The early 924 and the 944 models are powered by very different engines – 2.0 in the 924, 2.5 in the 944 and 924S. The 944 2.5 was the basis for all 944 engines to the end of the series, although significant changes and improvements occurred throughout its life.
The 2.0 Liter 924 and 931 (924 Turbo) was an iron block, aluminum head engine that was installed in different configurations in many vehicles. Produced by VW, it displaced 1984cc – just under two liters – and if properly maintained it was quite the durable engine for its day. My first Porsche was a ’78 924 that our family drove almost 250,000 miles, then sold it on for more miles.
Engine Mounting
One of the biggest differences between the engines and therefore the two models is how the engine is mounted in the front subframe. The 944 engine mounts into an aluminum crossmember – the one that also mounts the front control arms and the steering rack. The 944 engine sits on top of the crossmember on two mounts.
The 924 has a similar crossmember, made from stamped steel instead of aluminum, that bolts to the subframe rails and mounts the control arms and the steering rack, but the engine does not touch it! Instead, there are steel engine mount “tabs” high and to the rear of the engine compartment. The engine has two heavy steel mounting tabs bolted to it, each with a replaceable engine mount that hangs the engine from the engine compartment steel instead of to a cross member that is bolted to a subframe. The diagram shows the driver side engine mount. #7 is the stamped steel mount that bolts to the engine, #1 is the actual mount, and the top of #1 bolts to the tabs in the engine compartment.
This rather different arrangement between the 924 a
nd the 944 engine mountings is the primary reason why you cannot mount a 944 engine into a 924. And no, you cannot put the 944 crossmember into a 924 and then mount the 944 engine – at least not without a lot of cutting, welding and engineering. So if you want a 2.5L 944 engine, get a 944. If you want a 924 with a 2.5 944 engine, get a 924S.
The other bad news is that the original Porsche 924 engine mounts are difficult/impossible to find as new. The passenger side mount lives next to the exhaust header, very susceptible to the heat generated there, and the supply of them available is gone – the death knell of No Longer Available (NLA). The good news is that new aftermarket engine mounts are available. 924S944.com recommends Vibra-Technics mounts from Great Britain, available through Ideola’s Garage here in the U.S. We use Vibra-Technics race mounts on our SCCA ’82 924 Race Car with great results.
Fuel Injection
The 924 uses Bosch K-Jetronic mechanical fuel injection that was first introduced on the Porsche 911T in 1973. (It is also known generically in the U.S. as Continuous Injection System, or CIS) Electronically controlled fuel injection wasn’t generally available yet, and this system was the state-of-the-art for the day. 924 fuel injection is not complicated and there are few adjustments that are available for it. In a nutshell, fuel is pumped to a fuel distributor that then sends fuel to each of the injectors. The amount of fuel that is delivered to the injectors is regulated by the amount of air passing through the fuel distributor, which is controlled by the throttle body. In other words, pressing the gas pedal opens the throttle plates, requiring more air, which the fuel distributor understands and sends more fuel.
Rebuild kits for the fuel distributor are available on the market, and rebuilt fuel distributors are available. Rebuilding your fuel distributor is not difficult as long as you take your time and make sure all parts are clean.
Carburetors are an option for the 924, but without other engine modifications (expensive), the carb conversion isn’t a great idea. Be sure you are ready before jumping into that pool.
Conclusions
The information contained here explains why the lowly 924 has never been a popular choice for enthusiasts. The early 2.0L engine in the U.S. barely makes 100 horsepower, and there is no interchange with the later 2.5 engine. The 924T increased horsepower, but these have also been maligned over the years – and the newest of these cars, a 1982, is over 35 years old. Turbos also have their own set of issues. However, a very low miles 924 Turbo sold last week at the Mecum Auction in Kissimmee, FL, for just under $23,000. A low miles ’83 944 sold for just under $20,000.
The early 924 is a great little car – not powerful, but a great handling little car that with the proper maintenance, can be fun to drive for little money. Most of the parts are inexpensive if you are doing your own work, and since it shares many parts with VWs of the day, parts are available. But if you want the 2.5L engine, look only to the 944 and 924S cars that were produced and imported after 1983.
Thanks for this very helpful comparison of the 924 to the 944. While you provided a lot of information about the vast distinctions of the engine mounting systems in both cars, you left me wondering about the engines themselves. Of course, both are fairly well known, but I would like to know more about the potential for modification of the 924 engine and chassis that was the basis for the impressive racing history of the 924s that include: Carrera GT; Carrera GTR; GTP and GTS.
The Carrera GT/GTR/GTP/GTS were basically using the same configuration, but that was about it. They were highly specialized turbocharged, intercooler engines that borrowed from the success of the other racing Porsches of the day. We see 2.0L engines of the day making over 400 HP and are amazed…but today with the computerization that exists under the hood, it isn’t as surprising.
One thing that we do know about the racing 924’s of 1980-1982 is that they formed the basis for the production 944 in 1983. The brakes, chassis changes and driveline all came from the racing experience with the factory-built 924 racers. The 81-82 924 Turbo (931) street production cars used many of the components that were to be factory stock on the Series I 944, so we can say that the 944 came from the race track.
I will do more research and pen an article on the racing 924 efforts of that era. It was an interesting time.
It’s all very interesting.
Love the info. I bought my wife a 79 924 base model. And am currently rebuilding it. Not restoring since I am doing alot of modifications. Including converting it to e.f.i. and possibly supercharging it. Having a really hard time finding replacement engine internals though
The 1979 924 is the only year of the NA 924 with the G31 five-speed. Opinions vary on these gearboxes, but know that the shifter, shift linkage, torque tube, rear suspension (trans mounts to the suspension instead of the body) and some other peculiarities associated with this transmission. The Audi gearbox is not interchangeable without changing the suspension, torque tube, axles, shifter and shift linkage.
There is a guy in UK who makes a kit for the NA 924 2.0. (https://www.youtube.com/watch?v=biVROE4WFDw). The only drawback is that the supercharger is not compatible with a car equipped with Air Conditioning – it mounts where the compressor is found. While in some climates that is not a problem – here in Central Florida AC is a necessity for most of the year.
Best of luck with your project and keep us updated on your progress!
Kevin