Benefits of a knife-edged crank?
03-23-2006, 08:51 PM
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Benefits of a knife-edged crank?
I just pulled apart my block and my crank is knife-edged. I am debating re-using it in my new build and was wondering the advantages of a knife-edged crank over a stock crank?
Thanks!
Thanks!
03-23-2006, 11:12 PM
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is knife edging on a crank safe for a boosted motor? the reason i ask is because i heard taking all that weight off a crank is not good especially if its pressurized power. can anyone confirm this, or am i smoking crack.
03-23-2006, 11:13 PM
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Re: (HKSuperSi)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by HKSuperSi »</TD></TR><TR><TD CLASS="quote">is knife edging on a crank safe for a boosted motor? the reason i ask is because i heard taking all that weight off a crank is not good especially if its pressurized power. can anyone confirm this, or am i smoking crack.</TD></TR></TABLE>
i dont see how boost would have an effect on the crank. The crank isnt being pressurized...
i dont see how boost would have an effect on the crank. The crank isnt being pressurized...
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03-24-2006, 05:46 AM
#9
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Re: Benefits of a knife-edged crank? (turbotime)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by turbotime »</TD></TR><TR><TD CLASS="quote">so it reduces the weight of the crank as well?</TD></TR></TABLE>
well...yeah.
you have to remove material to form the knife edge on the counter weights so it's obviously lighter.
knife-edge benefits:
lighter rotating assembly = quicker/freer revs
less oil build-up on the counterweights
quicker oil shedding
moves through oil in the pan quicker
better hope they balanced it correctly though if you're gonna rev high.
well...yeah.
you have to remove material to form the knife edge on the counter weights so it's obviously lighter.
knife-edge benefits:
lighter rotating assembly = quicker/freer revs
less oil build-up on the counterweights
quicker oil shedding
moves through oil in the pan quicker
better hope they balanced it correctly though if you're gonna rev high.
03-24-2006, 05:53 AM
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I have been told by many sources that knife-edging is not prefered in an FI car because it makes the crank weaker. In boosted applications the idea is to make the bottom end stronger to withstand the greater forces created by the huge increase in horsepower, when you build a N/A motor the idea is to make the reciprocating assembly as light as possible which is where knife-edging is prefered because of the decreaded drag created by the crank and the decreased weight.
03-24-2006, 11:13 AM
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i may be wrong but i thought the main purpose of knife-edged cranks was to cut through oil better, thus reducing friction......honda cranks do not come in contect with oil in the pan tho
03-24-2006, 11:29 AM
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Re: (99B16Si)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 99B16Si »</TD></TR><TR><TD CLASS="quote">i may be wrong but i thought the main purpose of knife-edged cranks was to cut through oil better, thus reducing friction......honda cranks do not come in contect with oil in the pan tho</TD></TR></TABLE>
my understanding too but it would make it lighter which would prove just as beneficial...i see how it would make it weaker, you are removing material from the counterweights as long as it has enough weight to keep it in balance i dont see how that is going to make it weaker...
my understanding too but it would make it lighter which would prove just as beneficial...i see how it would make it weaker, you are removing material from the counterweights as long as it has enough weight to keep it in balance i dont see how that is going to make it weaker...
03-24-2006, 12:44 PM
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Originally wasn't knife edging for V8's with large crank throws.
Knife Edging looks to have aerodynamic benefits.
I think I've read this somewhere though.
Knife Edging looks to have aerodynamic benefits.
I think I've read this somewhere though.
03-24-2006, 12:53 PM
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Re: (WrecksHurt!)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by WrecksHurt! »</TD></TR><TR><TD CLASS="quote">Well, it seems to me, when on a turbo application, the pros do not outweigh the cons. I would just go with a micropolish and balance.</TD></TR></TABLE>
i am curious if there really are any cons unless it takes it out of balance i dont see how it will weaken it
i am curious if there really are any cons unless it takes it out of balance i dont see how it will weaken it
03-24-2006, 01:01 PM
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Re: (dornon13)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by dornon13 »</TD></TR><TR><TD CLASS="quote">i am curious if there really are any cons unless it takes it out of balance i dont see how it will weaken it</TD></TR></TABLE>
The higher you rev the bigger the counter weights need be.
So lighter rotating assembly has to be verified and whats taken out the crank for edging needs to be thought out.
The higher you rev the bigger the counter weights need be.
So lighter rotating assembly has to be verified and whats taken out the crank for edging needs to be thought out.
03-31-2006, 12:46 AM
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Re: (btotherizzle)
point out some facts first....
:the crank is a rotating assembily, it has counter wieghts to equal out the momentom of the pistons/rods..
:romoving area from the wieghts will not affect the strength, for they don't take the stress
:"if" the crank contacts the oil it will slow it down thus coasing drag and a loss of power.. think of it this way take your hand and with an open palm slap water... yeah it kinda stings... now take your hand and turn it sideways like you going to judo chop the water, goes threw much easer... it is the same way with the crank and oil
:when reving higher it just means things are spinning faster, no extra weight needs to be added, or taken away.. it just needs to be balenced or made even.. example..
say your bike has a warped rim from casing to much because you can't ride.. haha.. but yeah say your pedaling down the street you feel a little bit of a hump... but the faster you go the worse it gets... this is the same with all rotating masses
this hump will get worse and then soon cause failure...
:last of all.. boosting is a whole dif ballgame, you can't just single down a object like a crank being a week spot for boosting there are way to many aspects, and i have never heard of a honda crank failing unless it was something else first like a rod, piston, lack of oil...
:the crank is a rotating assembily, it has counter wieghts to equal out the momentom of the pistons/rods..
:romoving area from the wieghts will not affect the strength, for they don't take the stress
:"if" the crank contacts the oil it will slow it down thus coasing drag and a loss of power.. think of it this way take your hand and with an open palm slap water... yeah it kinda stings... now take your hand and turn it sideways like you going to judo chop the water, goes threw much easer... it is the same way with the crank and oil
:when reving higher it just means things are spinning faster, no extra weight needs to be added, or taken away.. it just needs to be balenced or made even.. example..
say your bike has a warped rim from casing to much because you can't ride.. haha.. but yeah say your pedaling down the street you feel a little bit of a hump... but the faster you go the worse it gets... this is the same with all rotating masses
this hump will get worse and then soon cause failure...
:last of all.. boosting is a whole dif ballgame, you can't just single down a object like a crank being a week spot for boosting there are way to many aspects, and i have never heard of a honda crank failing unless it was something else first like a rod, piston, lack of oil...
03-31-2006, 05:59 AM
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Re: (spiney360)
<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by spiney360 »</TD></TR><TR><TD CLASS="quote">point out some facts first....
:when reving higher it just means things are spinning faster, no extra weight needs to be added, or taken away..
.</TD></TR></TABLE>
Um what the hell are you talking about?
If you rev higher you acutally need bigger counter weights, but people lighten for performance reasons.
:when reving higher it just means things are spinning faster, no extra weight needs to be added, or taken away..
.</TD></TR></TABLE>
Um what the hell are you talking about?
If you rev higher you acutally need bigger counter weights, but people lighten for performance reasons.
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