Race motors, Steve, Henry and the lot

[Sprinter4]

I think this is is relative, but tell me if I'm hi-jacking the thread!

If you read my info, I've been racing for thirty something years, and I'm an engineer, so what. OK, I have a machine shop located out at the Larry Miller Motorsports Park, in Tooele, Utah. I have everything including a CNC milling center. But I'm not that familiar with the Porsche motor.

Now, I have a customer that wants me to design a set of needle bearing roller rocker arms for his 3.6 engine. It's in a GT-2 car. Money is no object.

I have two samples of the rocker arm. One is adjustable and one is the hydraulic version.

My customer is telling me he has broken both types in the past.

OK, I can work out the details about strength and a custom CNC'd rocker. But as I see it no one ever talks about broken rocker arms.

Do these items break on a regular basis in racing? I can see the possibility of an arm twisting under extreme situations. And needle bearings would definitely be an inprovement. And yes I would EDM oiling holes in the bearing for lubrication.

He talkes about way high RPM's well above 7,500 when he's racing. And I'll bet there is a missed shift on occasion.

But is his request reasonable?

Should I consider this project?

Should I consider 7075 T-6 aluminum as the base material? I know I could work out the details for strength and reliability. What is the maximum spring pressure at max lift on these engines? What kind of temperature will this part of the engine see? Are his valve springs causing valve float?

Would there be a market out there for additional sales?

Any suggestions would be appreciated.

[Grady Clay]

Sprinter4,

I’ll be at the event on May 15 for set-up with three prepped 997 Cup cars. Please email me your contact info to gradyclayathotmaildotcom.

I suspect this may be a dead-end project but I would like to exchange info so you can decide.

Best,
Grady

[cnavarro]

I too thought that 7075 or some other 7 series would be good, but it is too brittle to make rockers out of; that's the reason 6061 is used for billet rockers industry wide and the ones Pauter had made were of the same construction. I too agree with Grady that this may be a dead end project for mass production, but one off with a modest budget, who knows. Jesel might be a source for some of the components - the more you can re-use or source, the better.

[304065]

Hot rodding rocker arms

[Henry Schmidt]

quote:Originally posted by Sprinter4
......................................
I have two samples of the rocker arm. One is adjustable and one is the hydraulic version.

My customer is telling me he has broken both types in the past.............................................. ..

When breaking rockers are an issue for my race engine applications there are two easy remedies.
Early forged rockers and forged solid factory racing rockers.
I have never seen either of these break.

They also offer a slightly better rocker ratio over the stock cast rockers. 1.5:1 vs 1.45:1.


As for roller rockers, many mid eighties IMSA builders tried roller rockers with little or no success.
It is my understanding that rollers rockers have issues that are almost impossible to overcome.
If the plan is to redesign the cam tower as a starting point many issues will be addressed.
Aaron of Burn-Bros fame has looked into the possibilities and together with John (camgrinder) determined that roller rockers in 911 air cooled engines will not be a reasonable undertaking.

Perhaps Aaron or John will chime in on the subject.