1971 GMC Bus - Toro-Flow DH478

[Steve]

Here is a quick video of my bus. GM only built 510 of these short New Look buses making them the rarest of this well known style of buses. Many were repowered, however mine still retains the DH478 Toro-Flow engine. The aspect ratio of the video is off making the shape of the bus wrong, but you guys will only care about the sound of the engine, right??!

https://www.youtube.com/watch?v=RUku--Dr9Dc

[Steve]

Here is the engine in my bus.

[bobdylan]

Nice bus

[Funky61]

Great Video and sound! Sure brought back memories of living and Los Angeles and riding the RTD BUS. Now I know what I was hearing.

[6066gmcguy]

Great Little Fishbowl Bus you have there, I only spent 23 years of my life as a transit bus mechanic, worked on a lot of the New Look buses.

We had some 35 footers, and lot of 40 footers, all Detroit Diesel powered, 6V71 & 8V71.

they even have a 1954 GMC classic that has been in TV shows & Movies. its a 671 powered bus.

[bigblockv6]

The Bus looks fantastic:thumbsup:, what year is it? I grew up in San Francisco in the 70's and most of the busses there were the bigger fishbowl GMC's with 8V-71's. I loved the sound of those Detroits and they sure did get up and go, specially when compared to some of the old Mack Diesel inline 6 busses that were really slugs!! I even got a chance when I was 10 years old to ride in a tugboat on the San Francisco Bay that had just been repowered with two 8V-71's. It was an all nighter and I slept less than an hour actually in the engine room:ahhhh: It's good to see a DH478 bus though:thumbsup:

[TJ's GMC]

Great little bus! Even as a diesel at a certain RPM you still now it's a GMC V6. :thumbsup:

[dsljim]

Does anyone have any info or pictures of the turbocharged version they put in busses?

[bigblockv6]

There is one on Jolly's 6066 GMC Guy Page, look under Toro Flow Diesels:ok:

[Steve]

Does anyone have any info or pictures of the turbocharged version they put in busses?

I've never heard of the turbo version in a bus, at least in a GMC Transit bus.

[bigblockv6]

There was a military ambulance version of the fishbowl bus that had the twin turbo version of the DH478 designated as the DT478. I also saw a pic of one in a civilian full size fishbowl that may have been for the Australian market:thumbsup:

[BobBray]

I volunteer at a rail museum, and we have a '67 TDH3501 that we use for touring people around the grounds. The 3501 is about the last of the 'Old Looks'. The old bus runs very well, I just hope the engine stays together!

[Steve]

Nice! Got a photo? The 3501 was succeeded by the 3502 which was the last of that style. The 3301 New Look replaced the 3502 in 1969.

[BobBray]

Nice! Got a photo? The 3501 was succeeded by the 3502 which was the last of that style. The 3301 New Look replaced the 3502 in 1969.

I'll try to get a picture next time I go out. I know there was a 3502 in '68, but I am not sure what the differences were compared to a 3501.

[dsljim]

I've never heard of the turbo version in a bus, at least in a GMC Transit bus.
Mine came from a bus, the story I read was they were put in busses during the Vietnam era, and they were converted to ambulances.http://6066gmcguy.com/engines/DT-478-01.jpg

[bigblockv6]

I've got GMC service bulletins from the late 60's to 70's that mention the Turbo version DT478 in the military ambulances.

[BobBray]

The DT478 was used in rear engine GMC school bus chassis (DSPA 5000's?) that were built with Superior bodies for the U.S. Army. The buses could be converted into large ambulances, a common feature of Army buses at the time. As far as I have been able to find out, these buses were the only vehicles built to use the DT478, though there were marine versions of the turbocharged ToroFlow. Many of these buses were eventually re-engined with small Cummins V-8's after 8-10 years of service.

[bigblockv6]

GMC never posted Torque or any horsepower figures for the DT478, it be interesting if those could be found:helpsign:

[BobBray]

GMC never posted Torque or any horsepower figures for the DT478, it be interesting if those could be found:helpsign:

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.

[bigblockv6]

So that was during the era of the D478 ToroFlows rather than the DH478's. When I get a chance I'll check those bulletins. I do remember because od durability issues of the D478's and D637 engines GMC did have a recall campaign where modifications were made to these engines and they repainted from yellow to Alpine Green and re-designated as DH engines:thumbsup:

[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]

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]

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.