| Author | Message | ||
     Kevin Dennes (Kdennes) |
I am hoping that someone out there is able to help me please. I am at the stage of building/fitting the cowls for our EX2K with an IO550 Continental engine (brand new). Has anyone had the experience of using this combination and if so, did you use cowl flaps? If not, have you had any overheating during summer or long climb-outs? If you have installed them could you give me some dimensions and preferably some photographs please? I would be most grateful for your opinions and help on this subject please. Regards. Kevin (from Downunder) | ||
| Tom R. Hutchison (Tomhutch) |
Kevin, Take a look at: http://www.express-builder.com/gallery/album07/aan This is a picture of cowl flaps on a factory finished aircraft from the Express-Builder' s Gallery. It's the only picture I have at this point. Hope this helps. Tom | ||
| Phil & Margie Hodge (N410mp) |
Kevin - I have the IO550 without cowl flaps, and so far see no reason for them. A recent climb from 1660' to 10,500 at about 800 ft/min, ground temp 90F, everything was in the green. Phil | ||
| Reinhard Metz |
While I only have the Lycoming I/O-360, I also do not have cowl flaps, and stay in the green with plenty of margin (Max CHTs of ~400 deg. under worst case conditions). No cowl flaps seems to be the trend. The Cirrus SR-20 doesn't have any either (not sure about the SR22). Reinhard | ||
| Bill Copeland |
We don't have cowl flaps either and, with an IO-540 and a smallish oil cooler, we have opted for some climb restriction on a VERY hot day in West Texas. Otherwise no problem. We think the exit area has a lot to do with the cooling efficiency. Bill C | ||
| wayne norris |
How big are the exit holes on your cowls. Are your exhaust exits just cut into the bottom? I put covers on mine and have only the opeing for the nose gear. I am running hot, and was wondering how much I am going to have to cut the lower side open. | ||
| Kevin Dennes (Kdennes) |
WOW!! This really is a great medium for help. Thank you for your instant response. Wayne, I have not mounted my lower cowl yet and therefore I cannot answer your question re the exit holes. It does leave me with a further question to everyone who has kindly responded. How big are your exit holes? They are obviously large enough to ensure efficient cooling. Any help is most appreciated. Best regards. Kevin (from Downunder) | ||
| Gary Markwardt |
Kevin: I have the IO-550 & cowl flaps installed per the picture Tom referenced above. Even with the flaps, I am running a high oil temp during summmer months, about 205 to 210 F. It may have more to do with the engine baffling than cowl flaps. I understand the factory changed the front baffling some to improve air flow. I have sent mine back for rework, but have yet to see it. So, I can't tell you much more. Also, the baffling cutout in front of the oil cooler on mine was not as large as the factory is using now. I plan to change that as I reassemble -- beginning this week. By the way, I find if you fly with the cowl flaps open, they cost about 3-4 kts. airspeed. | ||
| Reinhard Metz |
I've been down the cowl outlet area road and have some data that may be useful. The bottom line is that outlet area is very important, and so is general shape in regard to efficiency. My initial cowl outlets were very tight to the pipes, comprising a total outlet area (excluding the pipes) of 24 sq. in., 12 per side. My CHT's were running 385 in flight typical, up to 450 in hot day or high altitude climbs. Oil temps were 190 to 200 on hot days. The outlets were also short and abruptly faired into the cowl in their side view, essentially following the curvature of the pipes. I decided that was all unacceptable and made new outlets that are bigger and much longer, more smoothely faired into the cowling where they originate at their forward point. The total area is now 52 sq. in., 26 per side. The difference in operation is huge: CHTs run about 335 in flight, about 400 max in hot day climbs. Oil temp is always between 170 and 180. And the best surprise was that despite the larger area, there was no speed impact due to the improved shape. FYI I have included a picture of the outlet cross section I traced for the area calculations. It is exact - on .2 inch graph paper. Inner line is the original inner contour of the old outlets, outer the new ones.  | ||
| Bill Copeland |
Re: Cowl Flaps While in my previous post I mentioned outlet area as a cooling factor, I forgot to mention that we have constructed a fiberglass cooling plenum to eliminate any cool air leaks. It eliminates the "rubber" baffling and completely seals the area above the cylinders, except for the opening into the oil cooler on the left rear. We also did extensive fairing of the inlets on the inside of the cowl to increase the efficiency of the airflow. If you have copies of the EXPRESS Link, the construction of the plemum is detailed in Issues 13 and 14. I will post the outlet areas and size of the oil cooler in a future post. Bill C | ||
| Kevin Dennes (Kdennes) |
Thank you all for your great and valued help. Regards. Kevin (from Downunder) | ||
| Bob Wallace |
Looks like I'm almost too late to add much to this discussion, but thought I'd throw this in. Started flying my express N428bw, last month, with 21 hours on it as of today. It has IO 550, and all flights have been in South Texas (hot !). I do not have cowl flaps. CHT, even in climb (115 kts) stays at 375. Oil temp does go to 210-215, on climbs up to 12,500. Cruise settings see 360 cht, 190 ot. I plan on modifing air flow to Oil cooler a little to improve. But with outside air temp at 100 DEG plus, its not doing to bad. |