s10 (s15) economy

[gasssaver87]

hi all, i just traded a couple of three wheelers for an 83 gmc s15. the engine (2.8 liter) is bad, but it has a 4 speed and 3.08 gears in the rear.

it is an extremely ugly truck, but that doesn't bother me none.

the previous owner couldn't tell me exact mpg numbers but was pretty sure it was around 18-20.

i was thinking that i could put another engine in, new fluids in it, do a grill block, electric fan (its current fan is solid, not even a clutch) an alignment, recurving the ignition timing while adding a hotter coil, and replacing the rochester POS with a weber Progressive that i have, dual exhaust and maybe eventually an RV cam it it seems like it would be worth it

I would much rather have a 4.3, but i would have to put bearings into an s10 t5 that i have, but i would probably need a different clutch/flywheel and a bellhousing as well.

does anybody know what these usually get for mpg? any guesses as to what i could get it up to?

[rvanengen]

hi all, i just traded a couple of three wheelers for an 83 gmc s15. the engine (2.8 liter) is bad, but it has a 4 speed and 3.08 gears in the rear.

it is an extremely ugly truck, but that doesn't bother me none.

the previous owner couldn't tell me exact mpg numbers but was pretty sure it was around 18-20.

i was thinking that i could put another engine in, new fluids in it, do a grill block, electric fan (its current fan is solid, not even a clutch) an alignment, recurving the ignition timing while adding a hotter coil, and replacing the rochester POS with a weber Progressive that i have, dual exhaust and maybe eventually an RV cam it it seems like it would be worth it

I would much rather have a 4.3, but i would have to put bearings into an s10 t5 that i have, but i would probably need a different clutch/flywheel and a bellhousing as well.

does anybody know what these usually get for mpg? any guesses as to what i could get it up to?

Way back when (late 80's), my father had an 84 S-10 Blazer 2.8 5-speed that seemed to be getting about 22 on the highway.

[caprice]

ouch:thumbdown: Bite the bullet Go for an "iron duke" 2.5 4 cylender. very common in other cars besides the s10 (translation: easy to find at the salvage yard). Plus "no one likes them" because it has the "weaker" engine. (translation: costs less to buy.) Save weight and friction, install a S10 manual steering box, if not equiped. You will apreciate narrower front tires though!

With a 5 speed and TBI:
24 City
30 Highway

Better milage than my Daewoo Leganza! haha :rolleyes: How sad is that?

I am starting to wish I put a used iron duke in my caprice. The car weighs the same as a s10, and more areo dynamic than a truck. It would would compliment a 6 speed transmission very nice! That definatly would be "out of the box" a 30+ MPG from a oversized car! I never need the power from my 350 anyway.

[Bill in Houston]

I was thinking Iron Duke too. But it sounds like maybe he wants a little more power.

The Caprice came with a V6 in the '80s, I think. Maybe one of those would be an easy swap?

[Wazabi Owner]

There's always the possibility of a "sloped" bed cover. I keep hearing people rave on about how it netted them huge increase on HWY mpg.

[jdham137]

I'm working on a belly pan for my and might have it done in a few days. I'll post pics when it's down. I think, and Phil Knox does too, that the belly pan will net better results than a sloped cover. A truck's underside is a aerodynamic engineer's nightmare. There's no attempt to smooth anything. The flatest surface is the gas tank and the rear bumper and frame members looks look as though they probably act like a drag chute for any airflow that makes it that far back. It's a mess and I can't wait to see what this does for my highway mileage.

John David

[rh77]

ouch:thumbdown: Bite the bullet Go for an "iron duke" 2.5 4 cylender. very common in other cars besides the s10 (translation: easy to find at the salvage yard).

Is that the one they put in the Celebrity? If so the Auto-trans is real bugger to repair...

RH77

[lovemysan]

I put a good many miles on a 93 s10. 2.8l 5spd It averaged around 24-26mpg hauling tools and misc stuff. Mostly rural small town driving. Its a tough little motor. My favorite of all s10 powerplants. At 200k with the original timing chain and something ticking in the motor it still got a steady 24mpg driven by my 19yr old brother.

[Bill in Houston]

Is that the one they put in the Celebrity? If so the Auto-trans is real bugger to repair...

RH77
Probably the same one but thankfully the S-10 would be a rear drive. I think that the iron duke was their main (maybe only) 4 cylinder until the Quad4 replaced it.

[Maillemann]

I had an '85 GMC S-15 for many years, and with the 2.8L 2bbl engine I averaged just under 20 MPG almost invariably. Lots of city, would be around 18-19, lots of highway, 20-21. Most I ever got out of it was just shy of 24, but this was with an auto trans and 4WD. I'll echo the comment on the engine's reliability - it was pretty bulletproof. Very few issues right up to the 280,000 mile mark when I gave it away.

[Wazabi Owner]

Should of mentioned earlier - DOH - I'd go with a 2.5. Used to have a 2.8 GMC Jimmy 4WD new in 1986 - dog that got bad mileage.

[VetteOwner]

yea sounds about right...

my dad has a celebrity he bought for $100 a few months ago, gets about 24mpg with an auto trans. body is rusted badly, 3 matching wheels, and brown with black paint spots...looks liek crap but sure as hell noone gonna steal it. best work car ever. if it gets in an accident no big loss, engien blows up, no biggie, still gets better mpg than his van so he doesnt care, and door dings you wont notice/care.

also is hilarious to see peoples reactions when you park it right next to thier mercedes, bmw, proshe, etc...

[caprice]

For an "Iron Duke 101" ;) Go to:
http://en.wikipedia.org/wiki/GM_Iron_Duke_engine

It was made from 1977 to 1993! Went in to MANY vehicles ranging from the Pontiac Fiero, to Post Office delevery trucks! Has small block bell housing bolt pattern, so it should take the 5 speed gearbox, Or a T-56 6 speed transmission :D

This same engine apperentlly can mate up to ether transverse (FWD) or RWD transmissions. Differnt Transmissions!! Same engine.

I'm sure you can scoop up an old FWD celebrity or buick, that nobody wants, and just pluck the engine out. For cheep, like Vettowner.

Perhaps you could use a thinner gasket to bost compression. Also High power ignition should help. You can custom burn FE chips for the TBI, if equipped.

The 4.3 liter in the caprice was only 130 hp. they useed to have the shoertbaxe rfoer

[Bill in Houston]

The shoertbaxe rfoer was a great engine! Hee hee!

Small block bolt pattern, wow. What a world of possibilities that opens up...

The only reason I ever heard of the Iron Duke was that we had one. In our BOAT! It was a great balance of power, weight, and fuel economy when compared to the other engines of the time.

[Telco]

Man, must be something seriously wrong with my 2.8L auto then. It was getting 14 highway 17 city before I installed an electric fan, now it's seeing 17 city 19 hwy. Very disappointing. My engine is a recent rebuild too. Probably the crappy Crane cam I installed since I didn't want to run the crappy regrind cam that came with the engine, and Comp was back ordered about 3 weeks. I couldn't wait on them, needed the truck for work. Bummer.