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ltn6a

Active Member
Hi All

Not quite as the heading says but would like the thoughts of those with more experiance than me.I am building a RV6a with a io-320b1a and just about to install the air box.The question is do i install the carb heat flap door thing as well as the filter bypass door on the bottom of the airbox.From the threads i have read the door flap dose not appear to introduce much heat any way.
Your Thoughts please


Mark
 
Most everyone I know does NOT have the bottom "alternate air" intake. It does not have good history. It is not for carb heat. It is for alt air if the filter gets clogged.
 
Thanks for that Mel but what about the trap door on the top of the plate with the tube to the crossover pipe ? Any comments on its performance

Mark
 
ltn6a said:
Thanks for that Mel but what about the trap door on the top of the plate with the tube to the crossover pipe ? Any comments on its performance
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You'll want to install that part. It's not as effective as some aircraft, but it does work. I know of no one who's elimimated that part.

As to the other (alternate air on the bottom), I installed the latest version that attaches a sliding door with a cable. It's been kind of a pain to keep it together, as rivets eventually work loose from the fiberglass. I now have a metal plate that sanwiches the fiberglass. You'll just have to decide if you're going to suck in that one time bird, or wad of icy slush. It came about because an aircraft did suck in enough slush around the filter to stop airflow.

L.Adamson ---- RV6A
 
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As far as carb heat goes, the standard round tube that goes on the crossover duct doesn't provide much heat. I'd suggest a full heat muff from Robbins Wings. It just draws air from the cowl interior like the other one, but provides more heat. The alternate air door on the bottom of the air box may never be needed, but it's a safety device. I've had mine in place for two years (200+ hours) and have had no problems with it, although, other than checking it, it's never been used. I would go with what the plans call for. Beef up the fiberglass with some glassed in metal backing plates if you're concerned about the rivets pulling out. Mine, built according to plans have been fine though.
 
I did not install the bypass door but instead minimized the concern of flow blockage by installing a SS screen in the inlet. I did the same thing on my previous plane and could not discern any measurable change in engine performance.

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ltn6a said:
Hi All

Not quite as the heading says but would like the thoughts of those with more experiance than me.I am building a RV6a with a io-320b1a and just about to install the air box.The question is do i install the carb heat flap door thing as well as the filter bypass door on the bottom of the airbox.From the threads i have read the door flap dose not appear to introduce much heat any way.
Your Thoughts please


Mark
Click to expand...

Fuel injected engines (it looks like you are using one) generally are not equipped with carb. heat. They do not have a venturi icing problem.

That being said...it is a good idea to have either a way to block the inlet to prevent engine stoppage because of an iced over inlet or air filter, or have a selectable alternate air to use in case the inlet or filter has become iced over.
 
Cheers Guys

Thanks for all the informed information,Just need to run it past my inspector now.

Mark:)
 
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