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Wrecking Yard Diesel Engine Options For Jeeps - Blowing Smoke

Posted in How To: Engine on November 4, 2014
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Given the reemerging popularity of diesel engines at the OE level, it’s no surprise that the aftermarket has jumped back on the diesel bandwagon, and rightly so. Today’s direct-injection turbocharged diesel engines are so far removed from that of the old mechanical-pump rattle boxes of years’ past, it is hard to even compare the two.

While Mercedes-Benz and Volkswagen have both been at the forefront of reliable and efficient diesel technology for years, Jeep is just now catching up in the U.S. Currently, the only new Jeep being offered with a diesel engine on U.S. soil is the Grand Cherokee, but we suspect that company’s diesel portfolio could expand in the not-so-distant future. The 240 hp and 420 lb-ft of torque 3.0L EcoDiesel in the Grand Cherokee is proof of what the modern diesel engine is capable of. The 30 mpg rating only helps the case.

If you’re gung-ho about swapping in a diesel engine in your Jeep and don’t want to re-invent the wheel, there are some supported options. In this article, we’re taking a closer look at the three most affordable and easily sourced diesel engines: the Cummins 4BT, Mercedes Benz OM617, and Volkswagen 1.9L.

Cummins 4BT
When it comes to diesel engine swaps, the 3.9L Cummins 4BT is by far the most common. With its mass availability and overall simplicity, the inline-four-cylinder diesel has become the go-to for Wranglers and FSJs. Often thought of as the little brother of the much-loved 5.9L Cummins, the 4BT is slightly easier to package but has all of the long-lasting attributes of its bigger bro. Weighing in at roughly 800 pounds, the 4BT has an overall length of 30 inches, a full five inches shorter than the 12-valve 5.9L.

From 1983 to 1998, the 4BT was an 8-valve engine. Later models were 16-valve. The turbocharged 4BT is a non-intercooled engine, which means it will not require you to fit a space-robbing intercooler up front (although, if you have the room, we recommend it). One major misconception about the 4BT is that it makes a lot of power in stock form. This is incorrect.

From the factory, most 4BT engines were only squeezing out around 105 hp and 265 lb-ft of torque. These power ratings vary slightly depending on application. Later-model versions (known as the 4BTA) cranked out a more impressive 170 hp and 420 lb-ft of torque. Both the 4BT and 4BTA are capable of turning out tremendous amounts of power (think 500 hp), but it’s not going to be simple turn of a screw to get those kind of ponies. Electronic controls were all but non-existent on early models, which makes the 4BT one of the easiest engines to swap.

Aside from the weight of the engine, one of the major drawbacks of the 3.9L is that for the most part, the engine is an unrefined rattlebox that can shake out your fillings while idling. It’s important to understand that the 4BT was used in everything from chippers to delivery vans. It’s a workhorse powerplant that was never intended for your Wrangler’s framerails. The fact that there are multiple conversion kits and transmission options for the 4BT increases the simplicity for those looking to convert to diesel. Our best advice to anyone interested in a 4BT swap is to test drive a rig with one swapped in, if possible. If you can live with the noise, vibration, and smoke, it’s a great option.

Koch Enterprises

Aaron Reeves Garage

Bruiser Conversions

Jeff Daniels Jeep Customizing

Mercedes-Benz OM617
Mercedes-Benz has been in the diesel game longer than most. Dating back to the ’30s, Mercedes-Benz was equipping its car line with diesel engines. The company’s OM617, which appeared throughout the ‘70s and ‘80s in 300-series cars, has even found support in the Jeep community. While there have been a few iterations of the 3.0L inline-five-cylinder engine, maybe the most popular (and easiest to come by) are the later-model turbocharged versions. Similar to the 4BT, the power numbers for the inline-five are not overly impressive. Expect around 120 hp and 180 lb-ft of torque from a turbocharged version.

Post 1985, you could also find a six-cylinder variant of this engine that produced around 140 hp. The turbocharged six-cylinder engines are slightly longer and a little more expensive to come by. If you are serious about performance, we would skip past the any of the non-turbo models all together. Seriously, swapping in a diesel engine with 79 hp isn’t worth the trouble!

Similar to the mechanical-injection 4BT, the OM617 can be tuned to get more power. At nearly 331⁄2 inches, the five-cylinder OM617 is pretty long, so spacing can be a challenge. The 27-inch overall height could also pose problems. Compared to other diesel engines, the turbocharged 3.0L is somewhat inexpensive, but coming across one in a wrecking yard might be a challenge. Given that many of these oil burners are still on the road today, we would look to online forums and classifieds to grab a running car. Expect to spend around $2,000-$5,000 depending on the car and miles for a running Benz.

These engines are known to go into the 500,000 mile range and are great for delivering solid fuel economy numbers. Compared to a modern Mercedes-Benz diesel, these cars and engines are pretty archaic. The good news is they don’t need a lot of extra computers or gadgets to get them running in a Jeep. Adjusting the ALDA valve (the part that increases fuel when boost levels rise) is almost always necessary to get the engines back in shape. As is the case with older diesels, expect plenty of rattles, shakes, and smoke. Oh, and these engines will leave an oil spot or two in your driveway.

4x4 Labs

Volkswagen 1.9L TDI
The Germans love their diesels, but just as Mercedes struggled early on with coal-rolling clunkers, Volkswagen had its share of missteps. While, the 1.9L diesel isn’t the only diesel engine you’ll find in the Volkswagen catalog, it’s one of the most supported and easily sourced next to the 1.6L. When VW first introduced its Turbocharged Direct Injection (TDI) engine 1996 to North America, it was an instant hit in many ways.

Sure, it only cranked out 90 hp, but the 150 lb-ft of torque and quick-spooling turbo gave it life in their sporty sedans. The fact that it was quiet even by today’s standards makes it stand out in the pack. The TDI VWs have drawn an enthusiast market, which has spilled over into the 4x4 world. Companies now offer complete engine conversion kits for the 1.9L and 1.6L engines.

The largest complaint from many about the 1.9L is its lack of power and efficiency when partnered with a heavy 4x4. Given that the late-model diesels have a host of electronics and are computer controlled, the direct-injection engines can be more costly to tune and install. One bonus for those looking to upgrade their Wrangler engine, the 1.9L actually weighs slightly less than the stock four-cylinder.

HPA Motorsports

Diesel Thoughts
One motivating factor we often hear when it comes to doing a diesel engine conversion is that the user wants increased fuel economy. Don’t let this be the only driving force behind your diesel dreams, because you might be disappointed. On average, we routinely encounter diesel-swapped rigs netting around 20 mpg—some more, some less. The cost of the conversion typically negates most fuel savings as we’d expect to spend at least $5,000, and that’s doing the work ourselves.

Another challenge tends to be packaging. A turbocharged diesel engine requires extra space for exhaust and intake routing. Cooler air-intake temps will increase performance and efficiency, so plan on routing an intercooler. The added weight can upset the balance of a rig and make for goofy handling on- and off-road. This will be more noticeable in a short-wheelbase Jeep. As is the case with any major investment, do your research and plan on it costing twice as much as you are expecting.

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