Gentlemen:
Looking for ideas, suggestions, pros, cons etc. I don't know how to post a picture or sketch on this forum so will describe what I have in mind and hopefully you will understand what I'm talking about.
I'm installing a Ellison TBI onto my Pitts S1 engine. The engine is a Lycoming O-320 with the intake on the bottom of the oil sump. I made the air plenum per the installation instructions from Ellison. It is 7.5" diameter and 4.5" high and contains the air filter. Because the distance between the front of the air plenum and the front of the cowl is so short, my plan is to have a 3" tube coming out of the front of this plenum and protruding through the front of the cowl as my intake air source.
Ellison also says you should have carburetor heat installed. As most of you know there is very little room inside a Pitts S1 cowl. With the air plenum below the TBI it is very close to the inside of the bottom cowl both below and forward. Therefor I don't have room for a separate hot air box.
What I have been trying to do is come up with a way to incorporate the hot air intake into the 3" diameter intake tube. The problem I'm having is coming up with a way to shut off the incoming cold air and open the hot air intake in a round tube. My plan is to weld a 2" diameter tube to the outside of the 3" tube 90 Deg. or perpendicular to the 3" tube for the hot air intake.
Here is where I need suggestions or advise. I was thinking is it really necessary to shut off the incoming cold air when using carb heat. Could I just install a butterfly, similar to a throttle butterfly in a carburetor, in the 2" hot air tube and just open or shut the hot air on or off . It seems there would be a venture effect caused by the incoming cold air past the 2" tube which would draw hot air into the intake. There is no question the intake would draw from both sources when the hot air butterfly was open, but would it be enough. According to FAR 23.1093 the temperature rise with carb heat only has to be 90 Deg. F.
I hope I made myself clear enough for you to understand me. Would appreciate any advise, thoughts, suggestions or if anyone has been down this road before what the results were.
Thank you all very much in advance.
Looking for ideas, suggestions, pros, cons etc. I don't know how to post a picture or sketch on this forum so will describe what I have in mind and hopefully you will understand what I'm talking about.
I'm installing a Ellison TBI onto my Pitts S1 engine. The engine is a Lycoming O-320 with the intake on the bottom of the oil sump. I made the air plenum per the installation instructions from Ellison. It is 7.5" diameter and 4.5" high and contains the air filter. Because the distance between the front of the air plenum and the front of the cowl is so short, my plan is to have a 3" tube coming out of the front of this plenum and protruding through the front of the cowl as my intake air source.
Ellison also says you should have carburetor heat installed. As most of you know there is very little room inside a Pitts S1 cowl. With the air plenum below the TBI it is very close to the inside of the bottom cowl both below and forward. Therefor I don't have room for a separate hot air box.
What I have been trying to do is come up with a way to incorporate the hot air intake into the 3" diameter intake tube. The problem I'm having is coming up with a way to shut off the incoming cold air and open the hot air intake in a round tube. My plan is to weld a 2" diameter tube to the outside of the 3" tube 90 Deg. or perpendicular to the 3" tube for the hot air intake.
Here is where I need suggestions or advise. I was thinking is it really necessary to shut off the incoming cold air when using carb heat. Could I just install a butterfly, similar to a throttle butterfly in a carburetor, in the 2" hot air tube and just open or shut the hot air on or off . It seems there would be a venture effect caused by the incoming cold air past the 2" tube which would draw hot air into the intake. There is no question the intake would draw from both sources when the hot air butterfly was open, but would it be enough. According to FAR 23.1093 the temperature rise with carb heat only has to be 90 Deg. F.
I hope I made myself clear enough for you to understand me. Would appreciate any advise, thoughts, suggestions or if anyone has been down this road before what the results were.
Thank you all very much in advance.
