fact 101: HARMONIC BALANCER honda k-series k24z7 civic si pulley fb6 fg4

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team3d

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harmonic balancer is a device that added to crossplane v8 engine around 70yrs ago by car manufacturers (gm, ford, etc...) to absorb vibrations

the reason why they need an external device to reduce vibrations is becuase crossplane v8's crankshaft can't be balance to 0 (can balance close to 0) due to it's length. with crossplane's firing order and unbalance-able crankshaft, it create more vibrations that the crankshaft's counterweight can't canceled and thus the "band-aid" fix is to add counterweight to the end of the crankshaft to remove the additional vibrations, to put it in a simple term, they need to "filter" the vibration twice...


now, lets look at our engine, if you look through 9th gen civic's parts catalog, you will not find harmonic balancer. because we don't have harmonic balancer.. we have crank pulley.

k24z7, like most inline 4 engine, we have very short crankshaft. all late model inline 4 engine are internally balanced & due to the advance design of a Japanese engine, our crankshaft's counterweight can cancel out primary vibrations almost 100%, thus we do not use or need harmonic balancer.

k24z7 crankshaft with counterweight.... this is the device honda use to cancel out primary vibrations... not harmonic balancer
Honda Civic 10th gen fact 101: HARMONIC BALANCER honda k-series k24z7 civic si pulley fb6 fg4 1-L


but due to the vertical design of the inline 4, our engine have 2 sets of vibrations... it's why the crankshaft counter weight only can cancel out the primary vibrations... to cancel out the secondary vibrations, most inline 4 engine will add balance shafts under the crankshaft. the balance shaft will cancel out secondary vibrations cause by the design of the engine.

k24z7 oil pump with balance shaft.... this is the device honda use to cancel out secondary vibrations... not harmonic balancer
Honda Civic 10th gen fact 101: HARMONIC BALANCER honda k-series k24z7 civic si pulley fb6 fg4 Motovicity%20Honda%20K24%20build%20-%20block-75-L




i hope this will clears things up... the problem with this urban myth is cause by both sides...

the consumers especially 1st timers will not know anything about this because this is very technical... so the false information keep spreading like a snowball,

but the blame is to the tuner/vendors, for the past 20yrs, there are too many tuners/vendors without proper engine knowledge/foundation start their own shop, brand, company and when a consumer ask questions about pulley, they don't know the answer either..... just becuase a person can race a car, install a turbo kit or tune your ecu doesn't mean he understand how mechanical parts function, especially this particular knowledge requires a basic understanding on various engine designs..


in conclusion, yes, light weight, underdrive pulley are perfectly safe for k24z7.... will it make any power ? of-course it will... if it doesn't why car manufactures spend 100's of millions developing electric water pump & electric power steering ? and if you can't link electric water pump/power steering to light weight, underdrive pulley ? go to library and pick up some automotive engineering books to read... it will benefit you if you really like cars...


team3d......
 

Micah

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light weight pulley & underdrive light weight pulley are the same thing, the only difference is the size...
What is the point of this thread?

Is there an aftermarket pulley you are advocating?
 
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I need an udp for the 2.0l. Also a fact.
 

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Some information in this post is accurate, some is not. Mainly the conclusion is not. This is due to not having all the facts or evidence to be able to make the conclusion.

Every engine is different in terms of dampening, balance, material, and effective mass so you cannot use a lifespan analysis of one engine to accurately predict what will happen in this one. Even if the shaft is better balanced, the tolerances probably are too, and it doesn't mean it will react the same way when the filtering system is changed (yes mass is a part of it).

No one here other than a handful of Honda engineers can accurately predict much it will affect the engine's life. But yes, JUST LIKE TUNING, to some extent IT WILL.

If you want the mathematical derivation here is a decent reference to start : link

I don't care if someone wants to take the risk of reducing mass. Reducing the shaft mass on it own MAY be tolerable but with the combination of [reduced damping] and [larger harmonic amplitude (from tuning for more power)], the risk is magnified. These cars tend to have over engineered engines as a default so it may still be an acceptable risk.
 

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Since people are afraid of lightweight crankshaft pulleys because it'll affect their engine's crankshaft bearing's lifespan, perhaps there needs to be another market. Create a market to install a heavier than stock harmonic balancer so you can increase your engine's crankshaft ball bearing life. All one would need to do is to show ligthtweight pulleys on a damaged engine. Or even stock pulleys that have failed. Hrrrmmm........ I may be on to something. Be right back.
 
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Some information in this post is accurate, some is not. Mainly the conclusion is not. This is due to not having all the facts or evidence to be able to make the conclusion.

Every engine is different in terms of dampening, balance, material, and effective mass so you cannot use a lifespan analysis of one engine to accurately predict what will happen in this one. Even if the shaft is better balanced, the tolerances probably are too, and it doesn't mean it will react the same way when the filtering system is changed (yes mass is a part of it).

No one here other than a handful of Honda engineers can accurately predict much it will affect the engine's life. But yes, JUST LIKE TUNING, to some extent IT WILL.

If you want the mathematical derivation here is a decent reference to start : link

I don't care if someone wants to take the risk of reducing mass. Reducing the shaft mass on it own MAY be tolerable but with the combination of [reduced damping] and [larger harmonic amplitude (from tuning for more power)], the risk is magnified. These cars tend to have over engineered engines as a default so it may still be an acceptable risk.

this is a factory honda type-r pulley...
Honda Civic 10th gen fact 101: HARMONIC BALANCER honda k-series k24z7 civic si pulley fb6 fg4 type-r pulley
 
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this is a factory honda type-r pulley...
type-r pulley.jpg
Wow! That looks not different than any of the lightweight pulleys I've purchased in the past.
 
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google harmonic balancer or crank pulley, click on image, the image you will mostly see are failed factory crank pulley/harmonic balancer, rubber deteriorated overtime, eventually it's gonna split.

this is very similar to wheels construction, 1pc forged wheels are superior over 2pc welded becuase it is much easier for weld part falls apart and detach from the center disc. it's why they later design bolt in 2pc & 3pc wheels, unfortunately.. they are extremely weak in performance (compare to 1pc wheels)

Honda Civic 10th gen fact 101: HARMONIC BALANCER honda k-series k24z7 civic si pulley fb6 fg4 harmonic balancer
 
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here is oem honda pulley for the k-series...

on the left is factory type-r pulley (under drive) on the right is what you gonna find on 90% of the k series engine (non-under drive) include 8th & 9th civic, accord, tsx, element, crv etc...

honda use underdrive pulley on many of their more performance oriented engines to reduce parasitic drag..
Honda Civic 10th gen fact 101: HARMONIC BALANCER honda k-series k24z7 civic si pulley fb6 fg4 TYPE R VS R40


from hot rod magazine link: http://www.hotrod.com/articles/pull/

Underdrive Pulleys
The biggest drawback to belt-driven accessory systems is that it takes precious horsepower to turn them. One method of regaining some of the power lost to the parasitic drag effect is to underdrive the system. In most cases, accessories like the water pump, A/C compressor, and power-steering pump can be safely slowed down by 25 percent; alternator speed should stay within about 10 percent or less of its stock speed because alternator output tends to fall rapidly as rpm decreases. Underdrive is generally achieved by swapping a smaller crank pulley in conjunction with slightly larger water-pump and alternator pulleys.

If we swap our imaginary small-block’s 651/48-inch crank pulley to a smaller 5-inch crank pulley, we can underdrive the water and power-steering pumps by the right amount, but not without also adversely affecting the alternator. By slowing the rotating rpm of the alternator, charging output can be reduced enough to cause the headlights to dim at idle and prevent the battery from properly charging. The simple fix is to replace the 211/42-inch alternator pulley with a smaller 2-inch pulley and raise the rotating rpm from 2,000 back to 2,500, which is only 150 rpm less than the original 2,650 with the larger 651/48-inch crank pulley. In the process, we’ve reduced the speed of the other accessories relative to the crankshaft speed, reduced parasitic drag, and gained a few extra ponies. And to think we used to hate math in grade school.
 

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If I could get some accessory pulleys that can have a reduced diameter as well, I'd be all over getting an under driven piece. No doubt! Mainly the alternator pulley as is mentioned.
 
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If I could get some accessory pulleys that can have a reduced diameter as well, I'd be all over getting an under driven piece. No doubt! Mainly the alternator pulley as is mentioned.
honda's belt driven system consist of 1) oil pump 2) power steering pump 3) alternator 4) water pump 5) A/C

in today's car... the belt driven system no longer need to drive water pump & power steering pump because they are all gone electric.. the less accessories belt system needs to drive, the less parasitic drag it will cause, that = more power = better mpg

this is why so many race cars remove their a/c and power steering, not becuase they like it, it's becuase remove these 2 units reduces parasitic drag

this is the best example... with ktuned electric water pump kit + no power steering & no a/c, the belt driven system all it got is, ep3 tensioner & alternator... and they probably have a balance shaft oil pump delete too.. just balance shaft oil pump delete will free up 8hp....
Honda Civic 10th gen fact 101: HARMONIC BALANCER honda k-series k24z7 civic si pulley fb6 fg4 ktuned water pump 1
Honda Civic 10th gen fact 101: HARMONIC BALANCER honda k-series k24z7 civic si pulley fb6 fg4 ktuned water pum
 
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