ArVeeNiner

ArVeeNiner

Well Known Member
Does anybody with a Sam James set up get an RPM drop when applying carb heat? I get nothing. I do see the carb inlet temperature increase slightly when I run up and put on the carb heat but I get no RPM drop or stumble at all.

Will James suggested perhaps a bigger heat muff.
 
I have the Sam James setup ....

...and barely see a drop when I open the alt air. When the DAR and I did the taxi test, he asked me to open the alt air while he watched the RPM. It took a seemingly l-o-n-g time, but eventually it showed about a 20 RPM drop. He had me repeat it, and it did the same. If it weren't for a digital tach, I'd have no idea there was an RPM drop.
 
My -6 never showed a drop that was statistically significant when it had the original Vans snorkel. I changed to a Robbinswings muff that draws air from between the two crossover pipes, and now get a noticeable, measurable drop of up to 50 rpm (depending on outside air conditions).
 
For the past 15-years, I get no RPM drop with carb heat. IF you have a constant speed prop, you will most likely not get an RPM drop with carb heat.

None of the carb heat setups on an RV meet FAR 23 requirements that I know about. An EXPERIMENTAL is not required to meet FAR 23. FAR 23 wants to see a 100 degrees F increase. I have yet to see an RV that will get a 100 degrees F temperature increase with carb heat.

I also have Carb Air Temp prop since the airplane has been flying. In over 2,656 flying hours, I have never detected any carb ice on my RV-6. That does not mean that I will not detect carb ice in the future. I am just saying that I am comfortable with carb heat that is less than what FAR 23 requires on my RV.
 
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