1971 GMC Bus - Toro-Flow DH478

[BobBray]

I think those buses were built '65-'66. BTW, our TDH3501 had it's original D478 replaced with a 'green' ToroFlow II in the early 70's. We have all the service records for it. Interesting reading!

[bigblockv6]

Around 72 GMC dropped the Toroflow name and renamed the DH478 as a "Turbium" 7.8 Diesel engine.

[BobBray]

Originally Posted by bigblockv6

Around 72 GMC dropped the Toroflow name and renamed the DH478 as a "Turbium" 7.8 Diesel engine.

Interesting, right around the time GMC was screwing around with gas turbine powered Astro 95's! I can hear the salesman now: Turbine, Turbium, it's basically the same thing........

[POWERSTROKE]

Originally Posted by BobBray

Interesting, right around the time GMC was screwing around with gas turbine powered Astro 95's! I can hear the salesman now: Turbine, Turbium, it's basically the same thing........

The big truck companies playing with turbine engine power was a great time! When companies made enough money on production items to develop and build stylized prototypes to actually road test. International probably put more miles on their turbine truck than anybody else. International even bought Solar Turbine Company with plans to offer turbine power on all their equipment. Ford built a nice tractor/trailer and fairly quickly killed the project. Chevy built a tractor/trailer too. Dodge/Chrysler also played with turbine cars, not so much larger trucks. And it seems Mack built a prototype too but I couldn't find any pictures. Most of that activity produced runable prototypes on the road in 1964 &'65. GMC still playing with one in '72 seems like they maybe thought they could solve the problems the turbine had, excessive fuel use and the huge amount of really hot exhaust gases they had to cool before releasing exhaust to the environment.

The lighter weight of the turbine, and the compact size were attractive to truck companies, but most weight savings and extra room would be needed to carry extra fuel. The big gas and diesel trucks I've driven got around 3-4 miles per gallon, turbines maybe half that distance per gallon or less. That big of carbon footprint from hydrocarbons to move freight sounds environmentally reckless. A turbo-diesel now days releases a tiny fraction of the pollution and goes 2 to 4 times farther on a gallon of fuel!

Was talking to a guy the other day. His 2015 C-1500 Chevy 4-door pickup with V-4-6-8 engine gets 24-27 mpg of the cheapest gas he can find, even E-85 with slightly lower mpg.

[Jmccal]

Could I get a copy of the DT service bulletins?

[Jmccal]

Originally Posted by BobBray

Good question. It is as if GMC was testing the DT478 in the Army buses, maybe they were not sure how much boost it could stand. This was all before the ToroFlow II came out, so it was right during the time GMC was having issues with the ToroFlows.

This is a project i’m working on.

[BobBray]

You want to turbocharge a Toroflow? The DT 478 in the buses was rare to begin with, and I believe the Army ended up changed replacing the DT's with small Cummins V-8's. However, there were turbocharged Toroflow marine engines in boats. You might find more information about the marine engines.

[Jmccal]

I’ve got a dt478 and actually found one of the two turbos in Italy last year.