Roller Rockers Anyone ????

[Natchamp]

Fellow Pelicanites,

Here's a worldwide exclusive for you I've always thought roller rockers would be a good thing for our motors so I've started designing some. I've still got a lot of homework to do narrowing down the materials, etc. but wanted to share my first draft.

The intent is to leave the valve side of the rocker as well as the pivot point pretty much as stock. Most of the friction is from the cam lobe so that is where the roller will be. Clearence and packaging is a real challenge and I want everything to fit within stock valve covers.

Here is a side by side of the oem rocker and my first draft version.



For the broadband peoples, here is an avi video showing both of them full 360.

6 Meg Video of them rotating 360

[cgarr]

Now get some needle bearings in there!

[TimT]

Interested,

Im doing a cam swap on my personal track car, If you want to to some Beta testing on the product... the time is right...

I change cams like I change clothes LOL

I am really interested in this.. and am willing to be a real life test of the product... however it will only be track miles...

[Walko]

I am interested as long as it won't be adding weight

Michael

[Natchamp]

No needle bearings, stock bushing for the pivot.

Track testing would be great actually but I won't be ready for at least a little while.

I should have also mentioned the intent is to not require a special cam. Just bolt these units in and go! cheers.

[JeremyD]

Very cool Mark -

[the]

Did Porsche ever use rollers on any of their 911 engines (including 996/997, GT2, GT3, Turbo, etc.)? It seems like a good idea.

[TimT]

"Special cams"

Not really... I seem to change cam grinds every year or so.. Just happens I'm just about to receive a new set of cams.... Will install the rockers, and will track the car.. 7800-8200 rpm

Have been intererested in something like this for awhile....

[2.7RACER]

How do you plan to lube the roller?

[tctnd]

The roller looks way too narrow to me. Roller rockers sold by speed shops have a similar sized roller over the other end meant to reduce side loading on the valve stem. Rollers on the cam typically are similar in width to a "plain" cam follower. Don't mean to sound critical, but these are highly loaded components.
Also, If you mean to use standard cams, the roller will need to have the same radius as the standard pad or the effective cam profile will be radically altered.
regards,
Phil

[vreference]

Oh ha, when I read "Roller Rocker" I was thinking needle bearings as well considering that's traditionally what a roller rocker involves. Since the engine doesn't have lifters I guess it's fair to call this part a roller rocker?

Excellent though! It's shocking that Porsche didn't implement a roller valvetrain a very long time ago and absurd that they didn't move that direction for the Carrera 3.2. The only thing more amazing is that, to the best of my knowledge, there is no aftermarket roller part available!

Talk about free horsepower! Sign me up! Hopefully the stock equipment will allow for a large enough roller.

BONUS: I believe this would end the oil woes for the Air-Cooled people. Wouldn't it?

[911pcars]

I agree with Phil. Can you make the roller wider as well as make the rocker lighter at the same time? A slightly increased rocker ratio will provide a slight increase in valve lift. I believe factory is 1.4:1. The forged factory rockers are 1.5:1.

This is also one area that can reduce frictional losses in an engine.

There's some potential for liability in case the rocker arm breaks and some engine insurance because it breaks.

The former is self-explanatory. The latter refers to the situation where valve touches piston at high engine speed. Something's got to give. In the case of most engines, the valve punches a hole in the piston and/or the valve head bends. In 911s, the rocker arm is the sacrificial parts. It breaks (in half usually) and saves the valve train and piston from catastrophic damage (usually).

However, a light as well as strong rocker arm should mitigate the above situation. Press on. It's an excellent idea. Make em as cost effective as domestic hod rod parts, even make them competitive with factory prices, and you'll still corner the market.

Sherwood

[onboost]

Nice concept Mark.. can't wait to see final product...

cgarr: Needle bearings in Porsche engine? Ha! that's all we need.. do you know what that would be like if a rocker failed and dumped the needles? The entire engine and oiling system would get fragged! Ask me how I know!! Just lost one on my Harley last month.. 96" stroker motor. Happened at low speed, haven't seen any damaged yet.. not even to the cam but most of the needles are missing and I sure they're somewhere in the oiling system!

tctnd : I think you can be sure that Mark will be covering all those bases before this product hits the street. I've seen nothing but precision pieces come out of Hargett.

Paul

[cashflyer]

Titanium.

[Jeff Higgins]

I'm not sure there is anything to be gained here other than added weight and complexity.

The drag race boys started using roller lifters years ago, but for a far different reason than one would suspect. It has nothing to do with decreased valve train drag, higher rpm capability, or anything like that. It was done mostly as a necessity when cam lift and duration started dramatically increasing.

A pushrod V-8 is restricted in the diameter of its lifters by, well, the diameter of the lifter bores. With a relative small diameter lifter, and very steep, tall ramp angles on the cam lobes, it does not take long before the cam lobe wants to hit the edge of the lifter. The lifters have a very small diameter, flat bottom. That limits cam profile a great deal. The roller lifter was meant to mitigate that.

Our motors, with the sweeping radius of the rocker arm face where it bears upon the cam, do not have that problem. The one piece rocker arm is a very simple, fool proof, effective solution in our motors. I think adding a roller will needlessly complicate what is now a very elegant design.

Needle bearings have no place in rocker arms. I've had similar experiences with Harleys puking the needles from theirs. XR 750's (the flat track racers) ran them for awhile, then went back to bushings. Think about this; they do not rotate through a full revolution; they "rock" (hence their name...). And they rock under a great deal of load from the valve spring. That load is pushing them up, away from the valve. All of the load is on the bottom of the bushing; look at the wear pattern in a well worn rocker arm. If there were any kind of roller or needle bearing in there, only the bottom couple of needles would ever see any load. And they soon break.

Anyway, I hate to come off as such a wet blanket. Sorry, Mark, but I think you are answering the proverbial question that was never asked.

[JeremyD]

JB Racing makes some for Triumph engines but no porsche stuff listed

[HawgRyder]

I think Jeff has almost the right idea...the roller rockers were used to reduce the drag on the cam when the spring pressure was raised to prevent or delay valve "bounce" at higher RPM's.
The pressure fed back through the rocker to the cam would tear the lobe apart because it forced the lubrication out of the contact point.
Bob

[cgarr]

Well said Jeff, Thats what I thought, isn't the roller usually on the valve? I would think with all the oil in there you would get some skidding of the roller on the cam lobe.

[GaryR]

Originally Posted by JeremyD

JB Racing makes some for Triumph engines but no porsche stuff listed

If I put those in I would have to get clear valve covers...

[racing97]

Great concept, but you will have to design a cam and it will have to have a Kidney shaped lobe to duplicate the acceleration of even the existing OEM shaft.

regards