Oil burners powering cars they were never really meant to power...

Diesels have received an increasingly bad rep over the past decade. They’ve been shunned by some as too dirty to run, a view strengthened by all the climate change advocates throwing their arms in the air announcing our impending mass extinction by global warming. However, there are those (rare) people who still appreciate the good old compression-ignition engine and who will go to great lengths to retrofit a car they like with an oil burner to satisfy themselves.

On my quest to find the craziest diesel swaps that the internet has to offer, I’ve assembled this list of ten examples that are not only cool but also support the idea that a diesel swap is a valid swap... at least in my mind. Keep in mind that some of the swaps on the list are easier to achieve than others as they require an extensive reengineering of the vehicle.

In some cases, the (often bigger) new engine won’t fit where it intended to, and it either gets moved to the middle of the car or serious hacking of the engine bay and firewall need to take place. But once the work on one of these is done, it will not only be super fast (if you use a turbocharged diesel) but also frugal. And, if you tune it well (which you should), it won’t spew out that much sooty black smoke out the back (or the hood, side, or wherever you feel like re-routing the exhaust to).

Renault Kangoo - Mercedes OM606

The Renault Kangoo is ubiquitous throughout Europe and used for short range delivery jobs of all kinds (although there’s a less common passenger variant too), and a large percentage of the examples you see will be powered by a diesel engine. However, there is always room for improvement when it comes to engines, and few diesel engines are more highly appreciated than Mercedes’ OM606 unit.

It’s a 3.0-liter, straight-six, turbocharged diesel built from 1993 to 2001 and used to power the E300 and S300 diesel models of that period, as well as the G-Class off-roader (that model is branded G300).

Power was rated at 174 horsepower and torque at 330 Nm / 243 pound-feet, but people who use it for their project cars frequently get it to make closer to 400 horsepower and 600 Nm / 442 pound-feet.

In this Kangoo, its builders estimate it’s pushing out 400 to 500 horsepower, considerably more than the 70 or so horsepower output of its original 1.5-liter diesel. It also appears to have been converted to rear-wheel drive, which is why you get to see it drifting on a frozen lake in the accompanying video.

Read our full review on the 2009 Renault Kangoo.

Mazda RX-8 - Cummins 6BT

Many people are scared of the prospect of owning a Mazda RX-8 for one very simple reason: they think the car’s factory Wankel rotary engine is unreliable, prone to excessive wear, and is temperamental. They’re certainly right to a degree, and proof of this is found in the plethora of dirt-cheap RX-8s out there for sale with a blown engine. One such car from the U.K. ended up with a completely new and very different engine that’s much bigger than what it had before, and it’s considerably more torquey too.

And here I was thinking the cheap RX-8 I saw for sale in Lithuania a few years ago with a 75 horsepower Renault 1.4-liter engine was the craziest RX-8 swap ever - it clearly wasn’t because this particular one now runs a Cummins 6BT, a 5.9-liter straight-six turbo diesel.

Yep, the engine you’d see under the hood of an early 1990s Ram pickup has been transplanted into the front of an RX-8.

This swap epitomizes the idea that you have to do a lot of cutting and hacking to fit a new (larger) engine into your car. For this build, they’ve had to eliminate a huge part of the firewall and the central transmission tunnel just to make it fit. Remember, the original Wankel is a packaging miracle, and it’s being replaced with something that just isn’t. The builders don’t mention what kind of power and torque numbers the new engine is putting out, but one thing’s certain - it can certainly turn rear tires into smoke very easily.

Read our full review on the 2010 - 2011 Mazda RX-8.

Mazda MX-5 / Miata - Cummins 4BT

Here’s another Cummins-swapped Mazda, but one that’s wasn’t just built to do parking lot donuts like the RX-8 above - this 1990 MX-5 Miata actually takes part in drift competitions where it has no trouble spinning its rear tires thanks to the mighty torque figure of its Cummins, 4BT, four-cylinder diesel. Now, I’m sure you’ve heard of a straight-pipe exhaust, but this car literally has a straight-up exhaust - it genuinely juts straight up out of the engine and makes the car look a bit droll.

The 4BT Cummins is smaller than the 6BT, it’s a 3.9-liter four-cylinder that, in most regular applications, makes around 100 horsepower.

That’s less than the Miata’s original 1.6-liter made, but with that intercooler proudly sticking out the front and what appears to be a larger turbo, it probably exceeds the original’s power output - it’s probably easily also got twice the torque.

This Miata was designed as a drift car, and there are plenty of videos on it going around various tracks sideways, with smoke billowing from its exhaust and rear tires at the same time. It’s a nice build overall, but had it been a bit cleaner and less silly looking (more of a sleeper), I think it would have gained even more notoriety than it did since it was built in 2016.

Read our full review on the 2018 Mazda MX-5.

Chevrolet Camaro SS - Duramax 6.6-liter V8

Time for the first V-8 on this list, and probably one of the cleanest and best builds I found while researching for this piece. Unlike most other cars featured here, this fifth-gen Camaro SS looks perplexingly stock and apparently there was no hacking of the firewall when installing its new engine.

It now runs a 6.6-liter Duramax V-8 diesel, but unless you heard it running or saw the black plumes it leaves in its wake, you wouldn’t know it.

This is the kind of build that I’m sure everybody would prefer, especially if you compare it to what the MX-5 above looked like even when they declared it “done.” What’s even more impressive is the fact that (according to the builder) all of the car’s original electronics work with the new power plant, and it not only looks like a stock Camaro SS but also operates like one from the inside.

Maybe a manual transmission could have made this build better and the car a bit more engaging to drive. Now the power is channeled to the rear wheels via a Hydra-Matic 6L90 automatic which certainly makes it easier to drive. In the same video, though, the builder also showcases an older build of a Dodge Charger diesel swap, and that car does have a manual swap to go with the new engine.

Read our full review on the 2019 Chevrolet Camaro.

Pontiac Fiero - VW 1.9 TDI

The Fiero (1984 - 1988) was Pontiac’s first two-seater since the late 1930s, and when it was launched, it was GM’s answer to the Toyota MR2 and other small sports cars. It proved quite successful, selling some 370,000 units in total, even if performance and reliability weren’t really its strong points. From the factory, it came with either a 2.5-liter, four-cylinder or a 2.8-liter, V-6 located in between the passenger compartment and the rear axle.

Many Fieros had their stock power plants removed and replaced with a peppier GM engine - you could even plonk a big V-8 in there with some cutting and hacking - but very few if any ever got diesel engines.

This particular one has a year 2000 Volkswagen TDI engine out of a Jetta.

It’s not the most powerful diesel out there at 90 horsepower in stock form, but still highly tunable and mostly reliable.

We don’t know if the engine had any specific work done on it to increase its power output, but the owner does mention the car is able to hit 55.2 mpg / 4.3 l/100km.

Pontiac Tempest Cummins 6BT

Time for another six-cylinder Cummins 6BT swap, this time under the hood of a 1970s Pontiac Tempest. Many of these cars came with V-8s from the factory, but they were also available with six-cylinder engines, so this six-pot swap isn’t a major departure.

The Cummins 6BT can be tuned to make a lot of power and torque, so this swapped Tempest is probably quicker than the factory six-cylinder.

Not that many details on the build are mentioned, though, and all you can gather is really what you can see in the two videos dedicated to the project. We do know it has a manual transmission with what appears to be the actual stick used in the truck the engine came out of - it’s quite long, and it looks a bit awkward to shift from a usual car-like driving position.

So while we don’t know exactly how much power it makes, it’s clearly enough to easily overpower the rear tires and do all kinds of burnouts and donuts in this. And, like most such builds, no care was given to where the exhaust comes out, so it comes right out of the engine bay and over the passenger side of the windscreen.

Ford F-250 with Mercedes OM606

Now, this has to be my favorite build of the entire list, even though I’m not that into pickups. But this 1980s Ford F-250 is just so cool with its Mercedes OM606 six-cylinder that’s apparently been tuned to make around 500 horsepower. Now that sounds like a lot of fun in this vehicle, especially with the manual gearbox that it’s mated to.

This engine is really great for swapping because it’s relatively compact, highly durable, and it also has potential to make a lot more power than its stock sub-200-horsepower rating.

It also sounds really creamy smooth even without any kind of exhaust muffling, and it’s just really enjoyable to really lean on it and relish in its blend of noise and torque.

It even makes a non-truck guy like myself see the light and actually imagine what it’d be like driving one of these. Plus this generation of Ford F-250 just looks right from most angles and, while it certainly looks dated compared to modern trucks, I think it has a lot of aesthetic appeal (i.e. it’s aged well from a visual standpoint).

Read our full review on the 2017 Ford Super Duty.

Smart with VW 1.9 TDI

There isn’t a lot of space in the engine compartment of a Smart car, located above and slightly in front of the rear axle. Such a car usually has a sub-1.0-liter three-cylinder but this modified example is apparently motivated by a VW-sourced, 1.9-liter, TDI that’s also been tuned to deliver far more power than it did in stock form. The result is a very quick drag car, one that even needs a wheelie bar sticking out the back so that it doesn’t land on its tailgate after a vigorous start.

The engine now apparently makes some 230 horsepower (around double the average power these types of engines usually make) and it enables this Smart to complete the quarter mile in a very impressive 13 seconds at 170 km/h or 105 mph.

The car would probably not be very useful on the road, especially if it really needs the wheelie bar a lot and every strong start would run the risk of flipping the car.

Read our full review on the 2015 Smart Fortwo.

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