May 29, 2024

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The Cars Maniacs

This 1971 Plymouth GTX-R Custom Gets A V10 Dodge Viper Engine

This 1971 Plymouth GTX-R Custom Gets A V10 Dodge Viper Engine

We’re sure you remember the awesome 1970 Plymouth Roadrunner that Dominic Toretto drives in the Fast and the Furious series. Now this Plymouth GTX-R Custom might just blow that in its dust. Created by Horsepower Northwest, this restomod is on a seriously rare car and has been executed beautifully.


The lengths to which detailing has been done are commendable by the Washington-based tuner. And the best bit is that Horsepower Northwest built their vehicles to be driven, and not just added to an elaborate garage collection.

Additionally, unlike the Plymouth Road Runner Green Goblin we wrote about earlier which had a 425 hp V8, the Plymouth GTX-R gets a V10 heart from the Dodge Viper bringing it up to the serious section of the supercar segment. Nothing wrong with denting some egos with a 1971 restomod on the track, in fact even your opponents will encourage it. Although not many will be able to keep up with a 630-hp Viper V10! This is a wild crossover between two iconic muscle car makers – Plymouth and Dodge.

Related: Check Out These Epic Muscle Cars Left For Junk Including A Plymouth Road Runner


Breathtaking Bodywork On This Plymouth GTX-R Custom

Starting with the design, one of our favorite designers, Abimelec Arellano created the render for this gorgeous build. He has kept the design lines unostentatious and plans to make it much more attractive for collectors and drivers alike. The F8 green color with a PG DBC base layer matches seamlessly with the bronze custom alloy wheels.

The alloys themselves are a major part of the butch design, 18X8 inches up front and 19X11 inches at the rear. The black perpendicular racing strips add sheer strength to the muscle body, don’t they?!

The engine swap also required an increase in the length of the entire body, which also makes it more aerodynamic. Two of the headlights have been swapped for cold air intakes, which more or less look like nostrils similar to what you see on the Dodge Demon. And the frameless doors just define that classic retro appeal on the Plymouth GTX-R Custom.

Related: Mopar Madness: A 1970s Dodge Charger, Super Bee, And Challenger Are Spectacular Barn Finds

Special Components For A Robust Performance Car

This is because it is not just a power boost, but the V10 has also necessitated the need for significant changes under the hood to compensate for the larger size. The third generation 8.4 liter V10 engine has been placed in and dyno tested for 630 hp of maximum power and 660 lb-ft peak torque by the renowned Prefix performance.

This should be enough to tell you that this machine is for performance driving and not just a showboat. The powerful engine is paired with a high-performance Magnum T56 6-speed manual transmission which is one of the most robust transmissions in the market currently. The setup is further supported by a 3.70 TrueTrac differential further reinforcing the driveline.

To harness all that performance, Horsepower Northwest has equipped 14-inch Baer 6P disc brakes on the Plymouth GTX-R Custom appropriately. Engineers have also stiffened the fully welded chassis giving the GTX-R enough rigidity for enhanced handling characteristics and drag racing duties. There is a Cerakote ceramic baked coating on the engine components, trim pieces, and some interior hard bits to handle all that heat.

Yes, all this has complicated preserving critical components and new fabrications have been made to compensate. Completing the build are those awesome side exiting exhausts just in front of the rear wheels. Admittedly, there is nothing cooler than a restomod with side-mounted exhausts. Good work Northwest.

Interior Matches The Plymouth’s Retro appeal

As the engine is picked up from the Viper, the interior too follows the design language of the venerable Dodge. The inside of the Plymouth GTX-R Custom is a combination of black and tan, with the seat stitching reminiscent of the Viper. The headliner is particularly interesting made from a single piece and has perfect finishing.

The black center console contrasts well with the tan on the rest of the dashboard. Not sure if those black carpets look that cool though, but the perforated metal pedals more than make up for that. There are more noticeable details like the flushed front and rear glass, power windows, and Classic gauges with the GTX-R logo.

There is a one-off dash plaque to prove the ultra rarity of this beautiful build. Not sure if it has a stereo, and that may be appropriate because you’ll barely be able to hear over that massive V10 roar. The V8 may be the staple for all muscle cars, but we promise the V10 is even more glorious to listen to. It provides a higher rpm range and a sharper throttle response.

There were a few cuts and welds to fit it all in the engine bay, but we trust the re-engineering is thorough. Go take a look, and listen, at the Plymouth GTX-R Custom yourself displayed at the 2022 Houston Auction 20-22 October at NRG Center.

Sources: Horsepower Northwest, Plymouth, Dodge