M1028: Turbo 6.2 or 6.5 swap?

[TortoiseSixTwo]

I have an M1028 CUCV in reasonable stock condition. I have done a bit of work on it, chiefly rebuilding the transmission and sending the IP to Huckstorf for a rebuild. I recently obtained a stock turbo civilian '96 6.5 engine, an aftermarket PMD relocate kit for the DB-4, and extra DB-4, and a set of marine injectors. I would like to hear some advice about which path would be the best to take to get some improved power out of the truck:

1: Swap the 6.5 in in place of the 6.2, stock

2: Swap the 6.5 in in place of the 6.2, with the DB-2 IP from the 6.2, the marine injectors, and the gear-driven timing from the 6.2 in place of the 6.5's timing chain.

3: Keep the 6.2 in place, but replace the passenger side manifold and add the turbo from the 6.5 to it, and swap the injectors.

 

[Barrman]

What are your end goals for the truck?

I ask because the 6.2 has the small throat combustion chambers. While the 6.5 has bigger throats. If you are just going to be cruising around at 50 mph empty and don’t want to slow down on hills and maybe accelerate 0-50 .001 second faster then putting the turbo on the 6.2 will be just right and your mpg will probably go up.

Putting in the 6.5 will have you using a little more fuel and more time on boost before coolant temps get out of control climbing hills aggressively or towing.

Either way, the cross over pipe will be in the way of the front drive shaft. Getting the down pipe to run inside the frame rails is another issue.

 

[TortoiseSixTwo]

What are your end goals for the truck?

I’d like to get enough power and acceleration out of the truck to be able to pull a trailer or dolly with another vehicle on it without seriously backing up traffic, and to be able to not have to slow down to 25 mph to get up a hill with two yards of gravel in the bed. I’m of course open ti the possibility that this is not immediately possible.

if I understand you correctly, are you suggesting that adding a turbo to the 6.2 would make only a marginal improvement?

 

[Barrman]

I didn’t mean to give that impression. A turbo on a 6.2 is an amazing thing. However, even with a turbo you will not keep up with any diesel made in the last 25 years and probably not any V8 and most V6 gas trucks with the same load made in the last 20 years.

Your M1028 is limited by gearing and a 3 speed transmission from any speed faster than 50-60 mph. The 6.2/6.5 are indirect injection engines. Great for mpg and light load use. Because the fire starts in the pre combustion cups and then has to go through the throat to the cylinder. Power with a turbo is throttled by the throat size and the heat generated there. Basically, you can be cruising along at 50 mph with no boost, get to a hill, boost will build and you will maintain speed effortlessly. All is good. But, if the hill is steep enough and or long enough. You could max out around 8-10 psi of boost and start to loose speed. More than likely though you will be climbing at 5 or so psi and all that heat in the cylinder head will transfer to the coolant. Eventually, either your Exhaust Gas Temperature will get up to or over 1100° or around the same time your coolant temperature will start getting up to the 220° area. Both will require you to be watching the gauges and for you to back off the power.

My signature has 2 links in it. The Cowdog thread is about my GEP 6500 Banks turbo 4x4 3/4 ton Suburban build and driving experience over the past 10 years or so. I go into great detail the limitations of a turbo on a 6.5 and how I have worked around them. The other link is my YouTube channel. I have several videos about adding a turbo to a 6.2/6.5 and how to make it work.

 

[TortoiseSixTwo]

Oh wow, I didn't know that was you! I've been watching your videos since I very first bought the truck. It was one of your videos that helped me figure out that I had the pink wire for the injection pump on the wrong terminal.

I used to have an early '99 Ford F-250 with a 7.3. If I could get to a reasonable approximation of that level of power, that would more than fit my needs. I have no illusions about getting power like a modern turbo diesel, but I'd like to see what I can do with this truck. It's got very low mileage and is in really great cosmetic shape all around, so if I could up the performance and fuel economy, it'd be about perfect.