Valvetrain lightening, For higher revs.... Options

[TimT]

QUOTE

How come you dont use aluminum or titanium rockers...I mean make them..

Fatigue strength, cost, workability, longevity.

The benefits of lightening cast rockers, are small, but when trying to find every drop of performance every little thing adds up..

The Moment of Inertia of a rocker arm that only moves a few tenths of an inch is small to begin with

[alpha434]

QUOTE (TimT @ Mar 12 2006, 07:44 PM)

QUOTE How come you dont use aluminum or titanium rockers...I mean make them.. Fatigue strength, cost, workability, longevity. The benifits of lightening cast rockers, are small, but when trying to find every drop of performance everty little thing adds up.. The Moment of Inertia of a rocker arm that only moves a few tenths of an inch is small to begin with,

It's really R&D time to make them. None of the above. If there was truly a will to make them, then we would.


And....

directional carbon fiber reinforced titanium rod.

Think about that.

[TimT]

QUOTE

None of the above. If there was truly a will to make them, then we would.

Simply wrong,

a number of years ago someone floated some aluminum roller rocker arms for 911s...

in the end the cost/complexity/benefit of them never exceeded that of the off the shelf Porsche rockers.

Someone has made improved 911 rockers..

and yes I realize Im not talking 914 now

Clay Dopke used take cast rockers, stress relieve them, shot peen, polish, etc..

Do me a favor and tell me the MOI of a stock rocker arm, and one of your lightened rocker arms?

By no means am I slamming your work... just making an observation that this is on the extreme end of performance benefits

[Brett W]

The gains found in lightening the rocker arms ar most very minimal. As TimT said. MOI is very small. The biggest change you can make to the valve train is in the valve and lifter pushrod side.

You can take the stock rockers and fit them with needle bearings for a decent upgrade. You really won't see much in the way of HP improvement, but the "rev-ability" of the engine will improve as will heat going into the oil.

One thing that many people over look is camshaft design. That is one area where our engines are at a major disadvantange. When we start "lofting" the valves over the nose of the cam we really haven't gotten into anything exciting.

[Jake Raby]

Wait till you see the heads that we just finished for the LN Engineering 356/616 project engine....

Len boosted the head flow by 25% with NO welding necessary from some new seat and port profiles...

We'll be posting pics soon for the 180HP street engine we are building for LN Engineering..

No more 10mm valve stems either!

I prefer stock rockers over anything aftermarket.. Losing the "Self oiling" characteristic is a step backward IMHO... I have broken ONE stock rocker and that was just 2 weeks ago and it happened out of the blue on the dyno...

Rockers are one of those items the aftermarket can't make money on if they make them better than the factory, and trust me we have looked into and even made some rockers along the way and they have not superceded stock! I have a set of Titanium TIV rockers that one of my FP 914 customers paid 1600 bucks for, they are sitting on the shelf while BOTH of his engines have stock TIV rockers on them and they will remain that way as long as I'm assembling his engines...

[alpha434]

NHRA top fuel drag cars use aluminum rockers.

High maintenance is the cost of high performance. A revised head design would be optimal.

Lightening the valvetrain and reciprocating components is what I would call "the point of refinement." It's where you've already gotten a lot from your car and have to walk a hundred miles to get that last 5 horses.

And I wasn't going to mention the needle bearing trick. I didn't know anyone else knew that. Oh well. Run your breather to the exhaust while you're at it.

[Brett W]

QUOTE

Run your breather to the exhaust while you're at it.

SCCA and many other organizations get a little ill about that trick. You are better off with a super tight motor and a large dry sump pump. That can pull 15in if it is setup right.

Do that and you can run 2 ring pistons and all kinds of other cool stuff.

[Mueller]

QUOTE (alpha434 @ Mar 12 2006, 10:59 PM)

And I wasn't going to mention the needle bearing trick. I didn't know anyone else knew that. Oh well. Run your breather to the exhaust while you're at it.

don't worry too much about your "tricks", 'cause I highly doubt you or your engine builder has many that everyone else knows about or has tried already (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)

needle bearings have been used in that application years before you even got your drivers license (IMG:http://www.914world.com/bbs2/html/emoticons/wacko.gif)