Killer K5: Mountain Machine’s Compound Turbo 4BT-Swapped K5 Blazer

I’m sure by now you’ve all seen the Humvee built by Steve Ortner and Mountain Machine. The one with a compound turbo 12-valve Cummins shoehorned in it. The company responsible for that amazing build has brought us this killer K5 Chevy Blazer with a built 4BT Cummins in it, and as you could guess, it’s outfitted with another set of compound turbos.

This is no ordinary K5. Packing a 4BT Cummins with compound turbos, this is capable of pushing some nice numbers for a unit that is fairly light on its feet.

To start the build, Ortner’s crew tore the whole truck down to a bare frame and placed the body on a rotisserie.  They blasted the frame and epoxy coated it to make it virtually timeless. His employees also fixed the metal on the body of the truck while it was on the rotisserie making sure everything was perfect.

With all the groundwork done on the body and chassis, Ortner and his guys installed a BDS Suspension lift on the truck including some high-quality shocks and stabilizers from the folks at Fox Shocks. These upgrades will ensure that this truck will handle as many weekends on the sand dunes as Ortner can afford.

Dream To Reality

This CUCV isn’t just nice to look at, it’s right at home on the sand dunes.

As an experienced off-roader like Ortner, he knew that in order for the truck to work well in varying terrain, it would need much more than just a quality suspension lift and high-end shocks. Thus, the truck was outfitted with axles from a 1-ton wrecker using a Dana 60 in the front and a 14-bolt full floater in the rear. Both axles have Detroit Lockers and are geared to 4:56 for some healthy climbing capabilities.

To compliment all of the other off-road goodies, Ortner outfitted the truck with Raceline monster bead lock wheels using some healthy 38-inch Mickey Thompson Baja Pro tires. The bead locks will allow for the tires to be aired down for extra grip in more slippery circumstances and give the truck an aggressive off-road look.

In order to keep the riders safe, they decided to outfit the K5 with a full roll cage.

The cage is tied into the frame in six spots guaranteeing the most safety possible. Because Ortner plans on using the truck extensively off-road and wanted to remain comfortable for hours on end he concluded that Corbeau suspension seats were a must and included a bench seat in the back for his grandkids to utilize. Included in the interior are a few creature comforts such as a Dakota Digital dash which really modernizes this nasty K5.

Racing suspension seats to ensure the truck remains comfortable regardless of the terrain.

Now that all of the suspension and chassis work is covered it’s time to move onto the heart of this killer Blazer. When Ortner was planning this truck he knew a heart transplant was a must. Thus the K5 was diesel swapped with a very powerful and torquey 4BT Cummins diesel.

Diesel Power, Baby

The compact size of the 4BT makes a great candidate for engine swaps in tighter chassis configurations. It is also virtually identical to a 12v Cummins, which makes it highly modifiable.  Steve knew this when building the K5 and decided that a highly modified 4BT would be perfect. Unfortunately, the 4BT comes with around 100 horsepower factory which is nowhere near enough. The crew at Mountain Machine knew they had to remedy this issue.

The 4BT fits right at home in the engine bay of this K5 even with its large turbos.

To start Steve had the 4BT outfitted with a 12mm P pump from Farrell Diesel Service that feeds some large 5x.018 injectors from Industrial Injection all supported on a Waterman lift pump. The Mountain Machine crew was also able to utilize their in-house designed billet front timing cover on this build which just so happens to be the mount for the lift pump.  The front cover helps to add a decent bit of bling to the engine and allows for easier access to adjust the timing on the p-pump.

Inside of this 4-cylinder-Cummins beast is a Hamilton 188/220 camshaft along with Hamilton lifters and valve springs. This cam helps increase engine performance and efficiency dramatically over stock and the valve springs help to ensure the valvetrain is nice and controlled during high boost and reving circumstances. With plenty of fuel and tons of air to come, Ortner says the mighty 4BT should make 500 horsepower or more when he gets a chance to put it on the dyno.

The 5k looks just fine on the pavement as well.

Large Apex Turbochargers hang off of this rowdy little 4BT. These Apex turbos utilize a new design in which the compressor wheel and turbine wheel in some cases do not have an installation nut on them. This means that the wheels are able to scoop the maximum amount of air possible. We think the K5 is the perfect place to utilize this new technology!

The Apex turbos are set up in a compound configuration with the large atmospheric turbo being a 76mm compressor by 82mm turbine and the smaller manifold turbo being a 64.5mm compressor by 73.4mm turbine. Both of these turbos sport some nice internal features including a 360-degree thrust bearing on the manifold turbo and a triple ball bearing setup on the atmospheric turbo. The cornerstone of this crazy compound turbo system is a high-quality Steed Speed manifold which is just icing on the cake.

When Ortner visualized this CUCV he knew he wanted a bench seat in the back for the grandkids to ride along.

With large turbos comes a lot of compressed air which really needs an after-cooler, so Mountain Machine turned to a Frozen Boost to handle all of their intercooler needs. Of course with a highly custom build like this, there are no piping kits available for any of the intercooler or turbocharger piping so Ortner turned to Vibrant Performance to supply all of the piping and plumbing for the K5. He utilized the Vibrant HD clamps throughout the whole piping kit to ensure a perfect seal with no boot failure issues.

With all of these top-of-the-line products on the K5, there is one thing that can’t be overlooked if we intend on getting anywhere. The Blazer was outfitted with a 4L80E built by Accurate Transmission and utilizes a hefty triple disc torque converter from Phil at DPC Converters. This will ensure that Ortner can put all of the immense diesel torque to the tires efficiently while playing in the sand or on the trails.

With a high-profile build such as this and an extensive parts list, Ortner would like to personally thank his whole team that worked on the K5, Ed Larsen, Casey Jewell, Carl Sparks, and Dough Strimpel, who poured so much of their time into achieving this monumental task. Steve would also like to thank some of the companies who pitched in to make this killer project a reality, “BDS was a huge help, and also Vibrant performance, Mickey Thompson was huge as well and gave us a killer deal on the tires.”

We at Diesel Army love extensive builds such as this one that showcases what our industry is all about and we’d like to thank Steve Ortner for working with us on covering the build. As always make sure you stay tuned to Diesel Army for all your latest news and build features.

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About the author

Keaton Samples

Keaton grew up messing with diesel trucks, in fact, his dad owns a diesel shop, which is where Keaton is currently employed since the age of 14. I fell in love with midsized diesel trucks around the age of 15-16 and eventually bought my own.
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