[tasdrouille]

I have a couple questions in regards to intake flow and resulting pumping losses.

Anyone knows why the throttle is typically a butterfly valve? I clearly remember from Hucho's book that a gate valve has a significantly smaller impact on the flow. Why don't we see throttle bodies equiped with gate valves? (or maybe I should just look at more cars..)

Also, I was always told that what had the most impact on pumping losses was the throttle plate, but now I read that CVVT can reduce pumping losses at light loads by 80%, so it looks like the valves timing would be the main culprit, no? I'm a bit confused.