1973 IH Travelette: which engine would you use?

Quote:

Originally Posted by ihlinuxdude

Hi all!
I'm in the middle of restoring/upgrading/modernizing my 1973 IH Travelette.
For those of you unfamiliar with light duty Internationals, it's a 3/4ton rated, 6,700lb crewcab, I've added little doodads like 1ton springs 4wd, dually rear(as I recall it's a dana 70 with 3.53 gear) dana 60 front.

My question is, what engine would you put in such a beast? I'm pretty comfortable with Gm 6.2ls but I'd like to keep it all International, like a 6.9 7.3 or DT-466. But at the moment mileage is more of a concern for me. I am told that a correctly tuned Cummins 5.9 is capable of near 30mpg.

I'm looking for the best compromise between power, reliability, but most importantly mileage.

any input is very appreciated!

For mileage, reliability and power, it is hard to beat the 5.9 Cummins. For my 1990 Cummins powered Suburban, I'm getting around 26 mpg on the freeway. It would be similar in weight to your Travelette. I'm running the engine behind a 6 speed manual transmission and Gear Vendors overdrive and 3.73 rear end. With the setup, the engine spins at 1430 rpm's at 65 mph. Also keep in mind, I keep my speeds under 65 mph. Going faster would probably degrade fuel economy very quickly with the boxy front end.

I also have a 82 Suburban with the 6.2. It'll get nearly 30 mpg on the freeway but has a lot less power than the Cummins. Also, it is 2 wheel drive and has 3.08 gears. The 6.2 will get very good gas mileage with smaller precombustion chambers but that's at the expense of power. Power for this engine is 130 hp stock. Power can be increased with a free flowing exhaust.

Your 3.53 gearing would work well behind a Cummins. A manual tranny such as an NV4500 or NV5600 would give you several mpg's over an auto. Unfortunately, a dually rear is counterproductive for good mpg's but gives good stability for towing. Also, a pre 98 12 valve engine is what you want. The 88-93 Cummins with the VE pump makes less noise, is simpler but is good for only 500-600 hp. The 94-98 Cummins 12 Valve has a P pump and is good for over 1000 hp but is noisier and has a more complicated fueling system.

I know less about the Navistar. I've heard the 6.9 was the most reliable of the bunch. The 7.3 powerstroke got better gas mileage and had much more power but was much more complicated. However, a known issue with these engines is cavitation in the cylinders.