I remember reading awhile back that phantom grip made a set of these but I havent been able to locate a set. Is there any advantage to a lightweight rocker on an all motor setup or is stock what most ppl are running ?

 

A lightweight rocker certainly would be nice, but unfortunately, like most parts for h22s, none are made....

Just as a quick analysis of why it would be nicer, a lighter rocker would just lighten the head up, since they are fixed to the rocker shafts and also sprung directly, their weight doesn't make much of a different in how hard they are to push

Now, a rocker that had a different ratio would be something to think about....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bb4ever &raquo;</TD></TR><TR><TD CLASS="quote">

Just as a quick analysis of why it would be nicer, a lighter rocker would just lighten the head up, since they are fixed to the rocker shafts and also sprung directly, their weight doesn't make much of a different in how hard they are to push
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Think of the speeds those things must reach at high rpms...a little weight lost would surely have some benefit.

 

Yeah that weight thing is definately a factor to think about. I've also heard of the phantom grip rockers but have never actually seen them.

bump for anyone who knows.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Hawkze_2.3 &raquo;</TD></TR><TR><TD CLASS="quote">Think of the speeds those things must reach at high rpms...a little weight lost would surely have some benefit.</TD></TR></TABLE>

It would seem so, but I keep trying to analyze the physics behind it in my head right now

All I can think of is as follows:

Situation 1: Spring fully extended, rocker at full height, cam lobe on its way around

As soon as the lobe hits the rocker arm, the forces are as follows, a force on the axis of the valve spring (not quite straight up, but on some angle to vertical, its probably about 30-40 degrees), the gravitational force of the weight of the rocker arm (straight down), and the force of the lobe on the pad of the rocker (ideally, the direction of this force would be the negative of the spring force, so I will assume its close)

So in that situation, the heavier arm has the advantage in getting down with less force from the cam lobe, which would result in less parasitic loss

Situation 2: Spring compressed to max lift of the lobe, rocker down, cam lobe on the exit route

The forces now are only the valvespring pushing back up, and the gravity on the rocker, the less the gravity holds the rocker down, the more "help" the valvespring gives the cam in rotating

Soooo, I have arrived at three facts
1) The forces cancel out as far as I can see, and weight has no effect on the parasitic losses in the motor
2) The only benefits of lighter arms would be less wear on the moving parts around them and overall a lighter cylinder head
3) I probably have no idea what I'm talking about at this point (I just finished 5 hours of electrical engineering homework)

 

Yeah, every bit of wheight seems to have exponetial efects do to high RPM's. Yet seeing how the rocker arm's motion is dependent on other direct forces, it's hard to say...

 

Gravity is really not a concern with rocker arms....they're stuck to the head no matter what. The way that weight is going to affect them is their inertia or resistance to change of direction ( I hope I used the right words there ).

If they're lighter it will be less of a parasitic loss in the head overall. Just like titanium retainers or even lighter pistons: less weight to waste the engines power on moving.

I haven't had coffee yet so I hope that made sense.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bb4ever &raquo;</TD></TR><TR><TD CLASS="quote">A lightweight rocker certainly would be nice, but unfortunately, like most parts for h22s, none are made....

Just as a quick analysis of why it would be nicer, a lighter rocker would just lighten the head up, since they are fixed to the rocker shafts and also sprung directly, their weight doesn't make much of a different in how hard they are to push

Now, a rocker that had a different ratio would be something to think about.... </TD></TR></TABLE>

I thought I remembered seeing phantom grip ones AWHILE back ?

 

Yea hawk that definitely makes sense, though gravity has an effect on everything, here it would be pretty negligable

I'll take a look around, though I know some will be coming out in the near future that may or may not incorporate a change in the rocker ratio