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Old 03-19-2012, 02:53 PM   #61
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Default Re: Valve Train/Cam Design

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Originally Posted by Warp Speed View Post
EVERYTHING in an engine is a trade off/compromise. What we are looking for is the most efficient/effective way to deliver the needed/required valve motion.

Would it not be better to get as much work done by the rocker (as allowed by architecture/body length) as possible, and get the rest with lobe and lifter?

This way the velocities of the heaviest (highest mass) components are kept to a minimum?

Pressure angle can be optimized for a given core size/valve lift??

On the R07 stuff, how good is the "geometry" from the lifter to the valve stem? Are you allowed to rotate or move the lifter bores?
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Old 03-19-2012, 03:27 PM   #62
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Default Re: Valve Train/Cam Design

This may be a dumb question but does the camshaft grinding equipment that we have today have the percision to grind a lobe for a higher ratio rocker 2.2-2.3+?

Reason im asking is the rocker just multiply's the motion of the cam lobe. It actually multiply's any action on that side of the rocker (pushrod/lifter movement). The more the ratio the more it multiply's, so i would think the lobe would have to be ground extremely percise and the pushrod / lifter extremely rigid in order for the valve motion to be stable with a 2.2-2.3 + ratio.
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Old 03-19-2012, 03:44 PM   #63
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Default Re: Valve Train/Cam Design

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This may be a dumb question but does the camshaft grinding equipment that we have today have the percision to grind a lobe for a higher ratio rocker 2.2-2.3+?
Yes.
The Dodge NASCAR cams I developed used a 2.37:1 rocker ratio.
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Old 03-19-2012, 03:57 PM   #64
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Default Re: Valve Train/Cam Design

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Yes.
The Dodge NASCAR cams I developed used a 2.37:1 rocker ratio.
Thats alot of rocker.
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Old 03-19-2012, 04:16 PM   #65
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Default Re: Valve Train/Cam Design

Quote:
Originally Posted by Warp Speed View Post
EVERYTHING in an engine is a trade off/compromise. What we are looking for is the most efficient/effective way to deliver the needed/required valve motion.

Would it not be better to get as much work done by the rocker (as allowed by architecture/body length) as possible, and get the rest with lobe and lifter?

This way the velocities of the heaviest (highest mass) components are kept to a minimum?

Pressure angle can be optimized for a given core size/valve lift??

Can't say I disagree with this except to say the cam and lifter is what's doing the work. Seems to be a lot of thinking from the valve back to the cam...but I see it the other direction. The more ratio on the rocker, the more "work" the cam and lifter have to do. Less motion, but more load. I thought one of the benefits of the larger dia. cam cores was to get the lobe to do more work and get away from the long ratio on the rockers...
Intuitively I go back and forth on what's better, (more or less ratio) but I'm sure enough testing has proven one better than the other.
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Old 03-19-2012, 05:06 PM   #66
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Default Re: Valve Train/Cam Design

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Originally Posted by shawns engines View Post
Thats alot of rocker.
Yes, but it allowed us to run .820" lift, with only 145lbs on the seat, and 415lbs open.
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Old 03-19-2012, 05:15 PM   #67
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Default Re: Valve Train/Cam Design

Ok, so if the goal was 1.00-1.050 lift with a 65mm cam core, and 9500 rpms, would you use more lobe or more rocker ratio?. So far my plan is 1.8 rocker ratio and custom .575 lobe. Durability and a stable valvetrain is the key here since 40 psi boost will be used. I'm trying to learn just like everyone else, so go easy.
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Old 03-19-2012, 05:25 PM   #68
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Default Re: Valve Train/Cam Design

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Yes, but it allowed us to run .820" lift, with only 145lbs on the seat, and 415lbs open.
Those numbers are all realitive thought. Jake on this forum with his valvetrain that Tom and someone else designed was able to run .860+ lift, with only 135lbs on the seat. And that was with a 1.85 rocker. So im not sure that the rocker was the only thing allowing you to do that. Lobe design probably played a large role.

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Old 03-19-2012, 05:37 PM   #69
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Default Re: Valve Train/Cam Design

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On the R07 stuff, how good is the "geometry" from the lifter to the valve stem? Are you allowed to rotate or move the lifter bores?
We're not really allowed to move ANYTHING from the original, submited blue-print. But as designed, it is pretty good.
To move just about anything requires a re-submission to Nascar. Being how the last 5-6 years have gone, their not ready to give the Chevy guy's much anytime soon!
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Old 03-19-2012, 05:44 PM   #70
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Default Re: Valve Train/Cam Design

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Originally Posted by scott foxwell View Post
Seems to be a lot of thinking from the valve back to the cam...


Is not the "Valve" , and controling it's motion relative to the piston/cycle what we are REALLY concerned about?!?!?!
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Old 03-19-2012, 06:10 PM   #71
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Default Re: Valve Train/Cam Design

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Is not the "Valve" , and controling it's motion relative to the piston/cycle what we are REALLY concerned about?!?!?!
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Yes, the valve "motion" is what makes the power. You can have that motion in a controlled (semi-controlled?) state or in a chaotic bust everything to $#!+ state (but oh boy she makes some power ). Two identical valve motions with two very different results. Pick your poison.
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Old 03-19-2012, 06:12 PM   #72
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Default Re: Valve Train/Cam Design

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We're not really allowed to move ANYTHING from the original, submited blue-print. But as designed, it is pretty good.
I bet it is, being those are race bred blocks.
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Old 03-19-2012, 06:14 PM   #73
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Default Re: Valve Train/Cam Design

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Originally Posted by Ben Mens View Post
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Yes, the valve "motion" is what makes the power. You can have that motion in a controlled (semi-controlled?) state or in a chaotic bust everything to $#!+ state (but oh boy she makes some power ). Two identical valve motions with two very different results. Pick your poison.
If the valve motion is the same, so is the power...
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Old 03-19-2012, 06:21 PM   #74
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Default Re: Valve Train/Cam Design

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Originally Posted by CamKing View Post
Yes, but it allowed us to run .820" lift, with only 145lbs on the seat, and 415lbs open.
Camking
What spring pressure are they running in the sprint cup flat tappet engines ?
Are they using .875 lifter ? They turn those engines to 9600rpm.
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Old 03-19-2012, 06:30 PM   #75
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Default Re: Valve Train/Cam Design

So I have an honest, loaded question. Do you think there is a difference in endurance vs. an drag engine in the ratio vs lobe? I mean RPM is RPM, but much different application than just going up and down.

I ask because I don't know anyone running big ratio rockers on a big lift (.980+) application. In fact I just got some rockers for a buddy that picked up a S-O-T-A. engine and they were 1.85/1.8.
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