Supplemental cooling for the Sport Cub

[Pete D]

All right, we finally have about an hour and a half on this plane with the mods on it and I have a few numbers to report.

First, little bit about the engine. Its an O-200A, the original engine just like all the other Sport Cubs have. It had about 125 hours on it and no issues before this, the owner just wanted to pump it up a little bit, so here is what it got (thanks to Bart at Aerosport Power, the same folks who assemble the CC-340s on the Carbon Cubs)

* Ported/polished

* High compression pistons

* 1 mag, 1 lightspeed Plasma III ignition

* Custom paint to match the airplane (yellow!)

* Chrome kit

Of course every one of the above will increase the temperatures in the engine, but they should go down a little as the new rings seat. I was seeing a steady 167 on oil temps and the highest CHT I saw was 404 after a hard climb. Typical CHTs in high power cruise were in the low to mid 300s, like 320 to 360. OAT was pretty low, like 40. This was with cowl flaps full open for break-in and the original oil cooler but with the taller (Gen II ) plenum. It looks like for those temps the cowl flaps could be closed up some if not all the way, pretty much what was expected but try to err on cool side rather than cooking it on the break-in and glazing the cylinders.

We have the prop off and to the prop shop. Its a long (float plane) prop pitched at 38", getting re-pitched to 40" With the mods this engine was turning a touch over 2500 static and in level flight if the throttle was opened all the way would go over 2900 RPM! But only about 110 mph indicated. By going only a couple of inches in pitch it should still produce lots of takeoff power but take it a little further away from red line at the top end in cruise.

Pete D.


DSCF2496.jpg

Screen shot of D180 just after leveling off from hard climb.

DSCF2426.jpg

Front end shot with yellow paint, big prop, etc.

[Pete D]

What is the full open position in terms of effective square inches? Or, simply put, what are the dimensions of the hole that must be cut for the cowl flaps?

The cross section of the opening is much different than the hole size cut. I'd estimate (just an eyeball guess here) that you cut something like an 10 inch square-ish hole in the cowling and the effective opening when installed is 10" by 1 to 3 inches, depending on what setting you have them on. Comes pre-drilled with 3 settings, "closed" which is about 1", middle setting is about 2" and full open is around 3"

Pete D.

[Centmont]

Except for the electronic ignition, I had these same changes performed on my engine by Bart (Aerosport). After breakin, I suspect you will find it running cooler than previously even without cowling flaps. To me this "cooling issue" is simple; burning fuel creates the heat; air moving over the engine cools it ( with some help from oil, but that too is dependent on air-flow). With the increased efficiency provided by flow-match/balance and, especially, the high-compression pistons, I increased 4" of prop and speed at least 10 mph. The airplane runs faster, higher up on step (cleaner profile thorough the air), and, as a result, there is more air moving thorugh the pressure cowl at the same fuel burn as before. This is a performance mod which is a great improvement. The paint and chrome...personal taste but looks nice Pete, you chased me around in Idaho, what do you think? Ralph

[Pete D]

Ralph,

Yeah, it was impressive, though actually being in the pilot's seat is the true test. I've gotten to fly a couple of these conversions and with the right prop it can be a truly impressive improvement. I like to say it "really wakes up the old O-200"

Pete D.

[RanRan]

Ralph,

Yeah, it was impressive, though actually being in the pilot's seat is the true test. I've gotten to fly a couple of these conversions and with the right prop it can be a truly impressive improvement. I like to say it "really wakes up the old O-200"

Pete D.

After talking with Ralph and Susan/Bart at Aero Sport - the O-200 can be tweaked with more horse power at about the same weight. Making the Sport Cub the sport pilot's dream machine at 120hp + *

* Add electronic ignition and it only gets better.

[Ndill]

Is that extended cear on a sportcub I see?

[Pete D]

Good eye! Yep, 3x3 gear was something else added. Currently on 8.00 x 6 tires, customer has 26" Bushwheels to go on at home.

Pete D.

[Ndill]

Cool.

[couleeone]

7AK is getting the cowling flap and will be testing the cooling over the next few days..AZ weather is approaching 100 degrees this weekend! Pete previously installed last summer the upgrade oil cooler and plenum which definitely helped but need more in AZ!!!

Will give reports as I fly.

Before flaps:

[Pete D]

Really looking forward to hearing real world results. Its been cool enough here that its hard to do any real testing because its not hot enough.

Pete D.