Light weight crank pulley good or bad

[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?

 

[JINEIL2EN]

1st things, i'm more to NA, not really familiar with big cap, big turbo here, if got oso, only L2s with some mod turbine.
so, i just talking bout NA here...
after changing the LCP, its really more better control of the pedal when i need some rev up to keep the powerband. but really big difren when rpm drop coz can play with some skill. after changing lighten flywheel, thats the big difren. rev up faster & drown faster as well. at 1st, it's kinda hard to control the rev coz i'm just a chicken kaki. after a few week of try & error, will know how to get in control, then u'll enjoy the revving....:proud:

correct me if i'm wrong, pls dun shoot me... just a newbie here..

 

[nicholas1007]

i heard that there's ppl install the LCP into vios & cause their cars' power steering pump bengkok.
y is that happen.

Bump: i heard that there's ppl install the LCP into vios & cause their cars' power steering pump bengkok.
y is that happen.

Bump: i heard that there's ppl install the LCP into vios & cause their cars' power steering pump bengkok.
y is that happen.

 

[JINEIL2EN]

i heard that there's ppl install the LCP into vios & cause their cars' power steering pump bengkok.
y is that happen.

Bump: i heard that there's ppl install the LCP into vios & cause their cars' power steering pump bengkok.
y is that happen.

Bump: i heard that there's ppl install the LCP into vios & cause their cars' power steering pump bengkok.
y is that happen.

ask their foreman who ketuk the rack 1...

 

[xbalance2002]

last time i also face the same issue as urs....

now like to rev more some time .....
but most of the time i drive like an old man .... slow slow on the highway....

 

[samlkm]

Hi guys,

I wonder if anyone of you have any info on where or with who I can custom make a crank shaft pulley for my ride ? Mine is a Ford Telstar 2.0 year 1999 NA model.

Thanks.

 

[zephon83]

i installed on Wira AB once, its on carb, 17" n its auto transmission...quite got some effect on it. the rev is more faster response...some oso say it can safe petrol too...

 

[tahr_bss]

So LCP is playing with torque force. Is there anyone here have any experience which one is better, lighter crank pulley or lighter rim?

 

[tigger5251]

LCP + skimmed flywheel, can beat the shit outta any stock car ANYTIME. So ppl are worried LCP and skimmed flywheel will suffer hill climb, yes, a bit hurting the pocket coz u no longer can resides on stock peak torque point (eg: 3000rpm peak torque). But it CAN hillclimb better than stock cars, but need to rev higher n more petrol is needed. It totally relies on the engine tuning too, too much highrev n climb Genting hill, halfway u can pop ur engine hood n experience engine sauna. Everything needed to be TUNED.

But mostly ppl uses LCP and skimmed flywheel, they also use SMALLER rimsize like 14", highcams, and management to overcome this problem of lossless of power during hill climb.

Just face the facts, LCP on a streetcar helps a tiny bit. Not worth to use LCP if ur car is not for thrills.

So, spend wisely. LCP do works, skimmed flywheel do works. They works very well for a race car, coz every little things moving connected to the engine, have to be light, instant respond, disregarding the noise, comfort or how much petrol wasted. The point is to WIN WIN WIN! U have to understand and see what is ur application using them.

To improve a stock car power, just rebore to bigger cylinders, end of story. If not satisfied, do port n polish. These are the REAL deals if u need engine respond to improve. U must compare and research, canot simply plonk in a performance part and hope it gives u kicks naturally with the way u drive to work like norm everyday.

 

[alamdamai1]

did a search on the most elusive question about our harmonic damper where at last manage to find some hard facts...

Plastic hub torsional vibration damper - Patent 4302986

i would like to quote a few statements from above article :-

"As the crankshaft is turning, each incremental application of torque, as occasioned by rapid fuel combustion in a cylinder, results in a slight acceleration of the metal adjacent the crank arm. When the metal recovers, due to its natural elasticity or resilience, it rotates slightly in the opposite direction. Such forces often result in torsional vibrations in the shaft. In a typical instance of torsional vibration, an engine crankshaft turning at a rate of 3000 r.p.m. simultaneously executes angular vibrations of an amplitude of from one-fourth degree to one degree at a frequency of 150 to 250 cycles per second."

"Thus whenever any rotary mass, such as a torsional vibration damper, is added to the crankshaft of an engine, the resonant frequency of that crankshaft is lowered. Such lowering may bring critical resonant vibration orders of the crankshaft near or within the operating range of speeds of the engine".

"It will now be apparent to the reader that the inertia of a rotary mass fixed to the crankshaft, for the purpose of completing a typical damper assembly, should be as small as possible. In this way, the crankshaft resonant frequencies may, in certain applications, be maintained as far as possible from the engine firing related frequencies."

FIG. 2 illustrates the action of the addition of a torsional vibration damper of the type shown in FIG. 1 on a resonant frequency response of the typical crankshaft in an internal combustion engine, the ordinate showing torsional vibration amplitude being in tenths of a degree.

FIG. 3 is a view similar to FIG. 2 and illustrates a torsional vibration damper tuned to a frequency above an optimum frequency.

FIG. 4 is a view similar to FIG. 3 and illustrates an arrangement of a torsional vibration damper tuned to a frequency below an optimum frequency.

FIG. 5 is a view similar to FIG. 1 and illustrates the effect on torsional vibration behavior of the addition of a typical cast iron hub to a crankshaft.

FIG. 6 is a view similar to FIG. 2 and illustrates the change in frequency response of a crankshaftdamper assembly with the use of a damper employing a plastic hub of this invention.

FIG. 7 is a view similar to FIG. 5 and illustrates an optimum manner of tuning the plastic hub vibration damper of this invention.

hence, in summary, can we conclude that if we use a non-dampened LCP, would the crankshaft resonant frequency be moved to the higher RPM beyond 4,000 which is then is safe to be used for our cars?

 

[tigger5251]

what u said is based on research of "patented" test. But the LCP has been inside my car for 3 yrs n nothing happened. comon! there is hell alot of other vibration from various parts of the engine!