" roller rockers"

[kepperly]

Why doesn't someone manufacture roller rocker arms for Porsche?? Wayne have you ever contacted comp cams and asked them. It would seem like almost free horsepower and an easy way to do it.

Keith Epperly
87 slant nose turbo look Carrera cabriolet

[jpnovak]

Generally there is physically not enough room within the cam tower to implement roller rockers. A rede$$$gn of the cam tower would be required.

There are some stories in the archives with more information.

[kepperly]

why WOULD THEY REQUIRE MOORE ROOM, THE ROLLER ENDS WOULD BE SLIGHTLY LAGER AND A ROLLER BEARING FULCRUM SHOULD BE THE SAME SIZE. ADJUSTMENT WOULD BE IDENTICAL WITH A SWIVEL FOOT.
KEITH EPPERLY
87 SLANT NOSE TURBO LOOK CARRERA CABRIOLET

[dad911]

http://forums.pelicanparts.com/porsche-911-technical-forum/403015-roller-rockers-anyone.html

http://forums.pelicanparts.com/911-engine-rebuilding-forum/343951-race-motors-steve-henry-lot.html#post3246094

[kenikh]

I talked this over a while ago with several of the engineering eggheads who frequent this site - these are the guys that make their livings on cams and engine building - all have tried and given up. The reasons are:

1. Width of the rocker journal prevents a strong enough setup with the full width roller, obtaining the proper ratio and clearing the valve covers - consensus is new cam towers would be needed.
2. Cam geometry totally changes - replacing the radius tip with a roller tip reduces the radius and slows down the camshaft action; you'd would need to calculate conversions for proven profiles to new geometry in going from sled rocker to roller rocker.
3. Normal chill cast camshafts wont work with a steel roller follower, so you would need some blanks made from 8620 steel. You'd need new billets to make usable cams.

By the time you get done with all of that, you might as well make new heads with a better valve angle, too.

[dshepp806]

Originally Posted by kenikh

i talked this over a while ago with several of the engineering eggheads who frequent this site - these are the guys that make their livings on cams and engine building - all have tried and given up. The reasons are:

1. Width of the rocker journal prevents a strong enough setup with the full width roller, obtaining the proper ratio and clearing the valve covers - consensus is new cam towers would be needed.
2. Cam geometry totally changes - replacing the radius tip with a roller tip reduces the radius and slows down the camshaft action; you'd would need to calculate conversions for proven profiles to new geometry in going from sled rocker to roller rocker.
3. Normal chill cast camshafts wont work with a steel roller follower, so you would need some blanks made from 8620 steel. You'd need new billets to make usable cams.

By the time you get done with all of that, you might as well make new heads with a better valve angle, too.

whew!!!!!!!! (meaning good info...)

[kenikh]

Credit goes to Camgrinder, Jamie and Burn Bros for most of this info.

[Steve@Rennsport]

Originally Posted by kenikh

By the time you get done with all of that, you might as well make new heads with a better valve angle, too.

You'd need new camshaft housings as well to accomodate different rockers and geometry.

Might as well make it a 4-valve engine, too.

[RWebb]

...then you'd need to flow water thru it to cool things off

say, while we're at it, why don't we see if we can eliminate the parts count and make it easier to assemble...

ooops! somebody already did that

[Flieger]

Originally Posted by kenikh

1. Width of the rocker journal prevents a strong enough setup with the full width roller, obtaining the proper ratio and clearing the valve covers - consensus is new cam towers would be needed.

He had that covered

[sc_rufctr]

It can be done with the stock cam towers and covers... The geometry and cams can all be worked out.

Back in the 70s these were made for Australian produced 6 cylinder engine with push rod vales.
Surely in 2009 this cam be done for the Porsche flat 6.

As you all should know it's been done for air cooled VWs for a long time.

I'm bit surprised that some professionals have given up on this idea.

[Flieger]

But if we had roller rockers, what would happen to all the oil threads and arguements? If we do not need Zinc and Phosphorous, then anything goes.

[Flieger]

I would also be interested to see any photos you might have of this setup.

[Formerly Steve Wilkinson]

I'm in.

[Steve@Rennsport]

Originally Posted by RWebb

...then you'd need to flow water thru it to cool things off

Not necessarily. Somewhere around here, I have a prototype air-cooled 911 4-valve head,...(I didn't make it).

[dfink]

Originally Posted by kepperly

Why doesn't someone manufacture roller rocker arms for Porsche?? Wayne have you ever contacted comp cams and asked them. It would seem like almost free horsepower and an easy way to do it.

Keith Epperly
87 slant nose turbo look Carrera cabriolet

I would guess it has something to do with money.

[RWebb]

Originally Posted by Steve@Rennsport

Not necessarily. Somewhere around here. I have a prototype air-cooled 911 4-valve head,...(I didn't make it).

that's interesting!

I always thought that P AG flowed water thru the heads to cool them.

of course, maybe it was a rejected prototype...

- do you know the history of it?

[Steve@Rennsport]

Originally Posted by RWebb

that's interesting!

I always thought that P AG flowed water thru the heads to cool them.

of course, maybe it was a rejected prototype...

- do you know the history of it?

PAG certainly DID water-cool them for best efficiency,......

The one I have was not made at the factory.

[gtc]

Has anyone tried putting a ceramic pad on the rocker, similar to the lifters that Schubeck racing made (sold by LN and Jake Raby)?