Supercharged 1969 Plymouth Road Runner

Red Dirt Hot Rod – Supercharged 1969 Plymouth Road Runner

Plans sometimes have a way of snowballing, especially when it comes to building a car. Just about every gearhead has a story about how “it started out as a brake job and turned into a complete restoration”, or something to that effect. This 1969 Road Runner is absolutely one of those stories. It rolled into the Red Dirt Rodz studio as a mildly restored original muscle car. It had shiny blue paint, a running 383 and bone-stock interior. Owner Joe McCalla III wanted to freshen some things up and to make it his own. So a deal was made, and the build was on.

In the high desert plains of Arizona, the Road Runner looks at home. Now there is that rascally Coyote?

In the high desert plains of Arizona, the Road Runner looks at home. Now there is that rascally Coyote?

 

The original plan was to add power disc brakes, an Edelbrock Performer RPM Power Package, and a fresh interior. A good plan, and easily achieved. The brakes and engine update were done relatively quickly, the interior however, was a different story. It seems that the previous “builder” glossed over some major issues with the floor pans, choosing to cover them up with roofing tin and lots of undercoating to hide the fact that this Road Runner paralleled another famous cartoon- the Flintstones. The driver-side floor pan was completely gone, and the rest of the pan had multiple smaller holes. There were similar issues found in the paint, so it was determined that a complete paint job was needed. The snowball had begun rolling down the hill.

At this point, the Road Runner was a lot worse off than they knew. During the course of the build, several cracks and serious rust damage were found in the front subframe, including a missing K-member mount, which has completely rusted through. Red Dirt Rodz took a step back from the plan and formulated a new one. Build the Road Runner into a full-on pro-touring show car.

Exterior

The outside of the car is mostly stock, with just a few subtle mods. The factory bumpers were welded up and smoothed, eliminating the large holes in the front bumper. Each side marker housing was removed and replaced with a frenched (recessed) pod build buy Red Dirt Rodz to install 2011-up Dodge Challenger side marker lenses, bringing the modern look to the vintage muscle car. The door locks were shaved and a set of Ring Brothers’ Camaro billet door handles were modified to operate the latches and installed into the doors.

The rear of the Road Runner is what most people will see when this car is on the road. Note the custom 2011 Challenger side markers on the rear quarter.

The rear of the Road Runner is what most people will see when this car is on the road. Note the custom 2011 Challenger side markers on the rear quarter.

 

The sheet metal wears two-tone DuPont Axalta Hot Hues waterbourne paint mixed in Sonic Boom on the sides (blue) and Blackened (black) up top. The black top half brings a stretched, lowered look to the car, adding a sinister flair. The two colors are separated with a hand-drawn pinstriped of Firecracker Red.

Powertrain

With the freshly-built 383 pushing out 400 horsepower thanks to the Edelbrock Power Package, the Road Runner needed something big to really make an impact. A Holley EFI retrofit system was ordered and installed. Instead of the traditional throttle-body system, Red Dirt Rodz chose to retrofit the intake with individual injectors and fuel rails, something not available in the aftermarket for Mopars big blocks. The spark is handled by a Mallory billet Unilite distributor and Hyfire 6 ignition box.

The supercharged 383 builds over 800 horsepower with 8 pounds of boost. On the right you can see the custom air box that brings fresh air into the engine.Also note the radically different firewall.

The supercharged 383 builds over 800 horsepower with 8 pounds of boost. On the right you can see the custom air box that brings fresh air into the engine.Also note the radically different firewall.

 

The focal point of the engine bay is the D1SC Procharger. Procharger does not make a Mopar system, so a kit was ordered for a Big Block Chevy, and modified to mount the self-oiling centrifugal supercharger to the 383. This system is intercooled (mounted behind the front bumper), plumbed with 3.5-inch tubing, using silicone hoses from Burns Stainless. The blower pushes 8 psi to the 383, and the final dyno numbers showed a whopping 750 horsepower to the rear wheels.

While the 727 is a very strong transmission in stock form, 900 horsepower is simply too much without modification. Red Dirt Rodz sourced a Super Street Fighter 727 trans from TCI, coupled with a matching 2,500-stall torque convertor for 1,000-hp capacity. This is a pro-touring car, so long road trips are part of the equation. To lower the revs on the highway, the transmission was fitted with a Gear Vendors overdrive. This drops the overall RPM of the engine from 3,500 at 65 to 2,000, making the Road Runner not only quieter on the road, but more fuel efficient as well. 

The 900-hp (flywheel) output of the engine proved too much for the rebuilt 8-3/4” differential, breaking teeth off the ring gear, so a custom Moser 60 rear end was installed. This is based on the Dana 60 design and can handle just about anything, making the drivetrain bulletproof.

Brakes

The original plan called for a stock-type single piston disc brake upgrade, but the new plan needed something better. A set of 3-piston brakes with 13-inch rotors at all four corners from Stainless Steel Brakes were installed to slow down the almost 20-foot long muscle car. Instead of relying of vacuum assist, a custom air over hydraulic braking system was designed and installed. This system uses components from big rig diesel trucks and uses air from the air ride tanks to operate it. There is tons of braking force behind the calipers from this design and the brakes do not suffer from a lack of vacuum.

This is the power plant for the air brake system. The air cylinder operates the hydraulic master cylinder just like a big rig.

This is the power plant for the air brake system. The air cylinder operates the hydraulic master cylinder just like a big rig.

 

Suspension

Not a single bolt was left unturned  on the Road Runner, including the suspension. The goal was a lowered stance with the ability to raise the car for speed bumps. A RideTech air suspension system was installed to get the B-body low to the ground and back up again at the touch of a button. The rear system uses the Ridetech AirBar, while the front requires the torsion bars to remain. This limits how low the car can go and still be raised up. Unfortunately, that is a drawback of the Plymouth design, there just isn’t room for larger air springs. The system runs dual air tanks and dual air compressors, one for the air ride and an isolated reserve tank for the air brakes to ensure that in the event of an air line failure, the brakes remain operational.

Interior

Stock upholstery just doesn’t work for a pro-touring car. The crew at Red Dirt Rodz designed a modern interior using ProCar bucket seats front and rear, a custom dash, and vacuum-formed door panels. The Autometer Custom Shop gauges were hand painted by Tom Kelly with a Road Runner and Coyote desert scene, and the Painless Wiring Phantom key push-to-start system brings in the modern technology. A Kenwood DVD head unit was paired with Boston Acoustic amps and speakers for an audio system that could compete with the raucous exhaust system.

The custom bucket seats are made by ProCar. The Red Dirt Rodz crew fabricated the panels to blend the rear buckets into the body.

The custom bucket seats are made by ProCar. The Red Dirt Rodz crew fabricated the panels to blend the rear buckets into the body.

 

The dash was heavily modified, even the glove box door was hand-fabricated.

The dash was heavily modified, even the glove box door was hand-fabricated.

 

Autometer's Custom Shop built the gauges that Red Dirt Rodz designed. Tom Kelly of Crazy Car Painters hand-painted the Road Runner and Coyote desert scene on each gauge face.

Autometer’s Custom Shop built the gauges that Red Dirt Rodz designed. Tom Kelly of Crazy Car Painters hand-painted the Road Runner and Coyote desert scene on each gauge face.

 

What pro-touring show car would be complete without a booming stereo system in a clean trunk?

What pro-touring show car would be complete without a booming stereo system in a clean trunk?

The end result of the build is an amazing pro-touring Road Runner that is at home on the show circuit as well as the track, and highway.  Even though the original build plan was left in the waste bin, a year later the project was done, receiving accolades from the Mopar Nation. Named one of the top 5 Mopars of the 2013 SEMA show, the Road Runner has been featured in numerous magazines, websites and several TV shows. Built for the Pentastar faithful, this is one seriously cool bird. Beep Beep!

about author

Jefferson Bryant

A life-long gearhead, Jefferson Bryant spends more time in the shop than anywhere else. His career began in the car audio industry as a shop manager, eventually working his way into a position at Rockford Fosgate as a product designer. In 2003, he began writing tech articles for magazines, and has been working as an automotive journalist ever since. His work has been featured in Car Craft, Hot Rod, Rod & Custom, Truckin’, Mopar Muscle, and many more. Jefferson has also written 4 books and produced countless videos. Jefferson operates Red Dirt Rodz, his personal garage studio, where all of his magazine articles and tech videos are produced.

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