There are two large scale car companies in the world that have chosen to embrace the 180 degree flat layout engines; Porsche and Subaru. Where Porsche has placed their flat engines in the back, Subaru has stuck them up in front of their sedans and wagons for years. The flat layout offers a sound unlike any other, as the exhaust pulses tend to be more individual and offset than many other engine layouts. The sound of a flat-four engine is nearly unmistakable, while a flat-six is truly unique. When it comes to cross-branding engine swaps, it seems that Subaru’s flat-four is a no-brainer for some Porsche owners.
In 1959, when this car was produced, turbocharged automobile engines were still a pipe dream, and wouldn’t come to fruition for another few years. Where Porsche was one of the major pioneers in turbocharging, and continues to produce some truly great turbocharged engines, it was Subaru who used this technology to give their relatively sedate sedans a giant shot of performance in the arm. Subaru began producing the WRX version of their Impreza sedan several years and many generations ago, and it has since blossomed into a truly capable sporting machine, and a great bargain in its market.
From 356 D to Outlaw
This car started life in the Drauz carrosserie workshops as the successor to the 356 Speedster, known as the Convertible D. Where the Speedster offered a relatively austere cabin, the Convertible D moved the same svelte bodywork further upmarket with amenities like roll up glass windows, replacing the plastic snap in side windows of the Speedster. The Convertible D was a truly great car, but was a very expensive proposition at the time, and didn’t sell a substantial number of units. The model was dropped from the lineup with the introduction of the 356B bodywork, and was a 1 year nameplate, replaced by the Roadster for 1960. Only 1330 examples of the Convertible D were ever produced, making it a truly rare bird.
By today’s standards, a 356 is downright slow. Sometimes, even keeping up with highway traffic can be a chore, as the original 1600 cc engine had horsepower measured with only two digits. When the current owner of this particular 356 decided that he wanted to tackle the Copperstate 1000 road rally, it was immediately known that the car would require additional ponies. The help came in the form of a Subaru 2.5 liter turbocharged engine, snatched from a modern WRX. Now sporting nearly 335 horsepower (the stock WRX puts out nearly 260 and Dyno Comp says they added another 60 to 70 hp), more than 3 times what it had when new, the Convertible D can now not only keep up with traffic, but is capable of demoralizing even the most rapid of sportscar owners.
Listen to How Great This Sounds on the Dyno
Dyno-comp tackled the engine tuning, using a stock WRX ECU with a Cobb AccessPort tuning piggyback. The swap was relatively simple, as the engine only needs the bare minimum to run, and there are several easy conversion kits for Porsche rear engine transaxles already on the market. While information on this car is relatively scarce (we’ve spoken with Dyno Comp and they’re working on getting us more info from the owner. If so, we’ll update the post accordingly), it would be safe to assume that the car has received a later Porsche gearbox, as the stock 356 ‘box would not be capable of this kind of power for very long. The new Subaru power not only endows the Porsche with a cadre of additional horses, the engine is also more economical, offering economy in the high 20s (miles per gallon), and is also much more efficient, with emissions much cleaner than the old air cooled motor.
While many purists will scoff at the idea of powering a rarity such as this Convertible D with anything other than the white gloved hands of their car staff, pushing only on the rear bumper to avoid scratching the paint, it is obvious that this car was built to be driven, and driven hard. After already having racked up 1000s of miles in testing and competing in road rallies, the car, and its owner, show no signs of slowing down.
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