Mpg-bbc vs sbc Suburban

[turbo350]

Definitely not buying a Sub for fuel mileage lol. But how much of a difference in mpgs in a 350 vs 454 Subs (89-90). Found an '89 2wd 454 t400 trans, 3.73 rear. Owner put an Edelbrock tbi intake on and says the power gain was noticeable. Would I be lucky to pull 11-12 mph with it? What mpg could I expect from the same Sub with a mostly stock 350 tbi?

[68Timber]

I haven't had a BBC square, but what people say is 10 mpg loaded or empty. With a SBC in good tune you can get mid to upper teens hwy only, 10 to 12 in town. What do you need it to do?

[kwin]

No one will believe this, if I had not seen it my self I would not.
When I purchased my suburban the original owner had installed a airaid system and he claimed that it got 21 mpg when he drove 110 kmh ( about 70 mph) I thought he was nuts.
Three weeks ago I had to go to edmonton on business and I was blown away by the mileage. I filled up in edmonton and drove 4.5 hours home and the gauge still showed 5/8 of a tank. It was six days of in town driving before I had to fill it. Its a big tank but still its reasonable!
I havent done the calculations but this thing is not bad at all on fuel.

We will see what a 6.0 does to it ! lol

I suspect this is the best a small block Suburban will do, might help with the comparison or just confuse things.

Keith

[YoungBurb88]

I myself drive a stock 4x4 Suburban, 1988 w/ TBI 350, and I get about 13mpg in city and when it's running right about 16-17mpg highway.... the 10mpg for the 454 is on par with what I've always heard about them.

But to quote Bruiser, "What do you need it do?"
Daily driver? Road trip land yacht?
or
Are you looking for something that will see less use, but more strenuous applications?

[turbo350]

For comparison, had an '87 g20 conversion van 350 tbi 700r4. Between myself and the original owner (who took it all over the country when new) never got better than 13 mpg ever and it was maintained meticulously.

[DBLSPRT68]

Originally Posted by kwin

No one will believe this, if I had not seen it my self I would not.
When I purchased my suburban the original owner had installed a airaid system and he claimed that it got 21 mpg when he drove 110 kmh ( about 70 mph) I thought he was nuts.
Three weeks ago I had to go to edmonton on business and I was blown away by the mileage. I filled up in edmonton and drove 4.5 hours home and the gauge still showed 5/8 of a tank. It was six days of in town driving before I had to fill it. Its a big tank but still its reasonable!
I havent done the calculations but this thing is not bad at all on fuel.

We will see what a 6.0 does to it ! lol

I suspect this is the best a small block Suburban will do, might help with the comparison or just confuse things.

Keith

I would think the lower rear end gears were swapped out for taller gears. A SBC V8 with 3.08 rear gears gets about 20 MPG. Also, my old 89 454 Suburban got about 10-12 MPG; doing 70 AND pulling a 5000 lb car/trailer combo!

[kwin]

Originally Posted by DBLSPRT68

I would think the lower rear end gears were swapped out for taller gears. A SBC V8 with 3.08 rear gears gets about 20 MPG. Also, my old 89 454 Suburban got about 10-12 MPG; doing 70 AND pulling a 5000 lb car/trailer combo!

That was my thought, and its sluggish off the line so a gear swap would make sense.

Keith