Light weight crank pulley good or bad

[hanslin]

to be honest,don't expect a lot of power for this mod.sometime it came back nil on
dyno.some claim to add around 5-6hp.the main thing is acceleration or pick-up.
like what sky sifu said.imagine shaving up to 2kg on ur crank pulley.it can turn faster
w/o much effort.that the reason y this thing was invented.

And make sure! it make from alu t6 or above but ur belt life is shorter due to heat transfer n non shock absorber :cheers:

 

[jswong]

Hmmm.. in all these posts, no one seem to mention the obvious.. that pulleys, pistons, etc. present parasitic DRAG for engines, but the flywheel is an ENERGY STORAGE DEVICE.

The function of the flywheel isn't to siphon off a portion of the engine's rotational output for other purposes, e.g. aircond and power steering pumps; neither is it a reciprocal mass that contributes to the frictional loss as a part of the power generation process, i.e. pistons.

Flywheels help to STORE the rotational energy of the crankshaft. Lightening the flywheel = reducing stored energy. Yes, your engine's spool-up feels "lighter", that's because less energy is being stored and hence it takes a shorter time for the engine to "fill up" the flywheel with kinetic energy. However, it's detrimental to regular driving because once you lift your foot off the pedal, the crankshaft loses its angular momentum quickly.

Lightened pulleys on the other hand actually reduce engine loss. Lightened pulleys + unlightened flywheel = easier to conserve engine crankshaft's angular momentum + lower rotational inertia. Lightened pulleys + lightened flywheel = harder to conserve engine crankshaft's angular momentum + lower rotational inertia.

For daily driveability, lightened pulleys + unlightened flywheel should be the proper combo.

Lightened crankshaft pulley may give similar "feel" to lightened flywheel, but the underlying principles are not exactly the same. Hence, lightened pulley =/= lightened flywheel.

Bump: Hmmm.. in all these posts, no one seem to mention the obvious.. that pulleys, pistons, etc. present parasitic DRAG for engines, but the flywheel is an ENERGY STORAGE DEVICE.

The function of the flywheel isn't to siphon off a portion of the engine's rotational output for other purposes, e.g. aircond and power steering pumps; neither is it a reciprocal mass that contributes to the frictional loss as a part of the power generation process, i.e. pistons.

Flywheels help to STORE the rotational energy of the crankshaft. Lightening the flywheel = reducing stored energy. Yes, your engine's spool-up feels "lighter", that's because less energy is being stored and hence it takes a shorter time for the engine to "fill up" the flywheel with kinetic energy. However, it's detrimental to regular driving because once you lift your foot off the pedal, the crankshaft loses its angular momentum quickly.

Lightened pulleys on the other hand actually reduce engine loss. Lightened pulleys + unlightened flywheel = easier to conserve engine crankshaft's angular momentum + lower rotational inertia. Lightened pulleys + lightened flywheel = harder to conserve engine crankshaft's angular momentum + lower rotational inertia.

For daily driveability, lightened pulleys + unlightened flywheel should be the proper combo.

Lightened crankshaft pulley may give similar "feel" to lightened flywheel, but the underlying principles are not exactly the same. Hence, lightened pulley =/= lightened flywheel.

 

[hanslin]

good one.....! sifu,than what stoping our motorsport to step out malaysia????

 

[TomHaRA]

huhuhu..cannot ek..if maybe LCP can safe a little bit on FC. still not try yet, but for sure i wont mess around with the final drive gear ratio. have to wait until my final gear kaput lor.

 

[ettm_14]

installed LCP on wira 1.5 Auto, fuel consumption improved maybe by 15-20%?

well it was about +/- 11km/liter
now about +/- 13km/liter

results varies due to heavier right foot....

Bump: installed LCP on wira 1.5 Auto, fuel consumption improved maybe by 15-20%?

well it was about +/- 11km/liter
now about +/- 13km/liter

results varies due to heavier right foot....

 

[Mitevo7]

Installed Redline LCP into my N16 Engine ... QG16DE ...

Pros
1. Lighter acceleration on flat road
2. Better FC
3. Love the little G

Cons
1. Detects very slight vibration on my seat when the air cond fan kicks in. (got a sensitive butt)
2. The car is hard to accelerate when exiting the corners in genting uphill compare to last time without the LCP ...
3. Slower to achieve 180 km/h compare to last time without LCP ...

Comments above are all based on hunches and personal opinions. Thank you for reading.

One more thing here, will the LCP affects the acceleration of the engine when driving uphill ? I heard from my friend who just graduated from Automotive engineering courses that told me although the weight on the Crankshaft is reduced, acceleration should be improved ... But because of losing the rotating mass on the crankshaft, it is slower to achieve topspeed and losing some acceleration on the hill driving. So is this theory true ?? He also commented that LCP is good for town drive with flat road. When on the hill it is better with the old pulley because got more momentum to push the pulley.

 

[ExceL]

1. Detects very slight vibration on my seat when the air cond fan kicks in. (got a sensitive butt)

did you jizz in yo pants? http://www.youtube.com/watch?v=4pXfHLUlZf4
Lyrics;

Don't? tell your friends or I'll say your a slut
Plus it's your fault, you were rubbing my butt
I'm very sensitive, some would say thats a plus

/off topic

sorry, had to do it.

 

[tofu_manic]

Installed Redline LCP into my N16 Engine ... QG16DE ...

Pros
1. Lighter acceleration on flat road
2. Better FC
3. Love the little G

Cons
1. Detects very slight vibration on my seat when the air cond fan kicks in. (got a sensitive butt)
2. The car is hard to accelerate when exiting the corners in genting uphill compare to last time without the LCP ...
3. Slower to achieve 180 km/h compare to last time without LCP ...

Comments above are all based on hunches and personal opinions. Thank you for reading.

One more thing here, will the LCP affects the acceleration of the engine when driving uphill ? I heard from my friend who just graduated from Automotive engineering courses that told me although the weight on the Crankshaft is reduced, acceleration should be improved ... But because of losing the rotating mass on the crankshaft, it is slower to achieve topspeed and losing some acceleration on the hill driving. So is this theory true ?? He also commented that LCP is good for town drive with flat road. When on the hill it is better with the old pulley because got more momentum to push the pulley.

As sifoo jswong has stated, the purpose of the flywheel is to store energy, not other parts, like LCPs, ive also never read any articles regarding LCPs causing a top speed drop, or affecting uphill driving

LCPs are so small and so much lighter than flywheels, how much momentum can it store that has an impact on driveability?(im noobish here, if can someone pls elaborate more by giving figures or something, kinda figure-dumb, LoL) If anything, day to day driveability has improved...taking off from standstill, as good as before

So is ur friend saying that with a larger, heavier, harder-to-spin crankshaft, it is easier to hit higher speeds? Up to what point?

 

[JINEIL2EN]

As sifoo jswong has stated, the purpose of the flywheel is to store energy, not other parts, like LCPs, ive also never read any articles regarding LCPs causing a top speed drop, or affecting uphill driving

LCPs are so small and so much lighter than flywheels, how much momentum can it store that has an impact on driveability?(im noobish here, if can someone pls elaborate more by giving figures or something, kinda figure-dumb, LoL) If anything, day to day driveability has improved...taking off from standstill, as good as before

So is ur friend saying that with a larger, heavier, harder-to-spin crankshaft, it is easier to hit higher speeds? Up to what point?

when downhill, ur fren's car can faster than urs by 3kph...

 

[Mitevo7]

So is ur friend saying that with a larger, heavier, harder-to-spin crankshaft, it is easier to hit higher speeds? Up to what point?[/QUOTE]

Nope he didn't say that either , he is saying that the stock pulley actually is somehow better than a lighter one when the matters comes to uphill ... That's all he said ...

 

[JINEIL2EN]

i think better in downhill instead of uphill...:hmmmm:

 

[tofu_manic]

So is ur friend saying that with a larger, heavier, harder-to-spin crankshaft, it is easier to hit higher speeds? Up to what point?

Nope he didn't say that either , he is saying that the stock pulley actually is somehow better than a lighter one when the matters comes to uphill ... That's all he said ...[/quote]

Kos he sed when the rotating mass on the crank is reduced, topspeed will be achieved slower....automatically this means a heavier crank will help achieve topspeed faster, no meh?

jineil2en, haha damn, i really dont have a clue about that

 

[JINEIL2EN]

Nope he didn't say that either , he is saying that the stock pulley actually is somehow better than a lighter one when the matters comes to uphill ... That's all he said ...

Kos he sed when the rotating mass on the crank is reduced, topspeed will be achieved slower....automatically this means a heavier crank will help achieve topspeed faster, no meh?

jineil2en, haha damn, i really dont have a clue about that[/QUOTE]

hahaha,... how bout go for some trying 1st...

i think ur fren can apply for new Newton Theory for his comment...mayb can get a Nobel:proud:

Bump: mayb u shld ask ur fren, RPM revving up more faster or slower can hits top speed more faster...

if he cannot answer or he answer rpm revving up more faster, pls slap him.

Bump: mayb u shld ask ur fren, RPM revving up more faster or slower can hits top speed more faster...

if he cannot answer or he answer rpm revving up more faster, pls slap him.

 

[Mitevo7]

Kos he sed when the rotating mass on the crank is reduced, topspeed will be achieved slower....automatically this means a heavier crank will help achieve topspeed faster, no meh?

jineil2en, haha damn, i really dont have a clue about that

hahaha,... how bout go for some trying 1st...

i think ur fren can apply for new Newton Theory for his comment...mayb can get a Nobel:proud:

Bump: mayb u shld ask ur fren, RPM revving up more faster or slower can hits top speed more faster...

if he cannot answer or he answer rpm revving up more faster, pls slap him.

Bump: mayb u shld ask ur fren, RPM revving up more faster or slower can hits top speed more faster...

if he cannot answer or he answer rpm revving up more faster, pls slap him.[/QUOTE]

Lighter yes it makes the engine easy to rev, but if taken it to a uphill drive, the initial acceleration from standstill will be easy and fast, that's a truth coz i did try it out myself ... The myth here is :" Once the car has built up speed, the moment we end the braking process and going to corner out from the hairspin, will it be easy or harder to build up speed again ... ? " What i found out for myself is, it is slightly harder ...

My friend just helping me to figure out the prob, becoz i am the one who really feels it is harder to drive uphill once i installed the LCP ... Plz don make fun of him gentlemen:rolleyes: He could be wrong in some terms perhaps.

PS : Just hope to get some answers here becoz lotsa research been done and no1 seems to know there is such prob ...

 

[jswong]

If more angular momentum is preserved, once the engine gets up to speed it takes less effort to keep going due to inertia.. a body in motion tends to stay in motion, remember?

With lesser crankshaft mass, it's easier to accelerate but harder to maintain the angular momentum. At high speeds, you tend to decelerate faster when you lift your foot off the pedal. When going uphill, it may be easier to pick up revs initially but your engine will have to work harder in order to maintain the angular momentum, which is necessary for maintaining the torque output. When you lift your foot off the throttle, if the angular momentum reduces rapidly, and so does your revs. So the engine will have to work a bit harder to get it up again.

This should be more pronounced with a lightened flywheel as compared to a lightened crank pulley. In any case, rotating masses present much higher apparent mass compared to reciprocating masses, so even a small reduction of rotating mass will result in a big reduction in apparent mass. For instance, I've read before that taking 2kg off the flywheel will result in over 100kgs lesser apparent mass on the crankshaft at around 2000 rpm.

 

[Mitevo7]

If more angular momentum is preserved, once the engine gets up to speed it takes less effort to keep going due to inertia.. a body in motion tends to stay in motion, remember?

With lesser crankshaft mass, it's easier to accelerate but harder to maintain the angular momentum. At high speeds, you tend to decelerate faster when you lift your foot off the pedal. When going uphill, it may be easier to pick up revs initially but your engine will have to work harder in order to maintain the angular momentum, which is necessary for maintaining the torque output. When you lift your foot off the throttle, if the angular momentum reduces rapidly, and so does your revs. So the engine will have to work a bit harder to get it up again.

This should be more pronounced with a lightened flywheel as compared to a lightened crank pulley. In any case, rotating masses present much higher apparent mass compared to reciprocating masses, so even a small reduction of rotating mass will result in a big reduction in apparent mass. For instance, I've read before that taking 2kg off the flywheel will result in over 100kgs lesser apparent mass on the crankshaft at around 2000 rpm.

That is one hell of a explanation !! Thx bro !! That is what my friend trying to say , the inertia and the maintaining of the angular momentum ... Well next time on the uphill section , think i should keep an eye on the rev ... Don't let the rev dropped lower than 3k rpm as my torque peak is at 3k according the sheet ... haha

 

[tofu_manic]

hahaha,... how bout go for some trying 1st...
Lighter yes it makes the engine easy to rev, but if taken it to a uphill drive, the initial acceleration from standstill will be easy and fast, that's a truth coz i did try it out myself ... The myth here is :" Once the car has built up speed, the moment we end the braking process and going to corner out from the hairspin, will it be easy or harder to build up speed again ... ? " What i found out for myself is, it is slightly harder ...

My friend just helping me to figure out the prob, becoz i am the one who really feels it is harder to drive uphill once i installed the LCP ... Plz don make fun of him gentlemen:rolleyes: He could be wrong in some terms perhaps.

PS : Just hope to get some answers here becoz lotsa research been done and no1 seems to know there is such prob ...

Nolah no making fun, really dunno the answer

the prob u faced, for me is not so noticeable, i guess my butt not so sensitive, heel and toe would help?

If more angular momentum is preserved, once the engine gets up to speed it takes less effort to keep going due to inertia.. a body in motion tends to stay in motion, remember?

With lesser crankshaft mass, it's easier to accelerate but harder to maintain the angular momentum. At high speeds, you tend to decelerate faster when you lift your foot off the pedal. When going uphill, it may be easier to pick up revs initially but your engine will have to work harder in order to maintain the angular momentum, which is necessary for maintaining the torque output. When you lift your foot off the throttle, if the angular momentum reduces rapidly, and so does your revs. So the engine will have to work a bit harder to get it up again.

This should be more pronounced with a lightened flywheel as compared to a lightened crank pulley. In any case, rotating masses present much higher apparent mass compared to reciprocating masses, so even a small reduction of rotating mass will result in a big reduction in apparent mass. For instance, I've read before that taking 2kg off the flywheel will result in over 100kgs lesser apparent mass on the crankshaft at around 2000 rpm.

Good explanation! Ive read this reasoning somewhere quite a while back, but one thing though, it explains what happens when u take ur feet off the pedal....now i ask, what happens if u 'dont' take your foot off the pedal, is there any way to tell (or calculate) whether it would be faster/easier to reach higher speeds/ go uphill with/without lightened crank/pulley?

Seriously seriously want to know, not asking because not believing/thinking im smart/everyone is wrong

 

[Mitevo7]

Nolah no making fun, really dunno the answer

the prob u faced, for me is not so noticeable, i guess my butt not so sensitive, heel and toe would help?

No problem bro, i don't mean any dissatisfaction as i respect every of the comments given by experts in this forum as i am still a freshmen in automotive and car enthusiast ... By the way, i am driving an auto trans n16 ... So very unfortunate, heel and toe is not applicable.

But i found out a solution for this ... This is just my pure opinion and experience, Lets take my car as example, i ad installed LCP for quite sometime and only take it genting hill drive for around 3 times. The prob i stated before it appears is because of my car's gear ratio and powerband hence i feel heavy when trying to push my car uphill. So now i revised my driving and look on my car's dyno sheet again ... My car's engine top peak achieved at 14.4kgm @ 4.4k RPM ... For that i always keep my car speed constant at 80 km/h when going up, before entering a corner, well my rev will surely drop fast becoz of the LCP when i lift off my leg from the pedal and press the brake, at the same time, i downshift to 2nd gear from 3rd gear, the rev goes up again around 3k ... By steadily steer the car into the corner, i can exit the corners constantly at 4x km/h to 50 km/h. The speed is varied depends on how tight is the corners ... Everytime i exit the corner, my rev is around 4k and still climbing to 5k before i shift up ... Well i know its kinda stressful to the engine, but i believe this little QG bastard that made from NISSAN is not going to kong so soon. Of course you need to properly service your car, use a better engine oil in order to drive as hard as me ... love my sentra

 

[phantomRX8]

i am not promoting anything but u guys can check a website by the name super damper. coz they got explaination there..sumthing to do with crank harmonics..says dat with lighter crank pulley, there will be more harmonic vibrations..even steve dinan frm bmw tuner dinan said these so called power pulleys is not good..maybe in long terms i guess..

 

[tofu_manic]

No problem bro, i don't mean any dissatisfaction as i respect every of the comments given by experts in this forum as i am still a freshmen in automotive and car enthusiast ... By the way, i am driving an auto trans n16 ... So very unfortunate, heel and toe is not applicable.

But i found out a solution for this ... This is just my pure opinion and experience, Lets take my car as example, i ad installed LCP for quite sometime and only take it genting hill drive for around 3 times. The prob i stated before it appears is because of my car's gear ratio and powerband hence i feel heavy when trying to push my car uphill. So now i revised my driving and look on my car's dyno sheet again ... My car's engine top peak achieved at 14.4kgm @ 4.4k RPM ... For that i always keep my car speed constant at 80 km/h when going up, before entering a corner, well my rev will surely drop fast becoz of the LCP when i lift off my leg from the pedal and press the brake, at the same time, i downshift to 2nd gear from 3rd gear, the rev goes up again around 3k ... By steadily steer the car into the corner, i can exit the corners constantly at 4x km/h to 50 km/h. The speed is varied depends on how tight is the corners ... Everytime i exit the corner, my rev is around 4k and still climbing to 5k before i shift up ... Well i know its kinda stressful to the engine, but i believe this little QG bastard that made from NISSAN is not going to kong so soon. Of course you need to properly service your car, use a better engine oil in order to drive as hard as me ... love my sentra

If kong, nevermind...get an sr20det

My current ride now, powerband is from 2.7k to 6.7k or so...the lcp brought the powerband slitely earlier with negligible difference up top (according to gtech) so it is flexible, have quite a broad powerband, good enough for a streeter

i am not promoting anything but u guys can check a website by the name super damper. coz they got explaination there..sumthing to do with crank harmonics..says dat with lighter crank pulley, there will be more harmonic vibrations..even steve dinan frm bmw tuner dinan said these so called power pulleys is not good..maybe in long terms i guess..

are they referring to dampened, or undampened pulleys? or both?