The Porsche 924 is a sports car produced by Porsche in Neckarsulm, Germany, from 1976 until 1988. A two-door, 2+2 coupé, the 924 replaced the 912E and 914 as the company's entry-level model.
Although the 928 was designed first, the 924 was the first production road-going Porsche to use water cooling and a front-engine, rear-wheel-drive layout. It was also the first Porsche to be offered with a conventional fully automatic transmission. Like the 914, the 924 began as a joint venture with Volkswagen (VW). Although VW canceled plans to sell a version under its own nameplate, opting to market the independently-developed Scirocco instead, the 924 was assembled in a VW-operated plant and initially used a VW engine.
The 924 made its public debut in November 1975, and a turbocharged version was introduced in 1978. In response to increasing competition, Porsche introduced an upgraded version with a new Porsche-built engine as the 944, which replaced the 924 in the U.S. in 1983. In 1985, VW discontinued the engine used in the 924, prompting Porsche to use a slightly detuned 944 engine instead, drop the Turbo model, rename the vehicle as the 924S, and reintroduce it in the U.S. The 924 was a sales success, with just over 150,000 produced.
History
The 924 was originally a joint project of Volkswagen and Porsche created by the Vertriebsgesellschaft (VG), the joint sales and marketing company funded by Porsche and VW to market and sell sports cars (Ludvigsen: Porsche, Excellence was Expected). For Volkswagen, it was intended to be that company's flagship coupé sports car, and was dubbed "Project 425" during its development. For Porsche, it was to be its entry-level sports car, replacing the 914. At the time, Volkswagen lacked a significant internal research and design division for developing sports cars; further, Porsche had been doing the bulk of the company's development work anyway, per a deal that went back to the 1940s. In keeping with this history, Porsche was contracted to develop a new sporting vehicle, with the caveat that this vehicle must work with an existing VW/Audi straight-four engine. Porsche chose a rear-wheel drive layout and a rear-mounted transaxle for the design to help provide 48/52 front/rear weight distribution; this slight rear weight bias aided both traction and brake balance.
The 1973 oil crisis, a series of automobile-related regulatory changes enacted during the 1970s, and a change of directors at Volkswagen made the case for a VW sports car less striking, and the 425 project was put on hold. After serious deliberation at VW, the project was scrapped entirely after a decision was made to move forward with the cheaper, more practical Golf-based Scirocco instead. Porsche, which needed a model to replace the 914, made a deal with Volkswagen leadership to buy the design back. The 914 was discontinued before the 924 entered production, which resulted in the reintroduction of the Porsche 912 to the North American market as the 912E for one year to fill the gap.
The deal specified that the car would be built at the ex-NSU factory in Neckarsulm, located north of the Porsche headquarters in Stuttgart, with Volkswagen becoming the subcontractor. Volkswagen employees would do the actual production line work (supervised by Porsche's own production specialists), and Porsche would own the design. The car made its debut at a November 1975 press launch at the harbour at La Grande Motte, Camargue in the south of France, rather than at a motor show. The relative cheapness of building the car made it both profitable and fairly easy for Porsche to finance. While it was criticised for its performance, it nevertheless became one of Porsche's best-selling models.
The original design used an Audi-sourced four-speed manual transmission from a front wheel drive car, albeit placed and used as a rear transaxle. It was mated to VW's EA831 2.0 L inline-four engine, variants of which were used in the Audi 100 and the Volkswagen LT van (common belief is that "the engine originated in the LT van", but it first appeared in the Audi car, and has a Porsche-designed cylinder head in 924 form). The Audi engine, equipped with a Weber/Holley carburetor, was also used in the 1977–1979 AMC Gremlin, Concord, and Spirit, as well as the AMC postal jeeps. The 924 engine used a new Porsche-designed cylinder head combined with Bosch K-Jetronic fuel injection, producing in European spec. United States vehicle emission standards limited the engine to just , which was then improved to in mid-1977 with the introduction of a catalytic converter and a slightly higher compression ratio. North American models also featured prominent low-speed impact bumpers that lacked integral fog lights at the front, and round reflective side-marker lamps front and rear. The four-speed manual was the only transmission available for the initial 1976 model, later this was replaced by a five-speed dog-leg unit. An Audi three-speed automatic was offered starting with the 1977.5 model. In 1980, the five-speed transmission was changed to a conventional H-pattern, with reverse now on the right beneath fifth gear.
In 1980, the North American model received some minor changes, including a three-way catalyst and slightly higher compression. Nonetheless, the strong Deutsche Mark and US inflation severely hampered sales, as a well equipped 924 could now easily cost twice as much as the considerably more powerful Nissan 280ZX.On its way to becoming a true Porsche, p. 154
In Japan, the 924 was sold at Mizwa Motors dealerships specialising in North American and European vehicles, with left hand drive for its entire generation.
A five-speed transmission, available in normally aspirated cars (type 016) starting in 1979 and standard on all turbos (type G31), was a dog-leg shift pattern Porsche unit, with first gear below reverse on the left side. This was robust, but expensive due to some 915 internal parts, and was replaced for 1980 with a normal H-pattern Audi five-speed on all non-turbo cars. This lighter duty design was not originally used on the more powerful 924 Turbo. The brakes were solid discs at the front and drums at the rear. The car was criticized in Car and Driver magazine for this braking arrangement, which was viewed as a step backward from the 914's standard four-wheel disc brakes. However, four-wheel disc brakes, five stud hubs and alloys from the 924 Turbo were available on the base 924 as an "S" package starting with the 1980 model year. Also, standard brakes could be optioned on the turbo as a cost-saving measure.
The overall styling was created by Dutch designer Harm Lagaay, a member of the Porsche styling team, with the folding headlights, sloping bonnet line and grille-less nose giving the car its popular wedge shape. The car went on sale in the US in July 1976 as a 1977 model, with a base price of $9,395. Porsche made small improvements to the 924 each model year between 1977 and 1985, but nothing major was changed on non-turbo cars. Turbo charged variants received many different, non-VW sourced parts, throughout the drive train, and when optioned with the M471 disc brake package and forged 16" wheels, the car was twice as expensive as a standard model.
While the car was praised for its styling, handling, fuel economy, and reliability, its available power became a point of criticism, as the US-spec engine only produced 95–110 hp. When the 924 Turbo models arrived, Car and Driver magazine said "Fast...at Last!" The later 924S had performance on par with the Turbo, but with much improved reliability, and at lower cost.
The 924 was discontinued in 1988, with Porsche marketing the 944 as its entry-level model.
924 Turbo
Porsche executives soon recognised the need for a higher-performance version of the 924 that could take advantage of the model's excellent balance and bridge the gap between the standard 924 and the 911. Having already found the benefits of turbochargers on several race cars and the 1975 911 Turbo (930), Porsche chose to use this technology for the 924, eventually introducing the 924 Turbo in 1978.
On release, the 924 Turbo was met with high praise from the automotive community and journalists alike. It was celebrated for its performance and handling, with build quality and more purposeful aesthetics garnering universal approval. Some criticised the turbocharged four-cylinder for its coarseness, but critics forgave it in exchange for its economy and remarkable power increase over the naturally-aspirated car. In their comparison against the Aston Martin V8, Porsche 928, Porsche 911 3.0SC, BMW 635 CSI and Lotus Éclat 523, Motor magazine found the 924 Turbo to be joint second in top speed (achieving an average of 142 mph) and second in 0-60 mph acceleration (achieving a time of 6.9 seconds), being topped only by the Aston V8 at 145 mph and Porsche 911 at 6.5 seconds, respectively, a remarkable feat considering the difference in displacement and price between the models.
To power the 924 Turbo, Porsche heavily revised the VW EA831 2.0 L I4 motor already used in the naturally aspirated 924, opting to hand assemble the engine at the Porsche factory in Zuffenhausen, Stuttgart. Porsche engineers designed and equipped it with a revised crankcase, connecting rods, cylinder-head gasket, crankshaft and a new aluminium-silicon alloy cylinder head. With the use of dished combustion chambers and specially shaped pistons, the compression ratio was reduced to 7.5:1, which helped better accommodate the KK&K K-26 turbocharger without inducing pre-ignition. Platinum tipped spark plugs were also used, and exhaust valve diameter was increased over the n/a engine. With of boost, output increased to at 5,500 rpm and of torque at 3,500 rpm. The 924 Turbo's engine assembly weighed about more, so front spring rates and anti-roll bars were revised. Weight distribution was now 49/51 compared to the original 924 figure of 48/52 front to rear.
In order to aid cooling, as well as to distinguish it from the standard 924, Porsche added a NACA duct in the hood; this helped heat escape when stationary, and caused hot air to be drawn out of the engine compartment due to low pressure induced by the louvred alloy engine under-tray when on the move. In addition to the NACA duct, four slotted air vents were installed in the badge panel, with open ducts added to either side of the front valance to aid cooling of the front brakes. 15-inch spoke-style alloy wheels, four-wheel disc brakes with five-stud hubs, and a five-speed racing pattern "dog-leg" transmission was fitted as standard. Power was transferred from the clutch plate to the gearbox through a larger diameter torque tube. Forged 16-inch flat wheels of the style used on the 928 were optional, but fitment specification was that of the 911, which the 924 shared wheel offsets with. A rubber duck-tail spoiler was fitted to the rear hatch, reducing the already low drag coefficient from .36 to .33. Internally, Porsche called the 924 Turbo the "931", much like the 911 Carrera Turbo, which had been known as "Type 930". Although right hand drive specific parts were denoted by the prefix "932", both left hand drive and right hand drive cars are referred to as "931"; this designation remains in common use by Porsche enthusiasts today.
The turbocharged VW EA831 engine allowed the 924 Turbo to accelerate to 60 mph in a similar time to the early iterations of the bigger, more powerful Porsche 928, and 911 SC, , thanks in part to a lighter curb weight, but it also brought reliability problems as was often seen in other turbocharged cars of the era. This was mostly due to the fact that the general public did not know how to operate or care for such an early oil cooled turbo setup. Allowing the engine to idle and turbo to cool before shutdown helps prevent turbo seal and component failure and as such greatly extends the turbo's lifespan.