To louver or not to louver

Would like to hear from southern RV10 builders about controlling oil temps and CHT's. I'm a short timer, 21hrs on Hobbs, and temps are running in the 430's.

I have the same problem

My CHTs are running high as well. Advice on how to handle it would be appreciated.

430 CHT in cruise, engine broken in, is not acceptable.
How are you leaning?
Check mag timing for too advanced, even on a new engine.
All the flexible baffles sealing properly?
All the little baffle holes ("leaks") sealed?

Hello Steve

Yes, install louvers to help with cooling issues.
All other things first though, and Bob is right about mag timing.
New Lycoming engines do not have their mags timed properly unless it came from Aerosport or other aftermarket builder.

Some pics here for you.
There is a butterfly valve on the inlet side of the oil cooler plenum.
I keep the cooler closed in the "frigid" California winter most of the time.
The louvers provided in the kit are not installed in the pictures yet but were final installed before first flight.
The oil cooler is an Airflow System 11 row cooler.

Welcome to VAF!

Paul, welcome to VAF.

Always good to have another 10 driver here

I will see temps over 400 in climb unless I keep the speed up to 140 mph or so, and also back the rpm down to 2300 area. I am flowing 28 gph on take off.

I added louvers to the side of the cowl, and they seemed to help in the 10--15 degree range IIRC.

Biggest help in my cooling woes was backing the timing off to 20 from 25. I am running 9:1 or a bit more, and Lasar ignition.

One other thing to check is the casting flash in the cooling fins between the rocker boxes.

Getting the cooling right is usually a lot of small steeps, not a single leap.

Tim Olson

See Tim Olsons write up on sealing air leaks to make all air go through fins. Easy, cheap, and it works.

Alan at Antisplat is close to having pilot controlled cowl flaps or something similar available for purchase to deal with this problem. I would wait to check that out before doing louvers. That's not to say you shouldn't optimize your baffles and fix air leaks - do that regardless.

Mike and others,

Climb temperatures should not be going over 380 during climb or ever.

I climb at 120KIAS (accurate to +/- 1) and I rarely see over 370 and NEVER over 380-385, in fact I can't recall the last time I saw 381-2.

The notion of setting the standard magneto at 20DBTDC is not necessary unless you are running high CR's, however there are folk with EI's that need to dial out some advance. But if you have a standard Vans cowl, IO540 from Vans or Aerosport or whoever as a standard CR and mags, this is the result you should see;

1. Climb temps below 380 at 120KIAS
2. ROP cruise at 355-370 max
3. LOP cruise at 300-335 max

This is with just the standard louvres in the bottom of the cowl either side of the nose gear, and no extra's. If you need to add extra louvres to get more DP across the upper/lower deck then by all means.

I am happy to communicate with some of you directly, but I will need to know a lot more about the installation and the fuel used, the timing used and the magneto's used.

Outside of that there are some excellent posts here by Dan Horton (DanH) who is very helpful with regards to cooling airflow and pressures.

Here is a typical day in the office. Zoom in via the link to see the data better.
http://s849.photobucket.com/user/jaba430/media/A100TAS17042LPH_zps3fcaaa71.jpg.html?sort=3&o=6



And before someone chimes in with "it is within Lycoming spec" do the research on what the effect of temperature has on strength of the alloy in the heads, and what the corresponding pressures might be all compared to an optimal solution.

Renaudvator said:

Would like to hear from southern RV10 builders about controlling oil temps and CHT's. I'm a short timer, 21hrs on Hobbs, and temps are running in the 430's.

Click to expand...

I'd try opening the exit area before installing louvers.
It is easy to try with some spacers, longer screws and some tape.

Additionally, is it getting enough fuel?

If I was going to put extra louvers on a 10, the first one would go right near the left stack at the cowling hot spot. Probably be able to skip having a heat barrier there.

cooling flaps

I would look into the electric cooling flaps offered at antisplataero.com, getting good reviews. Maybe a better solution than louvers.

ajay

The stock engine in the stock -10 cowl installed in the stock way with good stock baffles should not be running that hot. I would first go through the other suggestions for mag timing, leaning and baffle sealing. Louvers definitely help, and I especially think one on the side by the oil cooler is a good idea, but you should be able to get acceptable temps without extra louvers. I would start with good baffles and the other things mentioned and then add louvers. Extra exit area means extra drag. Inefficient cooling because of baffle leaks is what you want to avoid. Efficient cooling with good tight baffles is one of the things that make these planes faster than the Cherokees and Cessnas out there with massive inlets and terrible baffles.

Jesse said:

The stock engine in the stock -10 cowl installed in the stock way with good stock baffles should not be running that hot. I would first go through the other suggestions for mag timing, leaning and baffle sealing. Louvers definitely help, and I especially think one on the side by the oil cooler is a good idea, but you should be able to get acceptable temps without extra louvers. I would start with good baffles and the other things mentioned and then add louvers. Extra exit area means extra drag. Inefficient cooling because of baffle leaks is what you want to avoid. Efficient cooling with good tight baffles is one of the things that make these planes faster than the Cherokees and Cessnas out there with massive inlets and terrible baffles.

Click to expand...

Everything stock on mine and no extra louvers. I climb at 120 kias once above 1000' agl. CHT's run 380-385F on a 90F takeoff during climb. Always near gross. Once in low altitude cruise and LOP, Oil= 170-185F, CHT's= 320-340F. 100LL and Mags.

I also have a completely stock setup and see numbers similar to Wayne. I started at 425, and got down to 380 in the climb at 112 kts on a hot day. Followed the advice of posts from the website, other than increasing exit area. I suspect that solution could be effective, but you add drag, so there are better ways of reducing the temps.

Aaron

I had high temps at the start that required climb speeds af 130 or more knots to keep it below 415. I have a plenum, so it is tight. The temps did not drop much for the first 10 hours, but then slowly improved. I think it was at least 40 hours before it really broke in. Now I climb at 130 knots, 2500 rpm and full rich until above 5 K with temps around 360 -375. On hot days I still can see 400. Used mineral oil til 35 hours.

Check timing and leaks, then just keep putting on hours, it may just be slow to break in.

Air dams on baffling

When we were breaking in our -10, the front two cylinders ran hot --- on advice in the forum, started cutting down the air dams in front of the cylinders --- finally ended up eliminating them ---- life was good after that.