Tilting at windmills... (or, "1989 Suburban")
 

So, my wife has a 1989 6.2 liter diesel Suburban that she LOVES. There will be no convincing her to get a Matrix or something else that actually makes sense.

We've gotten 23-24 mpg with it, stock, specifically on three most-of-a-tank 65-70mph highway trips. Generally, though, it dwells in the 18 mpg range.

It needs a torque converter- the one in it has clearly worn itself into high-stall mode. Fortunately, I get to replace the torque converter with virtually no (additional) labor, if you ignore the time and cost of the new engine it needs.

So, since I'll be doing some portion of the work, I'm considering a few different things to do at the same time. I'm looking for feedback and thoughts, specifically for mileage and reliability. The Suburban is half ton, 2wd, 700R4 with overdrive, 3.08 rear gears, stock wheels/tires.

Considering (with varying levels of certainty):
Low stall (~1200) torque converter
Electric fans
Grill block/system, including...
...ram/cold air intake
Exhaust (?)
Synthetic fluids (dif and oil, at least- not sure what the 700R4 would like)

I've got some plans for aero as well. I can't convince her to lose the roof rack, but she hasn't noticed that I removed the crosspieces, and I've conveniently avoided putting the rear spoiler back on after 'accidentally' grabbing it and ripping it off. Although I'll need to replace the duct tape on the holes sometime soon (Kamm mounting points?). But I digress.

What else should I consider when the thing is all in pieces? Any other thoughts/suggestions?

Thank you!

Jon

Think she'll believe you if you tell her that the Kamm assembly was the ONLY item available that *fits* those empty rear spoiler holes (wink,wink)?

Ha. I can fool her occasionally, but that's probably a bit much.

MAN is there huge variety in engine prices!

New wrinkle- there's a fairly cheap, low mileage truck with a fuel tank and rust problem I could get for the engine and 4 speed OD manual. Any thoughts on whether the additional (probably $700 plus some labor) expense would net much efficiency gain over a good condition 700R4?

Jon

Yes. Leave it in pieces and park a Matrix in the driveway. "Lose" the engine and some other critical parts while you're at it.

Har.

(Wife loves Suburban) + (Cost(25-30mpg vehicle that can tow a smallish boat)) = (years and years before fiscal gain realized) + (unhappy wife)

Monetarily, I'd lose out on any smaller, more efficient car that I would trust for many years before the fuel cost caught up. So, I'm left with 'what's the best I can get out of what we have?'

Since rationality isn't part of the equation, who says we guys always have to remain so?

With you in spirit. :)

What engine do you plan to put back in? I'd think that its time to scrap the GM diesel and look for a 12 valve Cummins considering the huge aftermarket support for power AND economy mods on the engines.

If you don't off road it, maybe work in a drop kit when she's not looking?? lol

Your plan sounds good. I get half that with my 91 (same body style).

You are missing intended use though (city, highway, tow, hauling, etc).

A manual will gain some due to a direct drive without a pump. What is your wife's opinion of this though?
I would add:
-Deeper air dam
-The '82 year heads w/ studs
-Remove any excess weight (3rd row, roll pan, etc)
-Ride height reduction (plus the rest of the 100+ ideas page)
-Smooth wheel covers
-91 mirrors or delete
-Set of tires off a Tahoe hybrid

The biggie would be the horrible underside of these rigs.

What four speed manual? The biggest concern I would have is if you change the lengths of your transmission, you will have to change the length of your driveshaft. I swapped a NV4500 5 speed overdrive into my 91 K2500 LD in place of my 700R4/4L60, because it was within 1/8”. That was a 4x4 though, you would have to check for a 2wd. Or perhaps you don’t mind changing driveshaft lengths.

Anyway I went from 10.5-13 MPG with the 700R4 to 13-15.5 MPG with the NV4500, no real change in driving style. (Note 4x4, 5.7L TBI, RCLB 6 Lug K2500)