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Anyone use louvers to aid in cooling?

exerpts from X Jets

Another interesting finding was that the coating of the combustion chamber by combustion products had a significant effect in reducing heat transfer. Heat transfer decreased by 20 percent in the first 15 hours of operation and leveled off after 40 hours. The coating was measured at .008 inch after 90 hours. Now you know at least one reason why new engines run hotter!! On an engine which is consistently run with a rich mixture you can expect this coating to be much thicker and for the cylinder to run relatively cooler.




If all other conditions remained the same, ignition advance from 25 to 42 degrees caused an increase in heat transfer of 11.4 % in the test engine which resulted in higher CHT's. Without an ignition advance system you can expect your engine to run cooler than mine. Conversely, if you have Electronic Ignition, you can benefit by turning the ignition advance OFF if the CHT's are getting too hot in the climb.

These are some of the comments taken from the X-Jets that were posted earlier.

Some thought I am going through on the lightspeed ignition, and waiting
on the carbon buildup in the engine.

Just went through 10 hours. Want it to be 50.:D
 
I am at 19 hours on my new engine. I have seen the temps come down, but still a bit high in cruise at around 193 or so oil and 400-420 CHT. In the climb CHT's still go over 445. I have dual P-mags and would like to use the ignition timing advance features which are currently disabled. I still need to install my gear fairings, hopefully they'll give me a bit more airspeed and therefore more cooling. However, if they don't help, I am thinking louvers will. It seems if anything they'll help the CHTs, maybe not oil or marginally at best.
 
Cooling

Tony
Have you sealed the air ramps that you glassed to the top cowl.
If not air can flow thru them and down alongside the cowl outside of the baffles.
Just mentioned it in case you haven't done it yet.
Gerry
 
Gerald Clabots said:
Tony
Have you sealed the air ramps that you glassed to the top cowl.
If not air can flow thru them and down alongside the cowl outside of the baffles.
Just mentioned it in case you haven't done it yet.
Gerry
Click to expand...

I currently have the inlets taped up with foil tape to get the correct profile and will glass it later. It seems that it's not a simple as one would imaging to seal up the cowling. Right now I am working on gear fairing and hope an increase in airspeed will result in the necessary cooling flow.
 
Update

Well, after a year of dealing with high CHT's I finally broke down and installed my louvers.

Here was my previous temps with OAT's 30-75F.

Climb w - 410-425F+
Cruise 360-415 (depending on power setting 2300-2600 RPM, leaned 50-100ROP)

After installation of my louvers (50-65F OAT).

Climb 360-390F
Cruise 330-390 (depending on power setting 2300-2600 RPM, leaned 50-100ROP)

Needless to say I am very pleased. My temps were so good, that I was able to lean during my extended climb to 10.5K on my way home from Frasca today. The highest temp I saw was 390 and that was around 70% power. My best conservative estimate is that the louvers reduced my CHT's about 20-30F.

I put installed 2 louvers, one on each side of the snorkel. Please note that my results may not be the same you would experience. Just my particular installation made them very VERY effective.
 
Any chance of posting a few pictures? I am trying to get climb temps down as well and may need to go with louvers but not too excited about butchering my painted cowl.
 
Kokemiller said:
Any chance of posting a few pictures? I am trying to get climb temps down as well and may need to go with louvers but not too excited about butchering my painted cowl.
Click to expand...

Kelley,

I don't have any photos. My installation is just like Doug Reeves and others that are posted on the forum. Basically as far aft and as inbd as possible.
 
After 1 year

Bernie,
I like the tuft test.

Here are my results.
Lowered the lower cowl tunnel 2.5 inches.
No swirl marks on bottom of plane.
All with louvers uncovered.

Before---rough numbers
oil temp--230
Chts-----300-325

After
oil temp---185
Chts------280-315

Still working on it but I am getting closer.
I will cover the louvers and give some more numbers.

Pics on other thread here.
 
nice pictures on the other thread, bruce.

that's pretty much the way we lowered our cowl, too. although i admit we didn't shape it that smoothly, just slit it up and lowered the "flap" an inch or two, thereby getting a "steeper" angle / rear lip.

so you're saying you actually gained speed from lowering the cowl? or from mounting the louvers?

we could always give it a try covering the louvers as well and see what changes. i doubt though, that it would improve the turbulence at all... the tufts really speak for the louvers IMHO.

first target is really to lower the beating on the belly skin.
and second will be looking for some speed to be gained, we're doing about 165TAS @FL80 / 75% and approx 9.5 gph @ close to gross weight.
not a lame duck by any means but there is definitely some room for improvement. we always knew that the practically mandatory silencer/muffler over here would cost us some speed.

regards, bernie
 
Bernie,

Have not been able to do speed run yet. 95-100+ on the OAT and
very rough.

Still have some beating on the floor, and about the same as
before.
 
dan,

the vibration is confirmed to be aerodynamic.
we did remove the rubber connection in the hanger completely (short flight around the pattern), as did we try with different strengths of rubber. both changes were not noticeable.
also, the vibration is changing at different airspeeds and is almost not affected by power setting.
this leaves the cowling ramp / exhaust system shape / louvers as the primary sources

rgds, bernie
 
flyvans.com said:
dan, the vibration is confirmed to be aerodynamic....this leaves the cowling ramp / exhaust system shape / louvers as the primary sources
Click to expand...

Ok, perhaps a faired "tail" for the cowling ramp, with louvers in it like the one Larry Vetterman tried?
 
Just FYI, After the installation of my louvers there was a small but noticeable increase in vibration/noise on the belly.
 
boiling water

nucleus said:
215 F oil takes all the water out of your oil, 198 does not.

Hans
Click to expand...


Approximate Boiling Temperatures of Water

Altitude
Temperature

Sea Level
212 degrees F

984 ft.
210 degrees F

2,000 ft.
208 degrees F

3,000 ft.
206 degrees F

5,000 ft.
203 degrees F

7,500 ft.
198 degrees F

10,000 ft.
194 degrees F
Here is a chart for boiling water temperature vs altitude.
 
I get that the boiling temperature goes down with altitude - I just don't trust the temp reading to be all that accurate...

My go to source on this is a fellow who runs about twenty airplanes for pipeline inspection here in Montana. He told me that his cam problems went away when they went to 215 F as the target oil temperature.

Your mileage may vary!

Hans

NDrv8r said:
Approximate Boiling Temperatures of Water

Altitude
Temperature

Sea Level
212 degrees F

984 ft.
210 degrees F

2,000 ft.
208 degrees F

3,000 ft.
206 degrees F

5,000 ft.
203 degrees F

7,500 ft.
198 degrees F

10,000 ft.
194 degrees F
Here is a chart for boiling water temperature vs altitude.
Click to expand...
 
nucleus said:
My go to source on this is a fellow who runs about twenty airplanes for pipeline inspection here in Montana. He told me that his cam problems went away when they went to 215 F as the target oil temperature.
Click to expand...

Use an engine dryer system.
 
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