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Not as much as the brochure would have you believe;) In theory, there are numerous advantages. Some of them made it to reality, others are more than offset by inherent drawbacks.
 

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Blackwoodz said:
are we talking a few grams?


Stop by and check on my scale;) Then figure the forces at even half crank speed. Figure the added energy to move it in both directions, the added spring force, etc. Not many modern high rev engines use rollers.
 

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In our applications, roller cams have BIG gains over flat tappet cams.

Pops the valve open quicker, holds it open longer and pops it shut.

So much more time for air/fuel to flow in and spent gases to get out of the engine equals so much more power.

Notice the new plus R 4 valve went to a roller cam for a reason.

With good rollers the wear on the cam and drag is alot less than the non rollers.
 

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Blackwoodz said:
yeah but aren't modern MX thumpers just using a cam and bucket design with no rocker at all?
Some do , some dont, I really think his question is related to what we are doing right here and now?
 

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I'll look for my degree sheets. Theory doesn't always make it to metal;)

Hydrodynamic oil film keeps the friction from being as much an issue as the literature suggests. Dyno tests with plain-bearing engines converted to roller cranks and cams (Smokey Y) showed a lot of money spent for nothing. Looks good on ad slick, though. And, lifter face size and radius, base circle diameter has a LOT to do with opening speeds, at least in the real world. Our DOHC 4V V-12's had monstrous amounts of inverted-bucket friction at starter cranking speeds, but the numbers showed it all went away by the time the velocity and viscosity linked up. Scan the microfiche files for modern high RPM engines with rollerized valvetrains.



"How much better is a roller setup vs non roller?"... Pretty vague, so maybe the OP will elaborate further on his inquiry?
 

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Discussion Starter #11
Blackwoodz said:
yeah but aren't modern MX thumpers just using a cam and bucket design with no rocker at all?
Im talking about honda or kawi based mini heads.
 

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Matified said:
In our applications, roller cams have BIG gains over flat tappet cams.

Pops the valve open quicker, holds it open longer and pops it shut.

So much more time for air/fuel to flow in and spent gases to get out of the engine equals so much more power.

Notice the new plus R 4 valve went to a roller cam for a reason.

With good rollers the wear on the cam and drag is alot less than the non rollers.
Interesting. I know in the car motors i build they are awesome. Terry did you deleat something? I thought there was more?
 

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geezer said:
Interesting. I know in the car motors i build they are awesome. Terry did you deleat something? I thought there was more?


Yeah, but it wasn't relevant. I'd just mentioned that the entire potential of the roller hadn't been realized in currently available grinds, that a larger base-circle and lifter face radius, or inverted bucket can be just as quick, lighter, and less expensive. Or some thing like that;)
 
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