On 06/08/2010 02:29 AM, craig bastin wrote:
> The other thing worth consideration, is the longer (within reason) and
> smoother the transition from plenum to carb throat the better
> the perfomance, this allows the air to continue accelerating with
> minimal turbulence, giving the best possible atomisation of the fuel
> into the airflow. Hence the reason for the velocity stacks (trumpets)
> seen on a lot of natually aspirated race engine.
Keep in mind that the inlet pulses on a Rotax are not balanced. Each
carb has to feed two successive cylinders, and then pauses for two
successive cylinders. This causes turbulence, uneven mixture over the
two successive inlet cycles, and a lot of other problems. We can't do
much about this (except for fitting a much larger balance tube) so
efforts to smooth the air going into the carbs is probably pretty much
wasted.
Frans
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