CRANKSHAFT KNIFE EDGING, What is it? How do we do it and what are the benefits?
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- Опубликовано: 26 сен 2024
- In todays vlog, we show how we we knife edge a Renault 5 Turbo crankshaft for ultimate performance. We also show the progress on the Austin Healey engine build
What impresses me is the ability to produce interesting content on a daily basis. It's easy to get hung up on production values and forget that people value regular content that's produced to a good standard over cinematic quality!
Thanks so much, glad u enjoy 👍
I understand the knife edgeing reduces the cross sectional area presented to the air and oil in the crankcase. This reduces parasitic losses. To now balance this crank requires either heavy metal, which is not desireable, not be added back onto the counterweights. Or you drill the rod journals hollow to remove the equivalent mass as removed from the counterweights. I need to see that video.
Another method is presented by Dsvid Vizard in his PowerTec 10 series. In a couple of videos he goes into crankshaft balance for power. He illustrates adding weight directly opposite the rod journal because that is easier to visualize. Then he shows those same two weights at 90° to the rod journal center line and at the main center line. At this point the crank balance is not affected, just crankshaft weight. What he is demonstrating is removing weight off the front and rear faces of the counterweights as referenced to the rotation. If you remove say 20g from the counterweight as indicated by the balancer about opposite to the rod journal, by removing metal or weight from the front and rear, you can remove much more mass in total. If this is removed in such manner as to push oil droplets toward the main web, this oil is removed from interaction against the rotating assembly as it then runs down the main web to the sump. Instead of removing 20g from that counterweight, you could remove 40g or more. This lightens the whole crank and reduces rotational mass. This aids acceleration.
I've seen the same Power 10 clip. Good stuff! Car people make quite generous and encouraging family.
U didn’t really say whether there were any negatives around knife edging my understanding is that in some engines a higher mass crank is beneficial in quenching undersirable harmonics which can lead to crank failure I guess engines vary tho
Could you Please show us how you Balance the crankshaft ? That would be Excellent to see, im sure im not the only one that would enjoy that :) Cheers .
Wow! You have a winning formula of content here guys! Keep them coming, I'm sure I'm not the only bloke who love to watch them!
Thanks so much Daniel 👍🙌
old machinery is probably the best thanks for the video
what you and others do not realize, is that the counter weights are, counter weights ! they are there to offset a specific proportion of the reciprocating portion of the crank assembly
All this metal removal will enhance engine vibration, shorten main bearing life, and at worst
crank failure .... if your looking for free HP, best to look at the aerodynamics of leading and trailing edges
Exactly my thoughts my 540 we did leading only and why not put a vacuum pump on it as well. Got 25 free hp with it
You make no sense it still gets balance one would think they take off weight on the opposite side
@@RICHCREWSPLASHSET but there is no weight that can be removed from the opposing side ! The counterweight is set by a numerical value of reciprocating and rotational mass .... ask any engine designer and he will agree with my initial statement, I hope I do not sound like a knowit all prick, but I have forgotten more than most know about ICE
The next one on the balancing will be interesting! I think it's really going to be about the weight savings where you gain performance and responsiveness, but better cutting through the oil will be negligible. At 3k rpm there won't be a whole lot of oil to cut through, it's going to slosh all over the insides and not really be floating at crank lobe level
Messing with a dry sump build the big win I read about was mesh or chicken wire to grab the oil as it left the rotating parts. Apparently a lot bounces back into the crank.
When you've got something rotating, lowering the mass will lower the moment of inertia - and as that's mass x radius^2, the further away from the centre of rotation that is, the bigger the gain.
But the knife edging is not solely about cutting through the oil it’s about reducing windage in the sump and reducing the suction created by the piston traveling up the bore.
I just watched a Vizard video on this and, unless I've misunderstood, he says the counterweight should be shaped the other way so the high points are closest to the main bearings so the oil is flicked off away from the rods/pistons, thus reducing the windage losses. He quotes 7bhp at 7000rpm total gain from counterweight reshaping (with a more rounded profile), which I think was for a flat-plane V8, so should be similar for an inline-4.
I can see the logic to the way you've done it in the video, it does seem intuitive to have the most mass closer to the centreline of the journal crank throw it is balancing but I don't think that actually really matters as the crank isn't bending enough for it to be significant.
Awesome, brings back happy memories of my apprenticeship in the early 90s working on Colchester lathes 😊 and also in machine shop I worked at in the 2000s.
Good work 👍
wooohooo great to see a BMC C series engine in your workshop.
i rebuilt one for my 1955 Wolseley 6/90 several years ago with minimal machining required, the 6/90 has the 2.6L, my 1961 Wolseley 6/99 has the later 3.0 litre engine.
i've since acquired a couple of 6/90 parts cars with 2 more of the 2.6 engines, one of which i have had running.
Regards from Australia
Were they out of a Westminster? I've read they are an exceedingly heavy engine
@@stephenscholes4758 g'day stephen, no all my engines are genuine Wolseley engines, a friend here in Australia has an A90 Westminster that he had restored a few years ago, it was his father first car, it is much smaller than the 6/90, the later A99 & A110 were the same size as the Wolseley 6/99 and 6/110.
the A90 had a tiny single solex? carb, the 6/90 had twin SU, and the Austin Healey's with the BMC C engine had either twin or triple SU's (different head for the triples)
the 3.0 litre engine in the A99/6/99 & A110 and 6/99 and the Austin Healey 3000 were regarded as bullet proof, the earlier 2.6 litre engine from A99, 6/99 and AH 100/6 was doubly bullet proof, although a flaw was later discovered in that long term rust could erode from the water jacket into the oil feed to the head, there is a patch requiring drilling from the side and from the top and installing stainless steel sleeves to fix that issue, we have the AH folks to thank for finding that issue.
i'm just about to take the engine out again, as i now have the parts to fix the gearbox properly, i was unable to get all gears due to wear on the cross shafts and bronze selector forks, the engine sounds freaking awesome, and i can't wait to see how well the overdrive works now it is all connected properly. (dad in law fitted it but never installed the kickdown switch, and had a relay which would stick on, so he never got to utilise overdrive)
It's amazing to see the width to diameter ratio of the crank journals of the Healey six cylinder engine. Today it seems to be all about the larger diameter and narrow widths to give an overall shorter engine.
Remembering of course that engine was originally out of an Austin truck.
David Vizard recently did a very interesting video on knife edging and crank modifications.
do you have a link?
Here you go
ruclips.net/video/rQXCiaqdva0/видео.html
Seen this way of doing it many times. Its effective for reducing the rotating weight, but, imagine splitting each cylinder up, and think about how the remaining counterweight is offsetting the weight of the big end. Think about it long enough, and you will see how you are setting up mass that tries to flex the crank across the pins. Works fine when the crank is plenty strong, but no good in high stress applications, or where a long service life is required. Much much better to shape the leading and trailing edges of the counterweight, or if that is not enough, turn some material off the outside diameter.
I was just thinking that. Shaping the leading and trailing edge would help with windage. Shaping the radial edge wouldn't account for much, except for wind shear as it swings past the rod.
@@biohazardousBiker e già che ci siete consigliate di aggiustare la posizione dell'utensile perchè cosi non tornisce bene ;-)
It's a tight place for sure!
I was always thinking about turbulence in the oil pan whipping up the oil.
brilliant and very clever, you clearly know what you are doing 👍👍. Please vould you tell me what a flat plane crank is? and whats the difference?
Very nice! Great job with the video!
I had thought nife edge was really done much anymore. I was surprised to see that. Thank you.
Curious about the balance on that crank now that so much material has been removed and how you bring the crank back into balance nice video 😁👍
Looking forward to see how to balance these components! Good video guys
Fantastic Work, Thanks for the education. Following up with a video demonstrating how fast it could rev up would be nice!
I'm sure by "cut through the oil" you meant the oil falling and returning to the sump.
I can't believe how many people think the crank runs through the surface of the oil in the sump.
Windage...
@@gazzafloss Still doesn't go through the surface of the oil in the sump...
@@bcbc8649 I do realise that, #windage.
Stationary? No. But there's a chance with moderate G, also oils can foam, or at least used to when they ran more detergents due to impurities (shows my age with mineral oil based 20/50 engines). The last engine I worked on to any real depth had side and top baffle plates to keep the crank 'dry'. It was ultimately converted to a dry sump, but even with a pressurized casing and pumped extraction still had a hefty top baffle.
Great video 👍
My god reminds me of my dad as he had a Healy lol , I wish I could strip an engine and rebuild it
Glad you have made this video i was just thinking about this subject last night
That is a lot more weight off than I ever would have thought, should make the engine rev up more easily and better response. Good insight to this process.
Very interesting and informative video
Great stuff
Am very Interested in this stuff engine building . Need to learn everything .this is great video thank you
Thanks Mo
Knife edging: Old mod & good Idea!
Great stuff 👏
Fascinating.
Great video…..will get my mk1 golf gti lump to you next year!!!
Top man 👍
Good idea for short life racing motor
My tech that's doing my engine build is doing this to my Saturn SL2 3rd gen crank and I have an aluminum Fidanza flywheel as well. Just was curious to see what advantage it has. I'm doing SCAT forged rods, JE forged pistons 10 to 1 , port and polished head, mild intake valve deshrouding, mild bowl blending, dual intake cams, and after the 1000 mile break in period it'll be running 10 PSI with an E85 blend so it'll be Bruce Lee in the weight department with the polymer body panels, carbon fiber hood, and the Einkei RPF1 15X7 at 9.8 LBS per wheel. And I added a Mfactory LSD, just an expensive ordeal...lol
Interesting, I always wondered why more cranks are not knife edged for weight savings and less oil frothing at rpm. Balancing it would be nice to see to.
Lovely!
Every knife edged and balanced crank we’ve done in our race engines has crapped itself 😂.
Not surprising - the knife edging shown here has removed about half the counterweight. Each counterweight exists to oppose (balance) the crank pin, conrod big end and about half the piston and conrod small end, for the benefit of reducing crank bending loads and bearing loads. Reducing counterweights (or not having them in the first place) is ok for low revving engines and/or those with extra wide bearings and oversize crankshafts for small pistons (more likely in old, low power engines).
DV has a video explaining how much material can be removed and from where. Knife edging looks like a lazy way of getting a few faster revs. Basic rule of thumb is you can take off the crank the same weight you have reduced the rest of the rotating assembly by.
@@stuartwinter2758
I’ve always left it to machine shop to do tbh. I just send the cranks to be balanced these days, I balance all rods and pistons in house.
Engines I tune high rpm and knife edging isn’t allowed in the regs for bsb or wssp.
Great video , am I correct in assuming the engine has lighter pistons and rods allowing the weight removal from the crank ? Cheers
Great video
Good day... I need your help to understand something about 4 cylinder engine balancing... Please explain - how are inline 4s balanced to match the pistons & rods to their crankshaft? I've seen you(like in this vid)balance the crank & flywheel & clutch assembly - & in another vid, I've seen you balance a set of pistons & rods - but I've never seen you, or anybody for that matter, balance a piston
od set with their crank etc... Or is it that the pistons
ods balance themselves(as I imagine same happens when the crank pane is horizontal\vertical)... I want to have an idea of how much weight I'd be able to take off my crank, in regards to how much lighter my new piston
od combo is - or on the other hand, how much I can 'hack off' my stock crank... Thanks in advance... =]
Great video Lee, really educational
Back in the 1980s I raced 100cc karts - with uber high revving two strokes [circa 20K]. We used to get special knife edge conrods from the engine manufacturers and tuners - not sure if that's ever done on 4 stroke racing engines, maybe the revs aren't high enough to warrant that ?
Love to watch a detailed video on balancing. Is it still true that taking 1kg off the weight of the crank/piston assembly is like reducing the weight of the car by 100kg+?
More effect in the first few gears and not so much as you go up the gears?
No shot peening or 'riding process to replace the toughened surface you have machined away? Nor chamfering all those sharp edges including where balance holes were drilled?
Are you able to give 'figures' on what benefits there are? Such as BHP or acceleration
The Renault crankshaft is very clean meaning little to no oil staining. Have you done some kind of cleaning prior to the start of knive edging?
Fantastic video
makes me what to work there ace 👍
Cheers Aaron 🙌
Eventually if you look at this rotating and reciprocating mass problem for long enough you finish up at a gas turbine :o)
I suspect that operation voids the original manufacturer's warranty?
So if the webs are there to counter ballance the weight of the rods and pistons, after doing this, how do you now match the new crank weight to the rod/piston weight?
You can balance the entire engine assembly together. But it pays for everything to be balanced before doing so.
For example, old school turbos were heavy and could be balanced outside of the core, modern turbos have much more refined components that require balancing at every step of the process. Compressor wheel, turbine and shaft, turbine and shaft with the thrust washers, compressor wheel and nut. Then marked in a position to indicate the clocking angle for balance of everything. Fit into a core and balanced again with the seal rings fitted and an oil feed hooked up. The frequency of the imbalance pretty much defines how perfect the balance needs to be for a lasting product. Modern turbos go up to 300000 rpm so they need to be near perfect or the frequency of the imbalance will be so high it will simply wear out and make pleny of noise.
@@Blandy929 your talking about turbos which is completely different to lightening and balancing an engine as far as I can see.
Balance is Balance. The turbo was just an example. You are measuring for the same thing. I cant see an engine assembly ever having the balance a turbo does but there isnt a major requirement for that anyway. Its not gonna see super high rpm.
Look up dynamic balancing if your interested, id say thats the most common amongst rotating assemblies.
@@Blandy929 A turbo dosnt have the option of large amounts of weight removal, its a tiny amount to ballance them.
Should be forget turbos as there not what my question was about. Please.
ruclips.net/video/XjuGkXpha8Q/видео.html
The moment of inertia for a solid cylinder is I = 1 2 m r 2 .......
👍
It would be interesting to see a crank being tuftrided or nitrided and the difference.
I am an amateur but I wouldn't spend the money on it. I happened in to one once and it doesn't hold up if the bearing gets beat out of it and I have never seen a steel crank crack so I have always thought it was pointless.
Cutting into the original balance holes, does this not induce a whistle when the engine is running?
Interesting. How does that affect the pickup of an engine? Does it affect the torque at all?
Better pick up, less torque, but not really :o) The pinto I my van has a much bigger flywheel to make it happier at low rpm. I suppose I am saying a big flywheel stores more energy than a small one.
Stand an MTB upside down on it's seat and bars. Rotate the pedals by hand to get the rear wheel going really fast (use a high gear). Now take the wheel out and remove the tyre and inner tube and put the wheel back. Rotate the wheel to a high speed again. Feel how much less effort it takes without the tyre in place.
Increasing the rotational speed of any rotating mass requires the input of energy which is proportional to the value of the mass. Less mass, less energy required.
Thus, if you lighten the rotating assembly of a car's drivetrain (crank, fly, clutch, wheels, tyres) less energy is required to increase their rotational speed. That energy produced by the engine can now be used to accelerate the linear velocity of the car instead.
So to answer your questions directly, YES and YES.
The entire rotating mass acts as a flywheel to smooth out the power pulses from an IC engine. More mass = more smoothness. So there is a balance to be struck when building an engine. Reduce the rotating mass (especially from the outsides) and improve the responsiveness of the engine. Take a little off for a road engine = slight reduction in smoothness and small improvement in responsiveness. take tons of weight off for a race or rally engine and get huge improvement in responsiveness at the expense of smoothness (esp a rougher idle).
HTH
less inertia
My 68 Cooper S 1275 engine build has a wedged crank (knife edged). Engine builder is specing it for 7500rpm redline. lots of other changes to get to this point. 2 years in the making. (covid)
Why don't you knife edge the leading edge of the counter weights as well? Seems that would help it go though the oil rather than the flat face?
Im quite a Wiking fan from DK.. how many of those rotations pr. Minute is the lathe put on? Great jawb you do...
As those weights that are knife edged are to balance the pistons going up and down, do you need extra light pistons to keep it dynamically balanced?
The weight of the pistons is irrelevant. They aren't rotating.
@Wilbert If you are building a high performance engine - yes. Each counterweight exists to oppose (balance) the crank pin, conrod big end and about half the piston and conrod small end, for the benefit of reducing crank bending loads and bearing loads. Reducing counterweights (or not having them in the first place) is ok for low revving engines and/or those with extra wide bearings and oversize crankshafts for small pistons (more likely in old, low power engines).
@@e-curb piston weight is very important as is conrod end to end weight. it all adds to the harmonics and one piston or rod out of balance to the rest can lunch a motor in no time
@@abitofeverything9970 I never said having one piston heavier than any other isn't a problem. The weight of the pistons has no effect on the rotational balance of the crankshaft.
@@e-curb yes it does! The weight of the pistons and rods DOES affect the balance even though they are reciprocal not rotational. Watch some videos on crank balancing... Which iv done plenty... Bob weights... End to end, even weirghit wrist pins and C clips. Everything.
Should imagine there would be less drag on the crank and make the motor pick up a little quicker
in metalwork we always had suds on has anything changed ?
If I remember correctly,if the crank is made of cast iron then it's not reqd as cast iron is self lubricating.
Why do you use a 3 jaw chuck and not clock it in on a 4 jaw?
What it used to mean was making the leading edge of the counterweight aerodynamic by making it come to a point. Similar for the trailing edge of the counterweight. What you're doing here seems pretty pointless to me. It's messing up the balance.
would not dry sump kit be more advantageous than sloshing through oil?
It doesn't slosh through oil. The crank isn't submerged the oil is raining down onto it the same as a dry sump
Just shows how manual machines still have a place in the workshop.
why do cranks brake quicker after knife edging
Is "wedging" still a thing?
My man who I can’t say knife edges, gun drills tuftrides and nitrides the cranks
What's the machine called?
I never understood the purpose of knife edging other than weight. Inside the crankcase it is so turbulent and chaotic you're not going to gain anything drag wise. Air and oil are being flung in every direction you could possibly imagine.
Exactly, air and oil is being flung everywhere, but the stuff hitting stationary walls doesn't matter. The stuff that the crank hits does, every hit imparts energy, which now becomes waste energy instead of BHP. The less the crank webbing hits the less energy it's wasting, and hitting continuous rain drops of oil with a crank doing 7000rpm quickly adds up to quite a bit of energy.
I would think you would want to stay far away from those balance holes.
I worry about the balance of the crank being affected by this method .
I watched the follow up video which explained how the balancing works :)
Your definition if knife edging and mine aer completely different.
Love watching that can't wait to see more
Originally known as wedging the crank
😎👍👍
I can't believe people still think this is a good idea.
im doing this with a colchester lathe now. its Made in Danmark West. says colchester student ... wtf Student was a german air nazi something.. Colchester is dinmarc so I kind a support it.. your accent of danish is wrong mate. 5 stars thou... Odeeen.
Don't do it ,lighten the pistons and rods not the crank it will reduce the RPM
Oh boy, tractor engine mods….yawn.
You like useing Malory?
Did that 30 years ago .it worked very well for my application .