What are "Roller Rockers" and why better for high RPMs?

[domV8]

Was wondering -

What are the differences of "roller rockers" to the standard OE items - and what makes them better for hig-speed rpms..?

I often hear of "alloy roller rockers" - alloy I could see being lighter, and therefore might accelerate/deaccelerate quicker, making them more suitable for high revving, but what is the "roller rockers" part..?

Essentially - how are OE and roller rockers different..?

Many thanks,


Dom

[domV8]

Brummmie said:

I tried roller rockers on my LS motor, it gave it valve float as the weight of the bearing is over the tip and it accentuates the extra weight.

Is there any advantage to roller rockers for running higher rpms then? From the "HiFlow" page it looks like the rollers are there for minimising friction between the rocker and the valve stem..?

I see the effects that lightweight rockers have in terms of lowering reciprocating mass, and adjustment to rocker ratio could also have beneficial effects - but from Brummies post it would appear that he saw adverse effects from the offset weight, and valve float is exactly what you are trying to avoid when running higher RPMs...

So if looking to run higher rpms - would one choose simply a lightweight rocker, or a lightweight roller rocker..?

Many thanks,



Dom