924 1976 – 1985
In the early 1970’s Porsche was approached by the VW Audi group to design a flagship sports car for their marque. The idea for the 924 was born.
The 924 revived an idea that Porsche had not used since the 356 – to produce a car with appeal to the enthusiast from run of the mill parts at an affordable price. In this case Porsche made its selection from the Volkswagen & Audi parts bins. The 924 was significant for another reason. It was the first of a new generation of front-engined water-cooled Porsches that would soon unleash the 928 and see the 924 evolve into the 944 and eventually the 968.
Despite originating from a Volkswagen design the 924 has been recognised as a truly exceptional sports car. They are economical tourers, with “adequate” acceleration and capable of considerable speeds. Despite having solid front discs and drums at the rear, the braking is quite good, and having a fifty fifty weight split provides outstanding handling, allowing many a 924 with a skilled driver, to take on the much more powerful 911’s at track events.
With rear, if somewhat small, seats and practical luggage space, the car is ideally suited as a first Porsche for those on tight budgets. Being inexpensive, even quite poor cars will find buyers in the private market. So most cars change hands privately and cheaply or are in excellent condition, but are expensive.
The engine in the 924 is a reworked Volkswagen unit, originally designed as a diesel for their light trucks. These engines are remarkably reliable and can cover vast distances. Cylinder head gaskets generally fail by leaking into cylinder No.4. This is evident by a misfire in the mornings. It can be an expensive repair, but it will last a long time. The fuel injection system can be prone to playing up as the temperature controlling parts age. The parts themselves are relatively cheap but the diagnosis can be costly. Other problems can include air leaks from split & perished air hoses, causing hard to start, and rough running faults.
The 924 was originally equipped with a four-speed gearbox, while a five-speed gearbox and an automatic option were available in later years.
Clutches are cable operated and can be quite heavy, particularly for lady drivers. Steering is heavy, particularly at parking speed. Power steering was not an option.
Although they are inexpensive to buy – they cost just as much to repair as they did when they were new, and being older than average it is easy to overspend on a vehicle to bring it up to speed. Especially since their lower value often results in less care over the years service wise.
924 Turbo – 931 1979 - 1984
This vehicle was a bit of a wolf in sheep’s clothing. Capable of huge top speeds with large dollops of torque as the turbo charger went to work. Power increased from 125 to 175 Hp, this puts it in more of a weekend warrior sort of category than a practical day-to-day driver.
Compression was reduced slightly from the 924 to handle the boost, and a new head was implemented with better flow characteristics. Boost levels were moderate, 8-10psi. The engine was fitted with an oil cooler for durability. The Turbo came with a purpose built Getrag 5-speed transmission, rather than the Audi unit.
924 Turbos are most easily identifiable by the NACA duct in the hood on the right hand side and the slotted vents on the front nose on the badge panel below the Porsche badge.
Early examples were prone to some crank case breather issues causing smoke on hard acceleration. By 1982 digital ignition and more torque was on offer. Some imported examples are showing considerable corrosion, this can make even the simplest of jobs, drawn out and expensive.
It can be difficult and tiring to drive in traffic, as the dogleg first gear soon becomes annoying. The synchromesh on first and second gears is prone to failure in higher mileage or abused examples. Parts for these gearboxes are becoming difficult to source. When you can find them they are quite expensive.
Needless to say the brakes and suspension were upgraded for the turbo. Ventilated disc brakes and five stud wheel hubs were employed instead of the traditional four bolts of the Volkswagen. This suspension and brake package was developed into the 944 nearly unchanged.
924 Carrera GT – 937 1981
In 1981 Porsche took the 924 racing, in the 924 Carrera GT. To do so, they had to build enough of these examples to make them a “Production Car”. 406 were built, and only 16 were officially imported to Australia
Cosmetically, it foreshadowed the 944, with wide front guards to cover the wider track, the rear width was increased through the use of add-on flares. The 993 GT2 would copy this bolt on look many years later. The extra bodywork was all plastic. Bigger brakes were standard, 16" Fuchs rims and upgraded suspension. The engine made substantially more power (207Hp) than the 924 Turbo thanks to an intercooler, higher boost, and lower compression. The intercooler was mounted to the charge tube, going from the turbo to the throttle body, right over the cam cover to minimize turbo lag. However, getting airflow to this location was difficult, and resulted in the bonnet scoop over the cam cover.
924 S 1986 – 1988
In 1986, the 2.5 litre aluminium engine and drive train from the 944 were transplanted into the 924 body, and sold as the 924 S. Except for visual similarity with the 924, this is a very different car when it comes to performance, maintenance and upkeep. It was lighter, more aerodynamic and faster than a regular 944.
This car was never released in Australia.
944 1983 - 1991
Pre – 1986 (Series One)
Released in Australia in 1983, the early 944 overcame most of the disadvantages of both the 924 and 924 Turbo. With a lighter hydraulic clutch, and better torque from the engine at lower speeds, it was a vast improvement, the cars became easier to drive and much faster than the 924. Although still not quite as quick as a 924 Turbo in a straight line, the 944 could gain ground in nearly all situations due to the smoother power delivery of the new engine.
The engine was another reworking, though this time of a Porsche design. The all alloy single overhead cam engine was effectively half of the current 928 engine, with a displacement of 2.5 litres. This large capacity for a four-cylinder engine required the use of two contra rotating balance shafts, to cancel the resonant vibration inherent in large capacity four cylinder engines. These balance shafts were used under license from Mitsubishi. Essentially it looks like one half of an early 928 engine, though no major parts are interchangeable. Fuel and spark delivery was via a Bosch Digital Motor Electronic fuel injection system.
Perhaps the biggest drawback of these early cars was that very few had power steering. With the wider track and bigger wheels the steering became heavier than a 924. The dashboard cracking is another common fault of the cars, exacerbated by our harsh climate. They can be brought cheaply now, but again most have suffered from a lack of maintenance over the years and can prove expensive to bring back up to speed.
Post 1986 – (Series Two)
The first thing you notice about a post 1986 car is the dash. Oval in shape, very similar to the 928 instrument cluster. A revised seating position coupled with a higher steering wheel made the car much more ergonomically friendly to taller customers. A vastly improved heating and cooling system, Climate control with A/C was standard for all Australian cars.
Other changes included radio aerial removed, now part of the windscreen. Oil sump capacity, new front and rear cast aluminium control arms and semi-trailing arms, larger fuel tank, optional heated and power seats, revised starter, revisions in the mounting of the transaxle to reduce noise and vibration.
In 1989 a larger 2.7 litre engine was fitted for the last year of the standard 944.
Overall this model has very few faults, but unfortunately some cars come onto the market when problems are looming; typically they may need a clutch, water pump or a head gasket when brought.
Unless these cars have had regular maintenance work spread out over the years, even relatively cheap cars like these will need a “birthday” which can be costly. However as there is relatively little depreciation and not much alternative, avoiding costly repairs renders the car undriveable and a much less saleable item.
944 Turbo – 951 1986 – 1990
With appearances likened to that of the original and exciting 924 Carrera GT, the 944 Turbo represents a modern looking car with fantastic performance.
Utilizing KKK’s K26 turbocharger, an external oil cooler, and an air-to-air intercooler, it featured the new Bosch Motronic engine management, the first production car in the world to utilise adaptive cylinder knock control. The cylinder head was also modified with ceramic liners in the exhaust ports for better thermal efficiency, another first for a volume production car. It produced a respectable 220Hp
The new front end and rear under-valance panel allowed the car to reduce its drag coefficient to 0.33. Brakes were upgraded to fixed four spot Brembo units front and rear.
In 1989 power increased to 250Hp thanks to a modified turbo with redesigned vanes. The Bosch computer had different fuel/ignition/boost mapping to give higher boost over the entire RPM range compared to the original Turbo.
These cars came standard with the previous option only M030 Sports suspension with adjustable Koni front and rear shock absorbers. The front brakes were bigger again, this time callipers and discs were sourced from the 928 S4. Suspension included larger anti-roll bars and rear torsion bars. The clutch was upgraded, the transmission had a limited slip differential and an external oil cooler. 1st and 2nd gears were hardened for increased strength. It also had harder rubber suspension bushings all around.
In 1990 a 944 Turbo Cabriolet was released, but only built in limited numbers. Official figures vary, but less than 630 cars were produced. It was not sold in Australia.
These cars are comfortable in heavy traffic as well as being incredibly involving on the open road. Easily fulfilling a dual role, both the 220Hp and 250Hp turbos are very smooth, fast and well balanced.
Even with the much improved performance resulting from the inclusion of turbo charging, and the resulting high temperatures in the engine bay, the reliability of these engines is very high. Apart from some problems in the boost regulating system, there is little that regularly fails.
944 S 1987 – 1988
The 944 S was the company’s first foray into sixteen-valve engines. At the same 2.5 litre displacement as its forebears, the exhaust camshaft was driven by the cam belt, and the inlet cam, driven by a chain and tensioner assembly from the middle of the exhaust cam. This engine was developed at about the same time as many other companies released their first multi valve engines. Many had poor bottom end response and it took the industry several years to learn how to produce torque and power across the entire rev range. Porsche’s engine is no different, despite being quick when revved hard, it displays disappointing low-end response.
The S also received an updated transmission that featured a larger pinion gear; a weak point in the eight-valve cars. It had the same gear ratios as the 944 Turbo, but a shorter final drive ratio like the others.
This car was delivered to Australia, but in very limited numbers.
944 S2 1989 – 1991
The 944S2 took the normally aspirated sixteen-valve engine of the 944 S and increased its displacement to 3.0 litres - at 750 cc per cylinder, an impressive feat. It shared its body with that of the 944 Turbo, with its rounded nose and spoilers.
Under the skin, the 944S2 had the same wonderful Brembo brakes that graced the early Turbo. It also added a much-needed external oil cooler to the naturally aspirated engine.
With similar power to the early 944 Turbo, but no lag, they gave a power rush that improved all round performance to Turbo levels. They can be exceptionally reliable and good performers with quite different characteristics to that of the Turbo. Good examples are always in demand. With better throttle response, and slightly more low down torque than the Turbo, the result is a very fast car without turbo lag and a similarly immediate throttle response to that of a 911.
968 1992 – 1995
This was the final development of the original 924 and is heavily based upon the 944 S2, though with several significant changes. Body styling was changed to bring it into the new corporate image alongside the then new 928 GTS and the soon to be introduced 993. The engine received variable cam timing (Variocam); this was to provide further midrange torque. Again Porsche was the first volume manufacturer to provide such an innovation, now commonplace in nearly every car produced today. In an effort to reduce engine and driveline vibration, a dual mass flywheel was used, as had been successfully fitted on the 911.
An automatic transmission was on offer for the first time since 1989, when it had been deleted as not focused or sporting enough. It sat alongside a new six-speed manual in the options list. The Tiptronic was a 4-speed unit that opened a new market for Porsche. A very clever transmission, it was computer controlled with several different shift patterns that it could employ according to driving style and conditions. Varying from an early shift for maximum economy, to longer shifts, holding gears longer, for spirited driving. It incorporated a yaw sensor, and sensed throttle opening speeds to hold gears in corners and provided a dynamic kick down function to shift down gears before you entered a corner. The manual gearbox was still based on an Audi unit but with a sixth gear and revised, strengthened internals and ratios. It employed a different system of detents providing a much more positive gear selection feel. A torsen type limited slip differential was also available.
Released in two versions, a normal or road going car, and the Clubsport. A lightweight, track oriented unit, the Clubsport was also available in two trim levels, Touring and Track. The Touring had power windows, sunroof and series seats in front. The Track usually featured moulded body coloured race seats up front and the M030 option of bigger brakes with cross-drilled discs, adjustable shock absorbers and heavier, adjustable sway bars. Windows were usually manual, and the sunroof was deleted. Both Touring and Track had most of their sound deadening removed, and rear seats deleted. Feature wise internally these cars were almost identical to the 944 S2 that it replaced. The dash and heating systems were carried over almost unchanged. Only minor interior tweaks were made to the door trims and centre consoles in any effort to differentiate from its predecessor.
The modern looks and outstanding performance of these practical sports cars combined with the small numbers produced have increased demand, and prices for them remain quite high.
Some things to consider
The alloy four cylinder engine range shares a host of common parts and possible problems. I’ve tried to break them down here to the most common issues that arise. These are very strong engines that provide superb power delivery, and long life. Failures are usually avoidable and in most cases are predictable. However failure in any one of these components can be expensive to fix.
The cam and balance belts, once snapped, can cause severe engine damage. None of these four cylinder engines are a “free spinning” engine, ie valves and pistons can collide. The rollers, belt condition and tension should be checked at every service. Replacement of these belts should be carried out at no more than 80,000 km or eight years, which ever arrives first. At this time it is important that the tension and idler rollers be inspected for wear and replaced accordingly. Also the water pump is driven by the back of the cam belt and this too can cause premature belt failure if worn. The balance shaft belt is just as important as the cam belt. If poorly timed or snapped, the vibrations it would normally cancel can lead to the oil pump pick up fracturing and breaking off. Also the alternator and A/C compressor brackets can become damaged if this problem is not attended to due to their mass.
In all twin cam engines, 944 S, S2 and 968, the inlet cam shaft is driven by a chain from the exhaust cam shaft. This chain is tensioned by a unit mounted between the two camshafts, the chain running on two nylon tensioner pads. Porsche does not have any servicing requirements for these items. Unfortunately although owners have been made aware of the need to change cam belts regularly, this chain and tensioner assembly appears to have been ignored. In real life the cam chain starts to stretch and the nylon pads wear down. This causes excessive angle of attack at the base of the sprocket teeth on the camshaft, greatly shortening the life of the cam itself and worst case scenario is that eventually the sprocket teeth become so badly degraded that the cam timing slips and causes serious engine damage. Although it may be possible to change the worn cam chain and tensioner pads before they fail, the wear on the sprockets often requires that the camshafts have to be replaced as well.
The oil cooler in pre 1989 model cars and non-turbo engines is a water to oil heat exchanger, integral to the engine rather than the traditional external air to oil coolers as seen in the turbo and S2 engines. This small radiator sits in the coolant jacket of the engine itself. The oil cooler is sealed by two small O-rings. If these fail, oil is forced into the coolant, creating a brown sticky emulsion that will cause serious damage to the cooling system if left unattended.
As these all alloy engines heat up and cool down the continual expansion and contraction compresses and stretches the head gasket till it eventually fails or simply rots away. This is usually noticeable if the car is running hotter than usual or there is an excessive pressure in the top radiator hose. Left unattended these faults can become serious, but a replaced head gasket will last a very long time.
Vibrations and Engine Mounts
There are three major causes of vibration issues in the four cylinder engines. One is that the balance shaft is incorrectly timed or the belt has snapped. The issues created we have already covered. The clutch centres on the naturally aspirated engines are made of rubber, to try and absorb engine vibrations. This rubber centre breaks up and can cause a very noticeable clunk on and off drive and also a noticeable vibration through the entire rev range.
The engine mounts on all these cars are of the hydraulic or “silent bloc” type. These eventually leak and collapse. The right hand side usually fails first, as it has to deal with the added heat of the exhaust as well as the torque of the engine. This failure is usually most noticeable at start up, going away at higher RPM. An easy way to quickly check the engine mounts is to rev the engine by hand in the engine bay and watch. If the engine rocks left to right, then the mounts still have enough fluid in them to support the engine. If not, then the engine is effectively solidly mounted to the vehicle and the mounts should be replaced.