underdrive pulley

[xj0hnx]

From an Official Honda Technical training module number EN-17JA/1:
" Secondary vibrations in an engine are the result of uneven acceleration forces generated by the pistons rather than a weight imbalance."


This means NO MATTER HOW WELL BALANCED your engine is you will NEVER be able to cancel out engine vibration. To continue...

"To understand the diffrence in acceleration forces it is helpful to picture the motion of a connectig rod journal on the crankshaft(circular motion), the angle of the con-rod, and the motion of the piston as the crankshaft goes through one rotation.... In a 4-cylinder engine when each pair of pistons reaches TDC the amount of upward force is greater than the amount of downward force created by the other two pistons."

Adding belts for PS, AC change "harmonic balance", different length axles, different piston, rod, cam combos, etc...talk to people that make them, talk to Honda, talk to people that have been running them for years with no problems.

kthanx bye

 

[K2e2vin]

hes talking about torsional vibration...although it is almost impossible to eliminate it, it can be dampened.

 

[MikeBergy]

Originally posted by K2e2vin@Jul 5 2005, 04:34 PM
hes talking about torsional vibration...although it is almost impossible to eliminate it, it can be dampened.

[post=521064]Quoted post[/post]​

:word: it dampens the torque impulses created by the combustion process, and smooths it into a more continuous torque. It has nothing to do with shearing loads.

 

[xj0hnx]

Can someone offer up something that shows a B or D series crank pulley having a harmonic balancing that dampens engine vibration to lessen wear? Other than stories about other peoples worn bearing and oil pumps. Because if that's what we are going on, than I can site the guy here running UR pullies on his ATR H22A4 for quite a while with 0 problems, another guy running them on a 626, and I couple other people. Sorry, I have talked to manufacturers, Honda mechanics, or tuners, and find no reason not to run them due to "harmonic balancing" I wouldn't recommend them as a power modification, there's tons of things to do before that, but I certainly wouldn't tell someone not to get htem because they are going to destroy their motor.

 

[MikeBergy]

Originally posted by 92b16vx@Jul 5 2005, 04:43 PM
Can someone offer up something that shows a B or D series crank pulley having a harmonic balancing that dampens engine vibration to lessen wear? Other than stories about other peoples worn bearing and oil pumps. Because if that's what we are going on, than I can site the guy here running UR pullies on his ATR H22A4 for quite a while with 0 problems, another guy running them on a 626, and I couple other people. Sorry, I have talked to manufacturers, Honda mechanics, or tuners, and find no reason not to run them due to "harmonic balancing"

[post=521071]Quoted post[/post]​

rocket motorsports forums had a pretty lengthy thread on this subject, but he disabled a lot of the archived threads. I'll see what I can do to get you a working link.

 

[abdelsol]

If you will not tell them that they will destroy their motor. I will say they are subjecting your engine to harmful harmonic vibrations and run the risk of destroying their motor.

I don't know what is on every make, model, engine. But all the pulley's that mount to the front of the engine have considerable weight (factory). That weight is there for a very specific reason. That is to dampen the force vibrations from combustion. A single peice snout is better that a light weight one. It is designed to remove the worse of the harmonic vibrations. The second best design is a 2 piece with an Oring or rubber this rubber will absorb a wider range of vibrations. The best design available today is a damper that is sealed with silicon fluid.

Why? Because the critical frequency's change with speed, load, ect.

I think the confusion comes into play when the word balance is used. This has nothing to do with balancing. We can balance a wheel or any other recipocating object. but when we put varying tortional loads on the same object all the balancing in the world will not remove them. All the rotaing items in an engine are balenced. Flywheels, driveshafts, crankshafts, torque converters, wheels, and on and on. We even weight balance rods and pistons. So what are lightened pulley's for racing, when you are going to rebuild soon as to later.

This is from the unorthodox site:

"The pulleys on most of the new import and smaller domestic engines have an elastomer (rubber ring) incorporated into the pulley that looks similar to a harmonic damper. The elastomer in the OEM pulley serves as an isolator, which is there to suppress natural vibration and noise from the engine itself, the A/C compressor, P/S pump, and alternator. This is what the manufacturers call NVH (Noise Vibration & Harshness) when referring to noticeable noise and vibration in the passenger compartment. It is important to note that in these applications, this elastomer is somewhat inadequate in size, as well as life span, to act as an effective torsional damper. If you look at the pulleys on some of the imports there is no rubber to be found at all. We have samples of these, mostly from Acura/Honda, the Nissan Altima, 1.8L Eclipse, 2.3L Fords, Chrysler 2.2L's, and 1.8L VW's, to mention a few. This is not to say that with our pulleys you will hear a ton of noise or feel more vibration from your engine compartment. Most who have installed and driven a vehicle with our pulleys will notice the engine actually feels smoother. This is a natural result of replacing the heavy steel crank pulley with a CNC-machined aluminum pulley. NVH is variable and unique to every car. NVH will increase with the installation of an aftermarket intake and/or exhaust, for example. Think of OEM intake systems in newer cars, they use baffles and resonators in the intake to quiet all the intake noise. Aftermarket intakes eliminate these resonators and create dramatic increases in engine noise from the throttle opening and closing. So to most tuners, certain types of NVH can make the driving experience more enjoyable.

The purpose of a traditional harmonic damper is to protect against crank failure from torsional movement. This is not necessary in most modern engines because of the many advances in engine design and materials. Factors such as stroke, displacement, inline, V configurations, power output, etc., do determine when and how these harmonics and torsional movements occur."

The Engineers have a specific reason to have a damper on the snout of the crank. Every object has frequency's that are more harmful than others. Unorthodox is maketing their product and show you the HP gain and the torque gain. Ever wonder why they don't provide a Vibration study? They are well aware of the debate that is going on. If you owned the company wouldn't you dispell the "rumors" With hard fact and test data...... Bet your a$$ you would....

 

[xj0hnx]

The Engineers have a specific reason to have a damper on the snout of the crank. Every object has frequency's that are more harmful than others. Unorthodox is maketing their product and show you the HP gain and the torque gain. Ever wonder why they don't provide a Vibration study? They are well aware of the debate that is going on. If you owned the company wouldn't you dispell the "rumors" With hard fact and test data...... Bet your a$$ you would....

If I am taking away from this what I think you meant, you're saying that UR doesn't produce a vibration study so that they can sell their pullies.

Till someone takes 20, say B16As, and runs ten with a lightened pulley, and ten with an OEM pulley, then pulls them apart after XXXXX miles, and inspects/compares the bearings/oil pump/etc, than it is all theory. But I am not going to go by "I built my motor to perform, then drove it like a race car, and my bearings failed, so it must be the pulley because someone said something about harmonic balance on the intraweb"

I refuse to believe that the tiny rubber/plastic insert in any crank pulley is there to do anything other than stiffle noise slightly, or reduce impact form starting in an engine that is revving to 8000+ rpms. It just isn't going to do what people say it does, maybe if it was a thick rubber insert, ok. And wouldn't adding a lightened lflywheel have a similar effect on engine vibrations as a lightened pulley? Both are attached to the same piece of equipment on opposite ends, so if the weight of the OEM pully was to help control vibrations, wouldn't the flywheel be in the equation also? And would it matter if you had all the AC and PS belts too? Surely those would add or subtract some kind of dampening? I am not well versed in physics and what not, but in laymens terms the things I have read make more of a pro argument that a con against using them.

 

[abdelsol]

Yes, that is exactly what I am saying. Unorthodox is building pulley's for race where you expect to rebuild your engine frequently. In a race atmosphere a couple of Hp makes a big diference. For that application they make a great product.

Yes, the flywheel is a damper for the flange end of the Crank. Crude but the weight does dampen vibrations. In the 20's or 30's one manufacture put a flywheel on the shaft end of the crank. Many engines where failing during that period. Everyone was looking for a solution.

As Far as the Alt and power steering the Belts probably add a little dampening effect.

My physics are only okay, by no means an expert. But Think of it like this. If you took a tuning fork (the Crankshaft) and introduced a vibration. By adding weight (damper) to the fork you can control the frequency.

Another example. Ever look in your side view mirror while traveling down the highway. It is vibrating and making the image blury. If you where to add weight to it. you could control the frequency and improve the image. Thus the same in an engine.

I have read and believe that the vibration of the crankshaft at certian RPM's can flex enough to alter the timing. With everything that is being done to control the timing better, Why not use a product that helps the vibrations instead of allowing them to increase.

You may find this interesting reading. They refer to a paper, "A Practical Treatise on Engine Crankshaft Torsional Vibration Control" by Robert C. Bremer Jr. (SAE Paper SP-445, June 1979). I could not get to that paper, you have to be a SAE member. But both ATI and Fluidampr refers to it.
tortional vibration

Enjoy....

 

[xj0hnx]

I find it strangely ironic that in disputing literature from a maker of lighten pullies, you posted literature from a company that makes dampers

 

[MikeBergy]

Originally posted by 92b16vx@Jul 6 2005, 09:32 AM
I find it strangely ironic that in disputing literature from a maker of lighten pullies, you posted literature from a company that makes dampers

[post=521470]Quoted post[/post]​

I think he was just trying to post literature as a reply to your request for it. You asked for some proof that torsional vibration is a problem not addressed by solid lightweight pulley manufacturers, but it is a problem none the less. You are not going to find anything about the problems on any site that makes lightweight pulleys, because thenn they wouldn't sell as many. But, like I said before, and as you have stated, this probably is not a big problem for everyone. That, in my opinion, is because most people that buy these pulleys do not have a high powered machine, and so most engines don't even make enough torgue to make a difference one way or the other. Bottom line, if you make LOTS of power, you are probably more likely to have problems with Tors. Vibs, because the amplitude of the vib is going to be much larger. Mess with the internals of the motor, the frequency of the first and second vib. modes are gonig to be altered, in which case, the stock damper's effect is going to be less anyway, so you might have problems even with the stoock damper anyway, and this debate becomes a moot point. It isn't a problem at all if you tear your engine down after every race either.

 

[PhyRe]

im not expert on the situation but i drove my boys civic gsr with skunk2 IM 3" cat back(he thought it would be cool, its n/a) dc header mds and shit like that. o with p/s and a/c still hooked up. and then my car (civic gsr) with stock everything basically and no p/s or a/c and there was a a difference in pick up. right now i have the stock three belt pulley but i will be getting the stock itr that only weighs 1.8lbs and i say if honda made one then it must have been for a reason.

 

[MikeBergy]

Originally posted by PhyRe@Jul 6 2005, 10:10 AM
im not expert on the situation but i drove my boys civic gsr with skunk2 IM 3" cat back(he thought it would be cool, its n/a) dc header mds and shit like that. o with p/s and a/c still hooked up. and then my car (civic gsr) with stock everything basically and no p/s or a/c and there was a a difference in pick up. right now i have the stock three belt pulley but i will be getting the stock itr that only weighs 1.8lbs and i say if honda made one then it must have been for a reason.

[post=521505]Quoted post[/post]​

You are probably referring to the CTR n1 pulley, and it was made for racing purposes only. Keep in mind that they tear their engines down after every race, and that pulley was not designed for street use. Neverless, it's your engine. If you disconnect the PS and a/c, of course you are going to feel a little difference, ps annd a/c will suck like 5hp from your engine at peak operation, and 5hp is a noticeable gain.

 

[xj0hnx]

Originally posted by MikeBergy+Jul 6 2005, 06:05 PM-->

92b16vx

@Jul 6 2005, 09:32 AM
I find it strangely ironic that in disputing literature from a maker of lighten pullies, you posted literature from a company that makes dampers

[post=521470]Quoted post[/post]​

I think he was just trying to post literature as a reply to your request for it. You asked for some proof that torsional vibration is a problem not addressed by solid lightweight pulley manufacturers, but it is a problem none the less.

[post=521502]Quoted post[/post]​

Actually, I was hoping for a non biased informational source, that was the point of the irony statement. Fact is I don't believe that Honda takes the two pieces for a crank pulley, presses them together with the plastic shoud inside, then rebalances them to stop "harmonic distortion". I am sure some research was done on their part on the effects of their high revivng motors, and the weight design of their crank pullies, but I would like to see an unbiased comparison between the two. I just don't see a lighten crank pulley causing the damage people try to claim, when other mods will cause the same distortions in vibrations that people are attributing to failures caused by pullies.

 

[MikeBergy]

Well, an SAE publication is about as unbiased as you can get. you can buy a copy of the papers online, but I don't know how much they cost. I know that some AIAA papers I have had to buy for research were like 10 dollars.

 

[xj0hnx]

Yes, but do those SAE papers deal with the effects on Honda motors, or the effects on V8s? I am not keen on paying for something that is useless to the info I seek.

 

[MikeBergy]

Originally posted by 92b16vx@Jul 6 2005, 10:38 AM
Yes, but do those SAE papers deal with the effects on Honda motors, or the effects on V8s? I am not keen on paying for something that is useless to the info I seek.

[post=521533]Quoted post[/post]​

I highly doubt any particular engine was identified. torsional vibs are torsional vibs, physics and combustion cannot distinguish a honda from a ford. That is why we buy hondas instead of fords, because honda engineers do a bit more homework than the ford guys do.

 

[xj0hnx]

True, but most arguements I have read are citing v8's which are going to be a different playing field when talking about creating distortions that can damage a motor. Honda motors are balanced a lot better, and designed for high rpms.. Even Ati's site backs up what I am thinking to an extent...

The stock damper works just fine as long as you do not make many changes to the motor, such as HP or RPM, from when it was stock and if the damper is not very old. When you start changing those things, you cannot count on your stock damper to do its job. Not to mention if that damper is old and worn out, the outer ring has a good chance of slipping or even separating from the rest of the damper and coming off your engine completely!

This tells me that anytime you change anything (flywheel, pistons, rods, etc...) that deals with a motors function, especially rotating assembly, you are going to run a higher chance of damage. Of course a lot of reports are going to come from shops that have to fix engines, that's where people take them when they break, people don't take healthy engines to shops to have them torn apart and inspected for damage being done by modifications (well most people)

 

[MikeBergy]

Originally posted by 92b16vx@Jul 6 2005, 10:54 AM
True, but most arguements I have read are citing v8's which are going to be a different playing field when talking about creating distortions that can damage a motor. Honda motors are balanced a lot better, and designed for high rpms.. Even Ati's site backs up what I am thinking to an extent...

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. Also, the more cylinders you have firing, the less overall impulse torque load you are placing on the crank, because you have a more evenly distributed torque loading per cycle. The more the cylinders, the less vibrational problems. But torsional vibes are also affected by the shaft length that the torque is acting on, so it may be the case that the v8s have a bigger problem because the crank shaft is longer, but I don't know any specific cases.

 

[MikeBergy]

A simple Explanation : 1

simple explanation : 2

another interesting article.

yet another, but I don't know what these guys are advertising


another...

I googled up torsional vibration, and these are a few of the top hits.
enjoy

 

[xj0hnx]

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?