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

[Night Shadow <soltwede@ucsub.Colorado.EDU>]

Rather dated Kevin...as VW produced the hydrolic "Big Valve" head all by
themselves....

So where is this gain?

You EVER comapred the HP and TQ ratings of a Solid and Hydrolic JH???

Eric


On Sat, 16 Jan 1999, Kevin wrote:

> 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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