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The different Porsche 944 Turbo engines and the cars they were installed in.
Tuning the Porsche 944 Turbo is something that we at JMG Porsche have been doing extensively for many years. We redesigned the standard 2.5 Litre engine in 2005 to provide the worlds first 3.2 944 Turbo engines as well as building the very best 2.5, 2.8 and 3.0 engines for 944 Turbos. We have even tuned standard engines with over 100,000 miles on the clock to have over 400 horsepower reliably. So you could say we know what we are talking about.
In this series of articles, I plan on showing you what can be done with a 944 Turbo to improve its performance, you will learn what the limits are to the original components and what can be done to improve those components.
So first things first, we need to cover the basic engines installed into the 944 Turbo and the turbo chargers the factory connected to them.
Porsche officially launched three revisions of 944 Turbo engine. The M44.50, the M44.51 and the M44.52.
In 1985 when Porsche released the 944 Turbo, the original engine was an M44.50. With a capacity of 2.5 Litres, this engine was designed to be the test bed that the first customers of the 944 Turbo would be unwittingly testing for Porsche along with long term Porsche test cars, some fitted with a M44.50 engine as fitted to the production cars, others fitted with a M44.51 and some fitted with a M44.52. As Porsche were a low volume car manufacturer, this allowed Porsche to trim the production costs of the engines over time, as their test cars mileages rose higher without issues and the customers cars were monitored.
- This original version of the engine, the M44.50 featured the following:-
- Sodium filled exhaust valves
- Ceramic coated exhaust ports
- Modified engine block
- Thicker engine casting with higher density aluminium engine block
- Forged piston connecting rods
- Manual Cam belt tensioner
- K26/6 Turbo (Size 26 compressor matched with a size 6 exhaust turbine.)
This engine produced 220 bhp @ 6000 rpm and 243 ft-lb @ 3500 rpm, and was almost completely bullet proof. If anything Porsche knew it was capable of much higher performance, but due to the superior weight distribution of the 944 design, more performance would have made it faster than the companies flagship 911 Turbo on the road or track. Arguabley the 944 Turbo is faster on the bends and is certainly no slouch on the straights, so it was decided to limit power to 220 bhp.
Half way through 1986 the 944 turbo received the M44.51 engine which had now seen another year of testing in the factory road test cars, so it was put into production as the new engine for the 944 turbo. Much the same as the M44.50, but with the following differences.
- Thickness and density of the engine block reduced back to the same as a 944 non turbo to reduce production costs
- Cast piston con rods instead of the expensive forged con rods of the M44.50
For normal or tuning use, there is no difference between the M44.51 and the earlier M44.50 except these components were downgraded in the later 51 engine. However, for the engine builder wanting the best from factory components, a M44.50 block and M44.50 con rods are sought after.
The M44.51 engine still featured the same K26/6 turbocharger and provided the same power output of 220 bhp and 243 ft-lb torque.
During 1987, Porsche had finished testing with a new upgrade for the engine, an automatic cam belt tensioner, wider balance shaft belt (most earlier engines were upgraded during service belt replacements) and a deflector rail on the waterpump. Other than this, the engines are identical. This version of the engine continued until the Porsche 944 Turbo stopped production at the end of 1991 and the begining of 1992.
It is said that the M44.52 engine is one that produces 250 bhp, this is not true, but we will cover that in a moment.
The early cars before 1987 featured a different wheel offset to the later ones, something that changed with all Porsche models in that year, this was done to improve handling and road safety, although it is also said that these earlier cars are more edgy and track focused, partly due to the lack of option for anti lock brakes (ABS) and a limited slip differential, but also due to the geometry caused by the wheel offset, but thats for another article.
After 1987 the engine changed to the M44.51 engine, performance was unchanged, the wheels changed to the later offset and some extra options became available such as ABS.
In 1988 Porsche had been racing a more powerful and upgraded 944, the 944 Turbo cup for a little while and decided to make a special edition 944 Turbo, the 944 Turbo S. This featured the sports MO30 Suspension and brakes, a larger turbocharger, the K26/8 (Larger exhaust turbine and housing) and a limited slip differential (LSD) all lifted directly from the 944 Turbo Cup race cars. The Turbo S featured 250 bhp @ 6000 rpm and 258 ft-lb of torque, an impressive increase in power, but with slightly more lag than the 220 bhp versions with the smaller turbo. These cars were fitted with the same M44.51 engines that all 944 Turbos had for the previous year and the non turbo S cars of 1988.
The turbo S version of the car was sold as a limited edition, at a price premium. Much to the annoyance of Turbo S owners, the following year in 1989 Porsche upgraded the standard Porsche 944 Turbo so that all 944 Turbo's featured the same K26/8 Turbocharger, and so produced the same power output as a Turbo S. Although in most international markets, the MO30 suspension, brakes and LSD transmissions were still optional.
Over the years there also were many changes to the 944 Turbo other than what we have mentioned here, but we will cover those in other articles as time goes on. For the moment, we have been interested in the engines, the years and what changed, as well as getting rid of some myths at the same time.
By now, you should have a good understanding of the 944 Turbo and its history, as well as the engine and the differences in the engine types.
In the next installment we will look at the Porsche 944 Turbo, component by component, to assess the tuning limitations of each part...