Project Thunderbolt LS3 Miata (Part 12): It’s Done!

Project Thunderbolt lives.

Over a span of nine months, Tom Tharp of Tom’s Turbo Garage built an LS3 V8-powered Mazdaspeed Miata. Think of it as a modern interpretation of great V8 sports car like the Shelby Cobra and the Sunbeam Tiger.

“In my eyes this is the perfect sports car…one I had been building in my head since high school,” Tom said. “It’s lightweight, nimble, and packs an all-aluminum sledgehammer of horsepower and torque hiding under the hood.  This is my dream car fully realized.”

So what’s it like to drive this little beast? We’ll let Tom tell you:

“The first thing that strikes you is how easy it is to drive. The clutch is light and has a smooth, predictable range of travel. The transmission is almost telepathic in how it guides you from gear to gear. You can just put the car in any gear and drive. With so little weight to lug around, the torque just pulls you up hills and through turns without a care.

If you can tune out the V8 rumble and keep from dipping into that big, delicious vat of torque, you’ll find that all of the Miata’s handling and balance is still intact. None of the inherent beauty of the Miata’s chassis dynamics seems to have been lost in the conversion. That said, I haven’t pushed the car hard, so we’ll see if that’s the case with more aggressive driving.

The car is comfortable too. The interior is quiet while giving you just the right amount of V8 soundtrack to keep you company. It get’s hot and humid here in the South, so it’s great to be able to roll up the windows and crank up the A/C when the temperature goes from “unbearable” to “are you serious?

And, oh, that sound! I love a high-strung turbo four cylinder, but the sound this car makes is intoxicating. The LS3 is always tugging at the reigns, begging you to go!”

So now that Project Thunderbolt is in one piece and running, what’s next?

Tom is talking about a visit to the friendly chassis dyno to get some performance numbers, doing some track time, and of course carve up as many mountain roads as he can find.  Tom will be posting his adventures on his Tom’s Turbo Garage YouTube channel, so stop by and check ‘em out.

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After all of the modifications Tom made to it, the Titanium Gray Metallic Mazdaspeed Miata looks pretty much stock. The wheels are 16x7.5” Konig Rollers (KNG-51836) wrapped in sticky Falken Azenis RT615K tires (FAL-18300). “I liked the classic look and the 16-inch size fills the wheel well just right. You can also see those Wilwood brakes peeking out from behind the spokes.”

Under the hood is the star of the show, the Chevrolet Performance LS376/525 LS3 nestled perfectly between the Miata’s shock towers and looking right at home. Once the key is turned, the aggressive sound makes it known that the stock turbo four cylinder is no longer present.

The interior is factory original, right down to the stock leather shift knob. The only addition I made in here is the Innovate wideband air fuel ratio gauge, which is hidden in the glovebox.

Most of the changes made to the car are better seen from underneath. Tom shoehorned a Chevrolet Performance T-56 six-speed in there, upgraded to a Cadillac CTS-V Getrag differential, and fabricated the complete exhaust system.

Once a car is done, there’s only one thing left to do…rack up some miles! Check out the video to see and hear Project Thunderbolt carving up some mountain roads.

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Entire Project Thunderbolt Series Here