911 Engines: 2.0 - 2.2 - 2.4 litres

Porsche used 2.0 litre engines in the 911 from '65 until '69. These engines employed aluminum, sand-cast cases until 1969 when they began using pressure-cast magnesium ones. All of the 2.0 litre engines used a small, deep combustion chamber in the cylinder heads that was not ideal for breathing or combustion as well as being very prone to detonation at compression ratios over 9.5:1.

2.0 litre heads are not all the same; the 69 911S heads have the largest valves and valve seats for best breathing capacity on these small-bore engines. Other 2.0 heads can be made to work, they merely require a great deal of machine work to utilize the larger valves of the "S" model. These larger valves are also terribly expensive, making the 2.0 litre engines among the most expensive to get good power from. Twin-ignition is a prerequisite for any power level over 190 HP due to the required compression ratio that is necessary. The 911 head was finally improved in 1970 with the introduction of the 2.2 litre engines.

There are various bore & stroke combinations that can be used with these engines with great success. The differences lie in the shape of the power and torque curve. Due to the limitations imposed by the small combustion chambers, you are somewhat limited in bore increases with these engines. Using a 70.4mm crankshaft from the 2.4 and 2.7 litre engines, makes an excellent engine although its not inexpensive to do. We have seen over 235 HP from racing versions of these "long-stroke" 2.1 litre powerplants.

In 1970, the 2.2 litre engine was introduced. These were all magnesium-cased powerplants that featured larger valves and a better, more open combustion chamber with narrower valve angles. The flame propagation of these new heads with their shallower combustion chambers was much improved over the 2.0 litre ones and these engines were far less fussy about octane and tended to exhibit less detonation using the same compression ratios. The larger valves and ports incorporated into this design and the less shrouded valves gave much better breathing.

1972 was the first year that Porsche used the 70.4mm crankshaft when the 2.4 litre engine was used. These also lost some some compression due to emission regulations. Using the 2.2 litre higher-compression pistons in the 2.4 litre engine is a very cost effective way to gain power thoughout the entire RPM range. The later 2.4 litre engines also used the 7R version of the magnesium crankcase which is the strongest, stiffest version.

All of the camshafts used in the 2.0 through 2.4 are interchangeable as long as your camshaft choice has the required MFI drive if you need that. The most popular cams seem to be the "Solex" profile or the "S" profile for these engines for street-driven applications. The "S" cams are available in MFI or carburetor types and the "Solex" cams come in carburetor types only. Rennsport Systems can put any profile you want onto your camshafts provided that a suitable space-cam in the MFI pump can be found. Carbureted engines are far more flexible. 

Here is a rundown of camshafts found on Porsche 911 engines

(Coming soon)

We can also install various piston sets into these engines for more displacement and compression.  Cosworth also makes pistons for the 2.0 litre engines that are used quite successfully in racing engines. Pictured below is a custom set of JE Pistons.

Available sizes are:

80mm, 81mm, 84mm, 85mm for the 2.0-2.2-2.4 Litre Engines

Connecting rods are one of the most important things to upgrade in any engine that will see consistent operation above 7300 RPM. Since all of these small-bore engines must rev to generate good power, installing a set of aftermarket rods such as the Pauter Engineering ones pictured below, is a great investment in strength and reliability. These are quite cost effective when you factor the expense of rebuilding the stock rods and adding ARP or Raceware rod bolts and still not having the same RPM capability.

Porsche used various induction systems with this family of engines ranging from the original Solex carburetors to Weber triple-throat IDA's and IDS-series. In 1969, the Factory adapted the Bosch mechanical fuel injection system that they had used successfully on the 906 and 910 racers. This Bosch MFI system became practical when a 3-dimensional space cam was added to the pump to improve fuel economy and mid-range throttle response. The 911E and 911S received this system in 1969 and was continued with the 2.2 and 2.4 litre engines. 911T models used either Weber IDA 3C carburetors or Zenith carburetors. The first 2.4 litre 911T's were equipped with the Bosch MFI; later in 1973 Porsche used the Bosch K-Jetronic for the first time. This latter system is not considered a performance induction and should be replaced for any significant horsepower improvements.

The Bosch MFI systems varied between the "E" and "S" models in throttle diameter and injection pump settings. The "S" systems are highly recommended although quite expensive to rebuild. These systems can be used quite successfully on racing engines by enlarging the throttle bodies and having a street-type FI pump converted to RSR specification.

Performance exhaust systems for the 2.0 litre through 2.4 litre engines usually are comprised of SSI header-type heat exchangers or racing headers attached to either a twin-pipe sport muffler or a proper racing exhaust. 

Tech-Tip!

Magnecor Racing Spark Plug Cables

For Porsche air-cooled engines, these wire sets offer several advantages over any other competitive products.

Magnecor eliminated the troublesome resistor in the OEM plug connector that causes missing and intermittent cylinder operation. Instead, all of the required RFI and EMI supression is in the internal suppression of the wire. The Magnecor plug wire sets are the last ones that you will buy.

For Electromotive DIS Crank-fired ignitions, these are the only plug wires sets that will eliminate the RFI problems that these systems are quite susceptible to. The 5000+ ohms-per-foot cables rid the engine of strange mis-fires and random coil firings due to EMI interference. Plus, their resistance helps saturate the coil packs harder.

Magnecor Plug wire sets are available for all Porsche 911-930-964-993 engines. Electromotive Crank-Fire plug wire sets are custom made due to the variation in ignition unit mounting locations.

Call or E-mail us for specific information and pricing

info@rennsportsystems.com

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