Post-engine swap MPG?

[biomax]

I was originally thinking diesel swap, but now that unleaded has dropped 50% in cost, I'm rethinking my engine swap. Main factor for me is mpg. I'm interested in what ACTUAL (not estimated) mpg is for different engine/tranny combos.

Please post your swap details and mpg.

Thx

Robert

 

[lehiguy]

My drivetrain combo is in my signature below. I have not yet perfected the TBI, it is returning between 14 and 15 so far, most of that pulling a trailer. Before I put on the TBI, I got 17 MPG going to Moab and 16 MPG coming home on the last trip with a Rochester Quardrajet and distributor that I tuned myself. I loved the simplicity, but being a sucker for the possibility of getting even more from the motor I went to TBI. Time will tell if that was a good move, but it's done now...

 

[missipboy]

i've driven my 1hz/h55 combo with 32x11.50 and 3.73 gears a little over 1000 miles now and i've gotten just under 20mpg. that's all round' town driving. no long trips yet.

 

[Downey]

Here's some generalities:
(a) back in the carburetor days, most 6 cyls. got 12-14 mpg. Smaller 305 and 327 engines with 2 barrels or Q-jets got 16-17 mpg. Larger 350's with anything on them only got about 14 mpg. The 350's are built for torque, not mpg.
(b) todays fuel injected engines, particularly newer Vortecs are getting 17-20 mpg. Something wrong with the set-up if getting less than that, usually guys who think they don't need a VSS or some other part of the fuel injection system.
(c) next problem I've seen alot of is lame-o's who accessorize their engines (intake manifolds & carbs, cams, etc) with combinations of some hp/mpg equipment and some torque equipment---the two don't mix. When I'm building an engine for highest mpg possible, every item that goes onto/into that motor will be for mpg only!!!!!! Chevy V8's already have more low end torque than your 6 cyl., they really don't need more---I say build for mpg!!!!!

 

[rover67]

I got 16.5 on the hwy with 35's, h55f running in 4th gear with 3.73's still goin a gps'ed 70mph. Mileage has gone up since I installed a VSS, but I have not taken any good long trips to know what the average is. I am running a 5.3 vortec.

I get 13-15.5 in the city depending on how i drive. 15.5 is still beating traffic at lights, 13 is basically drag racing at lights.

mileage used to be 12-14 in the city before the VSS.

will be driving cross country again this dec. with the 35's probably really aired up and more work done the the ECU so i hope for better than 16.5. will let ya know.

 

[MANUCHAO]

If MPG is what you looking for.. you kidding yourself... Gas is bound to go up sooner or later....
I get about 18-19mpg with 33x10.5 and about 13mpg in the city..
Thats with a 5.3, AT and stock gears....
If you want fuel economy then go diesel...

G'luck to yah !!

 

[biomax]

Good stuff - keep 'em coming.

So what would be the best mpg option (whether gas or diesel), while retaining at least the same hp/tq from a stock 60/62?

I've yet to see any actual reported figures in the 20s. Can that happen with ANY setup in a 60/62?

thx

Robert

 

[ntsqd]

As a point of reference my '91 Suburban (160k TBI 350/700R4/NP241 on 285/16's with 3.73 gears & a 4" set of springs) gets ~14 if I run at or below the speed limit (in direct, OD is worse) and has done as good as 15.6 running light at a 75 mph average over a 230 mile drive.
HTH

 

[fliphkd778]

IIRC, somewhere on here I think I saw someone get 22 after dropping in a vortec.

 

[AGreekBoy]

i just did a 12ht diesel conversion and averaging 21-22 all the time. i have a light foot though. stock gears 3.70, 5 speed.

 

[Mace]

IIRC, somewhere on here I think I saw someone get 22 after dropping in a vortec.

once, downhill with a talilwind..

 

[lynchmob]

I get 19-24 with a 13BT in an FJ62 My 3B / 4 speed pickup gets about 20

 

[Tinker]

I've gotten 17 to/from mountains + around town, but mostly about 15: '98 5.7 Vortec/4L60E/411s/10.50X33 MTRs.

Diesels haven't been cost effective since the sulphur-free fuel was mandated. Only "free" lunch is bio, & then you're joining the pioneers who find out the hard way what essential fuel additives aren't in french fry oil.

I'm in general consensus with Mr. Downey, but I believe stock GM is prolly the cheapest "high"-mpg SBC setup. Leave that 180 Tstat in & keep your foot out of it (not easy right after the conversion - it's soooo much fun).