underdrive pulley

[MikeBergy]

Originally posted by 92b16vx@Jul 6 2005, 11:24 AM

Torsional vibs have nothing to do withthe physical balance of the motor, so what you said about distinguishing v8's from hondas is completely irrelevant.

How on earth do you figure that?

[post=521576]Quoted post[/post]​

Because the torsional vibs are directly related to the combustion in each cylinder; engine balance is a completely separate thing.

 

[xj0hnx]

Ok, I haven't read it all, but nothing thereeaddress that a lightened pulley, is going to be worse than a lightened flywheel. Hell I would think that since a pulley weighs a lot less, and the difference between a lightened flywheel and a lightened pulley, is proportionately less, that a lightened flywheel would have a much greater effect on said wear.

I am not trying to argue that torsional, or harmonic vibration doesn't effect engine wear, nor that modifying things like flywheels, crank pullies could adversly effect motor longevity. I am saying that replacing a crank pulley with a lighter one, is not going to be the downfall of your engine that people try to claim, as opposed to many other modifications that people do. There is a long line and pullies are not that close to the front of the line. I think you are getting that I am trying to say that none of these forces effect motors, and you can freely do what you like, and that is not true.

 

[xj0hnx]

Even this from one of the sites you posted supports my thinking...

Many engines, including virtually all V8’s, V6’s and inline 6’s, use a device on the free end of the crankshaft to attenuate the amplitude of what could otherwise become destructive torsional oscillations of the crank. These end-to-end torsional vibrations of the crankshaft are caused by the alternating compression and combustion pulses described above. Without an appropriate absorber, V8 crankshaft life can be measured in minutes at full power.

Many of the automotive 4-cylinder engines don’t require such an absorber, primarily because of their inherently higher stiffness-to-mass ratios. However, several automotive manufacturers have initially omitted a torsional absorber from early engine runs, only to find that crankshaft life was unacceptably short. The Nissan folks discovered this with the early 240-Z engines, which didn’t have an absorber, and therefore lasted only about 100 hours in automotive (i.e. VERY LIGHT DUTY) service.

Often, the vibration attenuating devices on the free end of an engine crankshaft are incorrectly referred to as "DAMPERS". In most cases, they are ABSORBERS. (That's not semantics. A damper dissipates energy, typically as heat. An absorber alternately stores and releases energy to counteract vibration. See VIBRATION BASICS.)

The elastomeric ("metal-ring-on-rubber-spring") devices used by the automotive industry (as well as by Teledyne Continental Motors on the GTSIO-520) are ABSORBERS which are tuned to counteract vibration at the frequency where the particular engine generates its worst torsional excitation.

Both Continental and Lycoming also use internal ABSORBERS in all their high-output engines. These absorbers are tuned to counteract particular orders of excitation. The internal absorbers consist of pendulous counterweights attached to the crankshaft cheeks by loose pins in hard bushings. The clearance between the pins and bushings establishes the torsional order which each counterweight absorbs.

One aftermarket device, the Fluidampr â„¢, really is a DAMPER. It dissipates energy by transforming it into heat by shearing action in a high viscosity fluid. Some race car people seem to like it, but it is banned from the top levels of NASCAR racing.

That type of damper is mildly effective over a wide range of excitations, but contrary to intuition and hype, it is significantly LESS effective in reducing vibration in a specific, targeted frequency range, the exact situation you have in an aircraft engine. (There is ample research in the engineering literature showing exactly that fact.)

Whatever device is used to absorb crankshaft internal torsional vibrations, it has an effect (usually small) on the excitation produced at the loaded end of the crankshaft around resonance. That device, together with the Mass Moment of Inertia of the devices attached to the output flange of the crankshaft, will affect not only the value of the crankshaft resonant frequency, but also will influence the longitudinal location of the torsional node on the crankshaft.

 

[MikeBergy]

Ok, I haven't read it all, but nothing thereeaddress that a lightened pulley, is going to be worse than a lightened flywheel. Hell I would think that since a pulley weighs a lot less, and the difference between a lightened flywheel and a lightened pulley, is proportionately less, that a lightened flywheel would have a much greater effect on said wear.

It all changes the torsional vibs on the crank, every component will have an effect. But the first and second modes are damped primarily by the pulley. Contrary to what you might think, Honda didn't just say "let's put this here piece a rubber between this here crank and pulley, and see what happens". It was designed to damp out a particular frequency. It was obviously important enough to put on there; it would've been cheaper to mnufacture a single-piece sold pulley.

Edit: How does that article contradict what I said?

I guess do whatever you want to your engine, it ultimately comes down to your choice. But IMO, any damping, or absorption, is better than none. more Vibes = more frequent rebuilds. If you are down for rebuilding you engine every year, then great. Maybe it will last longer than that, but honestly, there are so many factors that affect this is isn't even funny. The dampers/absorbers are designed to put the worst of the harmonic vibrations out oof the engines normal operating range. If you have zero damping, then you have zero control over the problems that may arise when operating an engine at one of its harmonic frequencies. But to each his own. I'll be doing my own research as soon as I have a good job and enough funding to perform the experiments.

 

[xj0hnx]

I know Honda didn't just throw one on, I have even stated as much previously. Honda also takes into account ride comfort and noise levels, along with running ascessories. And the pressed in runner lining is an industry standard, not just Hondas idea, and I seriously doubt that it is the make or break of an engine. And like I asked a long time ago, I would like to see what the effects of running a solid pulley, even the same size, just lighter are on two (preferably more) equivolent engines for extended periods of time. I just do not believe that that thin piece of rubber (which btw dries up after about 7 years to a hard plastic texture) is goping to absorb enough vibrations to make any difference whatsoever.

 

[erikespo]

Originally posted by 92b16vx@Jul 6 2005, 03:09 PM
I know Honda didn't just throw one on, I have even stated as much previously. Honda also takes into account ride comfort and noise levels, along with running ascessories. And the pressed in runner lining is an industry standard, not just Hondas idea, and I seriously doubt that it is the make or break of an engine. And like I asked a long time ago, I would like to see what the effects of running a solid pulley, even the same size, just lighter are on two (preferably more) equivolent engines for extended periods of time. I just do not believe that that thin piece of rubber (which btw dries up after about 7 years to a hard plastic texture) is goping to absorb enough vibrations to make any difference whatsoever.

[post=521619]Quoted post[/post]​

 

[MikeBergy]

Originally posted by 92b16vx@Jul 6 2005, 12:09 PM
I know Honda didn't just throw one on, I have even stated as much previously. Honda also takes into account ride comfort and noise levels, along with running ascessories. And the pressed in runner lining is an industry standard, not just Hondas idea, and I seriously doubt that it is the make or break of an engine. And like I asked a long time ago, I would like to see what the effects of running a solid pulley, even the same size, just lighter are on two (preferably more) equivolent engines for extended periods of time. I just do not believe that that thin piece of rubber (which btw dries up after about 7 years to a hard plastic texture) is goping to absorb enough vibrations to make any difference whatsoever.

[post=521619]Quoted post[/post]​

Well, belief can only be supported by evidence. It's not like that rubber is super soft to begin with, closer to the consistency of plastic anyway. Point is, it is going to give a lot easier than if it were metal, regardless of it's age.

 

[erikespo]

Who cares.. Let people put what ever they want on their engines... a dampener or not it does not effect your engine that much if any.

 

[dohcvtec_accord]

Originally posted by 92b16vx@Jul 6 2005, 12:09 PM
I know Honda didn't just throw one on, I have even stated as much previously. Honda also takes into account ride comfort and noise levels, along with running ascessories. And the pressed in runner lining is an industry standard, not just Hondas idea, and I seriously doubt that it is the make or break of an engine. And like I asked a long time ago, I would like to see what the effects of running a solid pulley, even the same size, just lighter are on two (preferably more) equivolent engines for extended periods of time. I just do not believe that that thin piece of rubber (which btw dries up after about 7 years to a hard plastic texture) is goping to absorb enough vibrations to make any difference whatsoever.

[post=521619]Quoted post[/post]​

I can tell you that I had a stock pulley on my WRX's EJ20 for about 30k miles, and I have now had a lightened (stock size) pulley for about 30k miles. There have been no noticeable impediments or problems thus far. It might not be *extended*, but I'll report back to you guys when I've got 90k on the engine.

 

[MikeBergy]

Originally posted by erikespo@Jul 6 2005, 12:24 PM
Who cares.. Let people put what ever they want on their engines... a dampener or not it does not effect your engine that much if any.

[post=521632]Quoted post[/post]​

spoken like a truly educated engineer.

 

[erikespo]

Fine you go ahead and redline your car with the stock pulley and i'll do it with out.. I garuantee they break at the same time.

 

[xj0hnx]

Originally posted by MikeBergy@Jul 6 2005, 08:20 PM
Well, belief can only be supported by evidence. It's not like that rubber is super soft to begin with, closer to the consistency of plastic anyway. Point is, it is going to give a lot easier than if it were metal, regardless of it's age.

[post=521627]Quoted post[/post]​

Right, but my point is, that I don't think that Honda put so much design into this wear item, that it is the corner stone of engine stability, nor that replacing it by using a lighter pulley that doesn't have one is going to destroy a motor.

 

[erikespo]

Your right it won't destroy a motor.. an out of balance motor that can rev very fast will though... Simple engineering is that the lighter your rotational mass the less wear you will have.

 

[xj0hnx]

Originally posted by dohcvtec_accord+Jul 6 2005, 08:24 PM-->

92b16vx

@Jul 6 2005, 12:09 PM
I know Honda didn't just throw one on, I have even stated as much previously. Honda also takes into account ride comfort and noise levels, along with running ascessories. And the pressed in runner lining is an industry standard, not just Hondas idea, and I seriously doubt that it is the make or break of an engine. And like I asked a long time ago, I would like to see what the effects of running a solid pulley, even the same size, just lighter are on two (preferably more) equivolent engines for extended periods of time. I just do not believe that that thin piece of rubber (which btw dries up after about 7 years to a hard plastic texture) is goping to absorb enough vibrations to make any difference whatsoever.

[post=521619]Quoted post[/post]​

I can tell you that I had a stock pulley on my WRX's EJ20 for about 30k miles, and I have now had a lightened (stock size) pulley for about 30k miles. There have been no noticeable impediments or problems thus far. It might not be *extended*, but I'll report back to you guys when I've got 90k on the engine.

[post=521633]Quoted post[/post]​

Thank you I know several people, one that I mentioned on a HTR, that have been using them for thousands and thousands of miles, and more than a couple years, and have had no problems whatsoever.

 

[MikeBergy]

Originally posted by dohcvtec_accord+Jul 6 2005, 12:24 PM-->

92b16vx

@Jul 6 2005, 12:09 PM
I know Honda didn't just throw one on, I have even stated as much previously. Honda also takes into account ride comfort and noise levels, along with running ascessories. And the pressed in runner lining is an industry standard, not just Hondas idea, and I seriously doubt that it is the make or break of an engine. And like I asked a long time ago, I would like to see what the effects of running a solid pulley, even the same size, just lighter are on two  (preferably more) equivolent engines for extended periods of time. I just do not believe that that thin piece of rubber (which btw dries up after about 7 years to a hard plastic texture) is goping to absorb enough vibrations to make any difference whatsoever.

[post=521619]Quoted post[/post]​

I can tell you that I had a stock pulley on my WRX's EJ20 for about 30k miles, and I have now had a lightened (stock size) pulley for about 30k miles. There have been no noticeable impediments or problems thus far. It might not be *extended*, but I'll report back to you guys when I've got 90k on the engine.

[post=521633]Quoted post[/post]​

the first and second modes of vibration might not be within the normal operating range of your engine, and in that case, you will have no more problems than you would with stock. That is my point for most of these posts. There are lots of parameters that effect how well yoour engine will hold up. But to not have a damper, I'm just saying you will have no control over the vibrations. Chances are your engine will be fine. Judging from the fact you went to vishnu, you will be fine
Vishnu is the shit. As for everyone else, as long as the pullley is designed to put the vibes out of the normal operating range, you are golden. The problem comes from poor engineering, and that is probably what is causing this whole problem to be a problem in the first place. Someone like OBX probably came out with a pulley set, and it sucked. Things like that just happen sometimes. It may be that some of the pulleys still have enough weight to move the harmonic frequencies away from the operating range, but I am not sure. I do know that solid pulleys do not damp/absorp the vibes at all, so if you hit one of those harmonics often enough, beware.

 

[MikeBergy]

Originally posted by erikespo@Jul 6 2005, 12:27 PM
Fine you go ahead and redline your car with the stock pulley and i'll do it with out.. I garuantee they break at the same time.

[post=521639]Quoted post[/post]​

Wow, don't post anymore

 

[erikespo]

Or maybe OBX sold some pulleys that were out or round or were not balanced and it created virbations.

 

[MikeBergy]

Originally posted by erikespo@Jul 6 2005, 12:29 PM
Your right it won't destroy a motor.. an out of balance motor that can rev very fast will though... Simple engineering is that the lighter your rotational mass the less wear you will have.

[post=521643]Quoted post[/post]​

Wrong once again. Where do you go to school?

<_<

 

[erikespo]

so heavier engine parts that have more enertial force are better for engines?

 

[dohcvtec_accord]

Originally posted by MikeBergy@Jul 6 2005, 12:36 PM
the first and second modes of vibration might not be within the normal operating range of your engine, and in that case, you will have no more problems than you would with stock. That is my point for most of these posts. There are lots of parameters that effect how well yoour engine will hold up. But to not have a damper, I'm just saying you will have no control over the vibrations. Chances are your engine will be fine. Judging from the fact you went to vishnu, you will be fine
Vishnu is the shit. As for everyone else, as long as the pullley is designed to put the vibes out of the normal operating range, you are golden. The problem comes from poor engineering, and that is probably what is causing this whole problem to be a problem in the first place. Someone like OBX probably came out with a pulley set, and it sucked. Things like that just happen sometimes. It may be that some of the pulleys still have enough weight to move the harmonic frequencies away from the operating range, but I am not sure. I do know that solid pulleys do not damp/absorp the vibes at all, so if you hit one of those harmonics often enough, beware.

[post=521650]Quoted post[/post]​

I think we need to extrapolate your post a little bit here to view the big picture. People have been, and will continue to, experience problems from a host of different mods to their car. Others won't experience any problems with the same mods. I think what we're really trying to say is, if you're going to mod your car, be ready for the problems associated with your dabbling. They can and WILL happen, even if you buy the best parts and have the best mechanics install them.