Hi guys,

I found this extremely amazing video of a high speed camera inside an engine cylinder. Since a lot of beginners don't know how their engines work, I thought I would post this. It looks like the engine is a 4 stroke because of the valves. For some reason, they don't show the complete cycle, but you get the idea.

http://www.youtube.com/watch?v=UvmBLqjaZxY

Enjoy!!!

if anyone can answer this question than I would love it

in real time how long would that have been?

that's one high speed camera, that has to be less that a couple seconds

More like , less than a second. Depends on the stroke of the engine .
By the looks of the combustion chamber , I would say this is a OHV , Honda or Briggs , single cylinder engine or something similar.

Ferocious Frankie,
There is one problem with the video you provided. It is of a gas powered engine that has a spark plug in it, not a glow engine with a glow plug.

Ken

Without knowing the rpm the engine was turning, there's no way to tell. So, I'll make an assumption, for the purposes of discussion, that the engine was turning 600 rpm. If you watch the video it appears the engine made 4 complete cycles. I figured this out by counting the intakes through the right valve. With this information, the following will tell you how long the video was, in real time, and assuming 600 rpm (note that I chose 600 because it makes the numbers easy).

600 revs per minute divided by 60 seconds gives 10 revs per second

4 revs divided by 10 revs per second gives .4 second.

So, assuming the engine was turning 600 rpm, the entire video was .4 second.

You can thank my 9th grade science teacher for this analysis, he's the one who taught me the method of making such calculations. It's easy once you know the method.

You can get a good understanding of why 4 cycles are more effecient and less poluting that 2 cycles.

How would that have even been filmed??? view in the cyclinder is up top right... hold in cylinder wall with something over the lens?
Mike

Not bad, but I would have estimated a much higher idle. 600 RPM is slow for most 4 cylinder engines.

I really like that video. That's awesome...


Keeping on track - How a model airplane engine works:

There are two types of "natural aspiration" for internal combustion engines.
Two Stroke/Cycle and Four Stroke/Cycle.

A two stroke engine intakes and exhausts at the same time.
Try to stay with me...
The piston is travelling upwards, (compressions stroke). The compressions stroke always just precedes fuel ignition.
While moving upwards, a vacuum is created in the crankcase. This vacuum draws air/fuel into the crankcase, (oil in the fuel lubricates the crankshaft, piston, and wrist pin).
The air/fuel mixture that was ingested last time around is ignited, and the piston is forced downward.
In the way down, the air/fuel mixture in the crankcase is compressed. As the piston approaches the bottom of its stroke, ports open on the side of the cylinder wall, (OK, they don't "OPEN", they are always there and open, but the top of the piston passes by them and they are now exposed to the inside of the combustion chamber).
One port allows the burned air/fuel mix to escape the combustion chamber, and the other allows the compressed air/fuel mix to enter the combustion chamber.

Got it so far? Good, 'cause that's it. The cycle starts all over again. Up - Bang! - Down - Intake AND exhaust, repeat

4 cycle engines work much differently.
We'll start with the intake stroke... The piston starts moving downward, and the intake valve opens allowing the air/fuel mixture to be drawn into the combustion chamber.
When the piston reaches the bottom of the stroke, the intake valve closes, and the piston starts to move upward, (Compression).
Once the piston reaches the top, the air fuel is ignited, creating high pressure causing the piston to be pushed down.
Once the piston is at the bottom of this stroke, the exhaust valve opens, and the upward movement of the piston pushes the exhaust out through the valve.
Start over.
This type of engine fires once every two revolutions.
The two stroke fires every one revolution.

Got it? OK, let's move on...

There are 3 types of ignition.
Spark, Diesel, and Semi-Diesel.

Spark is self explanitory. It uses a spark inside the combustion chamber to ignite the fuel/air mixture. Once it starts to burn, (not explode), the gasses expand creating pressure on the top of the piston, pushing it downward in the cylinder. Fuel is mixed with the air outside of the combustion chamber, and pulled into the chamber as a mixture.

Diesel uses compression of the air inside the combustion chamber to create heat. This heat is enough to ignite the fuel by itself, and if the fuel is mixed with the air before the compression cycle, you risk the chance of igniting the air/fuel mixture before it should be ingnitred and damage the engine. In a diesel, the fuel is atomized through an injector that pumps the fuel directly into the combustion chamber at the correct time.

A Semi-Diesel usually mixes the air and fuel before ingesting them into the combustion chamber like the spark ignition engine.
The air/fuel mixture is heated up just below ignition point during the compression cycle. The way it is ignited is with the aid of the glowplug.

OK, so how does the model airplane engine work?
Most model airplane engines are Semi-Diesel, two stroke engines.
There are 4 stroke semi diesel engines like the Sato's.
There are also, (for the gant scale planes), spark ignition two and four stroke engines.

Well, I hope that this long post anwers your questions regarding model plane engines without causing confusion.

Bob

yes, but 600 divided by 60 gave an easy number to work with in the next step.

If they used this engine, they could fit a whole camera crew inside...

http://people.bath.ac.uk/ccsshb/12cyl/

thanks for yor help i realised that without inside info it would be trickey

Yep, that's the only difference. I, like all the rest of you, could not believe my eyes. I always imagined what was going on in my car's engine and airplanes' engines. Now I know!.

I also wanted to clarify that this isn't my movie and I just found it.

Amazing!

There is just one small problem with your calculation, a 4 stroke completes takes only two cycles, not four to complete the process, so by using your calcs the entire video sequence is 0.2 seconds. If you think that is fast, if the engine is rotating at 16000rpm (Formula 1 and some bike engines rotate at this speed) a complete intake, compression, power and exhaust sequence would only take 0.0075 seconds. (and four your 2 stroke .46 engine spinning at 12000 rpm the complete intake, compression, power and exhaust sequence only takes 0.005 seconds)

I really like pointing people to this [link=http://www.keveney.com/Engines.html]webpage[/link] if they want they want to get the basics of how conventional and various other types of more exotic engines work.

Cheers
Pupmeister

Hey, Pup...

In your post you state There is just one small problem with your calculation, a 4 stroke completes takes only two cycles, not four to complete the process

OK, there is a reason why 4-cycle, and 4 stroke are interchangeable.
Suck - Squeeze - Bang - Blow
One, two, three, four.

Two stroke, or two cycle, up - down. Done.

Where do you think that 4 = 2 ???
I would fire your math instructor.
He said 4-stroke, not 4-revolutions.

Bob

I found a nice animation of the operation of a 4-stroke, or 4-cycle car engine here:
http://www.youtube.com/watch?v=43F5F...elated&search=

For starters, 4-stroke / 4 -cycle is not inter-changeable in my book.

It takes one revolution of the engine for a two stroke engine to complete its complete cycle (intake - compression - expansion - exhaust) see this webpage [link=http://www.keveney.com/twostroke.html]Animated Engines Two Stroke Cycle[/link].

For a four stroke engine it takes two revolutions to complete its cycle (not 4 revs as stated in piper_chucks calculations), if you do not believe me you can look at this webpage [link=http://www.keveney.com/otto.html]Four Stroke Engine[/link]

Maybe you should fire your maths-instructors

Cheers
Pupmeister

Woah ---
Hey, Pup, I am not disagreeing with the one rev for a two stroke, and two revs for a four stroke.
I am saying that if your math is correct, then what in the heck is a 4-cycle engine.
Are you saying that it takes 4 revolutions to complete the entire combustion process in a 4-cycle engine?

We try to help people here, not confuse them...

Bob

If you want to look in other terms, you can say that ALL internal combustion engines are 1-cycle, because in a 2-stroke, they complete one cycle in two strokes, and a four-stroke completes one cycle in 4 strokes, right?

DUH...

Bob

Oik kiddies, this thread was started to show off a cool video, not to start a war of semantics. More than needs to has been said, so play nice or I'm going to lock this one.

Ain't no discussion more worthless than people communicating by the print medium about that form of communications................