On Jun 4, 12:54*am, wrote:
On Jun 2, 9:45 pm, Billy Crabs wrote:

let me try to explain myself better, the amount of air that is drawn
into an engine is in direct coralation to cylinder volume and the cam
shafts "lift and duration" A valve can only stay open as long as the
cam lobe holds the lifter up, therefore only allowing as much air/fuel
as was scientificly formulated for the cylinder.
for instance, lets say you have two guys who are going to breath in
deep, now even if you are blowing an air hose in their faces, they are
only going to be able to inhale as much as there lungs will hold. *Now
lets say they are inhaling pot and when they blow out its put into a
"turbo", the turbine spins and sends the unused pot back to their
lungs, but it's still only as much as they hold in their
lungs(cylinder volume)

* * * * * Air density in the cylinder is governed by its pressure and
temperature. MUCH more air can be forced into the cylinder if the
manifold pressure is boosted; this is the principle behind getting
more power out of a given number of cubic inches. You need to do some
studying on the matter. I have, and I teach this stuff in college.

If you are teaching this stuff you might like to make use of the data
I put together on the C172 takeoff and landing performance. it is in
the form of an excel spreadsheet which shows the takeoff and landing
distance as a function of density altitude at different temperatures.
( derived from the Cessna tables of distance vs pressure altitude and
temperature. It clearly shows that the takeoff performance is not
simply a function of density altitude which all of the flight training
literature i have read and all my own training drummed in to me. And
perhaps you could come up with a better explanation than decreasing
air viscosity :) It is clearly engine related because the landing
distance data do fall on the same curve of distance vs density
altitude irrespective of temperature. The best explanation I have
heard is that higher for a given density will get the air into the
cyclinder faster ( ie you will just get closer to the equilibrating
the pressure between the outside and the cylinder.
Anyway the analysis can be downloaded from the following site ( this
is an australian pilots forum called straight and level downunder).
this link will take you direct to the download page. You are
welcome to join the forum too but you have to register for that ( to
keep the kooks out - or in depending on your perspective). but you
dont have to register to access the download section.
http://www.straightandleveldownunder.net/downloads.html

Terry
PPL Downunder