpg with my 357. my old 305 was wore on gas.

1/2 ton truck 4500 or so pounds.

3.73 gears and a built TH350 tranny.

I get 12-15 on a stock 350 in a short wheel base 2wd GMC pickup with a 350/t350 and 3.73 gears while doing 65-70mph.

WELL.hohoho,,,,,, I jest got the 3/4 ton cheyenne on the road last thursday so I guess thats one week on the road ,,so far 1/4
tank for 137 miles Hmmmmm.it may have something to do with the 20mph speed limit here and the fact im spending most of my driving time at idle in top.. the bugger goes anywhere in 4th at anything over 10mph this is one amazing vehicle ,,also a lot more fuel concious than the F250 or the little two litre Isuzu before it, I think Im in love

p shirkey

What size motor you runnin?

548 miles per tank. that must be a big tank.

I can go 250-260 miles per tank. 20 gal. runnin 2500-3000rpm.

P shirkey I get about the same with my Tbird and my camaro but after that 1st 1/4 tank it just sucks down, Drive a full tank and then figure it out. It could just be that first 1/4 that looks good. After a full tank it averages to about 17mpg hiway and 15mpg in the Tbird and 16 and 14 in the camaro.

I get any where from 10-12 with my 355, and thats with a TH350 and 3.42 gears at 70-75mph@ 3200-3400rpm. I get about 160 miles on a tank(15gal), 180 if I'm lucky,

My TBI 305 powered '87 gets around 20 to a gallon, my Daytona gets around 40.
I think several other considerations, besides raw cubic inches, need to be factored in. If you dump a ton of gas into a tiny motor (think "1000 CFM double pumper on a metro") you can get horrible mileage.

Chris

My 260 olds got about 20mpg at its best, and 10mpg at its worst, but a lot of that had to do with the carb. Any motor can be made fuel efficent, but at what price.

iTS got a 350 TBI and four on the floor,at 150miles I put ten gall
in and the fuel gauge showed a little more than i started with so i figure im getting around 16mpg,this is way better than i expected

same truck. same 3.73 rear gears. same TH350 tranny.
600cfm carb on 350. 695cfm on 454.

The latest analysis is 15.7 mpg and its still way above what i expected from this machine Im definitely in love with this one

12.4-15.2mpg

with my 357ci SB.

with everything being close to the same.

couple more lbs for the BB.

with the added cubic inches.

will it really draw much more fuel?

same carb. milder cam.

I used to have a 79 silverado 2wd 3/4 ton with 454/th400/4.11 gears new carb fresh tuneup and motor was GM crate with 10k when i bought the truck. Best I could get was 5/7mpg BABYING IT loaded unloaded it didn't matter. It was terrible and didn't have that much more power than a SB at least not enough to make it worth it. Was the first, last and only 454 I will ever own. Had alot of chevys with 350's and 305's 1 400sb and the 400 sb with a 2bbl would smoke the 454 and got about 12mpg in a 79 1/2 ton 4x4 with 6" lift 35" tires th-350 and 4.11 gears. If you want big-block go ford. 460's are tougher and get ALOT better gas mileage. I am not talking late 70's/current i am talking early 70's pre emission motors they kick a** I had a 78 f-250 4x4 4" lift 33" tires with a 70 460 dove II heads bored .40 over edelbrock performer cam intake and 750 edelbrock carb. 4.10 gears and a c/6 I always got 14mpg loaded or unloaded if i kept my foot out of the 4bbl and it had a 4 times the power of the crappy 454.