The very first Rover V8's (the Buick 215) had a 10.5:1 or 10.25:1 compression ratio however Land Rover reduced this down to 8.13:1 for many of their applications primarily due to the reduced availability of the higher octane fuels.
The original Rover V8 would only run on 100 octane or 5 Star fuel, this obviously was impractical in certain countries. Couple this with the fact that in 1973 there was the OPEC oil crisis which was repeated in 1979 and the Rover company clearly had to rethink it's flagship power unit.
Now interestingly enough if you reduce the compression ratio then you also move the band where the most torque is applied, now on Land Rover products, if you could put the peak of the torque curve as low down the rev range as possible then you would have a phenomenal power unit and by reducing the compression ratio that is exactly what happened.
So now to your answer.
Well head design is something that does indeed influence compression ratios, however in the Rover V8 unit it is all down to piston design. The Rover P5B and P6 of the late '60s and early 70's had almost flat piston crowns whereas the low compression versions have a more pronounceable dished piston crown. This is why the compression ratio is stamped on the block and not on the head.
RobStatistieken: Geplaatst door RobStewart — 06 Dec 2014, 21:31
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