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:
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 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.
