This 1967 Mustang Fastback Hides a Retired 1990s NASCAR Engine — the Owner Says Driving It Is Like ‘Going to Church’

A 1967 Mustang Fastback is running a genuine retired 1990s NASCAR engine good for 816 horsepower, and its owner treats every full-throttle pull like a Sunday ritual. See why fans are comparing the sound to a full-tilt Trans-Am car.

Under the hood of this 1967 Ford Mustang Fastback sits an engine that once turned real laps on a NASCAR oval sometime in the 1990s — not a tribute build, not a crate-engine stand-in, but a genuine retired race motor now making 816 horsepower in a 58-year-old street car. Serge, the collector who owns it, didn’t build this fastback to sit under a car cover between shows. He built it to be driven hard, and according to everyone who’s heard it run, “hard” barely covers it. Flared fenders, aggressive hood scoops, and a widened stance hint at what’s hiding underneath, but nothing quite prepares you for the sound of NASCAR-bred hardware waking up inside a car that once rolled off a Dearborn assembly line for grocery runs and stoplight drags alike. AutotopiaLA caught up with Serge to put the build through its paces, and the reaction says everything a spec sheet can’t.

The video is part of AutotopiaLA’s ongoing series profiling private collections and one-off builds, with host Shawn following Serge up north to check out several cars from his personal garage — this 816-horsepower Mustang stealing the segment outright. Serge walks through what separates this fastback from a typical restomod: instead of dropping in a modern LS or a crate Coyote, the build centers on a genuine retired NASCAR race motor, the kind of race-only hardware that almost never legally finds its way onto public roads. It’s paired with a body that’s been widened and flared to clear bigger wheels and tires, giving the Mustang a purposeful, track-day stance that separates it from a stock 1967 fastback at a glance.

Viewers who’ve watched the full 25-minute segment keep coming back to two things: the engine note, which more than one commenter compared to hearing a full-tilt Trans-Am car come alive, and the line Serge used to describe what happens when he actually gets on the throttle — a comment that had the video’s audience laughing within minutes of it going up. One commenter drew a direct comparison to a well-known modified Camaro nicknamed “Big Red,” calling it the highest compliment one gearhead build can pay another. Someone else wrote that the car looks totally different with its scoops, flares, and custom hood — unmistakably modified, yet still unmistakably a 1967 fastback underneath.

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Serge’s Mustang isn’t a one-off oddity in his garage, either — the AutotopiaLA visit framed it as one highlight among a broader personal collection, the kind serious collectors build over decades rather than assembling for a single show season. That context matters, because it means the fastback isn’t a first project or a flash-in-the-pan build. It’s the result of someone with the resources and patience to track down a legitimate retired racing engine and commit to making it street-legal, rather than settling for something easier to source and easier to insure.

The 1967 Redesign That Made This Build Possible

Builds like this one exist because of a decision Ford made back in 1967. That year, engineers widened the Mustang’s engine bay specifically to clear the FE-series big-block V8, making the 390-cubic-inch “S” code the first big-block ever offered in a factory Mustang. Rated at 320 horsepower and 427 lb-ft of torque from the factory, the 390 turned Ford’s compact pony car into a legitimate performance contender at a moment when the Pontiac GTO had already proven there was a market for oversized engines in mid-size bodies. That extra real estate under the hood is exactly what makes a modern swap like Serge’s feasible in the first place — decades before crate engines and LS swaps became mainstream shop work, the 1967 Mustang was already engineered to swallow something bigger than Ford’s own engineers had originally planned for.

A Retired NASCAR Engine, Built for the Street

What Serge’s Mustang is running isn’t a mystery motor cobbled together in a home garage — it’s a race-only V8 that spent its working life on a NASCAR oval sometime in the 1990s before being retired and repurposed for street duty. The comments under the video pin the engine’s character immediately: sky-high compression, a raw, race-bred bark, and throttle response that doesn’t exist in anything built for a showroom floor. One commenter singled out the engine’s roughly 15:1 compression and its race-fuel diet as the real giveaway that this build is more serious than it looks at a glance. The build and fabrication work is credited in the video to Anderson House O’ Speed, who widened the body and added the flares, hood scoops, and stance needed to actually put that kind of power down instead of just spinning the tires in a straight line.

According to Serge, driving the car hard isn’t an occasional treat reserved for car shows — it’s closer to a regular ritual. He jokingly told the AutotopiaLA crew that opening the throttle on this Mustang is basically “going to church,” a line that had viewers cracking up in the comments and that sums up exactly what this build is for. It isn’t a trailer queen or a garage ornament. It’s a numbers-be-damned street car built by someone who wanted to drive a genuine piece of NASCAR history on public roads — and by every account from people who’ve seen it in person, he’s succeeding.

A Fastback With Real Trans-Am Roots

There’s a fitting bit of history sitting underneath the modern swap. The 1967 Mustang Fastback wasn’t only a big-block platform — it was also Ford and Carroll Shelby’s weapon of choice in Trans-Am racing that same season. Shelby American built 26 K-code Mustang notchbacks to FIA Group 2 specification for 1967, stripped of radios and sound deadening but fitted with race-spec engines, brakes, and wheels. Driver Jerry Titus won both the 1967 Manufacturer’s Championship for Ford and the Driver’s Championship behind the wheel of a Shelby-prepared car, cementing the fastback’s reputation as a genuine racer wearing a street car’s sheet metal. Serge’s NASCAR-swapped fastback carries that same spirit forward nearly six decades later — a factory Mustang shape hiding motorsport-grade hardware, built by someone who wanted to drive the history rather than just look at it.

Builds like this rarely surface in public because retired racing engines are hard to source, harder to make street-legal, and usually reserved for private track cars rather than street-driven classics. It’s the extra work — the widened fenders, the custom fabrication, the willingness to actually drive something this valuable and this loud on public roads — that turns Serge’s Mustang from a numbers-matching investment into the kind of car people describe as one of the coolest builds they’ve seen. For a car built in 1967 to still be turning heads and drawing comparisons to modern pro-touring builds nearly sixty years later says as much about the original Mustang’s bones as it does about the retired NASCAR engine now living under its hood.

Watch the full video above and let us know your thoughts in the comments.