---------------------------------------------------------- RV-List Digest Archive --- Total Messages Posted Mon 08/08/11: 2 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 10:55 AM - Re: RV-8 Cowl Vents (Matt Dralle) 2. 12:44 PM - Re: Re: RV-8 Cowl Vents (thomas sargent) ________________________________ Message 1 _____________________________________ Time: 10:55:10 AM PST US From: Matt Dralle Subject: RV-List: Re: RV-8 Cowl Vents At 07:04 AM 8/8/2011 Monday, you wrote: >Dear Fellow RV-8 Builders, I now have 13 hours on my 0360 Lyc. Still having # 1 CHT get too hot before TOC. So I have to throttle back and stairstep up to altitude. Temps should be stable by now with 13 hours. So I bought from Avery the bottom cowl louvers to improve airflow. Talked to a couple RV-8 drivers both said the vents lowered CHTs about 20 degrees. Question is how is best to mount? What shape and size hole(s)? The bottom of the vent plate is flat while the cowl bottoms have compound curve surfaces. What is best for looks and effectiveness and strength? Hope to hear from someone, Bill of Georgia N288WP Hi Bill, I have an IO-390 210hp on my RV-8 with the standard cowling. I don't have any trouble with CHT's (generally well under 400f) and my oil temps are generally in the low 180'sf. If I take off on a hot day at sea level and climb hard, I can get the CHT on the hot cylinder to go over 400 but by that time I'm at 8000 ft and simply decreasing my angle slightly will bring it back down. The only "non-stock" aspect of my installation is the giant oil cooler I added to the back of the baffle. Its about twice the size of the stock one. Before you start cutting holes in your cowling, you might want to do some more investigation into the cause of the overheating. Might be indicative of something else. Plugged oil line to that cylinder, maybe a blocked fuel injector on that cylinder? Try swapping the injectors between the hottest and coolest cylinder and see what impact this has on the CHT. Here's some info on the oil cooler installation that has worked well for me: http://www.mattsrv8.com/users/display_log.php?user=MattsRV8&project=638&category=2972&log=90253&row=84 Matt - Matt Dralle RV-8 #82880 N998RV "Ruby Vixen" http://www.mattsrv8.com - Matt's Complete RV-8 Construction Log http://www.mattsrv8.com/Mishap - Landing Mishap Rebuild Log http://www.youtube.com/MattsRV8 - Matt's RV-8 HDTV YouTube Channel Status: 170+ Hours TTSN - Rebuilding Fuselage After Landing Mishap... ________________________________ Message 2 _____________________________________ Time: 12:44:30 PM PST US Subject: Re: RV-List: Re: RV-8 Cowl Vents From: thomas sargent Matt: I just made a simple mod that you should try before doing anything drastic like cutting holes in the cowl. On my 6A I duct taped on 2 wedges cut out of wooden 2x2 that were about 1.5" wide from the narrow edge back to the 3/8" wide trailing edge. They are about 5" long. They were nearly identical with the plastic rudder trim wedges that Avery sells. I put these on the bottom of the cowl where the exhaust pipes come out with the wide edge flush with the aft edge of the cowl. I saw an immediate drop in oil temps of at least 10 deg. F and probably 20 F. Last week I replaced them with 2 of the Avery rudder trim tabs, painted to match the plane and curved a bit to match the shape of the cowl. I think these work the same way the louvers work: The air going past the trailing edge causes a slight decrease in pressure that helps draw more air through the cowl. I only had to drill 4 screw holes in the cowl to mount them "permanently". I can remove them any time I want just by taking the screws out.. The cowl is otherwise a stock Van's cowl. I need to do some more flying (I'm in Tucson where there's plenty of hi temps this time of year) to test this, but the few flights I have done are very encouraging. I'll send pictures if you like. -- Tom Sargent, RV-6A ------------------------------------------------------------------------------------- Other Matronics Email List Services ------------------------------------------------------------------------------------- Post A New Message rv-list@matronics.com UN/SUBSCRIBE http://www.matronics.com/subscription List FAQ http://www.matronics.com/FAQ/RV-List.htm Web Forum Interface To Lists http://forums.matronics.com Matronics List Wiki http://wiki.matronics.com Full Archive Search Engine http://www.matronics.com/search 7-Day List Browse http://www.matronics.com/browse/rv-list Browse Digests http://www.matronics.com/digest/rv-list Browse Other Lists http://www.matronics.com/browse Live Online Chat! http://www.matronics.com/chat Archive Downloading http://www.matronics.com/archives Photo Share http://www.matronics.com/photoshare Other Email Lists http://www.matronics.com/emaillists Contributions http://www.matronics.com/contribution ------------------------------------------------------------------------------------- These Email List Services are sponsored solely by Matronics and through the generous Contributions of its members.