Your exhaust tunnels might be the component that favors this.  In my standard exhaust configuration, the high pressure area where exhaust dumps under the belly would be higher in climb (nose up), and this high pressure area curtails exhaust outlet, requiring additional work to exhaust the gases, robbing some HP and thus amplifying retained heat.  Your tunnels carry the exhaust back to the low pressure zone behind the wing root, and provides some facility to exiting gases that benefit heat exhaust.

We would love to see a picture of these tunnels.

I would also encourage some comments about LOP climbs at MAP 34" and above from the very wise George Braly.  His advice will be helpful.  Most of the professional Advance Engine talk is for either normally aspirated leaning or level cruise leaning via the BMP.

Jeff L

LIVP

Jeff,

that's interesting.  I wonder why you get those high temps.

I wonder what is different in our engine setups.

my CHT's are steady @380 in the max/max condition @140knots.

It's been tested to 20,000 in that config.

CHT's get better than that  with less power or more speed.

I have exhaust tunnel extensions which seem to make a huge difference for cooling.

also have ceramic coated exhaust.  I don't know how much of a factor that is.

 

Some will say that 2700rpm is a bad idea because of higher friction losses.

On the other hand the flame front always moves at the same speed so if the

crank is turning faster your theta pp (angle after top dead center where peak pressure occurs) is bigger

and the peak pressure is less.  ....which seems good for everything.  the pulse on the crank

is not as concentrated, the CHT's are lower.  assuming everything else is setup right.

 

Colyn

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