Cowl flaps are proving useful

[Battson]

Approaching 25 hours on the clock, the cylinders have started to reach their stabilised bedded-in state, and the temperatures have dropped back closer to their final values.

Here's a photo from a high-power cruise (75%) with the cowl flaps closed:

To save you the mental math, those CHTs are as follows, we don't have any other vents or outlets, just the tunnel:

#1	336.2	oF
#2	339.8	oF
#3	302	oF
#4	312.8	oF
#5	330.8	oF
#6	318.2	oF

Now everything has settled down, opening the cowl flaps in high-power cruise / shallow climb causes CHTs to drop by up to 20*F.
In a high-power climb at lower speed, opening the flaps gives 30*F extra cooling, and the hottest cylinder doesn't go above 380*F.
They the most useful in the descent, to keep the heat in and prevent shock cooling the cylinders. Rapid cooling is a apparently a problem, if we want to descend at a sensible rate. I want to further restrict the cowl outlet area (with flaps shut) to improve this warming effect.

There's a bit of temperature spread in our CHTs, with the middle pair of cylinders running colder than the rest. We will balance our injectors to try and even out the EGTs. Maybe that helps to level the CHTs even out a little bit too? Any other suggestions are welcome. I suspect the baffle-rubber is not sealing completely.

[rv8bldr]

Wow. That 72.5 LPH number is startling, although I realize you aren't leaned out. When I tool around in my RV-8 at about 145-150 kts, I have my IO-360 leaned out and burning about 30 LPH (about 50% power). It is going to be a mind shift to burn more fuel going a lot slower, but I am really looking forward to it anyway :-)

[Battson]

Wow. That 72.5 LPH number is startling, although I realize you aren't leaned out. When I tool around in my RV-8 at about 145-150 kts, I have my IO-360 leaned out and burning about 30 LPH (about 50% power). It is going to be a mind shift to burn more fuel going a lot slower, but I am really looking forward to it anyway :-)

You have nothing to worry about. Run it LOP and it gets back to 28L/hr, and she still gets along at a respectable speed. But flight plan at 60L/hr if you don't plan to lean at all.