First I would like everyone to realize that not all pullies are Unorthodoxracing pulleys. There are many companies making pullies now, some underdriven and some just lightweight. Also the quality differs from each manufactor and people have to realize that those having issues might be in the quality of the product and not the overall product itself.



The “Harmonic Balancer” Debate

People are getting their crank pulleys confused with the harmonic dampers found on 90 degree V6 / V8 engines. “Harmonic Balancer” is a term that is used loosely in the automotive industry. Technically, this type of device does not exist. The “balancer” part comes from engines that are externally balanced and have a counterweight cast into the damper, hence the merging of the two terms. None of the applications that we offer utilize a counterweight as part of the pulley as these engines are internally balanced.

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 some of the pulleys on older 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 feel’s 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.

Again, there is a lot of internet hearsay about the pulleys. When engine problems occur, too often people are quick to blame the pulley first, rather than taking the time to look logically into why there was a problem. We hope that after reading this you will understand the crank pulleys better.

 

However, increased NVH may set off the knock sensor and inadvertently pull ignition timing as a result. Plus, the gains aren't worth the effort involved, IMO.

Am I willing to spend the day finding this out? Probably not.
Would a dyno chart before and after showing gains change my mind? Maybe.

Prove it.

 

Yea I would like to see some dynos based on just with and without the pulleys. I would also like to see some neutral party evidence or opinion to take this debate to the next level.

 

I think in other words, don't buy the cheap pulley sets. Go with a reputable company. I've had an Unorthodox pulley on my civic since it had 18,000 miles on it and up to now, pass 156,000 miles, I haven't had any problems and the car ran better.

 

Well, to be perfectly honest, there are much better ways on the Evo to get that 10 or 15 or whatever horsepower without resorting to pulleys, underdriven or not. Hell, you can get to 400whp without touching engine internals (meaning bottom end) on a conservative tune.

Why would I risk anything with a pulley?

 

Something to consider is that the XEDE adjusts the knock sensor reading to the ECU. Better results may be gained from a pulley with other supporting mods.

 

The XEDE's knock adjust feature remaps the factory knock control system to better differentiate between actual knock and engine noise. Depending on the load and RPM, the knock signal can be attenuated or amplified. In other words, it's just not a straight attenuation of X%.

Regards,
shiv

 

...400whp with a conservative tune? What are you talking about? You call 400whp from a 271fwhp a conservative jump? The 4G63 is very strong, but... let's be real and honest.

I can not even do that with my own Xede, no matter what mods and how conservative we choose to be (unless you swap turbos or dramatically increase boost above any "reliable" trhreshold...)

Obviously, you do not seem to have installed and used any of these pulleys by yourself, for a long time. Therefore... I suggest you to just keep reading, until you do so.

Happy racing.

 

if you reread what he said you would notice that he said 400whp with out touching the block. it has been done before with only bolt ons (yes turbo swap, injectors and stand alones but they are all still bolt ones) aside from cams and gears. it has been done with a very safe tune using AEM and yes even the exed (Vishnu stage 2). look into the vishnu stage 2 yno sheet and you will notice that the tune is very safe and even the boost level is not that high. i think that 350whp-380whp is very attainable even without the pullies and yes it can be reliable and conservative.

just my 0.02c

 

If I bolt on a new head is it just a bolt on? Either way..
MR2 Turbo (3SGTE - 2.0L Inline 4 cylinder Turbo) with 180,000 miles 160,000 with underdrive pulley - no problems.
Slocus ( Zetec 2.0L Inline 4 cylinder ) with 60,000 miles 55,000 with underdrive pulley no problems.
Both with significant power gains and many hard track miles with many *HOURS* of WOT and much shifting and up and down the rev range.

4 first hand friends with Evos with underdrive pulleys, all dyno verified increased power and no problems.

Then again, if your worried, go spend the money on learning to drive at a local road racing circuit instead, then you still have your peace of mind and hopefully some skills and realization that your car is still way beyond your capabilities..

 

we both know that a bolt on turbo kit is a bolt on....

also, i hope that " go learn how to drive" remark wasn't meant for me...

 

Did Mitsu do something different on these newer 4g63's? The T/E/L 4g's DO have a balancer on them, separated by the elastomer ring. And if I remember correctly, most 4g tuners will not recommend underdrive pulleys unless they are built with the dapmener. Someone have a picture of a stock Evo 8 crank pulley?

 

gldnchild,

So what you are saying is there is no resonance in a crankshaft?

Resonance being a natural or harmonic property of a component that causes vibration at an identifiable frequency.

By your theory a harmonic damper is only intended to reduce noise at the accessory drive belt. An the weight of such a pulley is of no concern? Does putting x amount of weight on the end of spinning shaft have no impact on the resonant frequency?
Radial force does come into play whenever you spin something like a crankshaft at speed. The question is, what impact does this radial force have on the nose of the crankshaft with say 1 lb. of weight attached as opposed to 6 lbs of weight ( aside from the elastomeric damper contained in the 6 lb pulley).

You made your point in the other thread but still have not provided any scientific proof to your theories.
I'd like to see something like a Reed Resonant Tachometer used to display the frequency at which the most resonance is displayed with a stock pulley and then the same test performed with a solid, lightweight pulley.

I do not argue that the UR pulley is in fact noisier than the stock pulley. After removing it, I was suprised to see the difference in overall noise from the engine. But I think the design and purpose goes a little deeper then NVH.

Unfortunately for me I am not able to even sell the pulley on ebay. After 5 days I didn't get a single bid and nothing but questions about the pulley. Maybe if I were I sneaky person I could lie to these people to get it sold but I just don't work that way.

 

No it has the elastomer ring. Most modern engines don't use a "balancer", it's just a harmonic damper.

 

Yes, 400whp without going into the bottom end, a simple search will show you what success those that have bolted other turbochargers on have had.

If you can't do that with you Xede, I suggest you use some other form of engine management or learn how to use what you have. The potential's there.

You can get to 400whp keeping the pressure below 20psi if you have an efficient turbocharger and fuel system behind it.

I will use an aftermarket pulley when I feel I need to. With all this potential solely from a simple turbo kit without risking rod bearings, I takes my chances, as they say.

Will a pulley get me 10hp? Maybe. Let me know what you find out and maybe I'll buy one someday. Until then, I'll go with what I know works reliably.