Originally Posted by Tiger 74
CHT temps were up around 410-415 F oil up to 210 in climb...
Everything looked to be set up right, but the temps were too high...
I saw no noticeable reduction in speeds, so drag penalty seems low...
What did the temps do in cruise? A transient temp of 415 is not out of line, but at 70 OAT should be better, admittedly.
Do you have the bypass ducts on #3 and #1 to address the well known "zero fin depth issue"? Also, did you tune up your intercylinder baffles to seal ALL air leaks, or are they just installed staight out of the box?
Ignition timing is also a big factor.
Concerning the drag penalty, adding a massive increase in outlet area certainly hurts you. There's no way around that. Or more to the point, if you missed some of the details mentioned above, you have a lot of air running through the cowl that is not contributing to cooling, and THAT is where the drag is.