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fairlea(at)amtelecom.net
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 Posted: Wed Jun 14, 2006 8:04 am Post subject: Summer heating woes! |
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As well as all the excellent suggestions that Vince has I have a simple one that you can try that does not cost a cent! In the summer months remove your heat muff and all the associated tubing. You lose two ways with a heat muff on in the summer. One; it is still generating heat even when you are not using it and all the air that goes through it to the cabin in the winter is now circulating in the cowling. Two; with out the heat muff on you have just plugged a two inch hole in your baffles…. How hard do we work to plug every crack and crevice and then we dump this two inch hole of air out the back.
It might not make any difference but if you have an engine that is running warm what can it hurt to try it. I take mine off in the spring and put it on in the fall when the passengers start to complain.
Tom
From: owner-rocket-list-server(at)matronics.com [mailto:owner-rocket-list-server(at)matronics.com] On Behalf Of Frazier, Vincent A
Sent: June 14, 2006 10:59 AM
Subject: FW: Summer heating woes!
I'm no expert, but this info might be of use to someone out there in Rocketland.
Vince
From: **** (at)aol.com
Sent: Wednesday, June 14, 2006 9:00 AM
To: Frazier, Vincent A
Subject: Summer heating woes!
As the temps climb into the low 90's here my normal 195 oil temp has headed for 205, and the cylinders are running about 385 except number six which is 410. **** wanted me to try his "air ramps" in front of the 1 and 2 cylinders. I still think my air outlet under the back of the cowling is too tight. What do you think I should try first? What oil temp scares you? My oil temps are no problem in climb, but get hotter and hotter as the flight progresses. I left the oil dip stick loose on one flight and did notice the "backwards" air flow putting very small amounts of oil out on the front of the intake ducts.
I know, move to Alaska,
Cheers,
XXXXX
From: Frazier, Vincent A
Sent: Wednesday, June 14, 2006 9:55 AM
To:
Subject: RE: Summer heating woes!
**** ,
I sure wish I had a few photos of what's under your cowling!! I suppose that these are the first things that I'd try (in order of easiest 1st)
1) turn off the elctronic ignition advance and see if it affects the temps. Not sure if that is possible with your setup, but my Rose system could do that. The Rose system caused a large temp swing when it was on, towards higher CHTs. When running on a mag only, the EGTs went up (because the fuel was still burning as it left the cylinder.)
2) make sure that all air leaks are sealed. I used at least 2 tubes of red RTV around the baffles. Check the flexible baffle materials that seal to the top cowl, particularly around the case right behind the prop. I've seen HUGE air leaks there on many planes.
3) fly only when it's raining. Just kidding.
4) remove the upper gear intersection fairings (if you can safely fly without them holding your gear leg fairings in place) and see if you can shim the lower cowl air outlet open farther than it normally would be. I can do this on mine, but yours...???? Having the outlet propped open with a couple 5/8" spacers makes a measurable difference on mine.
5) have you removed the excess flashing that is found on many cylinder fins near the spark plugs? I'm told that it can cause higher temps. Refer to http://vincesrocket.com/Engine%20and%20Prop.htm . It's the first thing on the top of the page.
6) it's getting ugly now.... fly your plane to Hepler and leave it for at least 6 months while I test and rebuild the entire cooling system. Shouldn't cost more than $75,000 plus fuel for me to fly it everywhere between here and Florida. I can guarantee a temperature drop... but only during December.
7) you can add an airflow smoothing ramp around the engine mount tubes to help smooth the exiting air. It is easy to do, cheap, lightweight.... but may or may not help. It certainly won't hurt. Here is a photo of mine:
http://vincesrocket.com/2004-09-08/engine%20view%2014.jpg
 balance your injectors and run LOP per Don Rivera at Airflow Performance. Guaranteed to lower your cruising temps.
9) install louvers on the lower cowl. I believe that this helped drop the temps on my plane by at least 20 degrees, but I would try everything else first. I don't really think that I needed the louvers since my temps were fine for the way I fly the plane, local conditions, etc. I just had to do it because I wanted to see what effect they would have! (Same reason that I shortened the gear legs!.... experimental is more fun)
10) what oil cooler are you using? Some claim that the SW is the best. My Positech (get the latest revision if you don't have it already) works fine. I'm sure that you've already hammered this area, but have a second look.
11) I'm beginning to think that our inlets aren't very efficient either. Lopresti must have some reason to make those ugly round inlets. Adding a set of those would really screw up your paint.
12) get one of the super duper ultra cowls that some guys are using. I have no data on them. You're on your own. I'll wager that one of these would screw up your paint and your wallet.
Good luck,
Vince
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klwerner(at)comcast.net
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| Posted: Wed Jun 14, 2006 8:38 am Post subject: Summer heating woes! |
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Excellent idea Tom, never ever even thought of removing the heatmuff. And perhaps it will aid in hot air exit from a less crowded underside. Great thought, youdaman!
do not archive
[quote] ---
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