Air-Cooled Flat Six Twin Plug 3.4L Porsche Engine - Engine Builder Magazine
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Air-Cooled Flat Six Twin Plug 3.4L Porsche Engine


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Everyone has their favorite engines for one reason or another, and Workshop 5001 owner Marlon Goldberg will argue the air-cooled flat six Porsche engine is one of the best ever. Marlon has a rich background in Porsche cars and engines having worked for Porsche dealerships and at Singer Vehicle Design – a Porsche restoration company. However, he really got motivated to do his own thing when he met Dieter Inzenhofer, one of three partners who founded Andial, which was effectively Porsche Motorsport North America for a time.

Those experiences and desire to build great Porsche cars and engines led Goldberg to open Workshop 5001 seven years ago in South Central Los Angeles. The world Goldberg created at Workshop 5001 is one of Porsche wet dreams. His builds are completed as bare tub restorations, including Mil-Spec wiring, full interiors, motorsport suspension, custom components, and of course top-notch engine work.


As such, Marlon wanted his shop to be discrete, and that’s exactly why he chose the name Workshop 5001. People passing by wouldn’t know if it was a wood shop, a metal shop or something entirely different. They would only know that there was work being done.

And it’s a good thing too because many of Workshop 5001’s complete Porsche builds start at $500,000, and some are more than a million! In fact, Marlon’s builds are somewhere between art and car, or what he calls functional artwork. Everything in their cars is next level crazy, including the engines.


Today, we’re going to tell you about the details of a restored 1972 911 Porsche with an air-cooled, flat six, twin plug 3.4L engine. It’s our Engine of the Week.

The ’72 911, according to Marlon, is considered the holy grail because it’s the one year with the oil door, among other reasons. 

“They had to do away with the oil door because people were putting gas in the oil tank by accident back in the ‘70s,” he says. “The car has the oil tank in front of the rear axle so from a weight distribution standpoint, it was superior to every other 911 built up until ‘89.” 


Workshop 5001 decided this build would use mixed and matched parts from different eras of 911s to create a ‘what if’ car.

“Because of the huge interchangeability with Porsche cars, you can take almost any air-cooled Porsche motor from any year and stick it in any other year chassis from 1965 to 1998,” Goldberg says. “This particular engine I got from a 1986 911 that was 3.2L. For me it’s all about the motor in the car. The chassis is obviously done to the highest level, but it’s the house for this badass motor.”

Engine assembly and some machine work is done by Goldberg at Workshop 5001, while head work and dyno sessions are done at Randy Aase’s shop, Aasco.


Goldberg also works closely with well over 100 vendors who are intimately involved in each build to make them all come together, especially in a short period of time. On this 911 engine, Goldberg used titanium connecting rods, rockers and a straight cut intermediate gear all from Pauter.The engine also has CP pistons, Dema Elgin cams, Kinsler injection, and a MoTec M130 ECU and a MoTec PDM30. The rest of the parts in the engine are Porsche.

“It’s the first engine that we built with Kinsler injection,” Goldberg says.“When you want to improve a German engine, you’ve got to look at what some of these guys have done with American engines. That’s where a company like Kinsler comes into play. They’re dealing with flow and changing the taper of the intake and port matching and working with harmonic issues – they’re thinking about stuff on a different level than anyone who’s typically doing Porsche motors. That’s been a great relationship that I think is really taking our motors to the next level.” 


Workshop 5001 has also been working closely with Elring to seal their Porsche engines.

“There are some gaskets in this engine from Elring, and the conversation has just gotten started with Elring about developing a gasket kit with them,” he says. “They make most of these gaskets individually, but there’s really a need within the world of gasket kits for something that’s a premium product. As an engine builder, if you get a bad, dried out gasket or o-ring or it’s something you miss in assembly, especially with a Porsche motor, it can be a 40-50 hour mistake because this motor sort of stacks on itself.If something is leaking in the bottom end of the motor, you’ve got to take the whole thing back apart. So I wanted to develop something with Elring that helps us and potentially helps other engine builders.”


With this 3.4L flat six engine all sealed up and the restoration of this ’72 911 Porsche complete, the client will be enjoying 318 horsepower under the hood compared to a factory 208 horsepower. In other words – German engineering restored to its finest!

If you have an engine you’d like to see featured, please email [email protected]

Engine Builder Magazine