NASCAR Valve spring video at 7000rpm

[knighty]

for fellow sados like me......check out this high speed film of this NASCAR valve spring at 7000 RPM.......very interesting!.......the outer spring seems to flap around a fair bit.

http://www.youtube.com/watch?v=i_NpzU4pGjc

[Dennis.Doyle]

Originally Posted by knighty

for fellow sados like me......check out this high speed film of this NASCAR valve spring at 7000 RPM.......very interesting!.......the outer spring seems to flap around a fair bit.

http://www.youtube.com/watch?v=i_NpzU4pGjc

Looks like it could almost use some dampers

[dtype38]

The spring obviously has some internal damping as the amplitude of the "flap" decays from just after the valve closes. What I find more curious is that the top of the valve stem and the top collar of the spring bothe appear to wobble sideways when the valve is shut!

[Dennis.Doyle]

Originally Posted by dtype38

The spring obviously has some internal damping as the amplitude of the "flap" decays from just after the valve closes. What I find more curious is that the top of the valve stem and the top collar of the spring bothe appear to wobble sideways when the valve is shut!

Yes, I noticed that - guess he seriously needs some new guides

Can't explain the sideways wobble at all. Don't think it's faked though - those dots on the springs are exactly what you'd do for reference points.

[Notso Swift]

Are Nascars limited in max revs, some thing in the back of my mind says they are to 8500, but I can't remember.
I have seen a video (maybe one of the spring manufacture sites, not 100%) where they have a picture of the springs glowing red after a test.

[gttouring]

tjhey are not limited in rev- they were flirting with 9900 a few years back, some engine expirations... (Jeff gordons car at California it cracked at 10 K aor there abouts)
now they have a mandated rear end gear (final drive-track specific) to keep the revs under 9k i believe.

[Dennis.Doyle]

Difficult to imagine the one pictured getting to 9 without something falling to bits. Guess it reflects the horrendously square cam profiles used?

[Notso Swift]

I know they put a new top end in for every race such is the hammering involved. Like V8Supercars there are so many restrictions that the "free cam is the only way they can diffirentiate between the engines, at least a V8 lasts about 1200 km before a refresh, I guess the rev limit helps a fair bit (7500 on a V8)

[zefarelly]

Originally Posted by dtype38

The spring obviously has some internal damping as the amplitude of the "flap" decays from just after the valve closes. What I find more curious is that the top of the valve stem and the top collar of the spring bothe appear to wobble sideways when the valve is shut!

that would be of concern to me as well . . .and the roleer rocker doesn't apear to be moving so its not the camera. if they run wasted valves could the valves be flexing ?

[dtype38]

My guess would be its simply lateral flex of the valve stem. This might be being caused by the instability of the spring, but it could be that both are being caused by the rocker load not being purely axial. Either way, it looks like harmonic oscillation, so it could be specific that rpm only. If it's a problem, then the first things I'd do would be repeat that test at different rpm, and do a natural frequency analysis on the spring/collar/valve stem combination. Could be a very small change in valve stem or spring stiffness could completely eliminate all that movement.

[AU N EGL]

Lets see 7000 rpms, and they video was slowed down how much?

I think some ppl are making too big a deal about minor woble. The valves open and close so fast it doesn't make a difference, IMHO

NACAR engine builds are some of the best in the world, that is why they work for high dollar teams.

[Dennis.Doyle]

Originally Posted by AU N EGL

Lets see 7000 rpms, and they video was slowed down how much?

I think some ppl are making too big a deal about minor woble. The valves open and close so fast it doesn't make a difference, IMHO

NACAR engine builds are some of the best in the world, that is why they work for high dollar teams.

I did a rough timing of it and it seems to be slowed down about 24 times - that sounds more like a cine camera than high speed photography.

No one said it was a good example of a NASCAR engine - we have only got the caption to go on.

My guess is it's my mate's Pinto which has knackered valve guides because the foller rocker is not directly above the valve stem centreline.

Alternatively it could be from the NASCAR hall of shame & in the next frame the head came off the valve.

Either way I'm tempted to do a home video of mine to see what's going on.

[zac510]

The original source of that video is www.racingsprings.com (test004.avi) where there is no engine/speed attributed to it.
I just checked back on the site and noticed there are some new videos which must be worth a look at!

[Dennis.Doyle]

Originally Posted by Dennis.Doyle

I did a rough timing of it and it seems to be slowed down about 24 times - that sounds more like a cine camera than high speed photography.
....

Oops1 - SNAFU is the arithmetic department - should say it's slowed down by 142 times.

Oops2 - It's not a Pinto either!

Will check out that racesprings link before putting my foot further in my gob

[AU N EGL]

Originally Posted by Dennis.Doyle

Oops1 - SNAFU is the arithmetic department - should say it's slowed down by 142 times.

Oops2 - It's not a Pinto either!

Will check out that racesprings link before putting my foot further in my gob

Yes a 142 times seems more like it.

Dang if there is a video of the springs then a BOOM . .. . Ouch


Pinto with a V8 ????

[Dennis.Doyle]

Originally Posted by zac510

The original source of that video is www.racingsprings.com (test004.avi) where there is no engine/speed attributed to it.
I just checked back on the site and noticed there are some new videos which must be worth a look at!

Thanks - They most certainly are worth a look. On the originals you can see each frame and the valve bending is quite obvious. My favourite is the drag engine where the springs themselves are rotating at some enormous RPM. How do they do that & why so fast? Must be more than a shamfer/taper on the top of the valve stem surely?

[zac510]

Dennis, somebody should email them and ask if they can confirm that Nascar/7000rpm is correct.

[Dennis.Doyle]

Originally Posted by zac510

Dennis, somebody should email them and ask if they can confirm that Nascar/7000rpm is correct.

Consider it done. Be interesting to see if they comment on some of our comments - perhaps I should get a good lawyer, perhaps utube should too?

BTW The Nascar dual valve spring video at the bottom of their page says it's at 10K when you play it.

[Notso Swift]

Originally Posted by AU N EGL

Pinto with a V8 ????

While the pinto is a self destructing car in the US it is the small Ford single OHC motor in the reat of the world.

[AU N EGL]

Originally Posted by Notso Swift

While the pinto is a self destructing car in the US it is the small Ford single OHC motor in the reat of the world.

Ah - Yes there are a number of differnt names for cars in the US vs other parts of the world.

[zefarelly]

Originally Posted by Notso Swift

While the pinto is a self destructing car in the US it is the heaviest 4 cylinder Ford engine ever produced in the world to those of us in the UK .

thats what I thought

[Notso Swift]

Try to look at the positives... it is the basis for a motor that can pump out more than 500 hp in Cosworth turbo form

[Dennis.Doyle]

Originally Posted by Notso Swift

Try to look at the positives... it is the basis for a motor that can pump out more than 500 hp in Cosworth turbo form

I have to admit I don't actually have any mates....................................... with a pinto & I chose it rather hastily as an example of one of the most naff engines ever made. However, Notso is right, the bore & stroke are the same as a YB & I guess that weight gives it a strong block? Mind you, I'd want the steel crank from the latter.

BTW No reply from racesprings - when should we start chanting "It's all gone quiet over there"?

[R59]

Looking at the video, I see a roller rocker. I was under the hallucination that NASCAR (Cup) was flat-tappet - ie: old fashioned agricultural.

However, Busch and Craftsman Truck use rollers rockers/lifters etc...

And all types of motor run a up to 9K.

I use a dirt cam in mine, which means it's done it's best by about 8200, but produces crazy amounts of torque, which is great for getting out of corners, shredding tyres, and widening the grin on the driver's face.

Rob.

[Dennis.Doyle]

Got a reply from racesprings. They didn't explicitly confirm it was at 7K rpm, so I assume it was. Anyway, here's what they said:

"Thanks for the link. I knew alot of people were looking at these videos but I didn't realize over in the UK too! That's pretty cool.

Actually the video you commented on had pretty good control. The valves do move around a lot especially when very small stems are used. It is hard to imagine what happens at high speed but I have seen enough of it to know that things move all over the place. When you combine that with load cells, strain gages, lasers, etc. You know that the motion you see is real.

It was discussed a lot in a form called speedtalk as well."