Folks -

I'm installing the cabin heat option for my UL Power and am curious how you managed the fresh air supply for the heat exchanger.  I'm planning to pipe air to the passenger side tube on the muffler shroud as an intake, close off the middle tube, and then take hot air from the pilot side of the shroud to the cabin.

How did you guys arrange fresh air through the cowl ?



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NACA inlet and SCAT hose...

David- thanks for the quick reply! Can you report back as to how it's working, where you positioned the NACA, and which NACA you used? 

I apologize for all of the questions - I know these things can be tricky given the need to position the right vent in the right place.



Hi Wayne,  I've got a 260i in my 701 and found the NACA inlet to be too large and expensive.  I used the bottom corner of a one gallon milk jug for a form to mold the intake on and the pour spout to mold the inner outlet.  the milk jug form removes very  easily, fits the scat hose perfectly and looks very cool + makes a great story.  Works great!  Good luck,  Cheers,,,,,,,,,  Lynn      Once upon a time, "Croc 9"

Can send pic if ya want one.

Lynn - thanks a bunch for the info - really appreciate it.  If you think about it a pic would be great - please don't put yourself out though.


Hi Wayne, here are two pics.  I have the NACA vent on the left side.  It is shaped like this one shown in the link, but is not this carbon fiber version.  In the winter I route air into the heat exchange/muff box and take heated air to a heat control box mounted on the firewall and into the cabin.  This summer I removed the muff box and route fresh air directly to the heat control box into the cabin.

HTH,  Dave...

Dave - this helps tremendously, thanks so much.  I really appreciate it!

Dave - before I cut into the cowling I just want to check - are you are happy with the airflow you are getting with your vent in that location?  I'm sure you are but figured I'd validate :)  It looks like it's about in the middle of the cowl (front and back) so that's where I'll go too.

HI Wayne, I'm not sure how I could quantify the flow for comparative purposes.  On the ground with prop blast, I get noticeable flow thru.  In flight this winter, I had enough heat to fly without gloves at an OAT of 12F.  Warmest OAT so far this summer @ 83F and it was doing enough to keep comfortable along with the door vents.  I took no special consideration with placement other than when considering how I was going to make the SCAT runs to the muff and the the heat control box.  Long answer, but short answer is that it seems to work.  I will be at the hangar tomorrow and can pull a few measurements if you desire...


This is plenty of comparative information for me Dave - I have just read that placement can be critical and if you are getting flow that's all I need - especially the heat and 12 F statement.

If you think of taking a measurement from the back of the cowl to the rearmost portion of the vent and then the distance from the cowl split to the top that will be more than accurate enough. If not I'll eyeball it from your picture.

Thanks for taking the time to get back to me!

Wayne, haven't forgot, just haven't been to the hangar yet!  Hopefully Sunday or Monday for sure.


Ran ram air from back of right cylinder bank to muff heater, and two hoses through firewall near pedals.
Just little valves that came with the heater kit are installed on the firewall.  Summertime and I've removed the ram air hose going to the heater, and one of the heater hoses to the cabin. Put little caps on the inside of the cabin control valves to completely seal out heat.  Can always open the one side for those morning flights to 13K or so in the PNW.
I'm sure there are many many better setups.



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