[Shotimes] knife edge crank

[Ian Fisher]

Dunno
I've been off of shotimes for awhile. Someone had
mentioned it to me and since I don't know too much
about it, I was curious about what people have to say
about it. I'll be building my 3.2 this summer and will
need to get the bottom end balanced anyway so it was
something to think about way in the back of my mind.

Ian

--- Mark Mucher <mmucher@bellsouth.net> wrote:
> Haven't we had this conversation before?
> 
> I thought the crank NEVER hit a standing sump of oil
> - in fact there are
> baffles to prevent it from doing so...
> 
> If the crank was submerged in oil, I can see a
> benefit to knife edging, but
> it's not! 
> 
> (Or am I missing something?)
> 
> Mark
> 
> 
> -----Original Message-----
> From: shotimes-admin@autox.team.net
> [mailto:shotimes-admin@autox.team.net]
> On Behalf Of Ron Nottingham
> Sent: Sunday, May 09, 2004 8:54 AM
> To: shotimes@autox.team.net
> Subject: Re: [Shotimes] knife edge crank
> 
> What "knife edging" is, quite simply, grinding down
> the counter weights
> some, until they have an edge to them. I used to
> have a program/formula that
> could be used to calculate how much metal could be
> taken off. The effect of
> knife edging is so the crank does not slow any going
> through the oil, plus
> it is supposed to help at higher rpms to keep from
> aerating the oil. This is
> now mostly done to a crank when an engine is
> balanced and using lighter
> pistons and rods.
> 
> I could be wrong, but unless you have a lighter
> rotating assembly, I don't
> see any benefit to knife edging the SHO crank, since
> there is a windage
> tray. Sure, you are lightening the crank, and you
> /may/ gain a couple of hp,
> but at what expense? Erratic idle, probably, but
> that is not major. What you
> could end up with is a high speed imbalance.
> 
> OK, just looked through the good book on this...
> Smokey comes really close
> diety status, and whatever this man has said, I take
> like the Gospel. If you
> take more than 3 grams of weight off the counter
> weights, you WILL have to
> have the entire reciprocating assembly rebalanced.
> Wait a sec, that's for an
> already balanced engine. If you want to knife edge
> the crank, you will need
> to have the reciprocating assembly "balanced" first
> (you need to know the
> weights of the counter balancers and each
> corresponding piston/rod combo).
> There is a formula that is used to determine the
> balance needed for the rpm
> you want (you can not ever have a "perfectly"
> balanced engine, there will
> always be some different harmonics at different
> engine speeds). This will
> determine how much you can take off. Unless you are
> building a
> balls-to-the-wall maximum hp engine, Smokey doesn't
> this is too important.
> 
> Ron N. - Dalton, GA
> 90 SHO
> 89 325i
> (OO==00==OO)
> "It takes a man to suffer ignorance and smile"
> 
> 
> ----- Original Message -----
> From: "James White" <greensho@crown.net>
> To: <shotimes@autox.team.net>
> Sent: Sunday, May 09, 2004 2:19 AM
> Subject: Re: [Shotimes] knife edge crank
> 
> 
> > What is a "knife edge" on a crank?
> >
> > And how could anything with the crank effect idle?
> >
> > regards, Jim White - greensho@crown.net
> >
> > ----- Original Message ----- 
> > From: Ian Fisher <dataflash@yahoo.com>
> > To: <shotimes@autox.team.net>
> > Sent: Sunday, May 09, 2004 12:02 AM
> > Subject: [Shotimes] knife edge crank
> >
> >
> > > Has anyone had their V6 SHO crankshaft knife
> edged
> > > during a motor build up? Any thoughts on how it
> may
> > > effect idle or possibly cause other problems?
> > > Benefits?
> > >
> > > TIA
> > > Ian
> _______________________________________________
> Shotimes mailing list
> Shotimes@autox.team.net
> http://www.team.net/mailman/listinfo/shotimes



	
		
__________________________________
Do you Yahoo!?
Win a $20,000 Career Makeover at Yahoo! HotJobs  
http://hotjobs.sweepstakes.yahoo.com/careermakeover