mallred said:
I will attempt this, and please correct and educate if I have something wrong.
Mallred, remember that any naturally aspirated engine that used the Straubism coined "Richarson Comet Mark III" process....
...I mean the Otto Cycle already has ambient air pressure for it's advantage. It has 14.7psi (or thereabouts) pushing onto it, waiting for an opening. On the intake stroke the piston will create negative pressure allowing ambient air pressure to push air through the passages into the cylinder. Consider and call ambient air pressure the "Air Charge", or better yet "Air Density". Call 14.7psi (air pressure at sea level) an air density of 1 for this conversation.
A diesel engine is not throttled in the air intake. It is an open pathway (all drag not part of this conversation) to the cylinder, so when the piston pulls down, and the intake valve opens up the factor of "1" is allowed to push its way in. The diesel open air intake design allows this every stroke.
A gasser is throttled at the air intake (and please remember, I know very little about gassers...so please educate me) so when the piston moves down and the valve opens, and say for example the air intake is throttled at 50%, only .50 air density charge is allowed in. The piston volume is filled, just with .5 charge air. This .5 difference is the negative pressure, or vacuum that is created. The only time a gasser is not creating vacuum is with a full open throttle.
There is tons more for the reading at a variety of sites, but mehopes I have the basics correct on this post. Surf around the link on this post for some good reading.
hth's
gb
Last edited:
