Originally Posted by Lars
And the performance difference would be related to what... the oil spray nozzles applied to the pistons on the angle valve engines, which are lacking on the parallel valve engines? Or something else?
As always, thanks for posting.
If you compare the angle-valve and parallel-valve cylinders side-by-side you'll see that the angle-valvers have substantially more fin area than the parallelers.
I can't believe that the piston cooling nozzles will lower CHT's... much... but they will certainly raise oil temps. And I definitely see that in my own airplane. I'm running a Stewart-Warner 8406R in my -6 with an IO-360-A-series and can count on one hand how many times the CHT went over 400 in 460 hours of use. But, I see oil temps over 240 pretty often.