Jet Setter: 1984 Porsche 928S Turboshaft Powered

Have you ever been cruisin’ down the I90 outside of Cleveland and sorta thought you heard a jet, but the noises got uncomfortably loud, to the point you fully expect to see a 747 landing gear in your rear-view, expect you don’t…what you see is a red Porsche 928.  And then it blasts by you in a fog of Jet B and testosterone…suddenly you want one yourself.  Find this 1984 Porsche 928S with Boeing 502 turboshaft power  here on eBay bidding for $5,500 with a day to go, located in Painesville, OH.  Tip from Hunter.

The Porsche 928 was known as the German Camaro for its torquey V8 and muscle car attitude…but things change when remove the original V8 and replace it with a Boeing 502 (aka T-50) borrowed from a small Gyrodyne helicopter.  The seller doesn’t specify which version of 502 he used, but it could be rated anywhere from 150 horsepower to 350 horsepower depending on the original application and decade of manufacture since the 502 started life in the 1950s.

I happen to know a few things about turbine engines — first is that they produce very little torque — but it happens at crazy high RPM (50,000 for instance) so those little torques get multiplied in a gear reduction box before you put it into the transmission (located above on the far left).  Additionally, ff a turbocharged car has some turbo lag, then a turboshaft engine IS turbolag — and it might not be a big deal until waze shoves you into an unprotected left on a 4 lane highway at rush hour. 

In an internal combustion piston engine, you mash the loud pedal, the throttle plates open up, more air gets sucked in, more fuel added — presto, several combustion events later you are off and running. With a turboshaft, you mash on the pedal and a little more fuel gets added to the combustion chamber (you can’t just dump lots of fuel due to limits of flammability and stoichiometry), and the compressor turbine starts to spin faster which puts more air into the combustion chamber so you can add more fuel — this is called the bootstrap process…however, this only helps you go faster when the free power turbine is able to harness this excess energy (technically temperature or enthalpy) and put power out the power shaft into the gear reduction box.  By the time all of that stuff happens, you might have had a close encounter with a city bus — so any acceleration maneuvers in a turbine powered car must be planned well in advance.  Also, forget about any engine braking, power goes only one way in a turboshaft.  However, if you just want to drive around in a car that sounds like a jet at takeoff…I can’t imagine a better way to do it — because this would cost you easily $50k to build your own if you had the right connections.

Another thing that might surprise you about turbine engines is the parts cost.  You don’t simply head down to your local Pep boys to pickup a spark plug for $1.99 — the basic rule of thumb when it comes to aerospace parts is to add 10x-20x the cost when compared to a consumer good…and forget about something like a full engine teardown without the proper tools and know-how — do you know how to properly pre-load new foils on an air bearing…cause the guy at the independent Porsche shop won’t.  However, if you live near a small airport, you might be able to find a small time aircraft mechanic who is willing to help with something that doesn’t require FAA certifications.

See another….i dunno…thing? tips@dailyturismo.com