THE 5 HISTORIC DIESEL ENGINES THAT WON WW2 D

Today, we’re counting down five diesel engines that changed the course of World War II. And then, the world forgot about them. These engines rolled across beaches, built airfields under fire, and helped decide the outcome of the biggest war in history. A couple of them are going to surprise you.

Especially the one in the number one spot. It powered the most devastating military campaign of the entire war. Make sure to stick around for that one. We’re starting the list with an engine that sounds like it shouldn’t exist. Number five, the Guiberson T-1020. This engine was a radial diesel. If that doesn’t mean anything to you, picture the engine on a World War II fighter plane.

Those big round engines with cylinders arranged in a circle like spokes on a wheel. Now, imagine someone took that layout and made it run on diesel fuel instead of gasoline, then shoved it inside a tank. That’s the Guiberson T-1020. And in the early days of World War II, it powered one of the most important light tanks America had.

The M3 Stuart. The Guiberson was an air-cooled nine-cylinder radial diesel producing around 220 horsepower. For context, that’s less than most modern pickup trucks. But in 1940 and ’41, it was [music] enough to push a 14-ton light tank to speeds over 30 mph, which was genuinely [music] fast for a tank at that time.

The whole engine was about 3 ft across and surprisingly compact for what it could do. If you pop the engine deck on an early Stuart and looked inside, you’d see something that looked like it belonged in an airplane, not a tank. Because in a sense, it did. They had originally designed radial diesels for aviation use before the army came calling.

Here’s why the army wanted a diesel in the Stuart in the first place. In the Pacific, where the first Stuarts saw combat, gasoline was a logistical headache and a fire hazard. A tank full of gasoline that takes a hit turns into an inferno. Diesel is harder to ignite. And this engine gave the Stuart a meaningful advantage in survivability.

Think about that for a second. The men inside those Stuarts were already in a light tank, already outgunned by most Japanese anti-tank [music] weapons. Anything that reduced the chance of burning alive inside the hull was worth its weight in gold. Marines on Guadalcanal and in the Philippines ran these diesel Stuarts in some of the earliest armored engagements of the war, grinding through jungle terrain and coral roads that would have been brutal on any vehicle, let alone one carrying an experimental engine. The sound of this engine was something else entirely. It didn’t sound like a conventional diesel at all. It had a smoother, more even tone, closer to an aircraft engine than a truck motor, which made sense given its aviation heritage. Tankers who drove the diesel Stuart described a different feel from the gasoline version, a slightly different rhythm to the power delivery that you

either got used to or you didn’t. Now, the T-1020 wasn’t perfect. It was finicky to start in cold weather. Parts were hard to come by once the fighting moved to remote Pacific islands. And Guiberson was a small company that simply couldn’t produce engines at the volume the military needed. As Continental’s gasoline radial became more available, the diesel Stuart quietly disappeared from the front lines.

But for a brief window in 1941 and ’42, an air-cooled radial diesel, one of the strangest engine designs [music] ever put into a combat vehicle, was the power plant keeping tanks in the fight during some of the war’s darkest days. And here’s the kicker, Guiberson only built around a couple thousand of these engines total.

They were gone from front-line service by mid-1943. But the concept they proved, that diesel power belonged in armored vehicles, became the standard for virtually every Western main battle tank built after the war. The Guiberson was the proof of concept for an idea that took decades to fully arrive. If you think a radial diesel tank engine is strange, the next engine on this list didn’t fire a single shot.

But without it, the planes that won the air war might never have gotten off the ground. Number four, the Caterpillar D13000. Not every engine that wins a war goes into something that shoots. Some of them go into something that builds. The Caterpillar D13000 is one of the most important engines of World War II, and most people have never heard of it.

Because it didn’t power a tank or a ship. It powered bulldozers. And those bulldozers changed everything. The D13000 was a six-cylinder diesel producing around 120 to 140 horsepower, depending on the configuration. That’s modest by today’s standards, about what you’d find in a large sedan. But bolted into a Caterpillar D7 or D8 bulldozer, that engine could move mountains, literally.

These machines carved airstrips out of Pacific island jungles, cleared coral rubble off invasion beaches, and pushed roads through terrain that no wheeled vehicle could cross. If you’ve ever seen footage of a jungle airfield appearing out of nowhere on some tiny island in the middle of the Pacific, a Caterpillar diesel made that happen.

Here’s the thing most people don’t appreciate about the Pacific War. Air power decided it, and air power needed runways. Every island the Marines or the army took had to become a functioning airbase as fast as humanly possible, because the next island in the chain was only reachable if you had fighters and bombers close enough to cover the invasion.

The Navy Seabees, the construction battalions, drove those Caterpillar bulldozers onto beaches [music] that were still under enemy fire and started building before the fighting was even finished. Think about that. The operators sitting behind those D13000 diesels weren’t in armored vehicles. They were on open bulldozers, pushing dirt and coral while Japanese snipers and mortars were still active.

The Seabees suffered combat casualties doing construction work because the airfields couldn’t wait. The D13000 had a personality that matched the job. It was slow, heavy, and relentless. It didn’t rev high or make dramatic power, it just pulled low and steady, hour after hour, in heat that would put a man on his knees.

Operators who ran Cat bulldozers in the Pacific will tell you the engine never quit on them. The heat, the coral dust, the salt air that corroded everything else on the island, and the D13000 just kept turning over. Mechanics kept them running with whatever they had, and the engines made it easy because they were about as simple and overbuilt as a diesel gets.

Big, heavy, cast iron, and designed to take punishment that would crack a lighter engine in half. And it wasn’t just the Pacific. In Europe, Caterpillar dozers powered by these same engines cleared hedgerows in Normandy, built pontoon bridge approaches, and pushed rubble off roads so armor columns could advance.

After the breakout from the beaches, the advance moved only as fast as the engineers could clear the path. The Cat diesel was the engine that cleared it. Here’s something wild. The US military used more Caterpillar equipment in World War [music] II than any other single brand of machinery, more than tanks, more than trucks from any one manufacturer.

The humble bulldozer, powered by the D13000 diesel, was statistically one of the most important machines in the entire war. The Japanese military reportedly identified the bulldozer as one of the most decisive weapons they faced. Not because it could fight, but because it could turn a useless island into a functioning airbase in days.

That’s the kind of impact no spec sheet can capture. Think a bulldozer engine sounds modest compared to what’s coming? The next engine on this list didn’t serve in one type of vehicle or one branch of the military. It served in nearly all of them. Number three, the Detroit Diesel 6-71. If you had to pick a single engine that did the most jobs in the most places during the biggest war in history, the answer might be the Detroit Diesel 6-71.

The GM Series 71, the legendary 671 in its six-cylinder form, was everywhere. And when I say everywhere, I mean amphibious trucks, landing craft, tanks, generators, construction equipment, artillery prime movers, and about a dozen other applications that the military threw at it between 1938 and 1945.

The 6-71 was a two-stroke inline six-cylinder diesel. Now, here’s the thing about a two-stroke diesel that makes it different from the four-stroke engines most people are familiar with. In a regular four-stroke engine, each piston fires once every two revolutions of the crankshaft. In a two-stroke, it fires every single revolution.

That means for its size, a two-stroke produces more power more often. The trade-off is that it’s louder, it runs harder, and it’s not the most fuel-efficient design ever created. But in a war, where you need maximum power from the smallest possible package, those trade-offs were worth [music] it. The 6-71 displaced 426 cubic inches, about 7 L, and in its and in its military configurations produced anywhere from 165 to over 200 horsepower, depending on the application.

That might not sound like much, but remember, this engine was compact, light for its output, and it could be dropped into just about [music] anything with a flat surface and some mounting bolts. And the sound. If you’ve never heard a Detroit two-stroke diesel, it’s unlike anything else on the planet.

A high-pitched, rapid-fire scream that sounds more like a giant sewing machine than a conventional diesel. Once you’ve heard it, you never forget it. And veterans who served around 6-71 powered equipment could identify one by ear for the rest of their lives. It powered the DUKW, that remarkable amphibious truck that could drive off a ship, swim through ocean surf, crawl up a beach, and haul supplies straight to the front lines.

Every one of those DUKWs had a 6-71 under the hood. If you’ve ever seen footage of the D-Day invasion or the island-hopping campaign in the Pacific and watched those strange boat trucks driving out of the ocean and up the sand, >> [music] >> the engine making that happen was a 6-71. The men who operated DUKWs in combat surf will tell you that the moment between ocean and beach, when the wheels hit sand and the transmission engaged, and the whole vehicle lurched from floating to driving, was when you either trusted your engine or you didn’t. >> [music] >> The 6-71 almost always came through. Mechanics loved and hated the 6-71 in roughly equal measure. They loved it because [music] it was simple, parts were available, GM was producing these engines by the tens of thousands, and you could rebuild one in the field with basic tools if you had to. They hated it because the two-stroke design

meant it ran hot, it ate oil, and if you neglected the blower that forced air into the cylinders, the engine would let you know in the most dramatic way possible. But in wartime, simple beats sophisticated every time, and the 6-71 was about as simple as a diesel gets while still being genuinely useful.

Enjoying this trip through the diesel engines that went to war? Go ahead and hit that like button and subscribe. The top two entries on this list are absolute heavyweights, and you don’t want to miss them. Here’s something wild about the 6-71’s military career. After the war ended, surplus 6-71’s flooded the civilian market and launched [music] an entire industry of diesel trucking, marine power, and industrial applications.

The engine that won the war came home and helped build the post-war economy. Not a bad second act. If the 6-71 was the engine that did everything, the next engine on this list was the one that went everywhere the fighting was heaviest, inside the most iconic armored vehicle of the 20th century.

Number two, >> [music] >> the GM 6046. If that name doesn’t ring a bell, here’s what it was. Take two Detroit Diesel 6-71 engines, bolt them together side by side on a common mounting, connect them to a single drivetrain, and you’ve got the 6046, a twin six-cylinder two-stroke diesel producing a combined 410 horsepower.

And the machine it powered was the M4A2 Sherman, the diesel version of the most famous tank of World War II. Now, most people associate the Sherman with a gasoline [music] engine, and that’s fair. The majority of Shermans ran on gas, but the diesel variant, the M4A2, was produced in enormous numbers, >> [music] >> roughly 12,000 of them, and it saw some of the most intense ground combat of the entire war.

The United States Marine Corps used diesel Shermans extensively in the Pacific, where the reduced fire risk of diesel fuel was a life-or-death advantage. When a gasoline Sherman took a penetrating hit, the fuel could ignite catastrophically. Diesel fuel was far less volatile, and the crews who fought in M4A2s knew it.

That margin mattered when you were rolling toward a fortified Japanese position knowing that anti-tank [music] guns were waiting. The 6046 wasn’t elegant. Two engines bolted together is, honestly, a brute-force solution to a power problem, but sometimes brute force is exactly what you need. The engine compartment was packed, maintenance was more complicated than a single-engine setup, and mechanics working on one in the field had to deal with twice the components in a space that barely fit one engine comfortably. Field mechanics in the Pacific learned to work on these engines under tarps in tropical downpours, on [music] beaches still being shelled, with tools that had been dragged through salt water and sand. The guys who kept diesel Shermans running in the Pacific earned every bit of respect they got. But the combined output gave the 33-ton Sherman enough power to move at a respectable clip across terrain >> [music] >> that would stop most wheeled vehicles dead.

The torque of those two engines pulling together meant the diesel Sherman could claw through mud, climb grades, and push through obstacles with a stubbornness [music] that impressed the crews who drove them. And here’s where the story gets even bigger. Thousands of M4A2 diesel Shermans were sent to the Soviet Union through Lend-Lease.

The Soviets didn’t just accept them. They preferred the diesel Sherman over the gasoline versions. The Red Army already ran its own tanks on diesel, their supply lines were built around it, and Soviet tankers found the M4A2 reliable and well-suited to the Eastern [music] Front. Soviet crews called it dependable, and coming from an army that had already been fighting for years with their own formidable T-34 tanks, that was not a casual compliment.

The sound of a 6046 was unmistakable if you knew what you were listening for. Two 6-71 two-strokes screaming in tandem produced a distinctive high-pitched wail that was completely different from the gasoline Sherman’s throaty roar. Veterans who served around both variants could tell the difference from hundreds of yards away.

In the Pacific, that [music] sound meant Marine armor was moving up, and for the infantry who’d been waiting for tank support, it was one of the most welcome sounds in the war. Here’s something most people don’t know about the diesel Sherman’s legacy. After the war, multiple countries continued running M4A2 diesel Shermans in active military service for decades.

Israel used them in the 1948 Arab-Israeli War and continued operating modified versions into the 1970s. The 6046 didn’t just help win World War II. It kept showing up in conflicts around the world for 30 years after the factory stopped building them. That’s the kind of durability that no spec sheet can fully capture.

Now, everything on this list so far fought on the surface, on land or at sea. The number one engine operated in a completely different world, a world where the engine didn’t just move the machine, the engine was the machine’s lifeline, and the campaign it helped wage may [music] be the most decisive and least talked about campaign of the entire Second World War.

Number one, the GM EMD 16-278A. >> [screaming] [music] >> This engine was an absolute monster, 16 cylinders, around 1,600 horsepower per engine, and the fleet submarines that carried them typically had four, giving a single submarine over 6,000 combined horsepower from its diesel plants.

This was the primary engine of the Gato class and Balao class fleet submarines, the boats that [music] waged the most devastating naval campaign in modern history, the submarine war against Japan. Let me put the scale of what these engines helped accomplish into perspective. The submarines represented roughly 2% of US Navy personnel in the Pacific.

But that 2% running diesel-electric boats powered by engines like this one, sank over 55% of all Japanese shipping lost during the war. More than 5 million tons of merchant vessels and roughly 200 warships sent to the bottom by a submarine force that was in relative terms tiny. No other branch of any nation’s military achieved that kind [music] of disproportionate impact in the entire conflict.

This was a four-stroke V16 diesel engine, and it was a serious piece of machinery. Each engine was roughly 20 [music] ft long and weighed around 25,000 lb. That’s over 12 tons, just one engine. For perspective, four of these engines weighed more than a loaded semi-truck, and they were crammed into a pressure hole that was barely wide enough for two men to pass each other in the corridor.

Standing in the engine room of a Gato-class submarine was like standing inside a steel tube packed wall to wall with iron and noise. The engines dominated the space, massive, [music] dark, and radiating heat like furnaces. When all four main engines were running at full power on the surface, the noise was so intense that crewmen in the engine room communicated with hand signals because shouting was pointless.

You didn’t just hear these engines, you felt them in your chest, in your teeth, in the soles of your feet through the deck plates. These engines served a dual purpose [music] that made them the literal heartbeat of the submarine. On the surface, they drove the boat directly and charged the massive battery banks that powered the electric motors used underwater.

When the submarine dived, the diesels shut down. They can’t run submerged because they need air, and the boat ran on battery power alone. That meant every minute of surface running, every revolution of those 16-cylinder diesels, was banking the electrical energy that kept the crew alive and the boat fighting when they went [music] deep.

If the diesels couldn’t charge the batteries fast enough, the boat couldn’t stay submerged long enough to make an attack or evade a depth charge attack. The engines weren’t just propulsion, they were survival. Submarine crews developed a relationship with their engines that was different from any other branch of the military.

In a tank or a truck, engine failure means you stop. In a submarine, engine failure at the wrong moment means you can’t dive, can’t run, can’t evade. The men who kept the 16-278As running understood that their work in that deafening, sweltering engine room was directly [music] connected to whether the entire crew came home.

The engineering ratings, the sailors who lived with these engines, were among the most skilled and most respected men on the boat. The reliability of the 16-278A under combat conditions was remarkable. These engines endured depth charge attacks that shook the entire submarine so violently that light bulbs shattered and gauge needles bent.

They operated in the tropical heat of the South Pacific, where engine room temperatures could exceed 130°. They ran for patrol after patrol, war patrols that lasted 60 to 75 days at sea, and they kept running. When a boat limped back to port after a brutal patrol with battle damage and exhausted crew, the engines had usually held up better than the men.

And here’s the thing that puts this engine in the number one spot on this list. The submarine campaign in the Pacific didn’t just contribute to victory. Many historians argue it was the single most decisive factor in defeating Japan. Japan was an island nation that depended entirely on imported raw materials, oil, iron, rubber, food.

The submarines running these GM diesels systematically cut those supply lines. By late 1944, Japanese industry was starving for materials because the submarines had made the shipping lanes into a graveyard. The atomic bombs ended the war in August of 1945, but the submarine blockade had already made Japan’s defeat inevitable months before that.

And the engines that powered that blockade were GM diesels built in LaGrange, Illinois, and Cleveland, Ohio, running in pressure holes thousands of miles from home. Here’s something most people don’t realize. The submarine service suffered the highest casualty rate of any branch of the United States military in World War [music] II.

Roughly one in five submariners didn’t come home. The men who served alongside these engines knew the stakes every time they left port. The 16-278A didn’t just power a machine, it powered [music] a campaign that changed the course of the war, crewed by men who accepted odds that most people can’t imagine.

That’s why it sits at number one. From a nine-cylinder radial diesel in a light tank to a 16-cylinder submarine engine that helped strangle an empire, the diesels that fought World War II did more than just run. They carried men into the most dangerous places on Earth and brought most of them back.

Every engine on this list earned its place, not because of what it could do on a test bench, but because of what it did when the stakes were real and the margin for failure was zero. So, which engine on this list surprised you the most? Which one do you think we ranked too high or too low? Did we miss a World War II diesel that deserves a spot? [music] Maybe something from the Navy? Or a generator engine that kept entire bases alive? And if you or someone in your family ever served alongside any of these [music] engines, in a tank, on a sub, behind the wheel of a DUKW, or on a bulldozer pushing coral off a beach, we want to hear that story in the comments. Those are the stories that matter most. If you enjoyed this one, subscribe and hit the bell. We’ve got new videos every week covering the most incredible engines and machines ever built. [music]

See you in the next one.