Page 1 of 1
Ever wonder how a 4-stroke engine looks from the inside.
Posted: Fri Dec 14, 2007 3:14 am
by cessna170bdriver
Posted: Fri Dec 14, 2007 4:07 am
by bradbrady
very cool! .... what I didn't see, because they kept cuting away....is the intake valve opening just befor the exhaust valve closed... or am I looking at is bass ackwards?
brad
Posted: Fri Dec 14, 2007 4:19 am
by GAHorn
Some cams are lobed to open the intake just before the exhaust closes. This is called "overlap" and is done to take advantage of gases flowing out the exhaust in contributing to creating an impetus for the in-rush of fuel/air from the intake valve. Think of it as the exhaust gases leaving a slight vacuum behind which helps suck fresh fuel/air into the cylinder. Without overlap the atmosphere within the cylinder would have to come to a virtual stop at the end of each exhaust cycle... but with overlap the momentum of the flowing gases can be utilized to relieve the engine from the burden of using pure horsepower to motivate the inrush of intake gases.
Posted: Fri Dec 14, 2007 4:43 am
by bradbrady
gahorn wrote:Some cams are lobed to open the intake just before the exhaust closes. This is called "overlap" and is done to take advantage of gases flowing out the exhaust in contributing to creating an impetus for the in-rush of fuel/air from the intake valve. Think of it as the exhaust gases leaving a slight vacuum behind which helps suck fresh fuel/air into the cylinder. Without overlap the atmosphere within the cylinder would have to come to a virtual stop at the end of each exhaust cycle... but with overlap the momentum of the flowing gases can be utilized to relieve the engine from the burden of using pure horsepower to motivate the inrush of intake gases.
not to mention to help with cooling
brad
Posted: Fri Dec 14, 2007 7:03 pm
by HA
I got a closeup of the innards of my left engine on a C340 last week, easy to see how things work with the rod through the case like that
or don't work, now
Posted: Fri Dec 14, 2007 7:18 pm
by cessna170bdriver
bradbrady wrote:very cool! .... what I didn't see, because they kept cuting away....is the intake valve opening just befor the exhaust valve closed... or am I looking at is bass ackwards?
brad
Intake on the right side, exhaust on the left, as I see it.
Miles
