DOHC@14,200RPM video

[Demon-Xanth]

http://www.youtube.com/watch?v=VSDa-EUT3ZE

Enjoy.

 

[BW86]

that was awesome!

 

[SSSnail]

I kept moving back away from my monitor as the RPM goes higher...

 

[spidey07]

That's wild how the valve springs are turning ever so slightly. I guess it's from vibration.

 

[KK]

its amazing that those could open and close going so fast, you'd think the spring wouldn't be able to keep up. are they closing the whole way?

 

[Demo24]

its amazing that those could open and close going so fast, you'd think the spring wouldn't be able to keep up. are they closing the whole way?

I was thinking the same thing, and I wonder if that's where the 'smoke' came from.

 

[sjwaste]

its amazing that those could open and close going so fast, you'd think the spring wouldn't be able to keep up. are they closing the whole way?

I think so. 14,200 RPM is something like 235 RPS. Higher than the framerate of the video, so you're not going to see it all happen.

 

[sjwaste]

That's wild how the valve springs are turning ever so slightly. I guess it's from vibration.

I think that's pretty normal on DOHC applications. Have you ever done a valve adjustment on one? My car has a shim over bucket setup, and you can see that the wear is even around the circumference of the shim. I mean that as opposed to seeing a groove where the cam lobe would repeatedly rub the same part of the shim.

Even more awesome at 14k RPM.

 

[Eli]

Valves must turn during operation to seat properly. That is normal, for all engines. Older small engines even have devices called valve rotators built into the spring keepers to provide rotation, I assume before they figured out how to do it "naturally" without them.

The "smoke" isn't smoke, it's oil mist.

Yes, the valves are opening and closing all the way. If they were not, the engine would be experiencing what is known as "valve float", which is the limiting RPM factor for most stock engines.

Your lowly lawnmower engine will float the valves at ~5500RPM.

 

[Fenixgoon]

abso-friggin-lutely awesome!

 

[Meghan54]

And a look at the same run from the piston's point of view, looking up at the valves' faces.......

http://www.youtube.com/watch?v=Hr-LUB0tJJc&feature=channel

 

[amdhunter]

Did you guys break Youtube?

 

[CurseTheSky]

Sweet, this video is perfect for when I try to explain how engines work. People get the basic concept, but trying to explain timing / anything involving the cam(s), valves, springs, rockers, etc. is impossible.

 

[Eli]

Sweet, this video is perfect for when I try to explain how engines work. People get the basic concept, but trying to explain timing / anything involving the cam(s), valves, springs, rockers, etc. is impossible.

http://www.animatedengines.com/otto.shtml

 

[PlasmaBomb]

Great finds.

Any more?

 

[exdeath]

1) Lol at frame rate aliasing.

2) The valves are not supposed to turn like that. That means they are losing contact with the cam for a split second with each activation (eg: floating). Notice they stop spinning when the revs come down. Needs some stronger springs IMO.

http://www.youtube.com/watch?v=_REQ1PUM0rY

 

[Eli]

1) Lol at frame rate aliasing.

2) The valves are not supposed to turn like that. That means they are losing contact with the cam for a split second with each activation (eg: floating). Notice they stop spinning when the revs come down. Needs some stronger springs IMO.

http://www.youtube.com/watch?v=_REQ1PUM0rY

Negative. Valves are supposed to turn during operation. This is basic(Ok, maybe intermediate) engine operational theory.

It is possible they are floating, but the valves rotating isn't a symptom of that. I do not think they are floating, though, unless they have revved the engine past its redline. If it's running within its operational range, floating valves would be bad for emissions - not to mention cap max RPM. Notice that they're still turning even when they start loweing the RPMs.

They are still turning even at the lowest RPMs, it's just hard to see because the number of cycles per second is much lower.

 

[JulesMaximus]

Nice! This is as close to F1 engine technology you can get in a street legal vehicle.

I love bikes!

 

[JulesMaximus]

1) Lol at frame rate aliasing.

2) The valves are not supposed to turn like that. That means they are losing contact with the cam for a split second with each activation (eg: floating). Notice they stop spinning when the revs come down. Needs some stronger springs IMO.

http://www.youtube.com/watch?v=_REQ1PUM0rY

The redline of that bike is 14,200rpms bone stock, off the showroom floor. I seriously doubt there is anything wrong with the way those valves are working in that video.

 

[sjwaste]

Negative. Valves are supposed to turn during operation. This is basic(Ok, maybe intermediate) engine operational theory.

It is possible they are floating, but the valves rotating isn't a symptom of that. I do not think they are floating, though, unless they have revved the engine past its redline. If it's running within its operational range, floating valves would be bad for emissions - not to mention cap max RPM. Notice that they're still turning even when they start loweing the RPMs.

They are still turning even at the lowest RPMs, it's just hard to see because the number of cycles per second is much lower.

This is correct. The valve bucket/shim should rotate. Otherwise you don't have even wear, and that's bad should it ever jump after that.

There's a reason that service manuals for any shim over bucket design will specify an edge thickness spec for the shim and a maximum run from the center. It should wear that way.

 

[jhu]

I felt a need to put my hand in there. Good thing there was a glass screen in the way.

 

[PricklyPete]

I saw this on Autoblog the other day. This video pretty much sums up why I love automotive vehicles so much. They are engineering masterpieces.

While I'm not a huge fan of riding bikes...the engines are absolutely amazing.

 

[JulesMaximus]

I saw this on Autoblog the other day. This video pretty much sums up why I love automotive vehicles so much. They are engineering masterpieces.

While I'm not a huge fan of riding bikes...the engines are absolutely amazing.

Riding bikes is so much fun though, so much more visceral than driving a car. I'm totally hooked on riding, bikes have ruined cars for me for the most part.

 

[RichUK]

Why is this technology not applied to larger DOHC car engines (assuming that there is a technological difference between high revving smaller bike engines and larger car engines)?

EDIT: Lack of torque?

 

[overst33r]

Why is this technology not applied to larger DOHC car engines (assuming that there is a technological difference between high revving smaller bike engines and larger car engines)?

EDIT: Lack of torque?

Rotating mass?

As I understand it, essentially the difference between production car engines and F1 (20k+ RPM) engines comes down to material selection.

Simply put, moto's use smaller rotating assemblies and can therefore spin faster using the same materials as production car engines.