Unorthodox Pulleys Sets
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Re: Unorthodox Pulleys Sets
<blockquote><font class="small">In reply to:</font><hr>
Fluid,
Are you telling me that the same exact amount of energy is required to spin an object at rest as is required to continue to spin that same object already in motion?
Are you serious? Break out the pocket-protector, pal, and hit those books again.......
<hr></blockquote>
Are you saying it takes more energy (for example) to accelerate from 0-1000 RPM than it does to accelerate from 1000-2000 RPM? A pulley is accelerating any time the car is.
My apologies, but I do not know how to quote and respond to more than one post at a time on this board.
Edit - apparently I don't know how to quote either.
98 Maxima SE, 5-speed.
Next car, G35S 6MT?<P ID="edit"><FONT class="small"><EM>Edited by Anachronism on 01/21/04 11:37 AM.</EM></FONT></P>
Fluid,
Are you telling me that the same exact amount of energy is required to spin an object at rest as is required to continue to spin that same object already in motion?
Are you serious? Break out the pocket-protector, pal, and hit those books again.......
<hr></blockquote>
Are you saying it takes more energy (for example) to accelerate from 0-1000 RPM than it does to accelerate from 1000-2000 RPM? A pulley is accelerating any time the car is.
My apologies, but I do not know how to quote and respond to more than one post at a time on this board.
Edit - apparently I don't know how to quote either.
98 Maxima SE, 5-speed.
Next car, G35S 6MT?<P ID="edit"><FONT class="small"><EM>Edited by Anachronism on 01/21/04 11:37 AM.</EM></FONT></P>
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Re: Unorthodox Pulleys Sets
<blockquote><font class="small">In reply to:</font><hr>
If what you say is true, then it would be apparent that a set of your lighter weight pulleys would give HP gains even if they were the same exact diameter as OEM.
Do you have any dyno graphs to prove that?
<hr></blockquote>
A significant portion of the gains come from moveing the weight closer to the center. So a stock size pulley of the same weight would gain less than a underdrive pulley of the same weight. Plus a smaller pulley would be lighter if you wanted to make them the same strength. This is the same as the effect of larger rims hurting acceleration.
I don't understand all the calculations behind this but someone who does posted the calculations on Maxima.org. I belive these calculations are based on Unorthodoxes claim that one pound of weight saved equals approximatly 2.7 HP. Of course this is for a Maxima but the effect should be the same for any car even if the numbers are different. The post with the calculations is a little more than halfway down the page
Bottom line is a UDP would gain approximatly 8.7 HP from weight savings and moving mass closer to the center. A lightened pulley would gain approximatly 5.4 HP from weight savings. In addition the stock size pulley would have to be slightly heavier than the UDP to be the same strength and the UDP gets a couple HP from underdriving, so a stock size lightened pulley would only gain about half what a UDP would.
98 Maxima SE, 5-speed.
Next car, G35S 6MT?
If what you say is true, then it would be apparent that a set of your lighter weight pulleys would give HP gains even if they were the same exact diameter as OEM.
Do you have any dyno graphs to prove that?
<hr></blockquote>
A significant portion of the gains come from moveing the weight closer to the center. So a stock size pulley of the same weight would gain less than a underdrive pulley of the same weight. Plus a smaller pulley would be lighter if you wanted to make them the same strength. This is the same as the effect of larger rims hurting acceleration.
I don't understand all the calculations behind this but someone who does posted the calculations on Maxima.org. I belive these calculations are based on Unorthodoxes claim that one pound of weight saved equals approximatly 2.7 HP. Of course this is for a Maxima but the effect should be the same for any car even if the numbers are different. The post with the calculations is a little more than halfway down the page
Bottom line is a UDP would gain approximatly 8.7 HP from weight savings and moving mass closer to the center. A lightened pulley would gain approximatly 5.4 HP from weight savings. In addition the stock size pulley would have to be slightly heavier than the UDP to be the same strength and the UDP gets a couple HP from underdriving, so a stock size lightened pulley would only gain about half what a UDP would.
98 Maxima SE, 5-speed.
Next car, G35S 6MT?
Registered User
Joined: Aug 2003
Posts: 11
Likes: 0
Re: Unorthodox Pulleys Sets
<blockquote><font class="small">In reply to:</font><hr>
When it comes to rotational weight, like wheels or pulleys, what is most important? Having lower weight on something that is always stopping and starting (like a wheel, for example), or having lower weight on something that continues to turn (like pulleys, for example)?
Of course the correct answer would be the starting/stopping object (wheels).
Once your pulleys are spinning, right after engine start-up, it takes very little power to keep them spinning. As a matter of fact, the actual DRAG that the accessories produce robs 1000 times more power than the actual weight of the pulleys themselves.
Furthermore, I see you measure the weights of the pulleys in OUNCES to compare differences in weight between your pulleys and the OEM pulleys. Now, even if weight DID make a difference, how can you possibly expect anyone to believe that a few ounces could even make a difference?
<hr></blockquote>
The pulley is always accelerating from idle (or wherever you drop the clutch) to your shift point. The pulley is accelerating at a much faster rate than the wheels. Just to plug in some numbers that are not very accurate for illustrative purposes – To accelerate to 60 MPH your wheels must accelerate from 0-600 RPM. The crankshaft pulley will accelerate from 2000 to 6000 RPM in 1st gear than 4000-6000 RPM in second gear, a total of 6000 RPM. So the pulley is accelerating 10 times faster than the wheels. (Keep in mind these are rough approximations I pulled out of my …err hat) Plus a UDP moves rotational weight closer to the center, the only way you can do that with wheels is by getting smaller rims.
98 Maxima SE, 5-speed.
Next car, G35S 6MT?
When it comes to rotational weight, like wheels or pulleys, what is most important? Having lower weight on something that is always stopping and starting (like a wheel, for example), or having lower weight on something that continues to turn (like pulleys, for example)?
Of course the correct answer would be the starting/stopping object (wheels).
Once your pulleys are spinning, right after engine start-up, it takes very little power to keep them spinning. As a matter of fact, the actual DRAG that the accessories produce robs 1000 times more power than the actual weight of the pulleys themselves.
Furthermore, I see you measure the weights of the pulleys in OUNCES to compare differences in weight between your pulleys and the OEM pulleys. Now, even if weight DID make a difference, how can you possibly expect anyone to believe that a few ounces could even make a difference?
<hr></blockquote>
The pulley is always accelerating from idle (or wherever you drop the clutch) to your shift point. The pulley is accelerating at a much faster rate than the wheels. Just to plug in some numbers that are not very accurate for illustrative purposes – To accelerate to 60 MPH your wheels must accelerate from 0-600 RPM. The crankshaft pulley will accelerate from 2000 to 6000 RPM in 1st gear than 4000-6000 RPM in second gear, a total of 6000 RPM. So the pulley is accelerating 10 times faster than the wheels. (Keep in mind these are rough approximations I pulled out of my …err hat) Plus a UDP moves rotational weight closer to the center, the only way you can do that with wheels is by getting smaller rims.
98 Maxima SE, 5-speed.
Next car, G35S 6MT?
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Joined: Dec 2003
Posts: 19
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From: Cincinnati, OH
Re: Unorthodox Pulleys Sets
Lots of study hall physics professors out here! :-) I am not one of them, but I know some expert out here could calculate the amount of power it would take to spin and object with an OD of X and a weight of Y...and then change the weight to Z and see what the formula spits out. I bet the difference in the two numbers has lots of decimal places! :-)
Personally, I can't see how making two pullies a few oz. lighter will do JACK for rwhp or tq numbers. I installed an aluminum driveshaft in my Mustang, which shaved 8 POUNDS of rotational mass. Comparing corrected rwhp and tq numbers didn't show any tangible gains. I have seen several people pick up several rwhp with a lighter flywheel, however. But a flywheel has a big OD, and the weight savings is 10+ lbs. Takes a lot of energy to turn it!
Underdrives are a great bang for the buck mod on just about every car. And with a 110 amp alternator in the G35, its not an issue to underdrive all three pullies and still have charging at idle. Overheating in major temps @ idle in traffic may be a different story!
Does anyone (March, etc) make a 3 piece pulley set that is all underdrive? Do the G35 kits out there piggy-back the stock crank balancer or come with a new one?
-- Mike
'04 G35 6MT Sedan
Diamond Graphite
Personally, I can't see how making two pullies a few oz. lighter will do JACK for rwhp or tq numbers. I installed an aluminum driveshaft in my Mustang, which shaved 8 POUNDS of rotational mass. Comparing corrected rwhp and tq numbers didn't show any tangible gains. I have seen several people pick up several rwhp with a lighter flywheel, however. But a flywheel has a big OD, and the weight savings is 10+ lbs. Takes a lot of energy to turn it!
Underdrives are a great bang for the buck mod on just about every car. And with a 110 amp alternator in the G35, its not an issue to underdrive all three pullies and still have charging at idle. Overheating in major temps @ idle in traffic may be a different story!
Does anyone (March, etc) make a 3 piece pulley set that is all underdrive? Do the G35 kits out there piggy-back the stock crank balancer or come with a new one?
-- Mike
'04 G35 6MT Sedan
Diamond Graphite
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