asking tow vehicle advice
 

Hi! Been busy; not on here for a while, have enjoyed 3 cross country driving trips in the last few months.

I have an '85 factory diesel K10 Suburban which has been a get by tow rig, slow,but have enjoyed getting 14.5 mpg's while towing a 33 foot enclosed car trailer w load.

I possibly might want to professionally haul other people's cars in the future.
I felt like I needed a 3/4 ton.

I found, and now also have an '86 3/4 ton Burb that is the gas 350 with a great turbo 400. It is very peppy w a Holly 650 double pumper.

The first 'Burb can give me up to near 26mpg by itself on long trips.
This 2nd one is obviously way below that, but I've only driven it local, not towing, don't really know it well yet.

I love the 'Burb's 'cause with my quest bed from Walmart in the back, I have a studio apartment with full comfort to stay at RV parks on cross country trips all year round with a ceramic heater saving motel money, and being closer to GUARD the trailer and contents.

My original plan was to go full hog, and put an early 12V Cummings all fresh in
this 3/4 one. I would not be doing the work myself, so some serious $$$ would be going out.

I am VERY OLD SCHOOL, not into newer stuff, purposely delighted in finding this 2nd one w all manual windows, and old timey kick panel floor vents!
Reluctantly, at some point, A/C will probably be needed to be added though.

In the last 2 days, the thought has struck me to have the healthy all ready there 350 converted to PROPANE!!! I've heard that it could improve the mpg a little while of course leaving a MUCH GREENER FOOTPRINT!!!

Both 'Burbs have the 3.73 diff. ratio.

If I went w propane, would the lower mpg compared to a Cummings still put me ahead $$ wise as the Cummings coming to reality IS a big expense.

Remember, I'm 61 years old, and I'm thinking of keeping both rigs forever until I'M DONE!!!

I know it would be nice to have a manual trans. in it for possible downhill in the snow shifting, but that would be infrequent at best, where the turbo 400 would be just fine really.

I would only be doing this cross country towing as a part time job emphasizing
a somewhat relaxed pace w no concrete deadlines time wise. I am saying this since obviously propane may be hard to find at 10:30 at night somewhere
one hasn't been before.

The 1st 'Burb is just an emergency tow backup, and will still be enjoyed by itself in my personal life.

I know the relation of propane vs. gas prices is very weird right now, but know high gas prices will be coming back soon, probably with a vengance!!!

So given the fact that I won't change my mind about old Suburbans....(I would not want a Ford Expedition, even diesel, because of modern electronics); what is a better choice...............

12v Cummings made to be post nuclear still usable, or the 350 turned into
propane with an old distrib. w points waiting as a backup????


WHAT SAYTH YOU?????????????????????????????????????????????
Thanks!

Is the 12V Cummins what they call the 6BT engine? I think that one was in the Dodge Dakota for a while. I think you can convert the 1999-2004 VW TDI engines to use a mechanical fuel pump, but I am not sure you could ditch the computer completely. Really though, if you care about being eco-friendly, then the best diesel to get would be a late-generation with DEF and all the computer tuned variation gizmos. Propane would definitely be better, but I wonder if you could get the range you might want for long trips... and could you even get propane reliably on the highway?

Price out a running cummins and then figure out how much gas you can buy with that. Then if the math doesn't look convincing enough, add the price of labor and all the extra bits for the engine swap. I think you are looking at around $15-20k for the project and that's a lot of gas. Once you factor in the the mpg differences and cost of fuel you will find that break even is pretty far down the road. Constantly driving across the country will help reach that point faster but it may still be many years.

On the other hand, the cummins should be a much better towing power plant that could make the cross country trips more enjoyable for you.

Strictly speaking, the money is reason not to...but if it's what you want then money doesn't matter as much.

Personally, i would shy away from propane and cng. Gasoline is so easy to find/buy that people only run out when they forget about it. If you want more economy and towing power, just rebuild the engine for low speed operation and torque. Much cheaper than the 12v cummins route.

KISS is the way I'd go, if someone else is cover the cost of fuel run what you got.

If I felt a need to go Diesel I'd go 6.5 turbo, mechanical pump and beefed up 700r4, fraction of the cost of going Cummins.

I love my 6.5 na, trick 700r4, one ton axles, 456 Detroit locker in back. I tow a 35' Avion three axle bumper pull travel trailer. I get 17 mpg empty and about 11 towing.

You may want to go 3/4 ton.
The GM 14 bolt 10.5 full float axle is a lot tougher than the old 8.5 inch semi float.

If you have a TH700 you don't have to have 3.73 gears. The first and second gear ratios in a TH700 are numerically higher than a TH400.

Best thing to do to make it greener is put a turbo on it. A big turbo, not the sorry factory excuse for a turbo only designed to get the new trucks off the dealer lot, because it sounds like you tow a lot and could be at higher elevation.
A turbo will increase fuel economy, power and reduce smoke output.
And if you have the engine apart get the heads machines for valve seals.
The exhaust valves on the 6.2 motors don't have any seals and the seals on the intakes I would barely even call them seals.

Even though it might look outdated, the indirect injection used in the 6.5 is not that bad at all, as it tollerates low-quality Diesel fuel and even vegetable oils better than the direct injection used in the Cummins.

Propane would be my second-to-last fuel choice.

Thanks guys for the responses! The Cummings swap would be neat, but so much money out. This is just a work vehicle, not a DREAM vehicle. I'm INTO cars!
I'll stay with what I have for now, keeping it simple (KISS), and will probably refresh the radiator, get a better trans cooler, give it a pleasant paint job ( in my whole life, I've not ever had a vehicle completely repainted) Travel expenses to be covered by customers.

Direct injection problems on Cummins are overblown.
 

Yes, they can and do run into coking problems from poor set ups that run Waste Vegetable Oil (WVO), but that is the result of the poor conversion design and operation. The 94-98 12 valve Cummins are especially capable of running these free fuels with good reliability if the fuel system is designed well.