Building a truck for mileage, what would you do?

[arkoza63]

my 82 burb 3/4 ton 350, sm 465 trans, 3.73 gears, 235.85.16s gets 16 city 20 hwy

[captain carnage]

Whats an LE9? And yes the diesels do pretty well, they're just more expensive to repair.

[Stewart G Griffin]

Whats an LE9? And yes the diesels do pretty well, they're just more expensive to repair.

Basically a "high" (9.5-1) compression 305 from the factory----you said your's was stock as far as you knew.........

http://en.wikipedia.org/wiki/Chevrolet_small-block_engine#305

[captain carnage]

Oh thats very possible, its quite a peppy 305. Is there any way of telling if thats what I have.

[4x4x4x]

my suggestion is to look into adding propane injection to a 81+ 6.2 or 6.5 turbo diesel c or k truck. whille there is a cost adding this system, it is capible of increasing the efficency of the diesel engine and increasing the mpg. Diesel Power magazine had a competition between several build diesel trucks, one of them was a duramax chevy truck with propane injection, on the controlled mpg run it averaged an amazing 45mpg. we have a 85 k10 with a 6.5 banks turbo in it. 700r4, 33 1250r15, and using royal purple syntethic lubs. we consistently get up to 22+ mpg hwy by driving conservatively. i am very interested in the propane injection system, but am still doing research on the subject.

[87454westernhauler]

A lot of folks call me a liar when I tell them I have gotten as high as 16 with my 3/4T 454

Zeig, i beleive you. we have an 87 454 r30 dually that we were getting 16 miles with it too, just bob tailing though!

[zieg85]

A lot of folks call me a liar when I tell them I have gotten as high as 16 with my 3/4T 454

Zeig, i beleive you. we have an 87 454 r30 dually that we were getting 16 miles with it too, just bob tailing though!

Thanks... course pulling my car trailer it drops to 11 and if I push it on the highway it gets thirsty.  She likes 55-60 best.

[87454westernhauler]

usually run it between 2500 and 3000 rpms. thats its sweet area. it drops down to around 11 or 12 hauling our flat bed and horse trailer.

[monkeyspunk79]

Someone mentioned earlier the 4.3 engine and for just a plain DD that sees light duty...a carb'ed 4.3 and stick with a 3.08 would be just fine. Our family ran two Astro vans for years with a TBI 4.3 / 700R4 and I swear it was a 2.79 ratio. Plenty of low-end torque to get rolling or haul a load of 5 people and car parts...but on the highway it would get 25 mpg consistently. We never towed with them, but they hauled plenty of cargo and one lasted 280K before the motor needed work. Only turned about 1800 rpm on the freeway. I'd recommend the trusty 4.3 to anyone.

[Bodyswap]

Just get a 4.3L S10.  I had one in highschool and it did better than my 3/4 ton and was still able to haul several cars on a single axle car hauler.  Hauling the cars was all she wanted but she still did it just fine.

[Edahall]

I've got 2 Chevy Suburbans.  The 82 plain Jane Suburban 2 wheel drive, 1/2 ton, 700r4, 3.08 gears, came stock with the 6.2 diesel.  It would constantly get mid 20's on the highway but it was so low on power that it was a safety concern.  So I installed exhaust headers and dual 2-1/2" exhaust and a non EGR J code intake manifold.  Power went up considerably and mileage went up to 30 mpg on the freeway at 55-60 mph.  If I drive 70, mileage drops off quickly to about 24 mpg.  The 6.2 diesel can be built for excellent fuel economy but several things are needed to get there.  The most important thing is heads with small precombustion chambers.  The older 6.2 heads came with small precombustion chambers but later on, power became more important than fuel economy so larger precombustion chambers were installed.  So power went up and fuel economy went down.  That said, the newer heads with larger precombustion chambers can have small precombustion chambers installed to gain that efficiency.  The next important thing is a good free flowing exhaust.  Then next would be free flowing air filter and Non -EGR J code intake manifold.  Not having free flowing air flow into the engine just causes it to make black smoke rather than make power.  Also important for fuel economy is a tall rear end like 3.08's or 3.42's and tall and narrow tires that you can pump up to 50 psi.  The 1982 stock 6.2 came stock with 135 hp and with my setup, I'm probably running right around 170 hp.  It's not much but it gets you where you want and sips fuel.

The other Suburban is a 1990 that now has a 1989 VE pump Cummins engine.  This Suburban is 3/4 ton, 3.73 gears, 4 wheel drive and has all the bells and whistles.  Behind the engine is a 6 speed NV5600 manual and gear vendors auxilliary overdrive.  RPM's at 65 mph is 1320.  It also has larger oversize tires and a 2" lift.  At 60 mph, I get 26 mpg with the rig.  It doesn't get quite the fuel economy of the 82 Suburban but it weighs a lot more and has a lot more power.  Even with 10k pounds behind it, you don't slow down on the hills and it gets better fuel economy towing a heavy trailer than the 6.2.  However, for solo driving, it is overkill.  Way more power than you really need.

[Jim Rockford]

to me the extra cost of Diesel just doesn't make up for the difference anymore, Use to be it was lower than gas, but now its quite a bit more than gas,and I thought it was a 305 they had in 80 or 81 that they designed special for fuel mileage. had a good compression ratio somewhere in the lower 9's and a good qjet, might have had some steep rear gears etc  its around here somewhere.

[royo]

I know. give me a cummins motor. and i'll give you a 305

[77c10diesel]

My trouble is that I own a Cummins motor and can not afford it. It an 03 Common Rail that makes insane power, there is no end to the power it has. However, the $400 a month payment is killing me.
I do have a 77 that I swapped an Olds 350 Diesel into, but it is not finished yet. It is for my son and I hope to see 28-32 MPG out of it, but we'll see. (just no towing with it!)

[Jim Rockford]

I had a buddy with a 93 suburban with a 454 4l80e  it would get 16 empty but even if so much as a cricket jumped on the trailer hitch it was down to 11 ..lol