Re: stiffer valve springs

[charlie@elektro.cmhnet.org (Charlie Smith)]

Earlier, Brooks Ellis wrote:
>         
>         How would stiffer valve springs do for your redline? Would they bump
> it up a few hundred RPM? Perhaps lengthen the engine life for those of us
> who like to rack and roll near redline everywhere we go? 

    Yeah, stiffer valve springs will let you rev higher ... after you
    defeat the rev limiter - email me and I'll tell ya how to do that.
    How high do ya want to rev anyway?  I've seen 7500 once, and I don't
    think there was any hydraulic lifter pump up.  

    BUT - is it a good idea?  I don't think so.  Especially just done
    by itself; done with a much hotter cam that needs stiffer springs
    might be another story.  Reasons why I don't think so:

	a)  stiffer springs will cause greater wear on the cam lobes
	    and lifters.
	b)  as long as you can rev to whatever your redline is, and
	    don't get valve float or hydraulic lifter pump up, then
	    the stiffer springs won't do a thing for you.
	c)  If ya accidently rev it past the redline, stiffer springs
	    will probably keep the valves working to whatever higher
	    rev point where something else breaks ... rod bearings
	    anyone?
	d)  if this is a turbo engine, there are tons of things you want
	    to do before you even consider a higher rev limit.

Here's some open questions for everybody - 
    what did the factory use for a rev limit on their hotrods? 
    what gives up first when you consistently rev it past what point?
    what's the RPM range and red line on the Schrick cam grind?
    
I've had lots of experience (mine and associates) with Porsche race
engines, hotter cams, higher red lines, finding out what breaks first,
finding out what breaks next, and so on.  It's worth noting that on the
911 6 cylinder OHC engine, good stock valve springs sufficed for 
whatever you wanted to do, even the hottest cams.  If anybody wants to
hear more about some of that, let me know.

    - Charlie


Charlie Smith   charlie@elektro.cmhnet.org  614-471-1418  
Columbus, Ohio USA


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