I tried to understand this when watching other TH-cam channels, but they did not make sense. Your video shows these concepts in total clarity. Manifold pressure is in absolute terms. (atmospheric bearing down on the pool of mercury with the mercury tube vacant of all air) Vacuum gage pressure is in relative terms. (Gage diaphragm exposed to atmosphere on both sides, with the top of the tube always open ) . What a wonderful instructor you are sir!
Technically it is incorrect to say an engine "sucks" air in. The descending piston creates a low pressure and atmospheric pressure "pushes" the air into the engine. That is why at full throttle you will see the same, or very close to it, manifold pressure as atmospheric pressure. You have removed the obstruction of the throttle plate and allowed full atmospheric pressure to enter the intake system. This is one of the ways car racers test their engines intake systems for proper size...if you see more than a .5 inch of pressure loss at full throttle then the intake system is either too small or there is some restriction in the intake system. But a very nice and well done video in any case.
You are correct. I chose to explain it this way for clarity...so that more people could gain a better understanding. My goal was intelligibility without doing (significant) damage to the actual physics at play. I allude to this several times, especially at 15:19.
Excelent explanation. If I could make a suggestion, is adding the other half of the story. WOW the Prop lever (which controls the pitch) ends up affecting the engine RPM. For fixed-pitch propeller the throttle lever alone affects the manifold pressure and also affects the RPM of the engine (power and speed), and both are easier to understand/connect. What could be added to this video is how with variable-pitch propeller alters this relationaship between power and engine speed to understand when do we need more throttle or more pitch. Thanks a lot!!!
Jet guy (Airline) and getting back into recips,... You helped make this a great refresher and cleared some things up for me. Mike Busch says "Manifold Sucks"! It can be hard to grasp the concept, but you made it easy!!!
Thank you, sir, for your explanation! I have the 10hrs required for commercial certificate; I did not really understand the idea behind manifold pressure until now. thanks for taking your time to explain it this well.
Excellent explanation! The diagram was great as well. I'm a low time pilot looking to earn my complex endorsement very soon and was having trouble understanding how this worked. For some reason, the way you described it, clicked in my head. Now make a video on how it correlates to the prop settings of a constant speed prop and how why it's not recommended to have higher manifold pressure than prop speed. Still need my brain to click on that.
Hi, this is because if you have a high manifold pressure but a very low prop speed, there is a lot of force being exerted on the spring which governs the pitch of the propeller, and it can break!
your use of a pilot pen did not go unnoticed :)
I tried to understand this when watching other TH-cam channels, but they did not make sense. Your video shows these concepts in total clarity. Manifold pressure is in absolute terms. (atmospheric bearing down on the pool of mercury with the mercury tube vacant of all air) Vacuum gage pressure is in relative terms. (Gage diaphragm exposed to atmosphere on both sides, with the top of the tube always open ) . What a wonderful instructor you are sir!
Technically it is incorrect to say an engine "sucks" air in. The descending piston creates a low pressure and atmospheric pressure "pushes"
the air into the engine. That is why at full throttle you will see the same, or very close to it, manifold pressure as atmospheric pressure. You have
removed the obstruction of the throttle plate and allowed full atmospheric pressure to enter the intake system. This is one of the ways car racers
test their engines intake systems for proper size...if you see more than a .5 inch of pressure loss at full throttle then the intake system is either
too small or there is some restriction in the intake system. But a very nice and well done video in any case.
You are correct. I chose to explain it this way for clarity...so that more people could gain a better understanding. My goal was intelligibility without doing (significant) damage to the actual physics at play. I allude to this several times, especially at 15:19.
This was just beautiful.
Finally. Explained in a way that I could understand it. Thanks Man!
PS
And yes. You had to draw me a picture.😊
Amazing! Thank you so much!
I was so confused about MAP. Thanks to this video, this makes a ton more sense - thank you most kindly!
Excelent explanation. If I could make a suggestion, is adding the other half of the story. WOW the Prop lever (which controls the pitch) ends up affecting the engine RPM. For fixed-pitch propeller the throttle lever alone affects the manifold pressure and also affects the RPM of the engine (power and speed), and both are easier to understand/connect. What could be added to this video is how with variable-pitch propeller alters this relationaship between power and engine speed to understand when do we need more throttle or more pitch. Thanks a lot!!!
Jet guy (Airline) and getting back into recips,... You helped make this a great refresher and cleared some things up for me. Mike Busch says "Manifold Sucks"! It can be hard to grasp the concept, but you made it easy!!!
Thank you, sir, for your explanation! I have the 10hrs required for commercial certificate; I did not really understand the idea behind manifold pressure until now. thanks for taking your time to explain it this well.
Excellent explanation! The diagram was great as well. I'm a low time pilot looking to earn my complex endorsement very soon and was having trouble understanding how this worked. For some reason, the way you described it, clicked in my head. Now make a video on how it correlates to the prop settings of a constant speed prop and how why it's not recommended to have higher manifold pressure than prop speed. Still need my brain to click on that.
Hi, this is because if you have a high manifold pressure but a very low prop speed, there is a lot of force being exerted on the spring which governs the pitch of the propeller, and it can break!
Please make more videos , thank you it’s great
Thank you for making this video, it was great!
How can one increase pressure at altitude to produce more power? Turbo?
Great video, thank you. Helped a lot
Great explanation!
Excellent explanation
Great video and you just win a subscriber 👍
Thank you! Great explanaation!
Thank you. That was very well explained. I have a theoretical question - how would the M.P gauge behave in a single cylinder engine?
Well explained! Good job
Thanks. Very Good explanation!!
Excellent!
Great explanation..thank you.
Muito bom! Obrigado pela aula!
Excellent! Subscribed!
Outstanding!
When does manifold pressure increase
Appreciate it good work !!!
thanks
Standard atmospheric pressure is 29.92 in of mercury, so is there a reason that you’re off by .01 in?
No reason. Just picked a number.
Great stuff, subbed
waht about mixtur?
Would’ve been nice if you would’ve equated 29.92” of mercury to a PSI reading Say 14.7 or thereabouts