OCTOBER 2015 Questions....

I have noticed your use of plenums vs. baffles.  What were your reasons for doing this?   Results?   Cost?

     When I built my first corvair conversion in 2003 I used the standard aluminum baffling and seal system typical in most engine installations.   It is very functional and can be a clean installation.  At that time I was sporting a rear starter setup and an oil cooler mounted above the engine top cover.  In 2005  I installed a front starter and alternator setup and develop an new cowling for the KR series aircraft.  So I removed my setup and built the new one.  (pictured in Sport Aviation DEC 2006).  However, I began to notice certain issues.  One was that the cooling air over the right bank was blocked by the alternator installation. The main problem was that I was developing cracks in the front ring gear (a webbed Ford product).  I removed it and replaced it with another.  Within 20 hours that one started cracking as well.  I removed the front starter kit and returned to a newly designed rear starter setup.  This is what we currently market at Azalea Aviation.

Front Starter and Baffle Setup

I removed the engine and redesigned the rear starter with the help of another friend and integrated a 32 amp alternator into the rear.  I removed the harmonic balancer and lightened the whole package by about 6 lbs.   After seeing the plenums that Mark Langford had on his plane at one of the KR gatherings I thought I could really improve the looks and simplicity of the cooling system.   I took them to another level and have incorporated that system in all of our FWF kits as an option.  Removing the front starter and ring gear, alternator, brackets, and belts allows for much better airflow and gave me the room to really focus on my front bearing design.  After a couple weeks of work I had my design flying.

                            First IRA...Integrated Rear Alternator/Starter

I flew this combination in this particular airframe for a year before changing out the case to my first prototype IFB - Integrated Front Bearing.  Because the cowl was fitted I never changed that but all my future designs are incorporating a 12" Spinner (we carry) rather than the large 13" version.  This allows for a tighter cowl design and smoother airflow integration.   I flew with that combination up until 2012 when I sold the KR2S to a friend in Iowa.  It is still flying and has well over 1200 hrs on the airframe and about 700 hours on that engine.

                      Saberwing Installation   2700 cc IFB/IRA Spyder Conversion

  The Saberwing has a lot more engine cowl area than the KR had and will allow for more turbos.  It also allowed me to improve the oil cooling (by removing the stock cooler and using aftermarket ones from Summit Racing) and reduce drag overall.

Of course, the biggest reason for the plenum change was because not only do they cool well, but they look cool! and Sexy!    Whenever we remove the cowling for a show, they attract a lot of people.   The simplicity and cleanliness of the installation is attractive.  We currently are using these on most of our FWF installations and we have molds and can make these fairly easily.  They fit right up to our cowlings but can be modified for your needs.  They are easy to install and require very little maintenance. 

What do they cost?   Our plenum kits are typically about 250-350 dollars depending on what you are needing.  They come as a rough kit or a more finished kit if mated to a cowl we have designed.  We are still working on updating our product and sales listing.  Call if you have any questions.

What did I learn...the plenums work extremely well with directing and focusing the cooling air.  There is enough air (on the faster planes 125+) that a 2" scat hose off the back can be used for oil cooler air.  CHTs dropped about 35 degrees compared to the baffles.   In cold weather areas it easy to install a small plug with a reduced inlet.  There is more to learn and any input about improvements is desired.