Engine Swap Nirvana: The 500+ HP 8.2-Liter V8 Porsche-Cadillac 911 Eldorado Super Carrera

The moment mentioned above was a stroke of divine inspiration for the crankshaft realm because it allowed the coming into being of a very special 911. The 1981 Super Carrera Targa Cadillac 500 V8 – the FrankenPorschillac one-off that bends space-time, logic, automotive engineering, and wild dreams.

Ask any hardcore Porsche fundamentalist this deceptively simple question: “When was the first V8-powered 911 produced?” and then run for dear life. Alternatively, show them the car in this story – it might stop them in their tracks.

For the rest of the piston-minded population of our solar system, the dilemma is simple: sacrilege or genius? The show-stopper is a 911 SC Targa from 1981 – with a discrete modification. It has a slightly larger powerplant, courtesy of General Motors, vintage 1970. This 911 from ’81 has an 8.2-liter American V8 in it. The biggest and torquiest V8 regular-production Cadillac engine ever.

The owner – and author of this superb transplant – has had the small German sportscar since 2004. In his own words, he was struck by the lightning of inspiration for this project when he was 17. That was in 1975, when he came across “Peterson’s Complete Book of Engine Swapping No. 4” (see the article in the gallery).

Fast-forward three decades, and the dream began to materialize. “The engine swap was actually easy to do. Removing sheet metal and relocating the shocks gives a wide-open area. The Eldorado engine assembly fits with perfect axle alignment and the same single front/dual read mount points. Just make some motor mounts, constant-velocity joints, adaptors and axles, a custom radiator, and exhaust system. I built it once to test everything and then went all out with the final build.”

This is precisely what every regular, everyday, normal gearhead does on Saturdays – outrageous engine swaps (in their fantasies). But Michael Dyer Brooks of Newport Beach, California put his dream into metal. Lots and lots of metal, as we can observe in the gallery.

Of course, kicking out a meager three-liter boxer-six from its engine bay and throwing in a V8 that’s 2.73 times larger than the original motor isn’t exactly a finger-snapping job. In 2005, the rear-engined Super Carrera woke up from the anesthesia as a mid-engine 911 (again, use extra caution when uttering this phrase at Porsche Owner’s Clubs meetings).

The titanic 500 V8 is not every gearbox’s cup of tea, so a reliable, American transmission pairs with the engine. It is a rugged GM THM425 unit turned around – a “motorhome heavy-duty build, Trans-Go shift kit, and dual-pitch torque converter.”

The creator of this magnificently shocking automobile is right on point. “Those three items plus the final drive ratio modification can make this car scream like holy terror.” And the speed governor is adjustable – you know, to keep it on the ground (at all times).

The build is extraordinary in every sense of the word. A bespoke in-cabin faux luggage cover and a massive custom-built dual-purpose radiator under the rear deck lid cleverly conceal the mid-mounted engine. The aluminum heat exchanger cools the big 8.2-liter and the three-speed automatic via the electric twin fans.

The purpose of this ridiculously cool swap job is “fun, invention, having a goal, and building something new. What all car guys do.” (They wish!) “(…) here you have a truly unique and beautiful car that will never stop drawing a crowd.”

I can only imagine the moment when the Stuttgart Rearing Horse fanatics assemble around this engine bay. What a collective session of drop-the-jaw-in-awe it must be when reading the “Porsche” branding on the valve covers of that not-at-all-flat, not-a-six-pot monster. Talk about a severe “Cadillac Arrest” for the unsuspecting…

The engine didn’t just fly out of its 1970 Eldorado and crash-landed in an eleven-years-younger 911 Super Carrera. Its internals were forged and balanced, and a modified camshaft and valvetrain were installed along with aluminum heads.

Heavy-duty pumps for the lubrication and cooling systems were fitted. The exhaust manifolds received a double coat of ceramic protection – inside and out. The Cadillac ogre achieved a dyno GPA of 537 hp (545 ps) with the Magnaflow exhaust. Enough to make it very nose-happy under heavy throttle, but the owner insists the car is as drivable as it gets.

This alternate-universe 911 Super “Carrerado” 8.2-liter crossbreed is a reverse transaxle setup with the tranny behind the engine. The transmission is based on a Turbo Hydramatic 400, but designed for front-wheel drive cars (think Olds Toronado, Buick Riviera, or Caddy Eldorado from the Malaise era).

The gearbox internals rotate in the opposite direction, with the planetary gears cut on a reversed helical angle. A three-page list of modifications is available on the auction site – the car is for sale! – and a laconic forewarning should put bidders on high alert:

"Custom-built performance engine. Sold as is and shown. No warranty of any kind." (No kiddin’…) the seller adds that the car is accompanied by documentation, including the “Original to car Owner’s Manual & Warranty Book. Some sections on the powertrain may not apply.” (I wonder if any does).

The seller-owner-builder claims the firepower is well contained within the engine and does not overheat the cockpit. The ceramic coatings on the exhaust and the Marine insulation on the fake luggage cover keep heat transfer to bearable levels.

As a side note, the brakes are stock, and so are the suspensions – except the larger 30mm rear torsion bars. The Holley Sniper electronic fuel injection was installed in 2020, and the center of gravity is higher and forward (compared to a stock 1981 Porsche 911 SC Targa). The car does not have heating or air conditioning systems (probably due to the lack of space to install them).

The owner advises that “the buyer should open up the rear deck lid louvers for more airflow” and warns about the car’s tendency to lift the front end “if you’re going nuts with the throttle.”