2.7 litres of trouble

The 2.7 litre Porsche engine

The Porsche 911s built between 1975 and 1977 do not have the best of reputations. And unfortunately it is well deserved. Because in their haste to keep up with the competition the engineers at Porsche took a shortcut too many and prepared a Pandora’s Box of troubles for future Porsche owners.

The box itself is in the back; in the engine compartment. You really can’t miss it:

 

2.7 Porsche engine

 

You see, the previous 2.2 and 2.4 liter engines could not keep up with the competition such as the stupendously fast Jaguar E-type. So Porsche chose to increase the engine size to 2.7 litres. Normally a higher displacement is a good thing; like higher wages or Blunderbuss at volume 10 instead of 6, but only if you strengthen the engine to cope with the increased stress. Porsche did not do that. They kept their magnesium crankcase pretty much as it was.

To make matters worse, US emission laws forced Porsche to increase the engine’s operating temperature in order to burn off more residues. The combination of an increase in displacement and higher temperatures put more pressure on the crankcase, which in turn led to worn valve guides and broken cylinder studs.

So the 2.7 Porsche engine is the least popular choice among engine tuners. But it is not impossible to increase both output and reliability. You just need to address the root cause of most problems: The increase in temperature. For starters install a better fan and en extra oil cooler.

I haven’t decided what I will do with my 2.7 engine. It is somewhat healthy and had a partial top end restoration a few months back. But a recent trip down the German autobahn had it operating at an oil temperature of 130 degrees Celsius which is waaay to hot. I strongly suspect that new problems will soon raise their ugly head out from under the engine lid. So swapping to a 3.0 SC or 3.2 Carrera engine is quite tempting.

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