CHT temps up since installing Surefly

[DanH]

Originally Posted by penguin

Dan H, what ignition system(s) do you use and what is your static timing set to?

390 angle valve, EDIS w/ MegajoltE control, mapped at 23 BTDC fixed.

Like many EI's, the static timing set point is TDC.

The system allows entry of two independent advance maps with inflight switching. I've run a variety of advance schedules. Below is the currently installed map #2, but I've found little value in it with the angle valve. The other photo is typical at 23 fixed, peak EGT cruise, going home from OSH this year with the new 380-150 tires in the breeze.
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[Pittsartist]

Listen to the FCS (fly cool sh..) podcast with Skip Stewart where he is talking about his experiences having engines built with electronic ignition versus traditional mags.

Some real insights to be had - all based on extensive first hand experience (albeit with a different mission in mind). I think his summary of the differences is spot on.

[riobison]

Originally Posted by Pittsartist

Listen to the FCS (fly cool sh..) podcast with Skip Stewart where he is talking about his experiences having engines built with electronic ignition versus traditional mags.

Some real insights to be had - all based on extensive first hand experience (albeit with a different mission in mind). I think his summary of the differences is spot on.

Skip has a lot of video's, can you help us out with a link?

[rv8ch]

Originally Posted by DanH

... going home from OSH this year with the new 380-150 tires in the breeze.
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Dan, Are those numbers are without wheel pants? Or are you just noting that there is a bit more tire sticking down from the wheel pants? Thx.

[Coryb]

Thank you for all your responses. Since it is difficult to reach the Surefly to change the timing through the switches, I decided to look at airflow and the baffle first. I know I'm going to need to address the timing one way or another but the baffles seems to be the low hanging fruit. I used RTV to plug a couple of gaps near the intake ramps but I did not see a difference in CHT temps. I have a couple of holes in the back of the baffles. They each have plastic tubes that extend about 5 inches past the baffles. Nothing runs through them It's just a place for air to escape. I'm not sure if they are supposed to be there or not.

I also have a good size hole on one side where the engine mount is connected. I will attach photos. Should I fill any of these holes?

I know I will need to retard the timing or change my DIP switches to be fixed at some point also.

[DanH]

Blast tubes, doing nothing. Remove, and close the holes.

Looks like heaters at the cylinder bases. Probably some open gaps there.

The flap seals without wear marks indicate leakage.

[uk_figs]

Originally Posted by DanH

Blast tubes, doing nothing. Remove, and close the holes.

Dan
I have the blast tubes pointing at the mags, followed someone's advice and been there since the build in 2008, are you saying they are not needed and I can close those holes?
Figs

[Coryb]

Originally Posted by DanH

The flap seals without wear marks indicate leakage.

Here's the picture of the top cowl. Should I try to seal the gaps between the baffle material? Or do you think air is getting through over the whole top and I should replace the whole side of baffle material?

[DanH]

Originally Posted by uk_figs

Dan
I have the blast tubes pointing at the mags, followed someone's advice and been there since the build in 2008, are you saying they are not needed and I can close those holes?
Figs

Hi Figs. The vast majority of blast tube installations don't actually cool the specified component, in particular those which sorta, kinda fart in the general direction of the device. They're just a big leak, same as a crappy baffle seal.

A blast tube leading to a dedicated shroud can actually provide some cooling, but only when the airplane is moving. Repeated measurement says the highest temperatures are reached after shutdown, with or without blast tubes. Blast tubes or not, the component then operates hot for quite some time after re-start.

You said "mags". Slicks, or something else?

[DanH]

Originally Posted by Coryb

Here's the picture of the top cowl. Should I try to seal the gaps between the baffle material? Or do you think air is getting through over the whole top and I should replace the whole side of baffle material?

I am reminded of the old Dear Abby adage..."Any girl can get married if she sets her sights low enough".

The ultimate goal is zero leakage. You decide how good is good enough for you.

Picture is interesting. You have a number of small leaks, as evidenced by no baffle contact with the cowl (red circles). You also have a number of smudge spots where leaks have deposited soot and dirt (blue arrows). Note some are next to obvious no-contact gaps, and others are adjacent to contact, meaning they leak only when the engine is torqued from its resting position. It suggests the seals are old and hard in that area, as they no longer dynamically follow engine movement. Note the strip of smudge on the right side of your photo. That's the left baffle seal. From the seat, prop turns clockwise, engine torques CCW, and the left seal moves away from the cowl.
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