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Louvre placement

M

Mike Raviv

Member
Hi guys,
I have a couple louvers and time for me to decide on the location on the bottom cowling for them. Side or underneath. As it appears to me, if I select the sides, the louvers will be quite behind the cylinders which would result perhaps in a less-than-best cooling. Also, the exhausted hot air will go over the wing. For the underneath location I do not see any problem other than the unorthodox appearance.

Your comments please
BSTRGRDS
Mike
 
My 6A has the "under" location

Pretty well hidden, and must work well --- temps stay where they are supposed to.

Ron
 
Mike Raviv said:
Hi guys,
I have a couple louvers and time for me to decide on the location on the bottom cowling for them. Side or underneath. As it appears to me, if I select the sides, the louvers will be quite behind the cylinders which would result perhaps in a less-than-best cooling. Also, the exhausted hot air will go over the wing. For the underneath location I do not see any problem other than the unorthodox appearance.

Your comments please
BSTRGRDS
Mike
Click to expand...

My comment is that louvers create excess drag and I wouldn't install them on a new build. I'd do all of the right things (properly installed baffles, correct timing, proper full-power mixture, etc.), knowing that thousands of RV-6's and RV-7's are managing temperatures just fine without louvers. There is no reason yours can't be one of those...
 
Forget the louvers, get the Anti-splat cowl flap. No drag in flight and will reduce temperature by 20-30 degrees on a 90 degree day in Ga. I installed only one to see what the difference was. this is after I had installed 2 louvers.
One cowl flap made the difference... no need for two.

check it out. You'll never regret the decision.

Smilin' Jack
 
I would not install louvers. I bought a pair from Avery and installed them on the bottom. They did not make any difference. This was before Anti-Splat offered their cowl flaps. Now if I installed the cowl flaps I have to remove the louvers and glass in the opening, then cut new holes for the cowl flaps. Just have not had time to pursue it.
 
Louvre placement?

It is placed at the other end of the Tuileries gardens from the Place de la Concorde :D
 
When I installed louvres on the bottom of my 6A cowl CHTs dropped 40* instantly and the oil temp 15*. I had been chasing high CHTs for several years, doing everything that is meant to drop the temperatures. The temps did come down, but not by much and not far enough.

I put the louvres in as far back as I could and as close to the centre as the central scoop would allow. In my view the drag increase is minimal - I saw not drop in top speed - but the potential engine life increase is huge.

My conclusion is that the sbs cowls just don't flow enough air through them to properly cool the motor. I would not hesitate to install louvres again - although I would probably fly a new airplane for 50 hours to break in the motor and confirm where the CHTs are. Its always possible to throttle back to control the temps, but it should not be required. It should be possible to climb at 110 to 120kt and full throttle to 8000' on a hot day without exceeding 400* CHTs. It should be possible to cruise at any power setting at any altitude without exceeding 380* CHT. In the winter I have to blank off at least half of the louvres to get the temperatures up!

Pete
 
If you want more exit area, why buy louvers? Just make the exit larger. It's free.

In the winter I have to blank off at least half of the louvres to get the temperatures up!
Click to expand...

Which means you would be a lot better off with a variable exit.
 
Cowl flaps

I second Smilin Jack's vote for the Anti-Splat-Aero ez cowl flaps. I installed two in my 540 powered -7 in a few days. They solved my hi cht's and give a clean air flow for cruise with no excess cooling at low OAT. No brainer. Am no way affiliated with ASA but love their stuff and tech support. Woody.

Smilin' Jack said:
Forget the louvers, get the Anti-splat cowl flap. No drag in flight and will reduce temperature by 20-30 degrees on a 90 degree day in Ga. I installed only one to see what the difference was. this is after I had installed 2 louvers.
One cowl flap made the difference... no need for two.

check it out. You'll never regret the decision.

Smilin' Jack
Click to expand...
 
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