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GMC Twin Six V12

3

37chief

Well-known Member
Location
California
You never know what you will find on the internet. I ran across a GMC Twin Six V12 engine. Must have been an industrial engine. Anyone ever seen one? Brother drug home two Chrysler 6 industrial engines years ago. They are a little bigger than the car flat heat motor. Now they just sit. Stan
 
That engine was used in transport trucks a lot during the 50s and 60s.Variant of the 305 V6 truck engine. Over 700 cubic inches. May have also been used in industrial applications...
Ben
 
I never saw or drove one of those. I would think that they would need a BIG gas tank LOL! Probably a real powerhouse. We had some of the V6 versions they had a Long stroke crankshaft in them. the spark plugs were on the intake side of the head.
 
Available in OTR trucks in the 1960s.

Contrary to popular belief, they are not two 305 V6 engines though they did share bore, stroke and many parts.

High torque, low RPM and not as bad MPG as might be expected.

Quite common as irrigation engines.

There is a company in FL that buys, sells, builds them.

Dean
 
Saw this one at our local tractor show several years ago!
Said he could not get it enough cooling...!
I asked to hear it run-he was real snobbish about that-said he'd drive it thru the parade...! He was the last one, and there was so much other noise I still did not get to hear it run!


mvphoto32062.jpg




mvphoto32063.jpg
 
I had a neighbor who ordered a new GMC truck in about 1962-63 and had the 401 or 410 cubic inch V-6, it was like a 80 series Chev then, they fed cattle and pulled the livestock trailer with it,and then removed the 5th wheel,then put on a 16 foot grain box and hoist after dinner, and would use it too haul grain from the combine, I never did see how he had that put on there, but a friend seen them switch it,it was like 6 pins that they pulled out, and suspended the box and hoist, hung in a 4 post frame work,when they were under the cattle trailer! As far as i know they never had engine trouble with it !
 
Two 351 V-6 cast together, lots of fun to tune up with two carbs and distributors. The V-6 gas line were 305, 351, 401, and 478, diesels were 351, 478, and V-8 637 if I recall.
 
In the early 60's a Canadian trucking outfit ran a small fleet of Twin Six-powered GMC road tractors. We'd see them occasionally on the QEW between Hamilton and Buffalo.

The V12 powered tractors disappeared after just a couple years, replaced with Detroit 8v-71 diesel-powered tractors.

Incidentally the V12's smooth exhaust note was unique, and actually quite pleasing.
 
Saw one in a restored fire engine at a show last year. My Dad had a 305 V6 in a GMC pickup. I always loved the sound of those engines. Chronically hard to start, though. Went through starters. A few years ago I saw one just like Dad's at a used car place. Got in and turned the key, and it just groaned over. So familiar.
 
A neighbor had one in a tilt cab semi tractor in the early 60's. He was a milk hauler and ran a 140 mile round trip to Detroit every day. Lots of power to handle 80,000 lbs but I do remember him commenting that she was thirsty.
 
I had a GMC 2 ton truck with 305. It had no bed, just log bunks. It was a 1962. I remember how a friend always knew I was coming before I got there. The sound traveled up the hollow ahead of me.
 
There was a V16 also.

It may have been a 1 use engine in Transporter-erector truck-trailer rigs to haul Minuteman missiles from factory to silos. USAF.

Vern
 
Well there was missiles in North Dakota, the northern part, they always said they were pointed at Russia, but there obselete now again, i think the silos are empty
 
Bob

Re "Incidentally the V12's smooth exhaust note was unique, and actually quite pleasing. "

Not GMC but here is a bit on V12 exhaust notes. RR Merlins and Griffons had different firing orders and opposite rotations, which apparently result in quite different exhaust notes. A bit on that here

https://forum.keypublishing.com/forum/historic-aviation/135489-rolls-royce-griffon-question
 
When I was in elementary and high school, our school district had a large GMC "pusher" (rear engine) school bus powered by a GMC V-12. This was the main bus used for transportation to out of town events and it must have had several hundred thousand miles on it by the time it was retired.

The V-12s were used a lot in our area (eastern Colorado) as natural gas-powered irrigation engines. They would pretty much run forever in this role.

The 305 V-6 Jimmys were pretty common in pickups and trucks. They really were a true truck engine: not much horsepower but gobs of torque. Note that these engines were 60 degree bank, not the 90 degree bank (with offset crank) you see today. They were not cheap to make, but had a pretty long run and were easy to service. Changing a water pump on a V-6, for example, was a 30 minute job, while changing the water pump out on a small-block chevy was usually a lot of work.
 
I'm surprised that a Twin 6 could be packaged transversely in a pusher bus.

A local guy had a Blue Bird (Carpenter?) pusher with a 478 GMC V6 gasoline engine in the 60s. It had a wonderful sound.

Dean
 
Like others have said they were used in highway tractors years ago.

Photos do not do them justice, it is quite impressive to see one in person.

I went to look at a used car once and the guy had a complete fully dressed Chevy V-12 sitting in his garage and it was for sale.

I wanted it in the worst of ways, just because.

Then reality set in.

1- I couldn't afford it

2-I had nothing to put it in

3- I had no where to store it

4-I had no way to haul it

That was about 35 years ago and I still think about the what if's had I bought it.

The same fellow also had an AC Cobra for sale that his brother had perished in after a low speed roll over.

Other than damage to the windshield frame and steering wheel you never would have guessed the car had even been in an accident.

It was another one I could not quite afford at the time that I still kick myself for not selling something else to come up with the cash.
 
I still drive my dad's '64 GMC half T with the V-6 in it. Don't drive to very much, it thinks gas is still a quarter a gallon. If I could post pictures I would show everyone. I had some dings taken out and painted the same color, not sure what color that is, maybe a type of blue, would be very light if so. No power except under hood, AM radio.
 
. Here is the 2020 solution for light and medium duty applications . Without the cost and aggravation of a Tier IV diesel .
It would even make 115-140HP at 1800rpm for industrial duty.
 
DETERMINED - Did you mean to say you saw a "Chevrolet" V-12 or a GMC V-+2? Guy that lives about 5 miles
from me has a long nose early '60's GMC pickup with a GMC V-12, and a GMC steel cab tilt cab semi-tractor
with the GMC V-12, looks brand new.
Ford made a V-12, look up on Google, "Ford GAA engine, it's the V-8 version, 1100 cod, based off the
1650 cod V-12 60 degree design airplane engine Ford wanted to make for the Air Force before WW 2. Lincoln
and Cadillac made V-12's for luxury cars, Jaguar, and Detroit Diesel, CAT, Cummins, Waukesha Engines,
and several others. But I've never heard of a Chevrolet V-12. A Google search doesn't turn anything up,
it results in GMC V-12, even Mopar V-10, but NO Chevy V-12.
 
I've been predicting for some time now that the federales are inadvertently driving many applications back to gasoline.

Unless the nonsensical regulations change, I would expect gasoline engines to return to the utility tractor market in the foreseeable future.

Sadly, US manufacturers are afraid to invest in new technology because the feds can render their investments valueless with the ignorant stroke of a pen.

Dean
 
(quoted from post at 13:41:18 02/27/19) DETERMINED - Did you mean to say you saw a "Chevrolet" V-12 or a GMC V-+2? Guy that lives about 5 miles
from me has a long nose early '60's GMC pickup with a GMC V-12, and a GMC steel cab tilt cab semi-tractor
with the GMC V-12, looks brand new.
Ford made a V-12, look up on Google, "Ford GAA engine, it's the V-8 version, 1100 cod, based off the
1650 cod V-12 60 degree design airplane engine Ford wanted to make for the Air Force before WW 2. Lincoln
and Cadillac made V-12's for luxury cars, Jaguar, and Detroit Diesel, CAT, Cummins, Waukesha Engines,
and several others. But I've never heard of a Chevrolet V-12. A Google search doesn't turn anything up,
it results in GMC V-12, even Mopar V-10, but NO Chevy V-12.
Click to expand...


My apologies yes it would have been a GMC

The way I look at it a Dodge a Ram and a Fargo are all the same thing.

Same goes for Ford/Mercury

Chevrolet/GMC

Yes I know there are some differences but at the end of the day it still all boils down to should the money go in the left pocket or the right pocket.
 
The architecture of the LF3 is based on the naturally aspirated 3.6L V6 LFX, but with almost entirely
all-new components. The LF3 is the most powerful V6 ever from General Motors, it is also the most
power-dense six-cylinder engine in the midsize luxury segment. In the CTS Vsport, the LF3 makes 420
horsepower (313 kW) and 430 lb.-ft. (583 Nm). In the XTS Vsport, the engine makes 410 horsepower (306
kW) and 369 lb.-ft. of torque (500 Nm). All figures are SAE-certified.

Image result for cadillac xt5 v6 engine
The XT5 is initially available with only one engine, depending on the market. In the United States, it
has a 3.6-liter V6 used in other recent Cadillac models, producing 310 hp (231 kW) and 271 lb⋅ft (367
N⋅m) torque. The V6 includes automatic stop-start and cylinder deactivation to improve fuel economy.

How does these numbers stack up to a diesel?
 
> Here is the 2020 solution for light and medium duty applications . Without the cost and aggravation of a Tier IV diesel . It would even make 115-140HP at 1800rpm for industrial duty.

I don't think so. The 60-degree GMC V-6 and V-12 engines are a product of 1950's engineering. They had a good run, but no way will they be coming back anytime soon, even if the price of gasoline drops to pre-OPEC levels.

These engines are too heavy and too expensive to build to be competitive in the 21st century. It might be possible to improve on their high fuel consumption with electronic fuel injection, higher compression and better combustion chamber design. But how can you shave enough weight to make them competitive with a modern turbo-diesel like a Duramax? The V-12 weighs over 1200 lbs! And it's expensive to machine 60-degree engines, which is why nobody makes them. So it would cost as much as a Duramax, weigh more and probably produce less power while burning more fuel. On the plus side, with regular oil changes a modernized Jimmy should last pretty much forever.
 
Trains use them, river tugs use them. Had a 900 hp GM EMD V12 in the Tug Lone Star I decked on my last summer in high school. One sweet singing piece of machinery. Today they run 12s, some add 4 cylinders and employ some current technology and get 43 to 4400 hp out of them (GE ES44AC with the GEVO-12, EMD SD70AC (710G3C-ES 16 cylinder 4300 hp).
 
I expect that Kubota will be one of the pioneers in doing so, If they can convince themselves that the federales will not quickly render the investment valueless.

Dean
 
It is true that Chevrolet and GMC trucks are nearly identical these days but in the 1950s/1960s/early 1970s, they were not.

Dean
 
(quoted from post at 17:22:28 02/27/19) Trains use them, river tugs use them. Had a 900 hp GM EMD V12 in the Tug Lone Star I decked on my last summer in high school. One sweet singing piece of machinery. Today they run 12s, some add 4 cylinders and employ some current technology and get 43 to 4400 hp out of them (GE ES44AC with the GEVO-12, EMD SD70AC (710G3C-ES 16 cylinder 4300 hp).
Click to expand...


V12 engines also used in big wood chippers,cat engines I think,between 700 and 800 HP,torque in the 3000 lb.ft.range. Operator drops a 15 ft.long log,2 ft.+ diameter and the gov. kicks,a light puff of smoke and 15 seconds later what was a log is now chips in the trailer.
 

I missed having to go there and work on the missels by the skin of my teeth, I really didn’t want to go there. The rumor was there wasn’t anything between there and the North Pole but a barb wire fence and two strands were down. I didn’t do much better I went to Loring AFB in far north Maine and work on Hound Dog missels!
Elmo
 

Link did not stick . Here is some of the data .

2020 6.6L L8T Chevy
6.6L
401 HP @5200RPM
464 Torque @4000RPM
Direct injection
10.8:1 Compression ratio
87 octane. No AFM / DFM
GM 6 Speed Automatic
 
(quoted from post at 15:30:20 02/27/19) I've been predicting for some time now that the federales are inadvertently driving many applications back to gasoline.

Unless the nonsensical regulations change, I would expect gasoline engines to return to the utility tractor market in the foreseeable future.

Sadly, US manufacturers are afraid to invest in new technology because the feds can render their investments valueless with the ignorant stroke of a pen.

Dean
Click to expand...

GM was probably expecting H I L L A R Y to win and have the EPA enact Tier V and Tier VI emission regulations. Those regulations would have eliminated the diesel from small and light or medium duty applications.
That 6.6 would be a 110-140 HP engine at 1800rpm for industrial use.
 
(quoted from post at 19:14:38 02/27/19) Do you think Kubota will convert to smaller tractors to gas?
Click to expand...

I have posted several times the list of three and four cylinder spark ignition engines that Kubota sells.
They are designed with the exact same footprint and connections as the diesel.
There are for markets where LP or natural gas operation is required. Or in applications where the Tier IV diesel is plugging the particulate filter due to Granny driving.

Again ........http://www.kubotaengine.com/products/engines/vertical-gasoline-slash-lpg/kubota-wg-series-dual-fuel
 
(quoted from post at 19:14:38 02/27/19) Do you think Kubota will convert to smaller tractors to gas?
Click to expand...

I have posted several times the list of three and four cylinder spark ignition engines that Kubota sells.
They are designed with the exact same footprint and connections as the diesel.
There are for markets where LP or natural gas operation is required. Or in applications where the Tier IV diesel is plugging the particulate filter due to chronic Granny driving in light duty intermittent operation.

Again ........http://www.kubotaengine.com/products/engines/vertical-gasoline-slash-lpg/kubota-wg-series-dual-fuel
 
(quoted from post at 19:23:20 02/27/19) > Here is the 2020 solution for light and medium duty applications . Without the cost and aggravation of a Tier IV diesel . It would even make 115-140HP at 1800rpm for industrial duty.

I don't think so. The 60-degree GMC V-6 and V-12 engines are a product of 1950's engineering. They had a good run, but no way will they be coming back anytime soon, even if the price of gasoline drops to pre-OPEC levels.

These engines are too heavy and too expensive to build to be competitive in the 21st century. It might be possible to improve on their high fuel consumption with electronic fuel injection, higher compression and better combustion chamber design. But how can you shave enough weight to make them competitive with a modern turbo-diesel like a Duramax? The V-12 weighs over 1200 lbs! And it's expensive to machine 60-degree engines, which is why nobody makes them. So it would cost as much as a Duramax, weigh more and probably produce less power while burning more fuel. On the plus side, with regular oil changes a modernized Jimmy should last pretty much forever.
Click to expand...

My apologies for a missing cut and paste that was supposed to link to the Chevy LXX 6.6L gas truck engine .
Inadvertently made the V12 look like the answer instead of the new 401HP Chevy V8.

http://gmauthority.com/blog/2018/10/next-gen-gm-hd-trucks-to-introduce-new-6-6l-v-8-gasoline-engine/
 

The hound Dog was ahead of it's time. Carried up to 1.45Mt of bad news.
https://en.wikipedia.org/wiki/AGM-28_Hound_Dog
 
The RR Griffon has a sound all it's own. There is a unlimited modified puller from Cambridge IA that runs one in the River Rat. The Allison 1710 and Packard 2500 have a smooth sound to them, but the Griffon has a definite rhythm and louder than a pair of Hemis.
 
(quoted from post at 14:36:47 02/27/19) I'm surprised that a Twin 6 could be packaged transversely in a pusher bus.

A local guy had a Blue Bird (Carpenter?) pusher with a 478 GMC V6 gasoline engine in the 60s. It had a wonderful sound.

Dean
Click to expand...
MC also made a diesel V6 , 478 cubic inch ToroFloat , used in intermediate trucks, school buses and boats . Back in the 70's, Dudley Wooley, in Wabasso Florida, put one in a 3/4 ton chevy and claimed a record 60 mpg. Wooley was convinced he could get as much as 80 mpg., I don't know if he was able to do it. I have an article from a Florida paper reporting on him and one of those engines.
 
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