Knife Edging (Ask An Engine Builder Part 6)

[@pauloconnor7951]

Per David Vizard it throws oil in path of connection rod increasing resistence. Porsche and (another) tested it and went with another design that throws oil to main caps (no resistence) and increased power / faster revving.

[@temptnottheblade]

Nice, I arrived here after binge watching DV's videos. Another benefit of reducing windage is ensuring that the viscosity of the oil remains the same. One thing that I didn't grasp entirely was how to calculate the balancing. There must be a formula around.

[@BarrackObama-ds4jj]

​@@temptnotthebladedavid vizard is a blessing on this planet

[@meostars]

If it is found please do post it and/or forward it. Much appreciated. Cheers!

[@mikediamond1522]

David Vizard has a good video on profiling the leading edge of a ceank and another about balancing. Mike

[@petertrevena9460]

Love my son's video's & his mechanical knowledge of engine's! 🤙

[@mahabirmohan8843]

Greetings from Trinidad and tobago , very insightful series you have here

[@NEVER-LIFT]

Thanks 😄

[@ziadkabbani4479]

Quickly becoming one of the channels I look forward to seeing the most. Keep up the great work! Very informative

[@NEVER-LIFT]

Thanks mate I’m glad you like the videos I intend to do many more videos. I would have liked to have a few more done and uploaded but time is my biggest hurdle at the moment

[@martinfalls1023]

Thanks for that clear and direct explanation. Beats all the guff we get on soooo many sites.

[@anthonyfato7488]

Solid video man. Really enjoying the content

[@NEVER-LIFT]

Cheers 👍

[@mixter7x7]

I milled all the casting marks off my crankshaft. Polished and put radials on the ends of the counterweights and then re-balanced. All rods polished. I put silicone wipers inside my case to wipe the oil off the edges draining the oil into the scavenge pump scupper. Oil would not stick to my crank and rods. I also did some mods to my wheelie bar. I dropped 2 seconds on the 1/4. Most on the start being able to apply full power without spinning my back wheel.

[@NEVER-LIFT]

wow do you have photos? DM me on insta

[@mixter7x7]

@@NEVER-LIFT No pix. 25 years ago. Any photos went with my wife in our divorce. We did the balance calculation before milling/polishing the crank and could not remove any more material. You also kinda need some metal for a crankshaft. The motor wouldn't idle below 1000 rpm but would accelerate like nuts.

[@broughxtreme]

Some yrs ago I did a Datsun 1200 engine for speeway use in NZ. I went radical and COMPLETELY removed the counter weights. Shit that thing could buzz.

[@ryandeweese363]

Excellent video!! I was thinking about getting my crank knife edged but was only wanting to "Edge off" the same amount of weight I could drop with the new conrod and piston combo, say 200grams per combo, knife off the same on that counterweight... That way, atleast in my mindset, it would still keep the factory balance, just be matched lighter, and have the added benefits...

[@jamesrindley6215]

I know this is an old comment, but from my understanding the crankshaft balance mass doesn't fully offset the piston and conrod but instead about half of it. That's because you can never fully balance a reciprocating mass with a rotating one.

[@krusher74]

your idea makes sence to me, but i did not uderstand the guy in the video wanted a heavier counterbalance for more revs?

[@TRDKhanbrothers]

Awesome man, great info here, thanks for explaining the true definition of knife edging cranks

[@matthewpham]

Well I just learnt something new today. Good stuff 👍🏼

[@peanutsmcgonnagle2458]

'As someone in the business, none of the major manufacturers of crankshafts today, Crower, Bryant, Eagle, Callies, Scat, etc., no longer knife edge their racing crankshafts. But some used to, no doubt about it.

[@isaactezza]

Learnt so much from these, thank you so much

[@NEVER-LIFT]

Thanks for the feedback man 👍

[@radishtrader5591]

picked up a crankscrapper for windage

[@markolisica1132]

Properly explained!

[@exploranator]

Considering that the leading edges of the crank are impacting an incompressible fluid in the form of oil drops/windage, you have to ask yourself this: "Why don't they knife-edge the leading edges of the counterweights/throws?" If they knife-edged the leading edges and trailing edges, drag would be reduced, also, but literally no one in the history of engine building has ever done this, to my knowledge. Take it from a physicist: I have seen custom-carved cranks with a ROUND front edge on their crankshaft throws and counterweights, and that would be GREAT if it was for ONLY moving that crank through compressible air. However, it is NOT, so there is energy to be found by knife-edging not only the outer circumference of the crank parts to shed oil and cut through any windage, but the front and rear of the surfaces also. (relative to their motion through the emulsion of air and oil) I have found in the hot rodding game, the people who make the most money on selling hot rod parts are most often violently resistant to any innovation, but the facts will ever remain: ANY and ALL masses that are going through an incompressible or partially incompressible medium need to be razor-sharp on the trailing and leading edges to maximize efficiency and minimize wasted energy. Supersonic aircraft use razor-sharp leading edges on their nosecones. They don't have ROUND nosecones, because air at that speed (over sonic) behaves in an incompressible manner. The wing leading edges do not interact with the air in a predictable angle of attack, so they are rounded to maximize results over a broad envelope of angles of attack. I marvel at how completely these facts have been bypassed by designers of boat hulls AND other bodies in which fluid dynamics are critical. That round blob at the front of a submarine isn't for hydrodynamic efficiency. It is to provide a consistant interface between the sea water and the sonar dome. It's an acoustic refraction issue, not an issue of streamlining, as incompressible fluid (water) laughs in your face if you think it is easier to slice through with a blunt, rounded front end than with a sharp snoot. Look at how God made the fastest fish on Earth: the black swordfish. Isn't it interesting that it doesn't have a blunt prow on it, but instead, a long, gradually-tapering needle? Also in the top five: the mako shark. Does it have a basketball nose? Nope. Look and learn, hot rodders. Knife edge the leading, trailing, AND outer edges of your crankshafts, and you will find: A) less windage, absolutely obviously, due to oil slipping off of the crank outer circumference and less impartation of crank motion to the oil and air B) less drag due to a finer entry to the oil spray in the crankcase by the crank, and, C) less drag due to a finer departure of the air (emulsion, really) flow as the crank part continues past it, and the air being allowed to gracefully rejoin after being split by the body of the part in question D) less drag due to better airflow attachment to the surface, which makes (C) more likely to occur with minimal losses. We churn our crankcases like they are a brick in a butter mill, yet, our boat propellers are knife-edged on their leading AND trailing edges. Blunt leading edges super-completely-only achieve lowest drag if and ONLY if they are traveling ENTIRELY through a compressible medium. Also, I'm not even getting into the importance of area rule, which they have just recently discovered applies to subsonic AND sonic flow. There is lower drag available than what is being used. Lower drag and lower windage. Bodies travelling through compressible media DEMAND very-finely-pointed leading and trailing edges for minimum drag.

[@fuzzayd4601]

Pretty interesting. I never thought of the fact that the crank is balanced without rods or pistons on it. So the weight of the balanced crank shaft compensates for all those other unbalanced things. So less crank weight is a lower crank balance ratio. So stiffer springs for higher rpm mean more crank weight needed.

[@aergaetrhethaergertha2099]

Keen to see more content 🙏

[@NEVER-LIFT]

Working on it bro 👍

[@steves8014]

Good on the pros and cons of knife edging. Sounds like you'll keep the mass and rather have higher safe RPMs. If you were willing to take the time weighing and balancing how would you know if on your particular crank if you can get away with some lightening? Wouldn't simply using much lighter rods and pistons allow shaving counterbalance weights?

[@keithtobin5369]

Thank you for that information how about an inline six?

[@lastcent5140]

I'm really keen to hear more about all the things he's done to reduce oil starvation, or some more information on how he filled part of the water jacket with cement. Not things you see in any old 4age build or manual

[@lastcent5140]

Actually, I'd be interested in hearing his opinion on how much scoring on camshaft wear surfaces is too much. As you know, they're a bit concerning as they're solid pieces that wear on the head and cap

[@mtperformanceengines3508]

Concreating a block is a pretty old school method of strengthening the bores if you watch the 800hp build we explain a bit more but I will add it to the list of videos to do

[@thomasroth4695]

How does this affect oiling? Crank sling. drilling outside of counterweight vs center and knife edge. a crank to balance it isnt it

[@NEVER-LIFT]

It was just a point Mat made about how the crank travels through the oil in the sump and can cause aeration and knife edging may reduce that. He was just trying to give as many examples as he could on the spot to why people knife edge cranks

[@truckiedon4303]

Can a 2zz crankshafts knife edge work in a 7afe???

[@outsider7658]

Very interesting. One question though: How do I measure the weight of the amount of material to remove, from each counterweight? Eg, when I have a "complete" crank.

[@NEVER-LIFT]

Mat explained to me that the only way is to sacrifice a crank and cut it into pieces I think there might be a section of a crank on the bench in this video

[@krusher74]

you use a crank balancing machine.

[@damageincorporatedmetal43v73]

Furthermore, there's an automobile manufacturer that actually had a composite camshaft out of Asia. And they were able to use for Variable valve timing.

[@LeviSkinner-l9n]

I know this is an old post, but I just got here... anyway, my question for Matt: I've always heard there is an inverse correlation between performance and durability. I don't need more power but I'd like to increase the durability of my 4a-ge. What type of upgrades would you look into to make this particular engine bomb proof?

[@brianslicanderson3240]

Think about this! @ 200mph there is an excess of 2500 psi(per square inch) in water! Oil is thicker than water but a lighter specific gravity! Never the less hitting water, oil, Or concrete @200mph is going to produce a significant amount of hydrodynamic parasitic Drag! Especially in a stroker crank configureation w/3-5” of counter weight hanging out in the wind or oil in this instance! The bigger the crank diameter the higher the rotation mph! @ 7-8k rpm’s crank rotation mph is around 300mph depending on the stroke of the crank!

[@haroldhprittjr7007]

Do you know very much about the v-6 4.0 as in performance? I found that there use to be a bunch of different items for power adding but they’ve stop production or just don’t make anything any more . I can get builders that will make you things but it’s all one off things like custom crankshafts bore the block and sleeve it . I really would like to add some more compression and some larger cams . There use to be a cam company that kept them in stock but not any more. I seen were a guy makes his own but he’s about 2000$ for the set of 4 cams . I don’t think there’s any warranty of any kind on them . Oh nice video on knife edging the crank counter weights I’ve done just the leading edges before but nothing crazy like the crank at the beginning of the video . That’s extreme wow I couldn’t believe that. The motor is 1G-RFE 4.0 Toyota the first two years single vvt I’ve got a rebuilt set of heads I’ve already ported and polished I left the intake runners like a little rough I think I stoped at 120-180 grit but combustion chambers and exhaust are super smooth I went big on my exhaust to match my headers ! Thanks for the video I’m subscribed now !

[@lechela92kxngserumala3]

Uhm. Still mind boggled about the rpm limiter having to be reduced due to weight loss on the crankshaft because I have in my car taken out from my e30 a standard 318i crank shaft with 8 counter weights and replaced it with a 318is one that has 4 counterweights, so I find it hard to believe that knife edging your crankshaft is a bad idea at all as BMW have taken off 50% counterweight off their IS crank and it’s still as well balanced and and able to perform at it’s best. I feel like when you knife edge your crankshaft you should just make sure whatever you do on one side you do on the other to maintain the balance. Hope that I’m making sense. Even if you’re not running a flat 4, 6 or whatever, the crankshaft rotation balances itself out.

[@JohnDoe-mx1sq]

Yeah you just need the proper counterweight, not more or less. If you have more then the crankshaft itself will be putting the forces on the bearings, less and the acceleration/deceleration of the rods and pistons will be putting forces on the crankshaft. Crankshafts are balanced to rod and piston sets with bob weights. The RPM is limited by the camshaft, springs, and valves moreso than the balance of the crank. After that it is limited by the mass and geometry of the rod and piston which influences rod stress, piston speed/accel/decel, and mass which puts forces on the crank.

[@stevesolo16]

Can the knife edge crank be balanceable ?

[@dylanfry6078]

so a question springs to mind here (ive always thought knife edging was to do with reducing friction with the oil ... never heard of said idea about airating the oil) - are aftermarket 4age pistons available now, or possible to make for a worthwhile cost, where you could fully knife edge a 4a crank (and not have to keep rpm low)? - when would you make high hp and do it? ...im aware one of audi's engineering contractors is doing some interesting and promising looking r&d with 3d printing hollow spaces in piston material lately - I know the tech is there, but heaps too pricey as far as im aware ....?

[@jonathan7744]

Yes there are a couple different 4age 16v forged pistons available. Don't know much on the 20v side, never looked.

[@celicasaur]

Nice video :)

[@NEVER-LIFT]

Thanks mate

[@peterfuchs7822]

What about crank scraper. Thanks for the great videos.

[@markolisica1132]

Can you ask Matt for me, what would be a better motor for my skyline, Gallo 12 or Gallo 24?

[@mtperformanceengines3508]

Gallo 24 those motors taste mad

[@firstrespondergarage]

Yes usually the people that don't understand engine balance also call the harmonic damper a harmonic balancer.

[@NEVER-LIFT]

I'm probably guilty of this lol

[@TheRealFrankWizza]

I have a Porsche 944. The 2.5 in it, has 2 balance shafts. I always know that a harmonic balancer can't handle an unblanced rotating assembly, but what about an engine with balance shafts? I really like the design of this engine. It's very advanced for the time period.

[@geoffdeller7747]

they (Porsche) licenced the balance shaft technology from Mitsubishi.

[@xbns3828]

Wondering if he'd recommend the hall effect kit that you can find with mrp. Since he decided to go a different route with the jz reluctor

[@vwracingsrilanka8199]

Can we counter weight a standard crank by welling parts to it ?

[@krusher74]

you cant but they might break off at high revs or fuck up the heat treating of the crank, the right way is bore holes and fit weights (the weights are a material that are heavier than crank material)

[@gonefishing4903]

Does a 20v head fit on to a 7a block or even 3sge block?

[@ma61king]

Yes to 7A, need a different timing belt and tensioner mods, no to 3S

[@Samqdf]

What about putting heavier than steel slugs in the counterweights? I do know it is a known thing that can be done but I am guessing that it's too expensive to justify doing for most.

[@thebikecrafter8128]

i also think of that

[@juanmatos3959]

Good video, but I have a question, what are the things you need to do if you want to build a high revv motor

[@exploranator]

Knife-edge all edges of crank, stiff valve springs, titanium retainers, hollow valves, sodium-filled on exhaust side, lightest connecting rods and pistons you can afford, light flywheel, larger ports and passages leading to intake and exhaust valves, and a shorter stroke-to-bore ratio.

[@JohnMcMahon-yf5ks]

What about V engines?

[@Michael_Lorenson]

Excellent, thanks

[@sweetness34km]

I have a moldex crank knife edged not as sharp as this.

[@damageincorporatedmetal43v73]

I've often thought about this process. And that's what left me to ask about Connecting Rod ? Why do they not knife Blade them also? With carbon fiber, some of the composite that are available today. Why is someone not looking into this as a way to help a Gasoline or Diesel Engine more efficient. Like you've already stated it's about Aerodynamics. When they generate Electricity then don't cut through the air with a block of steel. they use a blade. When designing an engine for performance. Anything that in the path of the intake must go. That's why there is Porting and Polishing. Now back to the connecting rod it's not going to be straight up and down as one would think. It's either gonna have bent appearance, @ the aft. Or depending on the Manufacturer it might even be a bit off-center on Bore. 4cyl's taday are making more power than what most eight cyl's. Made back in the day. And now we've got supercharged, twin turbos That are pushing the limit. The lower half is the Heart of the engine. We've got today in this age Carbon Fiber Drive shaft's... Just think about it that's what creates inovation & yes Balance.

[@jonathan7744]

I think the reason is due to strength. to knife edge the rods you sacrifice too much strength to be worth it.

[@exploranator]

Though this is a valid point, the cost involved versus the technology investment would be phenomenal. Ultimately, if they just aggressively evacuated the crankcase, which is an existing technology, a few benefits would be realized, including less suspension of oil droplets in the less-viscous air mass.

[@liberaltears6328]

Would it be a good idea to polish the entire crankshaft on a Slant 6? Knife edge?

[@NEVER-LIFT]

every engine Mat builds he polishes the crankshaft

[@edros221]

I want to see you built a 2zzge engine😉

[@kemarjbrown1752]

I second this. Preferably 2zzge 2.0 on boost

[@edros221]

@@kemarjbrown1752 sounds great!.....👀👀👀

[@NEVER-LIFT]

Noted

[@donavenable]

I did knife edge on 4age 16v OEM crankshaft with the flywheel OEM crankshaft pulley OEM and thereafter balancing all three together.. What's your opinion on that..

[@broughxtreme]

Why do they knife edge the outside of the crank and not the leading edges? Doesn't make sence to me.

[@enricocolina9620]

nice video. plz. help me understand on some hi revving de-stroked 7afe engine from 85.5 mm stroke to 77mm stroke (custom 8 bolts) which makes 1.6 7age able to rev higher .should the custom crankshaft be heavier ?and the longer rods and pop up piston should it be lighter by how much? ratio. target is 11k rpm thank you.

[@Samqdf]

You are going to need the lightest piston and rod combination possible to do that. There is a formula that measures part of the con-rod weight and all the rotary weight to find out the correct counterweight mass. Here is an article on it: www.onallcylinders.com/2016/03/17/the-basics-of-crankshaft-balancing/ They say 50% of the rod weight but I have read that's dependent on the tuned RPM. At a minimum you are going to end up with a 15mm longer rod so that's some extra mass you will need to compensate for. With the combination you have listed it will give you a rod / stroke ratio of 1.78:1 pending on the exact length rod you go for. You goal is extreme, I would expect that you would need to make that ratio much higher again by pushing the pin height into the oil control ring. If the pin is shifted another 5mm further up then it's a 1.84:1 ratio which is a much better place to be. I only know of one proven and running 4age engine running at 11K and that person was using a custom piston that didn't even have a second compression ring. With all the above keep in mind I am not an engine builder, this is just so you might have a head start on what to research.

[@enricocolina9620]

thank you

[@robertfontaine3650]

I keep looking for dynamic balancing of rotating assemblies with knife edged cranks and not finding it. I would have though this would be an incredibly important step for any engine. Putting your engine out of balance seems like a generally shit idea. My expectation is that knife edging would be done only as much as is possible to keep the engine rotating assembly in balance but that doesn't seem to be the case.

[@jesusyeshuaelelyonelshadai6295]

Will it rev up faster with those cuts

[@bryanteet7635]

Stepdad had his bike knife edged still revs to 11,000 rpm fine. Is it only a car issue or something?

[@snap_oversteer]

Good video, my question is: When you use thinner headgasket/have decked block/head etc., is it necessary to run adjustable gears to compensante for the different crank/cam gears distance? I've heard about it somewhere, but I'd like to know if it's really necessary.

[@radishtrader5591]

ide say it wont effect that much, if you are worried just get a larger headgasket to compensated for the block/head

[@snap_oversteer]

@@radishtrader5591 Yeah, in my case I want to run TRD gasket to get compression ratio up a bit with GZE pistons. But I've also heard that no cam gears are needed and that it'll just have smaller tension on the belt.

[@radishtrader5591]

@@snap_oversteer tbh i didnt worry about that when i rebuilt my engine. i just ran the same setup that i had. i cant imagine it being a huge huge problem. if your mechanic inclined enouf you could drill your stock gears and make them like the trd gears

[@Samqdf]

From what I calculated previously it works out to close to only 1 degree of cam angle for every 1mm of change in height. To put it another way the difference it makes is insignificant.

[@TheObersalzburg]

Seeing that most cranks are mass produced on automated machinery that is easily programmable, and no engine manufacturer is knife edging their cranks, I have to say that if there was a significant benefit, it would be common from the factory. Spend your time and money on items that are actually important. Great video.

[@donnatalielucasheimbigner7598]

Also, if the engine is in a pickup or a SUV, the lighter crank will reduce the torque that the engine produces under sustained load, reducing its ability to keep RPM while being "lugged". The heavier mass is harder to get moving but will tend to stay moving longer & with less throttle input.

[@clemonthopkin4513]

I was considering swapping out my blacktop rods for silvertop rods and blacktop pistons on my next blacktop engine build...Now I am wondering if it will disturb the balance? To be honest my engine never sees 6k, so i am guessing it wont matter much. Great content as usual.

[@bryanduggan]

Never sees 6k? You only need a 4A-FE 😘

[@clemonthopkin4513]

@@bryanduggan nawnaw thats my baby. I dont need to press hard to go fast. 1/2 throttle is more than enough.

[@Samqdf]

All three models of 20V engines use the same part number crank so no it won't effect the balance any more than the standard variances. But why change the rods at all though if you are only using low revs? Besides they are 20 grams lighter.

[@SG-wp6sg]

And what about polishing instead of knife eddging?

[@NEVER-LIFT]

Mat likes to polish his cranks whenever he can

[@tarantula441]

Hi matt, will my blacktop 20v run more reliable with a silvertop oil pump and bearing tensioner combo? Versus the existing hydraulic tensioner?

[@JDMAE92RSI]

Yes.

[@mtperformanceengines3508]

Yes it's a much better system to run the 20v silvertop pump and tensioner and its also cheaper

[@jeronimodantas7792]

MAS ME DIGA AQUI UMA ;ESSA PREPARAÇAO SEM REDUZIR O PESO DO VOLANTE DO MOTOR NAO ADIANTA NADA

[@zAvAvAz]

moment of inertia?

[@lospadrinosofficial]

What do you think of the new GR86?

[@NEVER-LIFT]

I like it but I don't like the engine

[@victorbracamonte7152]

Subtítulos en español por favor

[@hendrix2478]

Why the music at the start. Lol

[@driverjamescopeland]

Knife edging a crank is useless, unless you're specifically building for limited RPM. The best option is to tungsten plug it, then reduce the overall profiles (axial, and radial) as much as possible.

[@NEVER-LIFT]

Best option is custom crank but I get your point 👍

[@driverjamescopeland]

@NEVER-LIFT - Everything I said, including knife-edging, would be custom. Did you mean something like a full billet crank?

[@NEVER-LIFT]

@@driverjamescopeland Yeah, I had the option of buying a TRD crank back in the day and after speaking to Mat I decided against it. If I want to go crazy Marine Crank is the best option (also the most expensive) I can have anything I want made and I'd just let Mat spec it out, It'll probably be a stroker crank. I also saw multiple Marine Crank boxes when we visited Hasselgren. I originally asked Mat about knife edging when we were coming up with a plan for my engine and he explained that it was a bad idea. I just asked the same question for the video to try and help people out.

[@wayneo7220]

I'd rather put the money in a dry sump than touch the crank if I want to reduce oil windage.

[@mikesperling8758]

I liked and subscribed to your video but I thought it was going to be something better. I thought we were talking about V8 stuff so whatever on a good note. You knife edge or bullnose and if you have a lathe you undercut. And if you are using a real expensive crankshaft from like Weinberg or other companies been there gun drilled and you make power. But that little stuff and how you knife edge the whole top off yeah you're completely taking all your counter weight away. Not talking bad just thought I was watching a good video

[@NEVER-LIFT]

lol I get it not everyone has a love for these little engines. I might need a V8 in my life soon though🤔 thanks for your support man

[@inaNis_]

I have a question! What’s a 9age? I’ve heard some rumors about it but I don’t really know what it is to be honest.

[@dylanfry6078]

1.9L-age

[@briancolvin6554]

I wouldn't have thought anyone would knife edge a crank without balancing....😅

[@krusher74]

people do allsorts with a grinder in a shed.

[@joesalazar770]

Only problem with removing all this weight is u loose torque always keep inind what torque is. It seems no one knows any longer.

[@NEVER-LIFT]

Torque is the reason I went 7a

[@bajanboyhood]

I wouldve though majority of the weight associated with crank counter weights and flywheels was related to idling at low rpm and driveability at low speeds. You're mentioning balance factor but a four cylinder engine fires 1 piston at a time. Most cars if not all cars dont make the same power on each cylinder wheres the balance factor there?

[@1magnit]

If you're spinning it up without bobweights then you're doing it wrong.

[@michaelwalker4799]

clown talks 3 min and wow