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Thread: 6.5L @ 32-mpg!

  1. #1
    Join Date
    Feb 2000
    Location
    Montana
    Posts
    11,398

    Arrow

    I spoke with a member from Florida yesterday who has been keeping a secret....

    He built a fuel economy rig a couple of years ago along the same general lines as I've been contemplating for some time now. In his case he combined a 1989 Chevy S-10 Blazer with a NA 6.5L, 5-speed manual and 3.42 gears. According to Allen Harrell, this 3200-lb combination produces 30+ mpg at Interstate speeds...

    In addition, he's beginning a new project using a 1999 or 2000 S-10 pickup, only this time with a 6.5TD. We talked about efficiency and whether a turbo would help or hurt. In this case, he plans to run the TD harder, so we agreed a turbo would likely help.

    With a little coaxing, I think we might be able work up an article. [img]smile.gif[/img]

    Jim

  2. #2
    Join Date
    Oct 2001
    Location
    NE CT
    Posts
    506

    Post

    cool!
    Mental-note, don't tell MP secrets
    1996 K1500 6.5, 1984 K5 6.2 Banks both \"Stock\" (tilting hand side-side like Sammy Davis in Cannonball Run)<br /><br />Got Boost?

  3. #3
    moondoggie Guest

    Post

    Good Day!

    Can't wait - hope you get an article out of him.

    Now if we can do something similar with a full-sized truck... When I 1st got my 82 (6.2, 4spd OD manual tranny, 3.08 gears) in (I think) 1990, EVERY TANK (summer) was between 26.0 & 27.9 mpg. I didn't even bother writing the numbers down back then - I'd drive 400 miles & switch tanks. Then I had a chart on the visor - if I bought between x & y gallons, that was 25.0 - 25.9 mpg, 26.0 - 26.9 mpg, or 27.0 - 27.9 etc etc. Even when I used in an emergency a couple years ago from November to about February, every tank was 24.something.

    Blessings!

  4. #4
    trbankii Guest

    Post

    Sounds interesting - definitely looking forward to the article. I'm a bit surprised that he can coax that much mileage out of that setup. My Toyota with a 2.4L four cylinder only gets about 25 to 26 mpg on the highway. Mine is 4x4 and I'm guessing this one is 2WD?

  5. #5
    Marty Lau Guest

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    I remember that Dr Lee's little Red truck had a 2.73 when he first got it. I would think on a S-10 size that gearing in taller than 3.42 would be help maybe 3.08 or 3.21 your not going to tow much with it. How did he stuff that 6.5 in an S-10??????? Must have beefed up the front suspension

  6. #6
    Join Date
    Sep 2003
    Location
    Howell, MI
    Posts
    181

    Post

    Thats cool, Ive been thinking of doing this for a couple years, I was figuring on getting around 30 mpg. I know a 6.2 or 6.5 would fit (as long as it doesnt have A/C) but my problem is that I live in the conntry and I drive alot of dirt roads and Iam sure the front suspension wouldnt live with all that pounding and the wieght on the front end, so I scraped the Idea
    -96 6.5TD K3500 Crew Cab Dually 4x4, 97 cooling mods, Dmax fan, 3.5" downpipe, 4.5" straight exhaust, intercooler, custom intake plenum, fast idle switch, Ranch Hand bumpers, Turbo Master, egt, boost, & trans gauges, 6" Superlift, K&N off the turbo.
    -88 6.2 3/4 burban 255K
    -83 6.2 CC C30 220K
    -82 6.2 1/2 4x4 burban 270K

  7. #7
    restoguy Guest

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    Definitley interested in hearing more about this swap. I have also been considering it, but I wanted to destroke the engine. It doesn't need to be that big, in my opinion, to move an S-dime and smaller displacement should produce better mileage...to a point. I tossed around the thought of building my own V6 version of a 6.5L too. But I think that would cost more in the long run than it would be worth. Even though the experience is worth more than any kind of financial return. I even considered the much hated 4.3 and 5.7 diesels. The 5.7 has about the same power as a 2.8 give or take and is roughly the size of a small block. My dad knew a couple people that had them in big Olds 88's back in the day and they reported 30-34mpg with them. Keep us posted!

  8. #8
    Join Date
    Feb 2000
    Location
    Montana
    Posts
    11,398

    Post

    Allen owns a well equipped commercial diesel shop, and is a big fan of the 6.2/6.5. He also works on the newer all-electronic Duramax/PSD/Cummins as part of his operation.

    We didn't go into how difficult it was to drop a 6.5 into the S-10, but he mentioned he is using the factory exhaust manifolds and a Banks NA exhaust system (2 into one Y-pipe, etc.). He's also using a Corvette aluminum radiator, which should be fine in a rig not used to tow.

    He mentioned his TD S-10 will be using a low compression engine using a GM-8 turbo and tuned for as much power as he can get without an intercooler (more of a hot-rod than his NA).

    Jim
    Last edited by More Power; 02-16-2006 at 17:00.

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