Risks of a lightened crank pulley

[C32b]

A lightened crank pulley is a common and relatively inexpensive modification that is commonly used to extract promised power of about 5-10. However, the risks that lie with doing such a mod when the end product is poorly constructed/engineered can be significant.

 

Sharing a link where Steve Dinan from Dinan BMW writes in detail on such risks.

 

http://www.dinancars.com/bmw/technial-info...harmonic-damper

 

Leave no doubts of the engineering behind the crank pulley you are about the purchase as the long term health of your engine may suffer if the inferior product is poorly balanced.

[Vhtfhwlego]

What for to do all these upgrades of 5/10HP unless really going for 0.xxx secs off track time.

Just add a turbo solve all your problems.

BHP not good enough afterwards? Change to a bigger one.

Still no good, wanna consider engine CC upgrade?

Still no good, wanna consider changing a better car?

 

Some people just like mod here & there and I would prefer a 1 shot do all.

Add Turbo, Fuel Injector, ECU, boost control then Dyno.... If that still not happy, that means that the turbo & fuel injector bought in the first place is not the items you want. If that you had "reached" the limit for the engine and not happy, either change the car or the engine.

 

[Yuan]

A lightened crank pulley is a common and relatively inexpensive modification that is commonly used to extract promised power of about 5-10. However, the risks that lie with doing such a mod when the end product is poorly constructed/engineered can be significant.

 

Sharing a link where Steve Dinan from Dinan BMW writes in detail on such risks.

 

http://www.dinancars.com/bmw/technial-info...harmonic-damper

 

Leave no doubts of the engineering behind the crank pulley you are about the purchase as the long term health of your engine may suffer if the inferior product is poorly balanced.

 

Stock ones are the best. Heard of lightened ones causing problems after some time of usage.

[So_nice]

i think lighten pulleys dun increase bhp at all. it juz improves ur throttle response.

[Rb26dett]

A lightened crank pulley is a common and relatively inexpensive modification that is commonly used to extract promised power of about 5-10. However, the risks that lie with doing such a mod when the end product is poorly constructed/engineered can be significant.

 

Sharing a link where Steve Dinan from Dinan BMW writes in detail on such risks.

 

http://www.dinancars.com/bmw/technial-info...harmonic-damper

 

Leave no doubts of the engineering behind the crank pulley you are about the purchase as the long term health of your engine may suffer if the inferior product is poorly balanced.

 

 

good info and link there norman.

[Smhomie]

Dinan's article has long been criticized by quite a few folks since his take (and bias) is towards BMW's longitudinally placed engines ie. engine ->drive shaft -> rear driven wheels.

 

Unless x designated which has all-wheel drive. MINI are all front wheel driven.

 

Most asian cars are front wheel driven. The engine is transversely placed ie. perpendicular to the axis

 

Inner crankshaft harmonics are not worrisome since such engines tend to have in-built counter rotating balance shafts at 2nd ring position.

 

Hope this clears

[Ken4555]

Stock ones are the best. Heard of lightened ones causing problems after some time of usage.

 

i guess stock is best in terms of pulleys...

 

but the fact is... many have installed and feel good about it with no problems...

some also have had problems and some have cracked before...

 

strut bars/stabilizer bars...etc... lower bars tie bars... all the bars... most say good...

some have chassis stress on certain areas of the car and cause cracks...

 

slotted crossed drill rotors... looks good and cools better....

also shorter life span and easier to warp...

 

even a port polish high com piston TC or SC or watever... all mods have pros and cons...

 

i guess the thing is... if you heavily mod up your car, pls dont expect it to last till the COE dies....

 

 

[Lowrider]

sometimes people mod their cars to get satisfaction out of whatever their formula is, they'd do it based on their knowledge, hearsay, or just itchy hands... a long the way some feel good about it, some dont coz maybe their mod failed... but whatever it is.. it's not so much about changing car to a better, powerful one... well those with very very deep pocket just might... the reasons they would mod their cars can vary from passionate to just simply wanna look different, from the looks to the power.. although there are people with less common sense or taste.. but no matter how irritating it seems, people are different and we cannot expect them to see things the way we do...

 

besides, for them it may not be so special to own a powerful car out of the box just like their neighbor

[Yuan]

i guess stock is best in terms of pulleys...

 

but the fact is... many have installed and feel good about it with no problems...

some also have had problems and some have cracked before...

 

strut bars/stabilizer bars...etc... lower bars tie bars... all the bars... most say good...

some have chassis stress on certain areas of the car and cause cracks...

 

slotted crossed drill rotors... looks good and cools better....

also shorter life span and easier to warp...

 

even a port polish high com piston TC or SC or watever... all mods have pros and cons...

 

i guess the thing is... if you heavily mod up your car, pls dont expect it to last till the COE dies....

 

All have its pros and cons. I believe if you do up your research wisely and know what you want, coupled with taking care of your machine well and regularly, it could last till the expiry of COE and can last beyond that.

[Aaron_soh80]

sometimes people mod their cars to get satisfaction out of whatever their formula is, they'd do it based on their knowledge, hearsay, or just itchy hands... a long the way some feel good about it, some dont coz maybe their mod failed... but whatever it is.. it's not so much about changing car to a better, powerful one... well those with very very deep pocket just might... the reasons they would mod their cars can vary from passionate to just simply wanna look different, from the looks to the power.. although there are people with less common sense or taste.. but no matter how irritating it seems, people are different and we cannot expect them to see things the way we do...

 

besides, for them it may not be so special to own a powerful car out of the box just like their neighbor

 

 

yupz..even thought change into more powerful car some pple still wan to mod & mod..i guess there is no end..

..maybe stock to them are lame..

[Mini-itx]

Changing to a lightened pulley is akin to a lightened flywheel. If really want to change, should change flywheel instead, not crank pulley. YOu get even better response compared to pulley. But it also got drawbacks like engine more likely to stall (for manual). Then less power when going uphill and thus need to step more. ITs due to Physics and not engine issue. A spinning flywheel stores energy. Lighter wheel has less energy.

[Vhtfhwlego]

Thanks for your point of view.

It had enlighted me .

[Mini-itx]

yupz..even thought change into more powerful car some pple still wan to mod & mod..i guess there is no end..

..maybe stock to them are lame..

 

Sometimes, modding is more like a hobby. Think of it as customising.

[Ken4555]

All have its pros and cons. I believe if you do up your research wisely and know what you want, coupled with taking care of your machine well and regularly, it could last till the expiry of COE and can last beyond that.

 

well maintained i guess it will last... think i was referring to like driving like mad man after modding the car.. then lifespan of the car shorter... hahaha

[C32b]

 

 

At the very least, Dinan's article does potentially benefit (as u mentioned) the longitudinally placed engined cars produced by BMW, Mercedes, mazda , nissan, honda and many others.

 

For the transversely mounted engines, I do believe that the risk still remains albeit perhaps to a smaller degree.

 

I would be interested to know (as I am not an engineer by trade) examples of cars which have the counter balance shaft. i'm not sure if the counter balance shaft you mentioned is available on all vehicles, asian or otherwise. Even if the balance shaft is there, the fact remains that the harmonic balance is changed. How much that poses as a risk, I am not sure.

 

Do know if the lessening of risk depends on if the crankshaft is shorter? I would like to learn what are the reasons such a harmonic balance change can impact some engine setups to a lesser degree and more in others.

[Yuan]

well maintained i guess it will last... think i was referring to like driving like mad man after modding the car.. then lifespan of the car shorter... hahaha

 

If that is the case, then even a fully stock car would have its lifespan shortened. I have seen one before. The owner neglected it and poorly maintained its condition. The car in its 4th year would have to be overhauled or scrapped.

[Smhomie]

At the very least, Dinan's article does potentially benefit (as u mentioned) the longitudinally placed engined cars produced by BMW, Mercedes, mazda , nissan, honda and many others.

 

For the transversely mounted engines, I do believe that the risk still remains albeit perhaps to a smaller degree.

 

I would be interested to know (as I am not an engineer by trade) examples of cars which have the counter balance shaft. i'm not sure if the counter balance shaft you mentioned is available on all vehicles, asian or otherwise. Even if the balance shaft is there, the fact remains that the harmonic balance is changed. How much that poses as a risk, I am not sure.

 

Do know if the lessening of risk depends on if the crankshaft is shorter? I would like to learn what are the reasons such a harmonic balance change can impact some engine setups to a lesser degree and more in others.

 

You may find more info and explanation through wikipedia on balance shafts. It is to counteract natural harmonics from the firing order to crankshaft based on asymmetry engine design in question.

 

More commonly found in inline 4 engines to knock out NVH effects to achieve smooth comfortable ride. I can think of toyota examples like wish, estima, camry, harrier that uses 1 and 2AZF(X)E engines that has plastic resin balance shafts.

 

Hope short answer helps

[C32b]

granted that the balance shafts exist but it is conceivable that changing the pulley will probably upset the harmonic balance (which was stabilized by the presence of the balancer) all over again. As to whether the change in balance is enough to result in actual engine underperformance, I really can't be sure. I would prefer to be safe rather than to be sorry though.