Re: HEEEEEEEELLLLLLLPPPPPPPP!!!!!!!!!!

[Kevin <aventari@cts.com>]

Here's what Robert Collins says about lightening the valve train, which
solid lifter definately do at a very reasonable price.

Lightening the valve train: 
Lightening the valve train enables your motor to rev quicker and higher,
thus have more horsepower and faster throttle response. All race motors
built at Drake Engineering either use Titanium (Ti) valves, or lightened
steel valves, and most certainly Ti valve spring retainers. No matter how
you look at it, lightening the valve train is a very expensive process. The
process would benefit all motors from race to street, but cost is the
inhibiting factor for street cars. 

And here's what he has to say on the subject of Hydraulic heads.. I can't
verify his claims, but Mr. Collins is a respected authority on the subject
of VW Performance..

The hydraulic head is the real nightmare. In this head, MUCH has changed.
The valves are shorter. The cam base circle is smaller. The distance
between the cam bearing bore centers and cam follower holding tray is much
smaller, therefore requiring clearance grinding for almost any (true) high
performance cam. The valve guide protrudes much farther into the ports. And
the valve spring depth is deeper (though the valve springs are the same
size). All this is because of the difference between hydraulic and
mechanical lifters. In order to make a big valve head from this head, some
serious decisions must be made: 

Do you keep the hydraulic lifters, or switch back to mechanical?
Valve length (dependant of type of lifters) 
Valve guide length (depends on type of lifters) 
When we designed the hydraulic BVH we made this, and only this assumption: 
This is a high performance head. 
Therefore, who cares about hydraulic lifters and the convenience of never
having to adjust the valves. Furthermore, there are performance penalties
for using the hydraulic lifters: a substantial weight penalty. And for all
high performance applications, a major quest is to lighten the valve train.
Since the decision was made scrap the hydraulic lifters, then this cleared
the way for other performance penalties: 

At 12:34 PM 1/15/99 -0700, you wrote:
>
>Uhh..they are only inferior in race applications....who runs their car at
>7500rpm all day long? Cause only at high rpm like that will you see the
>difference between them...now I don't mind adjusting valves...did it many
>times on my old JH motor (that was a pos...some idiot put RD pistons in
>it...and drove the fucker without a knock sensor....10.5:1...I got in that
>thing....knocked like a bitch....oh well...it lasted for a little
>while...wasn't all that surprised when it spun a rod bearing)...
>
>Ok...so I agree that they are inferior, but only at high rpm...
>
>I'd like to know where this performance difference your thinking of
>is...neither one makes and DAMN bit if difference to HP ratings or Torque
>ratings...
>
>Plus...it's not worth the time to change the head and oil pump that I
>have
>now....
>
>Especially since it's legal to have a hydrolic JH and run in DSP
>
>Eric
> 


Kevin Fry 
'81 S 1.8

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