Lightweight pulley & open pod

[M323]

Hi,

 

Any benefit of replacing to lightweight pulley, or doesn't help much!

 

Which open pod would u recommend?

 

thanks

[Chneo1982]

both are useless.

 

lighten pulley damage ur crank shaft.

 

get open pod might as well do a CAI.

[Biccat]

It has been widely documented that over the short term, these 2 mods will definitely improve your engine performance but over the long haul, they are actually bad for your engine:-

 

1) Lightweight pulley - With less inertia to overcome, the engine revs more easily and this translates into better pickup and possibly better consumption. However, the heavier crank pulley also acts as a dampener against any vibration due to imbalance. Without the dampening effect, the engine wears much faster and over time breaks down due to metal fatigue to a certain part.

 

2) Open pod uses high flow filter media which lets minutes dust and sand particles into the combustion chamber. Imagine what will happen with prolong breathing of these particulates into the combustion chamber.

 

Both of these mods were originally developed for racing over the period of a race only. Long term reliability is of secondary concern unlight road cars which are built to last 10 yrs of more. However, most of us do not have to face the detrimental effects of such mods cos our cars are usually sold or scrapped way b4 the useful 10 yrs is up.

[Orixy]

Both mods have their pros and cons.

 

Lightweight crank pulley:

Pros - More toward improving torque as it makes engine more revy from low end.

Cons - Unless you also lighten the flywheel together, the unbalanced crank system may damage the engine after prolong use.

 

Open Pod:

Pros - If done up properly with CAI, will help engine to "inhale" better and generate more bhp & torque.

Cos - If not done up properly - ie. common mistake is to allow the open pod to suck in hot air from within engine nay, then the result will be worst then stock intake setup.

[Sky8807]

Agrees

[Elfenstar]

Actually thats a misconception abt the lightened pulley. The problems arise not because of the weight but because many aftermarket pulleys do away with the harmonic balancer.

[Biccat]

Both the weight and the dampener build into the original crank pulley act together to reduce harmomonic vibration. I reproduced this article from the net:-

 

The other benefit of aftermarket pulleys is to reduce rotating mass. Here the simple aluminum crank pulley has a big advantage over the heavy stock pulley, but there's a reason it's so much lighter: It's missing the harmonic dampener. The reduction in rotating mass may be worth a couple of horsepower. But removing the dampener seems like a bad idea to us.

 

The factory crank pulley has a built-in harmonic dampener, in the form of a split design, with a thick rubber pad sandwiched between two steel sheels. The dampener is designed to absorb torsional and vertical vibrations from the crank. MOST underdrive crank pulleys (with the exception of the Buschur Racing model) do not have a harmonic dampener at all.

 

Torsional vibration is a twisting vibration caused by the pulses of each combustion event. The force of the piston causes the crank to deflect ever so slightly in the direction of the force, and when that force goes away the crank ever-so-slightly springs back. At certain frequencies the crank can resonate, making the vibration much worse. This is where the harmonic dampener comes into play.

 

Although many DSM owners have removed the harmonic dampener crank pulley without incident, doing so almost certainly increases crank bearing wear, and COULD lead to early failure of the crank or crank bearings. Just how much the life of these parts is shortened is unknown.

[Elfenstar]

theres nothing in your excerpt about the weight of the pulley other than reference to most aftermarket pulleys removing the damper to reduce weight. All the possible damage refered to is related to not having the damper. If you have a lightened pulley with a damper then there should be no problem.

[Biccat]

The other benefit of aftermarket pulleys is to reduce rotating mass. Here the simple aluminum crank pulley has a big advantage over the heavy stock pulley, but there's a reason it's so much lighter: It's missing the harmonic dampener. The reduction in rotating mass may be worth a couple of horsepower. But removing the dampener seems like a bad idea to us.

 

Aluminium is lighter than steel, hence its lower rotating mass apart from the harmonic dampener. Not all crank pulleys are build with harmonic dampeners for your information. In this case, the after-market pulley is still many times lighter than the factory fitted one.

 

Whatever the case, I think we are on the same wavelength on this:- Long term use of the after-market pulley is likely to affect the working life of the engine.

[Elfenstar]

Like i said, there is NOTHING in that excerpt that states that weight reduction in itself is a problem. It only states that removal of the damper is.

 

I only agree that its bad if theres no harmonic damper. I;m stating that the weight of pulley itself does not affect anything other than a slight increase in the speed of the drop of rpms when the car goes into neutral. companies such as AEM have lightened pulleys with the damper. No problems with those.

 

Do note though that a 1kg reduction in weight is roughly a saving of 4kg's in rotating force

Edited July 13, 2006 by Elfenstar

[Hattee]

There is always this concern on the potential damages sustained with loss in essential dampening on a mechanical system.

 

But I am not sure if really OEM crank pulley serves such a critical purpose in every car if we were to look at it a little closer on how it affects dampening at various conditions of operation.

 

Perhaps, most of us already notice the pitch at a given rpm, particularly up from idling, is always alot higher at N than at D or with gear. This might suggest the drive-train, design couplings, structural rigidity, precision, absorbers and even the gross weight are far more important dampers than just crank pulley. For some older cars and probably lighter ones, engine noise readily shows up when driving at higher rpm. Maybe this can differentiates a well-balanced (dampened), stable and probably quieter car from those lighter, vibration-prone and noisier ones as the rpm moves away from idling (interesting to hear some associating quiet idling with assurance of quality ride).

 

To understand how little the pulley can do on dampening, just remove the belt to the compressor, alternator and various pumps, the sound of idling becomes significantly sharper (even exhibiting vibration) and not proportional to the slight rise in idling rpm. It again shows many other anciliaries contribute more significant dampening than crank pulley. Assumption here is potentially damaging harmonics are always audible. Or are there other damaging higher harmonics? Even if there are ultrasonics for some very exceptional case, can crank pulley be of any use?

 

Having said this, heavier crank pulley does reduce potential damages whenever the engine is ram up at N for whatever reasons. The caveat for marginal reduction in inertia of crank pulley not causing damages is when the engine does not exhibit increase noise loaded at the higher rpm. Otherwise many among us using lighter crank pulley for more 2-3 years would have said something by now. They sure testify noticeable gain in pickup and even FC. Of course there might be some design with meagre dampening, further reduction of inertia in any aspect will introduce vibration, noise and wear.

 

Like many things in life, gain some will lose some. If there is nett 50% inertia reduction at the crank linkages, got to avoid ramming at N (3000 can sustain equiv wear of 6000). Also, shedding 3-5 kg from the pulley might be translated to 2-3% loss in drive train inertia resulting in a little lethargy in reaching the max speed, particularly uphill. Using incorrect pulley radius or requiring use of different size belt would soon lead to other problems related to a/con, hydraulic power, coolant circulation and battery.

 

It has been widely documented that over the short term, these 2 mods will definitely improve your engine performance but over the long haul, they are actually bad for your engine:-

 

1) Lightweight pulley - With less inertia to overcome, the engine revs more easily and this translates into better pickup and possibly better consumption. However, the heavier crank pulley also acts as a dampener against any vibration due to imbalance. Without the dampening effect, the engine wears much faster and over time breaks down due to metal fatigue to a certain part.

 

2) Open pod ...

[Mazel_tov]

fyi, the later batch of rpm pulleys DOES come w hamonic damper...i guess that shd debunk any discussions abt aftermarket pulleys not having it...i hv one installed in my ride, so far so gd...

[Ceratoisthebest]

Ya new batch got harmonic damperner. Much more safer le. I fixing mine soon

[D2843]

Hi, where you do it and the price. Me drive a M2, pm me if not convenience to post.

cheers,

[Kelpie]

fyi, the later batch of rpm pulleys DOES come w hamonic damper...i guess that shd debunk any discussions abt aftermarket pulleys not having it...i hv one installed in my ride, so far so gd...

 

Do you think there is a specific lifespan of an OEM RPM Pulley with Harmonic damper? Say, need to change every 3 years or certain KM? Does it enhance the Low end or high end or throughout the rpm in your car(Civic right?).

 

Regards,

[Ceratoisthebest]

Mine is a grp buy from other forum. Yr model have or not i dunno. Maybe u can check it out in hot stuff

[Hattee]

Don't exactly understand claim of having dampener (assuming precision balanced conditions). Maybe I am wrong. Thot dampener is essentially dead weight or inertia when it spins. Guess it can reduce localised low amplitude harmonics but probably not those generated from engine or drive-train. Too much of this weight can become unwanted loading.

 

Is there any lightweight pulley without dead weight per se?

 

Also, do you think any impact with your lightweight ramming your engine at N?

 

[Mazel_tov] --------

fyi, the later batch of rpm pulleys DOES come w hamonic damper...i guess that shd debunk any discussions abt aftermarket pulleys not having it...i hv one installed in my ride, so far so gd...

Edited August 22, 2006 by Hattee

[Mazel_tov]

As far as i know, any rotating mass needs to be balanced. This can be achieved by either shaving off matl, adding weights and the likes. Wat i gathered fm the net is that a aftermarket pulley w/o a harmonic damper wil result in vibration that may b detrimental to the engine in the long run. Tat was the reason y i held back till RPM came out w a pulley w damper tt resembles the stock pulley's construction. As far as i'm concerned, a similar sized pulley w similar harmonic damper layout n yet being lighter in weight definately merits some form of consideration. Appreciate your pointers on the pulley though. Perhaps other gurus/lao jiaos can proive a better insight?