Blazing Fast: The 11-second Sleeper SUV

Older diesel SUVs are 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 full-size, 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 McConnachie from building his own. It started when he 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 McConnachie 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, McConnachie removed the body from the Blazer, set it on the frame of the Ram, and then moved into the measuring stage. He had to be careful how much he cut out of the Dodge frame to fi t the Blazer body; in the end, a full 26 inches was removed from the Dodge chassis for it to work with the ’84 Chevy.

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Now, just because the Blazer is a body-swap doesn’t mean the project was easy. We’ve seen a lot of hackjob swaps that are just huge body lifts on stock frames, but McConnachie took a lot of time to integrate the body and make the Blazer look as factory as possible. For starters, he fabricated 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 modifi cations to the rear shackles, so they’d tuck nicely under the rear of the SUV. The biggest challenge was the front end, though, where he 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 McConnachie 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 the owner 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 4,000rpm governor springs, a Mack rack plug, and .022 delivery valves. The fuel plate was also removed, and timing was set at about 20 degrees. McConnachie 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 finds taken from Caterpillar engines, and McConnachie built the piping himself.

TRANNY WORK

McConnachie’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 super-low 1,700rpm stall converter with a custom stator was installed to give the Blazer lots of power both in and out of lock-up.

02_MBZ — With over 300,000 miles, the stock ’95 Dodge engine is somehow still hanging tough at more than 600 rear-wheel horsepower. The factory head bolts and head gasket are also still intact, even though the engine was assembled 20 years ago!

03_MBZ — One of the most impressive parts of the Blazer is its turbo system, which features 57mm and 74mm turbos from CAT engines to push an impressive 65psi of boost through the 5.9L Cummins engine.

04_MBZ — Not only did McConnachie 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 quickerspooling 1.10 A/R housing.

05_MBZ — A turbo speed sensor? Nope, it’s nitrous, although we’ve never seen it injected straight into a compressor wheel like this. McConnachie said that he runs a 0.078- inch jet, which is the largest his lines will allow. Since the engine already runs pretty lean, the extra oxygen is only worth about 50 hp at the rear wheels.

11_MBZ

07_MBZ — lthough the injection lines are stock, a fairly large set of 5×18 injectors (that McConnachie bought used) were added to the combination to give the truck the fueling it needed. Note the stock head bolts in this photo instead of the commonly used ARP studs.

08_MBZ — 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.

09_MBZ — 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 in a simple 3.5-inch single exhaust that turns down right in front of the rear bumper.

10_MBZ — The 3.36-geared Dana 80 rear end and rear suspension are both pretty simple, although McConnachie relocated the rear shackles and added a set of CalTracs traction bars. With a best 60-foot time of 1.67 seconds on slicks, the Blazer hooks quite well.

When his project was completed, even Steve McConnachie was a little surprised at how fast it was and how much power it made. He has dynoed the combination at 574 hp 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. McConnachie 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 Steve, how about building us one? DW

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Pinaki Bhattacharya

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