The Porsche 924
The Porsche 924
Some people deride the 924 because it uses humble VW/Audi parts. These people have never had the pleasure of owning one. The 924 is easily the cheapest way to achieve Porsche ownership. It is easy to maintain, fairly economical, has good luggage room, is fairly quick, has bags of character, great handling and is a very forgiving tutor. Also lots of these cars are available at breakers providing a huge supply of cheap parts. The engine block on the 924 & 924 Turbo is an VW/Audi unit with a re-worked head and fuel injection added. Properly maintained with regular oil changes these engines are good for up to 150000 miles without major service.
Porsche 924 began it's life as a concept vehicle. Volkswagen had contracted Porsche to design a car so that an Audi-VW joint venture might enter the market with a mid-priced sports car. However difficulties between VW and Porsche plus the end of the world oil crisis caused the idea to be dropped.
Following this Porsche acquired the rights to the car and the 924 was born. The car was designed from the outset by Porsche and was built by Porsche throughout. The 924 differs from earlier Porsche designs in a number of significant ways. The most obvious is the use of a front mounted water-cooled engine as opposed to the rear mounted air-cooled design of the 356 and 911. Also the engine is not bolted directly to the transmission as in the rear-engined cars, instead it is connected via a "drive tube" to the transmission/axle (transaxle) assembly at the rear of the car. This gives the 924 a near perfect 52:48% weight distribution and enhances the handling.
A number of variations of the 924 were manufactured to suit different markets the U.S. having the most variations due to the strict emission control laws, however the basic 924 design remained relatively unchanged from 1976 until 1985 with the introduction of the 924S which featured a new 2.5 litre engine which powered the 944.
The only major design change was the introduction of a turbocharged engine "924 turbo" and a special racing version with intercooled turbo engine the "924 carrera GT". Other options included 5 speed transmission and rear disc brakes as well as the usual items such as air conditioning and power windows/steering. Most of these item are absent on earlier models but were added as time progressed. Most of the "convenience" items were standard from about 1980 onward.
ENGINE
The 924 engine is a radical departure from previous Porsche designs, namely it is watercooled and mounted at the front of the vehicle. The engine is actually the same 2.0L engine short block as used in the Audi 100 with some minor modifications and a Porsche designed cylinder head. Engine Specifications (European cars) Type: Water cooled, single overhead camshaft, 4 cylinder, 4 stroke engine. Cylinder Head: Light Alloy. Cylinder Block: Cast Iron. Crankshaft: Forged Steel. Pistons: Cast Light Alloy.
Cooling:
Pressurized water/ethylene glycol coolant, electric fan with thermo switch. Compression: 9.3:1
Horsepower: 125HP at 5800 rpm (92 kW) Torque: 121.7ft-lb at 3500 rpm (16.8m-kg) Maximum rpm: 6500
FUEL SYSTEM
All European 924's are fitted with Bosch K-Jetronic (k-tronic) continuous injection system (CIS ) fuel injection. Although known as the k-tronic system it does not depend on electronics, but on the passage of air through a sensor plate. The system provides constant fuel output at the fuel injectors which is varied by the position of the sensor plate in the air stream. As air passes through the airflow meter, the sensor plate is lifted from rest. The sensor plate is connected to a pneumatic arm and the angle at which the sensor plate becomes stable depends on the airflow which is governed by the engine speed. The sensor plate pneumatic arm directly operated the fuel metering unit. The sensor plate arm moves a plunger in the metering bores of the metering unit (one for each injector) increasing or decreasing the injector fuel flow as required. The bores are specially machined to provide different air/fuel mixtures at different engine speeds. The Bosch k-tronic system is very reliable and easy to trouble-shoot system and is central to the 924's well known reliability although in hot weather the cars can be a little difficult to start.
MECHANICS
The Transmission and Transaxle assembly.The transmission and axle of the 924 are contained in the same housing located at the rear of the vehicle. The transaxle is connected to the clutch and engine v ia a drive shaft "tube". Together the engine, drive tube and transaxle form a rigid centre section around which the 924's body is hung. The 924 is available in 4-speed, two types of 5-speed (a Z shift and more conventional H shift) and a 3 speed automatic transmission. The location of the transaxle at the rear of the vehicle gives the 924 an near perfect weight distribution.
STEERING.
The steering of the 924 is of the standard rack and pinion type. The use of an eccentric cam operating the tie-rod ends gives the 924 an excellent forward turning circle. Later models introduced power steering.
FRONT SUSPENSION
The front suspension of the 924 is of the MacPherson strut type and is considered to be fully independent. The movement of the lower control arm (attached to the hub) is damped by the hydraulic strut to reduce road shocks.
REAR SUSPENSION.
There are two types of rear suspension used in the 924, however both are very similar. The rear suspension consists of trailing arms which are fully independent. Both arms are dampened with shock absorbers. The arms are sprung by use of a torsion bar system. The "spring bar" runs perpendicular to the direction of travel in a tube across the car. It is fixed at one end and the trailing arm rides on the other end. It is similar to that used in the earlier 911's and some VW's
