REFLECTOR: Vortex generators location for armpit cooling scoops

[Brian Michalk]

I am running armpit scoops, but mine are variable.

I have been battling high temps too, and decided to stop flight testing 
until the weather cools off.  I'm just not able to get much testing in 
to adjust variables to see the effects.

Unfortunately on my last flight I broke my rule and changed two 
variables at the same time.  Before flight I opened up the scoops, and 
advanced timing.  The result is that my #5 CHT was at redline.  The good 
news is that oil temps were down.

Your scoops are pretty big, and should work.  Have you looked at your 
plugs to see if you've got mixture/airflow or detonation problems?  EGT 
shows normal for #5?  Maybe compare the #3 and #5 plug.  The top ones.  
Do you have the baffles installed under the cylinders, or does the 
updraft have baffles over the top?  It's the baffles that go between the 
cylinders to force air through the fins.

On 8/14/2013 3:50 PM, Andrew Ellzey wrote:
> I am still battling a high CHT at cruse on my # 5 cylinder on my 
> updraft IO-540-E1A5, 300HP Lycoming engine. I can do full power climb 
> outs in the pattern all day without any issue. From everything that I 
> have read on this subject on the Reflector, this is common with the 
> arm pit cooling. The higher pitch angle in the pattern, and in a cruse 
> climb, forces plenty of cooling air into the scoops, but the cooling 
> ability drops off in level cruse fight attitudes. My question is, is 
> there anyone left on the reflector that is using the armpit cooling, 
> and do you have vortex generators in front of your armpit scoops to 
> help the airflow boundary layer adhesion to this area forward of the 
> armpit scoops? If you have vortex generators, what size, location, did 
> you make them, buy them, can you send a photo, please.
> I have swapped and calibrated my CHT probes, swapped the lowest CHT 
> cylinder fuel injector with my #5 injector. Nothing helps, it seems to 
> be tied with airflow into my scoops, or airflow inside my lower 
> cowling. If the addition of vortex generators doesn't  help, I will 
> probably have to install some additional baffling to redirect more air 
> to the aft two cylinders, #5, and #6. Cylinders 1, 2, 3, and 4 are 
> getting plenty of air, in fact they are running cooler than I like at 
> this time, but until I can get #5 CHT under control, I can't lean my 
> engine properly to know if I have adequate airflow for all cylinders 
> or not. Installing my gear doors seemed to help.
> Photo attached showing my armpit cooling scoops. The additional screws 
> under the armpit scoops, attaches a mating internal scoop that directs 
> the airflow to my aft lower cowling.
> Thanks again for your help,
> -----------------------------------------
> Andrew Ellzey
> N151AJ 10 hours into Phase 1 testing
>
>
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