The larger the TB, the greater the cross section per degree of shaft
rotation. So if all is equal save diameter, the stumble from over-lean surge
will always be greater from the larger TB. It will open to a larger cross
section than any smaller TB in a smaller movement of the throttle.
Conversely, the smaller TB amounts to opening the throttle more slowly for a
similar amount of throttle movement. And since slower movement of the throttle
is one strategy for avoiding the stumble problem, the smaller TB is already
doing that without any thought from the pilot. The same thinking for the
progressive 4 barrel carb. Two small holes to start, and as flow increases,
two larger holes to get to top power.
Lynn E. Hanover
Ah! Certainly makes sense to me. I just knew that whenever I
put on the Monster TB the engine would hesitate upon rapid open of throttle
whereas it did not with the smaller TB. Lynn, You need to compile
all this insight to throttle bodies pros/cons including the material you
presented regarding runner TB interaction. Marv, could post it to the
Fly Rotary website.
Ed