Pictures of Louver Install

All,

I'm planning to install louvers on my cowl (I know some may debate that but I've decided to do so), and I am interested to see pictures on installation location and method. I have the pre-honeycomb James cowl, so I am also thinking I could install them from the inside out. Would be interested in whatever pics people may have. Also, did you attach with screws / nutplates or just rivet on? It is an RV-7A, but I am interested in any pictures. Louvers are from Aviation Tech Products.


Thanks,
Scott

Hi Scott,

I installed louvers on both sides of the bottom aft inboard segment of my Sam James cowl (pre-honeycomb) several years ago. Check posting # 7 for a pic in the following thread:

http://www.vansairforce.com/community/showthread.php?t=59489

Can't remember what I said in the thread but the louvers are cut down from 11 openings per side to 6 openings per side. I put a very slight bend in the outer edges (about 2 degrees) to insure a flush fit to the bottom cowl and secured with six #6 flush ss screws and platenuts per side. The platenuts are attached to a collar of aluminum (032) which is on the inside of the cowl and is the size of the flange on the louvers. The collar is not attached to the cowl. The opening through the cowl is the size of the louver openings only--not the louver flange. Six holes are also drilled through the cowl for the screws around the primary opening. This way, when installed, the cowl is simply "sandwiched" between the outside louver plate and the platenut collar. I also have "blanks" which are simply an aluminum plate the same size as the louver plate which I install in the winter. Both the blanks and the louvers have been painted to match the airplane and almost "disappear".

Hope this helps,

Cheers,

db

Installed louvers and now use blanks

Hi Scott,

After reading the many posts on this subject at the time of my construction, I elected to install Louvers on both sides of the lower rear (bottom) of my cowl on my RV-7A. As a back-up, I also made a set of blanks the same size and had them painted the same colour as the cowl. I have a plenum set-up on my engine (IOF-360M1B) and after first flight based on the temps I was seeing, I removed the louvers and installed the blanks. Oil temperatures without the louvers run 185-190 degF and CHT's consistently run around 350 degF. I am glad I have the louvers available though at this stage I can share with you if everything is sealed properly, you may not ever need to have them. I just didn't want to take the risk of having to cut into an already painted cowl to install them later if indeed they were required.

Cheers, Greg (RV-7A, FADEC IOF-360M1B)

Greg,

Could you post temps with louvers installed.

Thanks,

Temps with Louvers installed

Hi Bruce,

Oil temps were fractionally cooler by around 5 deg F though the cylinder head temps didn't change noticeably after replaing the louvers with blanks. CHT's run around the 350deg F mark though no doubt some of this is managed by the FADEC system. It is the tail end of winter over here in Australia (flying temps 5 - 20 deg C) so ideal for a new engine run in. As stated, with Summer temps I may still need to have the louvers though will take it one step at a time. I flew 2.3 hours today and oil temp tracked 188-192 f the entire trip, with cylinder head temps in cruise 350 degs. Climb did see them run up to around the 400-420 mark though came back quickly once established in cruise at 75% plus power settings (Still running engine harder and over square for break-in / run-in period) One thing I did make sure on my build was to mount the Stewart Warner oil cooler as high as I could on the rear left of my engine beneath the plenum to have cool air to it and not obstructed/warmed by the #4 cylinder. I have seen a number of builders with the oil cooler down lower and think some problems could be experienced with the positioning of oil coolers lower on the rear of the baffles.

Hope this is helpful

Cheers, Greg

I recently put an RV-9 180 HP on a set of Baumann 2100 straight floats. It performs very well in take off and landing and has good cruise speeds for a floatplane. However my Cyl temps go to 430 on climb out and will come down to only 400 for #'s 2 & 4 in cruise at 65%. All this at 1000 to 2000 AGL and 65 f OATs. I am cruising around 140MPH at these settings and recognize that they would be lower at a normal wheel plane cruise. I installed a 3/4" X 10" ramp on the bottom of the cowl at the front of the opening that brought the temps down to their present levels (a reduction of around 8 degrees and am now contemplating installing louvers on the bottom on each side of the tunnel. At my slower airspeeds I am hoping that this will facilitate heat transfer. I would be very grateful for any input . Should I also consider opening the bottom by an inch or so? The baffling is quite good and #'s 1 & 3 are in the 370's in cruise. Carb is doing what it is supposed to do so no issue there. Oil temps are very good with highs around 200 or less in climb out and 180's in cruise. On wheels during climb out # 4 would get in the 420 range but would come down to the 370's in cruise. Help!

louvers are choked

I installed a set of louvers to the exit scoop of my -8 in much the same fashion as others who have posted. During my annual condition inspection I noticed the louver exits themselves are fairly choked - almost by 50%. I used a pair of needle nose pliers and opened them up significantly - est 30% increase in exit size. I have not flown yet and don't really expect much but it seemed kinda dumb to cut a hole in the lower cowl and then install louvers which were choked so much....

I have several louver shots and text on this page:

http://www.vincesrocket.com/Additions after 10-27-04.htm

It's on a Rocket, but the process and results should be the same on others.

I also made a slide in cover out of .016" aluminum so I can close these in the winter. It's not shown in the photos but fits inside and can be easily made with a few scraps of aluminum.

glassed in

I just glassed them in. RV-10
I don't know if I need them but I can always put a tape over them.