Tatra T815 engine swap

[Northern Mexican]

Hello! First post is a strange question for mechanically inclined Tatra owners. I'm considering buying a late eighties 6x6 815 TP directly from Eastern Europe. I would like to take out the giant air cooled V12 and put a shorter NA diesel (I have my eye on a 6CTA 8.3L Cummins, suggestions welcome), manual Allison transmission, etc. At the same time I would like to move the cab back and shorten the front to improve the approach angle. I've spoken to a couple heavy duty diesel shops around Central Alberta, and was reassured that it is very doable with the right amount of cash. On the other hand, I'm concerned about the fact that I haven't found a single mechanic who has worked on a Tatra, one guy saw an 8x8 once, lol. I want to get some opinions from people with actual Tatra experience, as to whether this endeavor is worth undertaking to begin with, if anyone has swapped an engine out, or frankly anything related to Tatra's. Thank you beforehand.
- Paul

 

[duncan]

Swapping the engine is a piece of cake (with the right tools, money and time). Why you would want to is beyond me, a 19 liter v12 turbo is beautiful.

Swapping the gearbox is a completely different story, it's mated to the drivetrain, this will require some serious engineering.

Shortening the frame during the engine swap is a nice idea, but you will run into a few interesting problems. The reason the overhang is so long is to allow the engine to sit low inside the frame for better weight distribution and a lower profile of the overall truck. If you move the engine back, it has to be moved up as well, because the steering rods, booster and front diff will be in the way and moving those is not a feasible option. When you move the engine up, be aware that the crosspin on the gearbox input shaft doesnt allow much more vertical play than it originally has.

Lastly, when you shorten the frame, you need a different cabin, find a new spot for the steering column, and so on....

 

[Northern Mexican]

Thank you for the info Duncan.
I've spoken to IPEX Tatra as a potential service/modification facility for the truck and this is what they said:
- they advised against any kind of frame shortening/cab relocation
- Re-powering the truck with a more modern V8 Tatra turbocharged engine would cost around 30K Euros (includes the necessary drivetrain upgrades to make the top speed 120km/h)
Even with the new engine the truck would burn 40+ liters/100km at 100 km/h speed...Wow, that would be the truck to take to an Earth Day rally or something alike, lol

 

[cranetruck]

You know 40l/100km isn't all that bad, a typical 5-ton burns that kind of fuel (approx 6 mpg)...although most won't run that fast.

 

[Northern Mexican]

Well, it just came as a surprise that the 40+l/100 km was the fuel consumption rate out of the newer fuel efficient engine. To my understanding I should be getting closer to 10mpg with a 8.3L Cummins after upgrading certain components. Correct me if I'm wrong please.

 

[duncan]

It's not just the efficiency of the engine. The amount of gearboxes, differentials, hub reduction, tires, etc are the big impact on the fuel consumption.

 

[tatra813]

A guy in the USA swapped his engine out for a Cummins 8.3. He said it had way more poer and torque. Used the same transmission just added the new motor......If I blow a motor I plan on the same thing