Lightweight Crank Pulley Check-In

[ramsack]

The energy is converted to heat. This can happen through any medium. I really don't understand your point at all. And the crank pulley spins and there is air moving under the car...this is where the heat goes, into the air. Also, some goes into the crank, but I'm sure the crank is warmer than the pulley, so the pulley is still a heatsink.

Removing your balance shafts can also cause oil pump failures, which causes engine bearing damage... There are a lot more people that have had oil pump failures, with a balance shaft removal, than people whom have had a crank break (there's only one I've heard of) yet you do a BSE and preach against a solid pulley.

This has been discussed to death. It is from people using non-OEM parts to eliminate the balance shaft. We are preaching to use an OEM part or better, that is of course dampened. Mitsubishi makes the parts to remove the balance shafts because they figured out it would be cheaper to not have them on the tinier engines used in the CHEAP colts and mirages. Comfort obviously had no place in designing those cars. It is also recommended to use straight-cut gears from the early pumps when eliminating the BS.

 

[KazooGS-T]

I know a couple of people who have used all OEM parts (oil pump/BSE/timing) and still had failures on new builds. You are correct about the straight cut gears, but there are very few people that know about them and it's still not a guarantee. The issue you get into with OEM parts or not, is the fact that the gears have the ability to separate or push away from each other.

If people so widely knew about the issues regarding this, you wouldn't see constant threads about oil pump failures after a BSE or on a new build with a BSE. People tear up OEM pumps, along with aftermarket pumps, with the latter being the more prevalent. The issue is still there. AMS makes a kit that will help to cure the problem, but it's not cheap comparatively speaking and lets face it, 98% of DSM'ers are REALLY cheap.

 

[ramsack]

It was obviously user-install error. You don't see cars with factory-installed non-BS pumps failing like that. Most of the reason factory things last longer is because everything is assembled in a controlled, sanitary environment, and the parts are brand new.

Installing a BS cannot cause bearing failure. It is so indirect what you are speaking of. Anything that can make an oil pump fail can cause bearing failure. We are talking here about a DIRECT cause, and not necessarily failure, but premature wear.

I also know people that have tried the DSM, and were total idiots about working on them, and guess what? Their shit failed. Now they go around saying they are a junk platform, which is 100% their opinion. Fact is their car operated completely fine and normal until they started messing with it. Someone can make a car fast, but you never see them work on it, so you assume they must know what they're doing.

 

[KazooGS-T]

It was obviously user-install error. You don't see cars with factory-installed non-BS pumps failing like that. Most of the reason factory things last longer is because everything is assembled in a controlled, sanitary environment, and the parts are brand new.

Installing a BS cannot cause bearing failure. It is so indirect what you are speaking of. Anything that can make an oil pump fail can cause bearing failure. We are talking here about a DIRECT cause, and not necessarily failure, but premature wear.

I also know people that have tried the DSM, and were total idiots about working on them, and guess what? Their shit failed. Now they go around saying they are a junk platform, which is 100% their opinion. Fact is their car operated completely fine and normal until they started messing with it. Someone can make a car fast, but you never see them work on it, so you assume they must know what they're doing.

There are some people with high hp builds that had these problems... Like I said this is a much more common problem than a crank pulley destroying bearings.

I still haven't seen any substantial proof that bearing failure is caused, because you are applying different concepts to one application; assuming they arrive at the same result.

In theory things can work out on paper, because it is theory. Just because something works out on paper does not mean it's real-world application will necessarily do the same.

The oil pump failure is a distinctly noted problem, which most people don't even connect the dots to, because the information is not out. You are applying a theory to your ideals, stating them to be fact and downplaying other problems that are much more dominant in the DSM world.

There are numerous people that use a solid pulley and never have a SINGLE problem. Like I've said, I've only seen one instance of crank failure where a solid pulley was used, and there are too many factors to decisively decide that the pulley was at fault.

I'm not saying the ATI doesn't make a great product, that serves a purpose, but I am saying that you are over-exaggerating a problem based upon no first hand knowledge of the issue.

 

[ramsack]

Pull me a ratio out of your ass of what you think the number of people who have a BSE vs. a solid pulley are? Then another stat of those 2 causing failures...

YOU think the crank pulley problem is exaggerated, and I feel your note about BSE causing pump failures is exaggerated, and TOTALLY user installation error. We all have our opinions. I'm sure the information is not out for the oil pump failure because when tearing things down those people probably saw their error or realized they used crappy parts.

Also, I bet there are ZERO failures when people use something like this AMS 4G63 Race Balance Shaft Eliminator Kit or had their own machined.

Even so I stick to my point about some engines not even coming with the shafts from the factory, and those pumps last just fine, making my point even better that it is user install error.

 

[KazooGS-T]

I already stated something about the AMS kit. Also, in that link they tell about the relation of a stub shaft to oil pump failure, reinforcing everything I said.

Please find factual information for yourself, speaking that you haven't even had the ability to find one defined failure based upon the use of a solid pulley.

You are grasping for breath here, making yourself look immature and pointing fingers. If you have no knowledge on a subject you are speaking about, and don't even have sources to come anywhere close to proving your point, you really don't need to talk.

 

[dsm-onster]

It causes no harm. Other platforms show failures. I will NOT bother posting all the results. OR even waste my time with just one. It's not material to the discussion because supporters demand specific evidence without even knowing the true nature behind the purpose. With that said. Running a balancer causes no harm; we can all strike an accord with that. Scientifically it makes sense; we can all strike an accord with that. the difference in the piece of mind for the rest of us is a minimal cost, and minimal loss in power.

How much does a crank flex? What is good for the goose is good for the gander. It's possible for e it to flex enough to damage the bearings. I only count one who's posted here with NO problems with their crank/bearings after running no balancer for substantial miles.

 

[ramsack]

I am not grasping for anything here. You came into a thread that was having a healthy discussion about crank pulleys and basically bashed everyone by saying it doesn't matter and trying to change the subject.

The AMS kit is for people eliminating something that was put there in place of a stock piece. As I said there are plenty of 4g## family engines out there from the factory without balance shafts that are fine. It's only when people modify something when things go wrong.

 

[KazooGS-T]

How much does a crank flex? What is good for the goose is good for the gander. It's possible for e it to flex enough to damage the bearings. I only count one who's posted here with NO problems with their crank/bearings after running no balancer for substantial miles.

I haven't seen ONE that's reported a problem while using a solid balancer. There have been a few people that said they've had one of their vehicle for a few years with no problem.

I am not grasping for anything here. You came into a thread that was having a healthy discussion about crank pulleys and basically bashed everyone by saying it doesn't matter and trying to change the subject.

The AMS kit is for people eliminating something that was put there in place of a stock piece. As I said there are plenty of 4g## family engines out there from the factory without balance shafts that are fine. It's only when people modify something when things go wrong.

I did not come into this thread bashing anyone, only showing a simple overlooked fact.

The balance shaft argument came up far before I ever posted, I related the issue of not having balance shafts to the crank pulley which was already previously, compared.

Also, with your line of thinking it's only when people modify something things go wrong is completely off. In that case, everyone's car on here should have blown up. The whole reason for modifications is to make improvements on lower quality/performance items.

Also, everything OEM manufactured isn't perfect... Look at the crankwalk issue with 7-bolts. A manufacture balances out quality with cost, choosing the right combination for profit. They don't make every decision with a high respect for engineering ideals, but rather for a profit margin.

 

[dsm-onster]

If it doesn't hurt and could very possibly help. . .

 

[KazooGS-T]

If it doesn't hurt and could very possibly help. . .

Ok, since you asked so nicely... I will give you a hug.

 

[dsm-onster]

Yea funny


Regardless of the current "prove it" banter thrown out around here by amateurs, the science is sound. And other platforms similar have seen failures. What reason is there for the balancer? Mitsu is in the game for profits like the rest of the world.

 

[KazooGS-T]

Yea funny


Regardless of the current "prove it" banter thrown out around here by amateurs, the science is sound. And other platforms similar have seen failures. What reason is there for the balancer? Mitsu is in the game for profits like the rest of the world.

It's there to run your power steering, air conditioning, and alternator. Other car manufacturers utilize a solid pulley/aftermarket produces them, and have used them for a long time with no ill-effects.

 

[ramsack]

Also, with your line of thinking it's only when people modify something things go wrong is completely off. In that case, everyone's car on here should have blown up. The whole reason for modifications is to make improvements on lower quality/performance items.

I was aiming at the point of when people modify their oil pump to accept the BSE stub. How many people measure clearances when tearing things down? Very few. The 7-bolt problem affected a tiny amount of people, and is blown way out of proportion, just like the Apple antenna crap lately. If it was me I would be pissed for having crankwalk happen, but not really pissed or anyone to blame but myself if I modified my oil pump and it failed.

Maybe we can agree that this is more of a platform-dependent thing to utilize dampened pulleys...?

A lot of manufacturers make things that are just meant to throw away and not last that long, because they are cheap. For instance the late Chevy Cavaliers that were automatic had no way to flush the fluid. No drain plug, no dipstick. I believe they did this to mean throw away your car when it breaks, and buy a Cobalt.

I think Mitsubishi cares more than that and put things on our cars to try to make them last. Call those things stupid, but I really don't believe you will get one of these cars to last 200k if you go and remove a lot of things like the balance shafts or put a solid crank pulley on, etc., even if you don't add more power. Add more power and things just get worse.

 

[dsm-onster]

It's there to run your power steering, air conditioning, and alternator. Other car manufacturers utilize a solid pulley/aftermarket produces them, and have used them for a long time with no ill-effects.

I am truely sorry. But I will be applying the opinion of a professional over yours What I have already posted: Crankshaft Dampers 101 - Mopar Muscle Magazine

Some of you seam to propone this will never happen. You need to provide evidence. more than 1-2. We's saying it will be a significant chance not 50% but why risk your motor for a 10-20% chance.

 

[KazooGS-T]

I am truely sorry. But I will be applying the opinion of a professional over yours What I have already posted: Crankshaft Dampers 101 - Mopar Muscle Magazine

Some of you seam to propone this will never happen. You need to provide evidence. more than 1-2. We's saying it will be a significant chance not 50% but why risk your motor for a 10-20% chance.

The pulley serves the purpose to run the power steering/ac/alternator. That is a main purpose.

It also says you can use aluminum and steel. That article says nothing negative about a solid pulley, it also applies to a block that has the camshaft located within it.

Every engine is different, some require different balancing techniques than others, especially pushrod engines. There are manufacturers that utilize a solid pulley, it's not a myth. Some engines require a certain weight of balance for their flywheels as well, ours do not.

I am by no means saying your are wrong, I'm just implying that different engine styles require drastically different balancing techniques. Most engines will not make it to 200k miles before having an issue, mechanical issues arise on every make and model of vehicle.

I think Mitsubishi cares more than that and put things on our cars to try to make them last. Call those things stupid, but I really don't believe you will get one of these cars to last 200k if you go and remove a lot of things like the balance shafts or put a solid crank pulley on, etc., even if you don't add more power. Add more power and things just get worse.

I completely agree. I was not trying to come in here and make people upset, only let people know there are other problems that are much more prevalent, and well documented. I do fully understand theoretical issues that can arise (I am a mechanical engineer), but issues that appear probable on paper do not always occur in a real-world application and the reverse as well.

 

[dsm-onster]

Having the cam inside the block has nothing to do with the balance of the crank. It says nothing negative about anything. It says why a damper is required.

Look at an I4 crank. You can see why it needs a "damper". Again, it's all on paper. But considier the difference in power. And considering there's no true collection of results, just one or two, you have to admit that there's nothing to base a decision on but the "theory".

 

[Colt4G63 also]

This thread is stupid. Most proponents for the soilid pulley just don't fully grasp the reason the damper exists. Saying "the crank is hardened so it can withstand those vibrations" is just assinine. Glass is hard, files are hard... See where I'm going with this? For those who don't: {Hard stuff shatters, soft stuff doesn't}

Did everyone not see the wine glass further up the thread. How is it not worth it? Every time you make your 6 extra horsepower, your crank is distorting and flexing around like that poor wine glass, and you are sitting there oblivious to the immenent peril that you are putting it in.

Yeah the glass didn't shatter instantly, and I'm sure that not EVERY glass will shatter on cue, or have that effect in the same amount of time, but when you can actually see what's happening (you can't on a crankshaft inside your engine), the risk is apparent and obvious.

"Some engines don't use a harminic damper" Yeah what, that crappy intrepid engine that blows up? Pretty much all engines have a harmonic damper, it's just not that easy to see on some, but it's there.

Ps. It's not really about how much power you are making, it's all about hitting that perfect pitch, and holding it there. If you knew exactly what that pitch was, and could run your engine at that pitch, and somehow keep it there, and have no damper, then your chances of catastrophic crankshaft failure would suddenly increase exponentially.

 

[300dollarGSX]

Humming beside a wine glass won't do shit because of 2 reasons, not enough amplitude, like we agree on, and the inaccuracies of the sound coming from a human, and not a machine.

The point I was trying to make about the glass is that even the frequency created by the device needed to be directed and amplified. Remove the device directing the waves and the glass vibrates much less. The glass analogy was just meant to point out that even objects that are more easily excited to resonance frequency still need a certain amount of force applied.

This thread is stupid. Most proponents for the soilid pulley just don't fully grasp the reason the damper exists. Saying "the crank is hardened so it can withstand those vibrations" is just assinine. Glass is hard, files are hard... See where I'm going with this? For those who don't: {Hard stuff shatters, soft stuff doesn't}

? Okay, I'm going to guess that it was me you are trying to quote in there. If you're going to quote me, please make sure you actually quote what was written. Did you even read what I and several others have tried to explain? I even suggested that using a Fluidampr was a better choice.

"Some engines don't use a harminic damper" Yeah what, that crappy intrepid engine that blows up? Pretty much all engines have a harmonic damper, it's just not that easy to see on some, but it's there.

Several smaller 4 cylinder engines lack a damper. My little Nissan Sentra with a 1.6L doesn't have one. It has a stamped steel crank pulley. It makes very little power and even less torque, but it has given me over 200k trouble free miles and gets 35+ MPG. As I have stated before, this doesn't mean that engines don't need them. It just means this crank isn't likely to reach a resonance frequency.

Ps. It's not really about how much power you are making, it's all about hitting that perfect pitch, and holding it there. If you knew exactly what that pitch was, and could run your engine at that pitch, and somehow keep it there, and have no damper, then your chances of catastrophic crankshaft failure would suddenly increase exponentially.

Your postscript is actually your most accurate statement. You're absolutely right, it's not all about how much power you are making. It is about the frequency. As I have posted before, though, the crankshaft is a spring. It is a torsional spring. Springs require a certain amount of force to start them to move, right? Blow off valves have a cracking pressure. Valve springs have an opening pressure. Well, the crankshaft works more like the spring that keeps the throttle plate closed, but the other examples are still useful for explaining that a certain amount of force is required to even start the movement. Since the crankshaft is a torsional spring and has several torque arms, or levers, it requires a certain amount of twisting force, or torque, to start those oscillations. A shorter, stiffer crank will take more torque before vibrating. That doesn't mean that it can't reach resonance frequency, though.

 

[dsm-onster]

4g series bearing failure from a solid pulley: Lightweight crank pulleys? - evolutionm.net



I'm too lazy to go through the math myself to findout if anywhere between 650-7500rpms the crank could be at a harmonic. If it wern't likely to see the resonant frequency, I would think the engineers would have known that and not have installed the "damper"; since the nissan sentra 1.6 doesn't have one and it's not about the power output. As it stands, apparently there is a forceful enough harmonic attained in the stock rpm range; qualifiers for that conclusion: the sole purpose of a damper, its presence, and capitalism. I don't need to go through the math to know that 234733 X 64748490 equals an undeniably huge number relative to 1+1 . Logic saves me.

Why is it that we always see the crank break between number 4 and the rear main? Because of the leverage from number one's twist. It's REAL, it's seen. There IS a vibration and it dOES do damage. Perhaps running much higher than stock oil pressures saves the bearings as the crank whipping adds up from the flywheel to the crankpulley. But there certainly is much more flex where the damper isn't present (hense, why a damper exists), screwing with cam and ignition timing alone. Plus wearing the crank prematurely. It's always "your call", but I4s have the below characteristic. Claiming this is a v8 thing or discussing rigidity is rather nulled by how intense the vibrations are for an inherently out of balance crank.

Balancer Tech.:

"The engine firing order provides the primary source of vibration. In a 4 cylinder four-stroke engine there are 2 combustion cycles per revolution - thus they produce even greater amplitudes of vibrations than a V8 which has four firing impulses each revolution ( fourth order vibration), or a 6 cylinder (three firing impulses per revolution -third order vibration)."

To the right there is a graph showing 2nd order excitation of a 4cylinder.

A patent for a torsional vibration damper:

 

[300dollarGSX]

From that very thread, post number 17: "Likewise, the intensity of the harmonics seems proportional to torque output, so a 500-600whp (or greater) setup is going to present a more serious situation."

Maybe his posts will hold more salt than mine for some reason, but the point I can't seem to make with anyone is:
A shorter crank + higher stiffness + high mass = lots of effort to reach resonance frequency
Now, again, I'm not saying that a damper or absorber isn't necessary. I'm trying to point out that the stiffness of the crank is relevant and to explain how those smaller 4 cylinder engines can get away without using a damper. They don't produce the torque necessary to bring the crank to resonance frequency, or if they do, they can't sustain it for any length of time.

Isn't torsional stiffness part of the very equation used to determine resonance frequency?

Honestly, I've never actually seen a broken 4g crank. I'll search to see if anybody has pictures. I do find it interesting that the broken cranks you have seen were broken between number 4 and the rear main. The vibrations usually get more intense as you move away from the flywheel. I suppose it is the side that actually has real resistance on it, though.

Yes, though, I do agree that the stock device was put there for a reason. I remember reading somewhere that these cars were some of the first to come with a 5 year powertrain warranty. I'm sure they wanted to make it as reliable as possible.

That's the second time I've noticed you say the crank is inherently out of balance. Why do you say that? It has a single plane and the rod journals are symmetrical end to end. Shouldn't that make it easy to balance? Now the fact that the pistons and rods are all moving up and down inline instead of opposing makes quite a bit of vibration with respect to the engine centerline, but that is engine vibration, not necessarily crankshaft vibration. The balance shafts were put in to cancel that out. The cranks factory absorber can only counteract torsional vibrations.

 

[donniekak]

Copied link from evom. This is the best condensed explanation of how a damper works, and why it's needed that i have read.
http://www.bhjdynamics.com/downloads/pdf/tech/BHJDynamics_Damper_Info.pdf

 

[Locke]

From that very thread, post number 17: "Likewise, the intensity of the harmonics seems proportional to torque output, so a 500-600whp (or greater) setup is going to present a more serious situation."

Maybe his posts will hold more salt than mine for some reason, but the point I can't seem to make with anyone is:
A shorter crank + higher stiffness + high mass = lots of effort to reach resonance frequency
Now, again, I'm not saying that a damper or absorber isn't necessary. I'm trying to point out that the stiffness of the crank is relevant and to explain how those smaller 4 cylinder engines can get away without using a damper. They don't produce the torque necessary to bring the crank to resonance frequency, or if they do, they can't sustain it for any length of time.

Engine torque has nothing to do with when the crank will reach it's natural frequency. This will be solely a function of RPM. The power applied to the crank will affect the intensity (or amplitude) of the effect. Lower output engines have less to worry about, because while still passing through RPM ranges which contribute to this, they produce less power thus keeping magnification to a minimum.

Cranks with a higher natural frequency may be outside the capabilities of the engine to match directly, (hell, maybe even all cranks) but the engine will pass through areas that will have still affect it, only to a lesser degree. Letting n=natural freq, then n/2, n/4, &c... The engine will all add to the amplitude of the vibration as RPM/2 pass these points, at a (presumably equal) decreasing rate. Any point that RPM/2 is outside of these ranges will work against the natural frequency.

 

[ramsack]

WHY DOES EVERYTHING LEAD BACK TO BALANCING???

Damping torsional vibrations have nothing to do with balance. This is what people need to get past! Maybe some engines don't need it because by the time these vibrations reach the end of the crank they can't be absorbed effectively. Manufacturers of engines have tons of equipment to measure these things. You do not. Mitsubishi measured this and decided they didn't like what they saw, so they added a damper! It is not just a pulley meant for driving accessories. You can't compare cars that don't even run accessories (1/4 mile only cars) because a damper won't stop wear in those engines. They are making a lot of power beyond ANY design limit on the engine, and they tear down and rebuild quite often, and can actually benefit from having no mass on the front of the engine. They are going for every little bit of extra power because money is no issue. We're talking about normal people who actually make use of these cars on the road, on a daily basis.

 

[dsm-onster]

From that very thread, post number 17: "Likewise, the intensity of the harmonics seems proportional to torque output, so a 500-600whp (or greater) setup is going to present a more serious situation."

Maybe his posts will hold more salt than mine for some reason, but the point I can't seem to make with anyone is:
A shorter crank + higher stiffness + high mass = lots of effort to reach resonance frequency
Now, again, I'm not saying that a damper or absorber isn't necessary. I'm trying to point out that the stiffness of the crank is relevant and to explain how those smaller 4 cylinder engines can get away without using a damper. They don't produce the torque necessary to bring the crank to resonance frequency, or if they do, they can't sustain it for any length of time.

Isn't torsional stiffness part of the very equation used to determine resonance frequency?

Honestly, I've never actually seen a broken 4g crank. I'll search to see if anybody has pictures. I do find it interesting that the broken cranks you have seen were broken between number 4 and the rear main. The vibrations usually get more intense as you move away from the flywheel. I suppose it is the side that actually has real resistance on it, though.

Yes, though, I do agree that the stock device was put there for a reason. I remember reading somewhere that these cars were some of the first to come with a 5 year powertrain warranty. I'm sure they wanted to make it as reliable as possible.

That's the second time I've noticed you say the crank is inherently out of balance. Why do you say that? It has a single plane and the rod journals are symmetrical end to end. Shouldn't that make it easy to balance? Now the fact that the pistons and rods are all moving up and down inline instead of opposing makes quite a bit of vibration with respect to the engine centerline, but that is engine vibration, not necessarily crankshaft vibration. The balance shafts were put in to cancel that out. The cranks factory absorber can only counteract torsional vibrations.

Another, better, way to say it: it cannot be made not to jumprope. There's more force being applied to the center than each end; about twice as much. Thus one reason you see why the amplitude of the 4cylinder vibration is so high. The other being the frequency of power strokes for the total length of the crank.

Also concerning what I put in bold. We're talking twisting. "twisting" is not bending of the crank arms. It is twisting the crank due to the forces exerted on the crank arms. Looking at it like this helps one appreciate how "easily" a crank twists. Yes, the leverage is greater with longer strokes. But there is still plenty of leverage there. Enough for a 4g61 to have been given a damper from the factory by the mitsu engineers.

Concerning what I underlined. He was tearing down his car after every few passes. How many miles of WOT is that? How many miles of WOT will you plan to use with your street car. Not being a proponent of street racing, you still have to see that you will put MANY MAN MANY more miles of hard use at a percentage of the torque required to kill the evo owner's motor in a few passes. Excitation energy is plenty enough since the engineers installed a damper on the stock 4g61 motor.

The crank continues to twist as you move away from the flywheel, yes. I already explained this. This is due to the sum of deflection of each lever. The individual deflection ends up being greatest at the damper (deflection from zero), but the most stress is at flywheel end since it is experiences leverage from each point after it. 4 veflects .4*. 3 deflects .4* relative to the second from the rear main. But deflects .8* relative to the rear main. And springs back with the help of number 4 springing back. So you're right and that is the very reason why it breaks between the rear main and number 4.

Since the weight of the flywheel acts to "ground" the crank on that end, a ligher flywheel theoretically would reduce some of the amplitude of the twisting as described above.