READ THIS BEFORE BUYING UNDERDRIVE PULLEY OR WELDING!!!
READ THIS BEFORE BUYING UNDERDRIVE PULLEY OR WELDING!!!
Thought I would re-post this in a new thread. Very important aspect of "failure prone" two piece "crank pulley"
http://en.wikipedia.org/wiki/Harmonic_balancer
http://en.wikipedia.org/wiki/Harmonic_balancer
Last edited by asand1; Aug 16, 2010 at 01:35 PM.
Performance enthusiasts have been known to remove harmonic balancers, usually when the balancer is attached to the crank pulley, deciding that they aren't necessary and their mass reduces the performance of the engine. However, this is unproven and potentially very risky because the danger of damage to the engine from the vibrations the damper is intended to prevent is too high.
...and then read this:
http://www.unorthodoxracing.com/faq.aspx#section2
Is my crank pulley a Damper (harmonic/torsional) or a harmonic balancer?
Crank pulleys are getting confused with a harmonic damper. Another term "Harmonic Balancer" is a loosely used term in the industry. Technically it does not exist. The "balancer" part comes from engines that are externally balanced and have a counterweight on the damper. None of the engines we make pulleys for use a balancer as they are all internally balanced.
The crank pulley on most import and small domestic engines has a rubber ring in the pulley making them look like a damper. The rubber ring quiets noise from the engine accessories (a/c, alternator, power steering, and water pump). The car manufacturers call it NVH control (Noise Vibration & Harshness) of noises that might be heard inside the car. It is important to know amount of weight mounted outside the rubber ring is too small in size to act as an effective damper. Many crank pulleys have no rubber at all. Examples are some Honda B & D Series engines, the Nissan Altima, the 1.8L Eclipse, 2.3L Fords, Chrysler 2.2L's, and 1.8L SOHC VW's. Most owners who have installed UR crank pulleys notice the engine feels smoother. This is because the stock crank pulley is not as well balanced as our crank pulley. NVH from the crank pulley is small but it can increase much more with the installation of aftermarket intake and/or exhausts. As an example stock intakes use baffles and resonators to quiet intake noise. Aftermarket intakes eliminate the resonators and create big increases in engine noise when you hit the throttle. To most car owners some type of NVH can make the driving experience more enjoyable because you can really hear the engine noises.
The traditional damper protects against crank failure from torsional movement and crankshaft frequencies. A damper is not necessary on most modern engines because of engine design. The reason why are things like shorter stroke length, smaller displacement, shorter piston dwell time, no piston pin off-sets. More importantly the actual tune (computer programming) is the biggest factor in the potential for engine damage. Poor tuning leads to detonation which is an engine killer that no damper can stop
http://www.unorthodoxracing.com/faq.aspx#section2
Is my crank pulley a Damper (harmonic/torsional) or a harmonic balancer?
Crank pulleys are getting confused with a harmonic damper. Another term "Harmonic Balancer" is a loosely used term in the industry. Technically it does not exist. The "balancer" part comes from engines that are externally balanced and have a counterweight on the damper. None of the engines we make pulleys for use a balancer as they are all internally balanced.
The crank pulley on most import and small domestic engines has a rubber ring in the pulley making them look like a damper. The rubber ring quiets noise from the engine accessories (a/c, alternator, power steering, and water pump). The car manufacturers call it NVH control (Noise Vibration & Harshness) of noises that might be heard inside the car. It is important to know amount of weight mounted outside the rubber ring is too small in size to act as an effective damper. Many crank pulleys have no rubber at all. Examples are some Honda B & D Series engines, the Nissan Altima, the 1.8L Eclipse, 2.3L Fords, Chrysler 2.2L's, and 1.8L SOHC VW's. Most owners who have installed UR crank pulleys notice the engine feels smoother. This is because the stock crank pulley is not as well balanced as our crank pulley. NVH from the crank pulley is small but it can increase much more with the installation of aftermarket intake and/or exhausts. As an example stock intakes use baffles and resonators to quiet intake noise. Aftermarket intakes eliminate the resonators and create big increases in engine noise when you hit the throttle. To most car owners some type of NVH can make the driving experience more enjoyable because you can really hear the engine noises.
The traditional damper protects against crank failure from torsional movement and crankshaft frequencies. A damper is not necessary on most modern engines because of engine design. The reason why are things like shorter stroke length, smaller displacement, shorter piston dwell time, no piston pin off-sets. More importantly the actual tune (computer programming) is the biggest factor in the potential for engine damage. Poor tuning leads to detonation which is an engine killer that no damper can stop
...and then read this:
http://www.unorthodoxracing.com/faq.aspx#section2
Is my crank pulley a Damper (harmonic/torsional) or a harmonic balancer?
Crank pulleys are getting confused with a harmonic damper. Another term "Harmonic Balancer" is a loosely used term in the industry. Technically it does not exist. The "balancer" part comes from engines that are externally balanced and have a counterweight on the damper. None of the engines we make pulleys for use a balancer as they are all internally balanced.
The crank pulley on most import and small domestic engines has a rubber ring in the pulley making them look like a damper. The rubber ring quiets noise from the engine accessories (a/c, alternator, power steering, and water pump). The car manufacturers call it NVH control (Noise Vibration & Harshness) of noises that might be heard inside the car. It is important to know amount of weight mounted outside the rubber ring is too small in size to act as an effective damper. Many crank pulleys have no rubber at all. Examples are some Honda B & D Series engines, the Nissan Altima, the 1.8L Eclipse, 2.3L Fords, Chrysler 2.2L's, and 1.8L SOHC VW's. Most owners who have installed UR crank pulleys notice the engine feels smoother. This is because the stock crank pulley is not as well balanced as our crank pulley. NVH from the crank pulley is small but it can increase much more with the installation of aftermarket intake and/or exhausts. As an example stock intakes use baffles and resonators to quiet intake noise. Aftermarket intakes eliminate the resonators and create big increases in engine noise when you hit the throttle. To most car owners some type of NVH can make the driving experience more enjoyable because you can really hear the engine noises.
The traditional damper protects against crank failure from torsional movement and crankshaft frequencies. A damper is not necessary on most modern engines because of engine design. The reason why are things like shorter stroke length, smaller displacement, shorter piston dwell time, no piston pin off-sets. More importantly the actual tune (computer programming) is the biggest factor in the potential for engine damage. Poor tuning leads to detonation which is an engine killer that no damper can stop
http://www.unorthodoxracing.com/faq.aspx#section2
Is my crank pulley a Damper (harmonic/torsional) or a harmonic balancer?
Crank pulleys are getting confused with a harmonic damper. Another term "Harmonic Balancer" is a loosely used term in the industry. Technically it does not exist. The "balancer" part comes from engines that are externally balanced and have a counterweight on the damper. None of the engines we make pulleys for use a balancer as they are all internally balanced.
The crank pulley on most import and small domestic engines has a rubber ring in the pulley making them look like a damper. The rubber ring quiets noise from the engine accessories (a/c, alternator, power steering, and water pump). The car manufacturers call it NVH control (Noise Vibration & Harshness) of noises that might be heard inside the car. It is important to know amount of weight mounted outside the rubber ring is too small in size to act as an effective damper. Many crank pulleys have no rubber at all. Examples are some Honda B & D Series engines, the Nissan Altima, the 1.8L Eclipse, 2.3L Fords, Chrysler 2.2L's, and 1.8L SOHC VW's. Most owners who have installed UR crank pulleys notice the engine feels smoother. This is because the stock crank pulley is not as well balanced as our crank pulley. NVH from the crank pulley is small but it can increase much more with the installation of aftermarket intake and/or exhausts. As an example stock intakes use baffles and resonators to quiet intake noise. Aftermarket intakes eliminate the resonators and create big increases in engine noise when you hit the throttle. To most car owners some type of NVH can make the driving experience more enjoyable because you can really hear the engine noises.
The traditional damper protects against crank failure from torsional movement and crankshaft frequencies. A damper is not necessary on most modern engines because of engine design. The reason why are things like shorter stroke length, smaller displacement, shorter piston dwell time, no piston pin off-sets. More importantly the actual tune (computer programming) is the biggest factor in the potential for engine damage. Poor tuning leads to detonation which is an engine killer that no damper can stop
Your turn.
Senior Member
Joined: Dec 2009
Posts: 469
I think we can say, if not that Unorthodox is wrong, that they have a vested interest in getting us to believe that harmonic balancers do not exist/are not important. We should read their advice and take it with a grain of salt.
That said, I'd agree that UDPs or damper removal probably aren't going to cause a massive upset in engine balance/NVH/engine longevity.
That said, I'd agree that UDPs or damper removal probably aren't going to cause a massive upset in engine balance/NVH/engine longevity.
Its not a matter of balancing, but rather one of torsional affects and harmonics. If you would prefer the term Harmonic Damper, I'll use that.
The fact that Nissan saw fit to use a two piece "pulley" bonded together with rubber tells me they thought it was necessary.
The NVH theory is BS. It was even said earlier in this thread that Some manufacturers (Honda) don't even use a damper, and they don't suffer NVH. I know VW doesn't either, those MFGs must have built a motor that doesn't need it, perhaps they have forged cranks, I don't know. Nissan, however, decided they did need it.
I'm not quoting Wiki as Gospel, I'm simply using it to illustrate something that has been common knowledge since the '50s, and I've know since I was in grade school (18 years ago).
The fact that Nissan saw fit to use a two piece "pulley" bonded together with rubber tells me they thought it was necessary.
The NVH theory is BS. It was even said earlier in this thread that Some manufacturers (Honda) don't even use a damper, and they don't suffer NVH. I know VW doesn't either, those MFGs must have built a motor that doesn't need it, perhaps they have forged cranks, I don't know. Nissan, however, decided they did need it.
I'm not quoting Wiki as Gospel, I'm simply using it to illustrate something that has been common knowledge since the '50s, and I've know since I was in grade school (18 years ago).
Senior Member
Joined: Dec 2009
Posts: 469
I don't disagree with you, but I think I don't consider it super-vital.
The VQ30 is a durable motor. It stands up to hundreds of thousands of miles of use without significant repairs or rebuilding. This means there's some degree of overbuilding going on with the VQ. The relatively small effect of having a non-damped pulley probably isn't going to be the deciding factor between a good motor and a trashed motor.
I'm not saying it's an irrelevant point, but when one modifies a factory motor one should know that there's a greater risk of something going wrong. A non-damped pulley isn't really (in my estimation) going to be on the list of biggest problems you could encounter. You might read those articles and (fairly and probably correctly) decide that the gain isn't worth the extra burden you put on the crank, but I suspect an FI setup (for example) would apply more additional stress, and that hasn't stopped the whole business in its tracks.
The VQ30 is a durable motor. It stands up to hundreds of thousands of miles of use without significant repairs or rebuilding. This means there's some degree of overbuilding going on with the VQ. The relatively small effect of having a non-damped pulley probably isn't going to be the deciding factor between a good motor and a trashed motor.
I'm not saying it's an irrelevant point, but when one modifies a factory motor one should know that there's a greater risk of something going wrong. A non-damped pulley isn't really (in my estimation) going to be on the list of biggest problems you could encounter. You might read those articles and (fairly and probably correctly) decide that the gain isn't worth the extra burden you put on the crank, but I suspect an FI setup (for example) would apply more additional stress, and that hasn't stopped the whole business in its tracks.
Member
Joined: Apr 2007
Posts: 52
Am I the only one noticing that
1. the article has a note at the top declaring that it has no cited sources which is as good as saying "these are all unsubstantiated claims"
2. the paragraph in question ends with a "citation needed" tag
3. the inline citations are from 1. car talk and 2. online dictionary and when you click on the online dictionary link it just takes you to a spammy page with a definition hidden amongst advertisements that reads like it was written by the same guy who wrote the wiki article on harmonic balancers.
4. the two "articles" linked at the end of the entry are, first an article from mopar magazine written by a 32 year old race car driver who's technical qualifications are "bears the responsibility of all fi eld-testing on ATI Torsional Super Dampers [ATI is his own company]. These patented used on most endurance engines built worldwide." He is a guy who's raced since he was 17 but there is also a huge typo and no mention of any technical degrees or qualifications in either the bio or on his website. This isn't to say that he isn't qualified, I'm sure he is but he too has a vested interest in crankshaft dampers because his company makes performance dampers for dodge engines.
the other article is from 1979 and everyone knows that we haven't made any engineering advancements since 1979...
so in conclusion, this is a nice discussion and all but
1. kevlo said it, no one's had engine failure from UD pulleys
2. we're arguing with our own speculations about a wikipedia article that may or may not be as legitimate as our speculations about it in this thread.
1. the article has a note at the top declaring that it has no cited sources which is as good as saying "these are all unsubstantiated claims"
2. the paragraph in question ends with a "citation needed" tag
3. the inline citations are from 1. car talk and 2. online dictionary and when you click on the online dictionary link it just takes you to a spammy page with a definition hidden amongst advertisements that reads like it was written by the same guy who wrote the wiki article on harmonic balancers.
4. the two "articles" linked at the end of the entry are, first an article from mopar magazine written by a 32 year old race car driver who's technical qualifications are "bears the responsibility of all fi eld-testing on ATI Torsional Super Dampers [ATI is his own company]. These patented used on most endurance engines built worldwide." He is a guy who's raced since he was 17 but there is also a huge typo and no mention of any technical degrees or qualifications in either the bio or on his website. This isn't to say that he isn't qualified, I'm sure he is but he too has a vested interest in crankshaft dampers because his company makes performance dampers for dodge engines.
the other article is from 1979 and everyone knows that we haven't made any engineering advancements since 1979...
so in conclusion, this is a nice discussion and all but
1. kevlo said it, no one's had engine failure from UD pulleys
2. we're arguing with our own speculations about a wikipedia article that may or may not be as legitimate as our speculations about it in this thread.
Cool.
So, Nissan decided it was needed, and now it's been removed.
I think the loud chorus of bleating over engine failures would be overwhelming!
*crickets chirping*
Well I'm not trying to overthrow the whole UDP movement. Just wanted to arm some people with a little understanding before they made their choices. Its good to know of possible risks and consequences before hand.
I'll admit that I've not read or heard anything about VQ's with broken cranks for whatever reason. I do think, however, that UDP's are over-hyped, Does anyone have dyno sheets that show an increase in acceleration or overall HP?
I'M sorry I'm Kinda old school, growing up with V8 RWD, high compression and cams. Its my belief that UDP,s offer such a minimal gain that the money could be better spent.
I'll admit that I've not read or heard anything about VQ's with broken cranks for whatever reason. I do think, however, that UDP's are over-hyped, Does anyone have dyno sheets that show an increase in acceleration or overall HP?
I'M sorry I'm Kinda old school, growing up with V8 RWD, high compression and cams. Its my belief that UDP,s offer such a minimal gain that the money could be better spent.
The VQ's are internally balanced (find a picture of the block and look @ how the pistons set), the harmonic dampener thingy is a bit overkill, but understood because V6's cannot be internally balanced perfectly (only engines that can be are I6s).
Harmonic Balancers are life or death for some other motors.... EG. V8s, and 4 bangers do something where there's a part of the crankshaft that spins twice the motor speed?? (Not sure on what piece spins, but there is an object that spins 2x the motor speed to balance out 4 bangers).
With that being said, the gains of a UDP aren't primarily HP, not going into detail why, not the topic @ hand.
Harmonic Balancers are life or death for some other motors.... EG. V8s, and 4 bangers do something where there's a part of the crankshaft that spins twice the motor speed?? (Not sure on what piece spins, but there is an object that spins 2x the motor speed to balance out 4 bangers).
With that being said, the gains of a UDP aren't primarily HP, not going into detail why, not the topic @ hand.
Last edited by aackshun; Aug 17, 2010 at 11:34 AM.
Senior Member
Joined: Dec 2009
Posts: 469
The VQ's are internally balanced (find a picture of the block and look @ how the pistons set), the harmonic dampener thingy is a bit overkill, but understood because V6's cannot be internally balanced perfectly (only engines that can be are I6s).
Harmonic Balancers are life or death for some other motors.... EG. V8s, and 4 bangers do something where there's a part of the crankshaft that spins twice the motor speed?? (Not sure on what piece spins, but there is an object that spins 2x the motor speed to balance out 4 bangers).
With that being said, the gains of a UDP aren't primarily HP, not going into detail why, not the topic @ hand.
Harmonic Balancers are life or death for some other motors.... EG. V8s, and 4 bangers do something where there's a part of the crankshaft that spins twice the motor speed?? (Not sure on what piece spins, but there is an object that spins 2x the motor speed to balance out 4 bangers).
With that being said, the gains of a UDP aren't primarily HP, not going into detail why, not the topic @ hand.
^ What this guy said, someone else can put what we said more elegantly to sum things up better.
Just as other have said, Our cars are internally balanced. Our cars do not use a harmonic balancer, they use a harmonic damper. There is a difference.
http://www.atiperformanceproducts.co...mper_dinan.htm
This has been discussed many times before in regards to our cars and the crank pulley.
http://forums.maxima.org/3515625-post24.html
http://forums.maxima.org/140640-post3.html
http://forums.maxima.org/2907485-post10.html
http://forums.maxima.org/4381913-post24.html
Many have run the UR UDP for years without any issues to the crank from any torsional vibration, myself included.
Others using the cheaper brand underdirve pullies have had issues with the pulley itself failing.
http://www.atiperformanceproducts.co...mper_dinan.htm
This has been discussed many times before in regards to our cars and the crank pulley.
http://forums.maxima.org/3515625-post24.html
http://forums.maxima.org/140640-post3.html
http://forums.maxima.org/2907485-post10.html
http://forums.maxima.org/4381913-post24.html
Many have run the UR UDP for years without any issues to the crank from any torsional vibration, myself included.
Others using the cheaper brand underdirve pullies have had issues with the pulley itself failing.
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