'91 5.9L Cummins vs '89 7.3L IDI. BUSES

[amstall]

So me and a buddy are looking at getting an old bus and converting it to a toyhauler/rv for our bikes and quads. We've got 2 spotted right now.

One is a '91 with a 1st gen 5.9L Cummins and a Allison J45 tranny 175,000 miles. The other is an '89 with a 7.3L IDI IH in it, auto tranny don't know what though and 29,000 miles.

As far as I know both engines are in good shape. Don't burn any oil or coolant or anything like that. What I'm worried about is the amount of weight I'll be putting behind this thing and still being able to get down the highway. Likely it'll be 8-9 guys with some quads (approx 300lb ea) in the bus and the rest on a trailer behind. This is a budget deal so I don't want to drop an extra thousand in the motor trying get more power or anything.

What do you guys think?

 

[ameristar1]

Since you are working with a lot of weight and want to spend as little money as possible, go with the Cummins powered vehicle. An IDI thats already is in a heavy chassis is a slow thing, and you'll have to walk in and turbo the thing to make it adequate. I thought about doing a long distance truck with an IDI and it just turned out not to be a good idea in unmodified form.
With the Cummins, just adding a few pieces will make it a lot better to drive, and mpg better too. You can't go too far with the 545 Allison, you'll hurt the transmission.
One of the members here (username: nevrenufhp) has free site that can get that engine turned up with minimal expense. Add a governor spring kit, do the KDP fix, a smaller turbine housing for the turbo and make the pump adjustments. It'll really make the bus fly.

 

[spg]

The AT545 transmission will need some help. At minimun a much tighter converter and extra trans cooling. Or convert to a manual transmission. I am in the 25K load range with truck and trailer and have had to update the AT545 and am now changing over to a Fuller 6 speed.

 

[snicklas]

amstall...... If you look in the this thread with TonkaDocs RV hauler, it is a 5.9 with and Allison.... Take a look at what he is doing, and the issues he has had. One thing to remember, he is making a living with this truck, so the recreational use that you will do, will not take the toll like his use is.......