Quote Originally Posted by jrevens View Post
Sturdee,

So, you are drawing air directly from outside the engine compartment when not using carb heat. It is a very different situation when the air is drawn from the relatively warmer top rear area of the engine compartment.
Morning jrevens,
the air box and filter are inside the top cowl as per the build Manuel Mk4 912 1993.
Believe me ice is forming inside the carb. Have had manifold drop due too it before carb temp probe installed.
the amount of air flowing through the round cowl in principal you would expect to be warmer after flowing over the engine however someone should measure that. As we know the carb temperature will be colder due to the mechanics of fuel vaporizing.
I think most of the airflow travels down and out the bottom cowl as there is no baffles inside the cowl or need for them as water cooled heads, only air cooled barrels.
I was sceptical until I had seen the probe temps so believe carb heat is nessecary especially in this climate.
I can select on or off. Stay safe
Sturdee