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CUMMINS BLAZER

600HP 11-SECOND SLEEPER SUV

Older diesel SUVs are definitely a sought after and desirable breed, but what kind of SUV should one buy? Excursions have plenty of room but often come with the troublesome 6.0L powerplant; Jeeps aren’t fullsize, and older Blazers and Suburbans can only be bought with tired old 6.2L or 6.5L engines. But what about a lightweight, short wheelbase Blazer with a Cummins? Doesn’t sound too bad, does it? As it turns out, lightweight, short wheelbase Blazers can’t be purchased with a diesel (sorry) but that didn’t stop California resident Steve Mc Connachie from building his own. It started when Mc Connachie acquired a ‘95 Dodge that was in bad shape, with more than 286,000 miles on it. Although many parts of the truck were shot, the driveline still looked good, so Mc Connachie decided to turn his Cummins-Blazer dream into reality.

FRAME SWAP

The Blazer part of the equation came in the form of a well-used ‘84 model. After some eyeballing, Mc Connachie removed the body from the Blazer, set it on the frame of the Ram, and then moved into he cut out of the Dodge frame to fit the Blazer body, and in the end, a full 26 inches was removed from the Dodge chassis for it to work with the ‘84 Chevy. Now just because the Blazer is a body-swap, doesn’t mean it was easy. We’ve seen a lot of hackjob swaps that are just huge body lifts on stock frames, but Mc Connachie took a lot of time to integrate the body and make the Blazer look as factory as possible. For starters, Mc Connachie fabricated up all ten body mounts to put the Blazer body on the Dodge frame, which was especially challenging since the Blazer and Dodge frames were of very different widths. He also made modifications to the rear shackles, so they would tuck nicely under the rear of the SUV. The biggest challenge was the front end, though, where Mc Connachie had to fit and mount the radiator, intercooler and all the other assorted hardware to keep the big Cummins alive.

DRIVELINE MODS

With a Blazer-Cummins creation sort of coming into focus, there was still one big issue it would be painfully slow. Even with the weight reduction to 5,200 pounds, the stock 160hp 12-valve wasn’t going to set any records, even in the diesel Blazer category. Since Mc Connachie had already done so much of the work himself, he decided to tackle the engine and transmission too. The 5.9L Cummins long block was still untouched as Mc Connachie took the “let’s hope it holds” approach to making power. The P-pump on the other hand, received a good amount of modification in the form of 4,000-rpm governor springs, a Mack rack plug, and .022 delivery valves. The fuel plate was also removed, and timing was set at about 20 degrees. Mc Connachie knew he wanted his Blazer to be responsive, so he decided to go with compound turbos, using a 57mm S200 for the top turbo, and a 74mm charger on the bottom. Both turbos were junkyard fi nds off of Caterpillar engines, and Mc Connachie built the piping himself.

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TRANNY WORK

Mc Connachie’s work also made its way into the transmission, where a TransGo shift kit was installed, along with a Sonnex input shaft. The 47RH transmission was also upgraded with a stronger 48RE rotating assembly, and new clutches were added. With the responsive turbocharger setup, a superlow 1700-rpm stall converter with a custom stator was installed to give the Blazer lots of power both in and out of lock-up. When his project was completed, even Mc Connachie was a little surprised at how fast it was and how much power it made. He’s dynoed the combination at 574 rwhp on fuel, and 625 hp to the wheels (with a little nitrous in the mix). With a set of drag slicks, the Blazer has clicked off 11.80s in the quarter mile on fuel, and 11.40s on nitrous. Mc Connachie even reported that he got 21 to 23 mpg while cruising from California to Iowa. With such impressive all-around performance, could Cummins diesel Blazers be the next big thing? Hey, Mc Connachie, how about building us one?DW

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With over 300,000 miles, the stock ‘95 Dodge engine is somehow still hanging tough at more than 600 rwhp. The factory head bolts and head gasket are also still intact, even though the engine was assembled 20 years ago!
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Since Mc Connachie was on a shoestring budget, he saved money wherever he could. The K&N air fi lter and prefi lter was bought used, and Mc Connachie fabbed up an intake system for the big turbo using PVC pipe from Home Depot, which then he spray painted gray to match the truck.
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Not only did Mc Connachie build the piping for the turbo system himself, he also hogged-out the wastegate on the small charger and replaced the huge 1.58 A/R housing on the large turbo with a much quicker-spooling 1.10 A/R housing.
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One of the most impressive parts of the Blazer is its turbo system, which features 57mm and 74mm turbos off of CAT engines to push an impressive 65psi of boost through the 5.9L Cummins engine.
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A turbo speed sensor? Nope, it’s nitrous, although we’ve never seen it injected straight into a compressor wheel like this. Mc Connachie said that he runs a 0.078-inch jet, which is the largest his lines will allow. Since Mc Connachie’s engine already runs pretty lean, the extra oxygen is only worth about 50 hp at the rear wheels.
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The Bosch P7100 injection pump in Mc Connachie’s Blazer might look stock, but it’s not. A Mack rack plug (which allows for more rack travel), a set of 4,000-rpm governor springs, and .022 delivery valves allow the mildly modified pump to fuel hard enough for more than 600 hp at the tires. The injection pump is supported by the stock lift pump, and a “pusher” electric pump off of a VP44 truck that was mounted in-tank.
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Although the injection lines are stock, a fairly large set of 5×18 injectors (that Mc Connachie bought used) were added to the combination to give the truck the fueling it needed. Also, note the stock head bolts in this photo instead of the commonly used ARP studs.
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A big part of keeping the truck a sleeper was to eschew the normal huge diesel exhaust. Instead of a huge chrome tip, the blazer relies on a simple 3.5-inch single exhaust that turns down right in front of the rear bumper.
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The 3.36-geared Dana 80 rearend and rear suspension are both pretty simple, although Mc Connachie relocated the rear shackles and added a set of CalTracs traction bars. With a best 60ft time of 1.67 seconds on slicks, the Blazer hooks quite well.
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A lot of work was put into mating the Blazer body to the Dodge frame, but after thousands of miles of road grime, it looks like it could have been factory.
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Inside Mc Connachie’s Blazer, the interior remains pretty much the same as it did in 1984, with the addition of a little wear and tear. The Blazer’s sleeper image extends to the inside as well, where no visible gauges hint at the extra power lurking under the hood.
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Perhaps the only outside clue that something unnatural happened are the 3rd Generation Dodge wheels, which are wrapped in 265/70/17 Savero GT Radials.

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