When I came across this fine shot of a 1940 Dodge delivering supplies to the fast-growing Howard Johnson’s restaurant chain, I was surprised to see the “DIESEL” badge on its hood. Hmm, diesels were quite uncommon yet in the US then, and those few that did exist were very large and heavy, built by Cummins or Waukesha or such, and not likely to fit under the Dodge’s rather modest sized hood.
I did a bit of searching, and to my surprise, this diesel engine was designed and built by Chrysler, starting in 1939. For one reason or another, it was only built through 1942, and never returned after the war. But it’s a fascinating historical footnote, especially to a company that pioneered diesel engines in light trucks three times afterwards until it found lasting success ; in 1962, using a Perkins, in 1978 using a Mitsubishi, and then of course finally in 1989, using the Cummins that it still sports today.
I found a quite comprehensive article on this engine at dieselworldmag.com. In the 1930s, diesel engines in trucks were making very slow headway in the US; less than a thousand were sold per year. In Europe, much higher fuel prices made them quite common, soon to be ubiquitous. Nevertheless, the improved economics were compelling, given that diesel (fuel oil) sold for $0.04 to $0.10 per gallon compared to $0.14 to $0.16 for gasoline. And of course the diesels used significantly less of it.
Chrysler was developing a new larger heavy duty flathead six inline six truck engine in the mid thirties, with 331 cubic inches. It decided to pursue a diesel version, with a totally different ohv head, of course, but with most of the block and its components shared. The key reason they could do so was because they licensed the Lanova Air-Chamber (a variation of a precombustion chamber), which significantly softened the typical pounding of early direct injection diesel engines. This was a key factor in their decision to proceed.
Here’s how the Lanova system worked:
The Lanova Power Cell was called the Twin Cyclone by Dodge. Here’s how it worked: The injector (upper) sprays across the combustion chamber, some directly into a small prechamber called an energy cell. The air in the cell is hotter than the rest of the combustion chamber, so about 40 percent of the fuel ignites in there and the flame front travels back out of the cell into the main chamber, creating turbulence and igniting the remaining 60 percent of the charge. Dodge claimed the initial combustion created 1,100 psi pressure in the cell but when the ignition occurred in the main chamber, it was only 700 psi overall. Combustion occurred slowly and gently, but surely. As a result, the Lanova system eased the stress on engine components during the power stroke so the engine structure could be made lighter duty… and lighter. It had the added benefit of making the engine smoother and quieter, an important part of transitioning the public to diesel. The Lanova diesels also delivered among the highest diesel fuel economy among the other systems out there at the time. It had some inherent power limitations but these did not count for much until later. As higher pressure injection systems evolved and were better able to atomize fuel, the Lanova Power Cell fell to the better-breathing, direct injected combustion engines with greater power density.
Precombustion chamber and Lanova Air-Cell diesels were attractive for these qualities, allowing lower pressure pumps (cheaper) and minimizing the intense loads on the pistons and bearings, as the combustion process was slowed down. Despite the claims above, they were inherently somewhat less efficient, which is why truck engines inevitably moved to only direct injection, and eventually cars too.
The T100 331 cubic inch diesel six had a 3.75″ bore and 5″ stroke, produced 100 hp @2600rpm and 226 ft.lbs. of torque at 1000 rpm. Somewhat interestingly, this was almost exactly the same as the T80 flathead gasoline version, rated at 100 hp @2800 rpm and 230 lb.ft. @800 rpm. Both engines got slight power boosts in 1941.
In 1938, Chrysler engineers compared the full-load fuel economy of the T80 gas and T84 diesel on a dynamometer at 2400, 1600 and 800 rpm. The results were telling. At 2400 rpm, the diesel used 6.6 gallons per hour while the gas engine used 10.7 gph. Even more dramatic, at full-load 800 rpm operation, the gasser stayed at about 10.7 gph while the diesel improved to 4.3 gph.
An over-the-road comparison of two otherwise identical 3-ton trucks showed the gas version getting 3.74 mpg and the diesel 5.23 mpg. That’s a solid 40% improvement, but then flathead engines intrinsically were a bit less efficient than ohv gas engines.
This shot shows the very low camshaft position that was a hallmark of flathead engines, and thus had to be shared.
The diesel required 24 volts for starting (four 6V batteries) but had a 6V system otherwise. This necessitated two generators; one 24-volt unit (the inner one driven by two belts) and one 6-volt (the piggyback, facing backwards), the belt for which also drove the vacuum pump.
Chrysler also made marine and military versions. but total numbers were quite low. Total diesel truck production from 1939-1942 was 606 units, and perhaps a few thousand military, marine and industrial units. It’s not known just exactly why Chrysler discontinued the diesel after the war; presumably it was either the demand was too low and/or there were issues with them.
It’s also possible that the GM two-stroke diesels that GMC started offering in its trucks in 1939 had some impact, as the their compact size and greater power output put the Dodge diesel at a disadvantage. Who knows? But at least we now know that Dodge was a pioneer in diesels going way back.
Related reading:
Automotive History: The Very Rare 1978 Dodge Diesel Pickup And The Missing Diesel Van
CC: 1992 Dodge D250 Cummins Diesel – Direct Injected Life Support
Wow, I have read quite a few things about Chrysler Corporation of the 1930s and 40s and have never, ever seen so much as a reference to these!
It is interesting that there was no wartime use for this powerplant. You would think that improved efficiency would be a big plus, but then maybe that would not outweigh the likely extra up-front cost and the fact that everyone was just so much more familiar with gas engines.
If most of the military fleet was gas powered, then introduction of a few diesels would have mandated a separate logistics effort to supply diesel fuel. One fuel for the battlefield has always been the goal, even today as JP8 is the single fuel for every vehicle and aircraft.
For most smaller military vehicles, #2 diesel rather than JP8 is the preferred fuel. Even gasoline can be used, but it is obviously not preferred for reasons of greater vulnerability to small arms fire.
Your point is quite valid though. In many fast moving tactical situations, parallel supply chains for different fuels are burdensome. The military answer to this has been to specify diesel engines with multi fuel capability.
Most military diesels can use alternate fuels like JP8 in a pinch. Power and capability are reduced vs. #2 diesel, but at least the darn things can be run until a diesel fuel chain can be established.
JP 8 is what military trucks that can also run on diesel have been using for a number of years
correct. To my knowledge the US Military went to JP 8 around 2005. Biggest issue is the lack of paraffin wax causing wear of fuel pumps.
Although the US military in WW2 was heavily gasoline oriented, they had a number of diesel vehicles too, powered by the GM 2-stroke units.
This unit was used in military applications, as general power units (winches and such) but just not in large quantities. I suspect Chrysler originally tooled up for a rather modest volume, and that was never increased for war production. Exactly why is unknown.
That’s because virtually every Radial Engine produced in the US were gasoline powered. There was only one Diesel Radial Engine manufacturer in the United States (i.e. Guiberson Radial Diesels) in WW2, and they produced them almost exclusively for the M3 Stuart tank…
During the war , our tanks , jeeps , military cars , and other stuff ran on gasoline . One of the Best advantages we had over the enemy was an Excellent supply system , run by what they called at the time “The Red Ball Express” .
IF we had used diesel power during the war , we would have been Trying to support TWO Different Types of power units , ie, gasoline AND diesel . Which would have increased the difficulty in supporting our troops . It is MUCH simpler to run Everything off of the Same Fuel , think for a moment of this scenario ; you have a jeep that won’t run anymore , may be a broken axle or stripped transmission or who knows what . You have a tank that needs fuel . You can drain the gasoline out of the broken down jeep and dump it into the army tank , this would be far preferable than having to look around for diesel fuel supplies while fighting on the front lines .
One of the big problems that Germany had during the war was trying to keep their supplies caught up with their front lines , many times they could not do it .
Very interesting footnote in Chrysler history. But I’m not sure I understand the need for two generators. Wouldn’t a single 6V suffice, with series/parallel switching at the batteries when the starter kicked in?
You could tap off for the 6V but it tends to create an inbalance in the batts over time. Basically trying to charge the one batt with the 6 volt loads all the time even when the other 3 are charged results in those getting over charged. You can kind of cheat this by setting the setpoint voltage a bit lower but in old lead acid batteries that also tends to reduce life span but it would make it more even. If the 6 volt loads were really small it also doesn’t matter as much. In general for max lifespan they way they did it was more reliable.
You nailed it. That’s why they did that. It would have been difficult to deal with the imbalances.
What a surprise, this is the very first article I read about these, never heard of them before.
I found one of these years ago in the Silverado/ Santiago canyon area of orange County. It was in decent shape then but there have been a few fires through there since.
The lights and heater fan would be the only users of electricity, and they could be run from just one of the series batteries. Might need more amps from the generator, but that would be a lot easier than two separate generators.
Most trucks were designed as a chassis that were intended to be fitted with custom bodies for various different applications. For applications that required electricity, 24v was generally the standard as it contemplated longer wiring runs through whatever body or trailer the truck electrical system was powering. Depending on how much draw was required by the truck body or trailer, a 6v. generator might have had trouble keeping up with the demand.
Lights used a bit more power back then and 6V is not that efficient at moving power around. The headlights used around 40W each so that’s 80 watts, Tail lamps are another 7-8 watts (20 when brakes are applied) Running lights on a truck may be another 6-8 3-5W bulbs. Lighting alone could be 140 watts which on a 6v system will put you over 20 amps. Which can create some real problems in tapped multi voltage bank. Car batteries tolerate abuse well, but I imagine you would still have issues.
The fact that it’s 24 and 6 make this more complicated then a 12 24 system. Because you need all 4 batteries in series for the 24V. on a 12 24 you can charge at 12 and use at 12 then combine in series with a solenoid for starting but that gets a bit more complicated with 4 batteries.
Aha! eBay has a few factory publications, including this one—Dodge is upfront about higher initial cost, and asks buyer to weigh that against fuel savings, etc:
(6) Full Diesel or “Semi-Diesel.”
I wonder if that refers to low compression spark ignition engines that could run on cheap “distillate fuel”. Grandpa’s 1938 International farm tractor was designed for it.
I think the Howard Johnson’s trailer is beautiful. I imagine it’s full of ice cream and Ipswich Tendersweet clams, but then again, it doesn’t look to be refrigerated. I’d love to see a trailer like that restored somewhere.
Come to an annual ATHS convention (Illinois state fairgrounds memorial day 2022)
https://aths.org/convention/
Buy your own off Wheels of Time. Very nice beer version at PNW truck museum Brooks, OR, near Salem, Oregon
Like most of us, I had no idea these existed. It raises so many questions.
If they didn’t sell many, I wonder whether the tooling went to the wartime scrap drives? Maybe that’s why it didn’t reappear postwar.
An OHV head on a flathead gas engine block – yet we had to wait until the Hemi for an OHV car engine. I guess they could sell all they could build postwar, but still….
There’s a lot of thoughtful engineering there, but that’s a very deep head; I wonder how much extra the thing weighed?
Much the same power output as the gas version; what a difference from most early diesels.
The lab test chart is impressive; I wonder what it was like in service?
Thanks for the link; you know where I’ll be….. 🙂
As I said, they did build several thousand for military power units during the war. Tey just decided not to continue building them after the war.
The diesel weighed about 200lbs more than the gasser.
June 1940: A Cali operator testifies to the fuel-mileage differential:
I am just catching up on my reading. This Lanova system is fascinating. In my years of selling trucks and my years of representing Cummins Diesels, I never heard of this. tHanks.
Thanks for this informative article on one of the most obscure aspects of pre-war Dodge trucks, have never heard before of their foray into Diesel technology. Its a shame they did not pursue it postwar, become one of the pioneers in the market.
Early 1940:
Curious to know if any have survived and if one can see or here one running?
The Dodge Diesel has always been somewhat of an enigma. The American Truck Historical Society covered it in their publication ‘Wheels Of Time’ some years ago, and there is at least one restored example in existence. The engine was supplied to the U.S. Navy during WWII, but I have not been able to find out what it was used for. Incidentally Mack used the Lanova combustion chamber design on their early diesels as well.
Great post – wasn’t aware of this one.
I remember reading in a separate article, stating how Germany was directly involved in the engines production. We entered the war, ties were severed. What I don’t understand, is how detroit diesel was able to continue making the two stroke. I’ve heard old timers talk about, how if you ever pulled the valve cover on a ’39 detroit, the injectors have swatiskas on them. Granted, that’s assuming the injectors are original to engine, but still.