ZPIracing Lightweight Pulley vs. NST Underdrive Pulley....
03-07-2006, 04:06 AM
#23
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Interested in this too. I don't think I'd like to go underdrive b/c I really don't want to lose any power to my accy stuff, especially since I have a big stereo and I'm thinking about s/c in the future (if it ever comes out for the atuo that is, lol 
)...
So, with a lightweight pulley, same size just lighter, how much more power are we talking about here?? And, how much does one cost?
)...So, with a lightweight pulley, same size just lighter, how much more power are we talking about here?? And, how much does one cost?
03-07-2006, 04:17 AM
#24
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Originally Posted by Shoelesscraig
Interested in this too. I don't think I'd like to go underdrive b/c I really don't want to lose any power to my accy stuff, especially since I have a big stereo and I'm thinking about s/c in the future (if it ever comes out for the atuo that is, lol )...
So, with a lightweight pulley, same size just lighter, how much more power are we talking about here?? And, how much does one cost?
)...So, with a lightweight pulley, same size just lighter, how much more power are we talking about here?? And, how much does one cost?
its not a matter of gaining power, its a matter of improving efficiency by reducing drag. This improvement would be roughly equal to HP gains slightly better than that of an intake.
03-07-2006, 04:29 AM
#26
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I would really like to see how the weight of the V2 compares to that of the NST underdrive. Stock pulley is 55 ounces, NST is 20 ounces, maybe one of us can find out the V2...
lets see who finds out first...
lets see who finds out first...
03-07-2006, 04:30 AM
#27
Originally Posted by hPower
OK, so as far as engineering is concerned, this is what I have learned recently. Most of this information comes from the conversations I have had with Mike from www.NonStopTuning.com on AIM, his screen name is NSTonAIM and he is great about giving out information. I suggest you talk to him if you have questions. Strap yourself in because this is going to be a long reply!
Basically, there are several benefits to be had with aftermarket pulleys.
1. They are much lighter than stock. Less weight means more throttle responce. You slap on a pulley (or set of pulleys) that is lighter than stock and you will see your car revving up faster and easier. Both NST and ZPI pulleys are lighter than stock and their benefits can easilly be seen on the butt dyno.
2. Underdriving. Some crank pulleys underdrive accessories. Underdrive means to slow down. An underdrive crank pulley will send less power to the accessories, and thus free up some extra horsepower that can be sent to the wheels instead. This is how you see extra WHP on a dyno. Underdrive is truely the way to go if you want more power at the wheels. NST crank pulleys underdrive, ZPI crank pulleys do not.
A properly designed underdrive crank pulley will slow down accessories to a point where they will still function properly and not loose any of their power. NST spends a lot of time and money on R&D so lets give them credit, they are not going to sell you a product that will make you not want to come back to them.
3. Overdrive. Very few companies right now, NST being one of them, are building overdrive pulleys like the ones you see for our alternators. Overdrive mans to speed up. By speeding up the alternator, an NST pulley will bring the alternator up to charge faster than a stock pulley would. This means the alternator will work more efficiently and will charge easier. People with stereo systems and extra lighting mods will love a pulley like this.
So that is the engineering disscussion you wanted. If you have more questions ask me and I will help you if I can. Or go to the source and ask for youself, www.NonStopTuning.com
Basically, there are several benefits to be had with aftermarket pulleys.
1. They are much lighter than stock. Less weight means more throttle responce. You slap on a pulley (or set of pulleys) that is lighter than stock and you will see your car revving up faster and easier. Both NST and ZPI pulleys are lighter than stock and their benefits can easilly be seen on the butt dyno.
2. Underdriving. Some crank pulleys underdrive accessories. Underdrive means to slow down. An underdrive crank pulley will send less power to the accessories, and thus free up some extra horsepower that can be sent to the wheels instead. This is how you see extra WHP on a dyno. Underdrive is truely the way to go if you want more power at the wheels. NST crank pulleys underdrive, ZPI crank pulleys do not.
A properly designed underdrive crank pulley will slow down accessories to a point where they will still function properly and not loose any of their power. NST spends a lot of time and money on R&D so lets give them credit, they are not going to sell you a product that will make you not want to come back to them.
3. Overdrive. Very few companies right now, NST being one of them, are building overdrive pulleys like the ones you see for our alternators. Overdrive mans to speed up. By speeding up the alternator, an NST pulley will bring the alternator up to charge faster than a stock pulley would. This means the alternator will work more efficiently and will charge easier. People with stereo systems and extra lighting mods will love a pulley like this.
So that is the engineering disscussion you wanted. If you have more questions ask me and I will help you if I can. Or go to the source and ask for youself, www.NonStopTuning.com
I felt that I was going to end up with more power with the NST set of pulleys so that was my reasoning for going with them. I would more then recommend going with the NST set up. Like stated before, if you have any questions no matter if you feel they are stupid or not, Mike can be reached almost all the time on AIM (NSTonAIM) or email.
03-07-2006, 12:07 PM
#28
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Although the underdrive pulley would be spining everything attached to the belt at slower speeds, the alternator pulley would spin the unit back up to normal speeds again.
If that is what you meant, then cool. Not an attack, just a clarification.
03-07-2006, 01:25 PM
#29
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Ok.... this is good...
So what you are saying is that there it isn't a linear effect on the pulleys... I am taking that to mean the NST alt pulley (an overdrive pulley) does not 'compensate' for the reduction in diameter of the crank underdrive pulley.
Am I off here?
So what you are saying is that there it isn't a linear effect on the pulleys... I am taking that to mean the NST alt pulley (an overdrive pulley) does not 'compensate' for the reduction in diameter of the crank underdrive pulley.
Am I off here?
03-07-2006, 02:05 PM
#30
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Originally Posted by sensay
I would really like to see how the weight of the V2 compares to that of the NST underdrive. Stock pulley is 55 ounces, NST is 20 ounces, maybe one of us can find out the V2...
lets see who finds out first...
lets see who finds out first...
03-07-2006, 02:11 PM
#31
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The belt will still turn slower with the under drive crank pulley. The crank sets the speed of the belt. Well the belt will only turn as fast as the crank pulley turns...Which brings us to the diameter of the pulley. So apparently size does matter. :D
Oh and the alternator is driven by the belt, so the alt. pulley size does not affect the underdriving of the crank pulley as it is a slave device, and not a master. The crank pulley is the master.
Oh and the alternator is driven by the belt, so the alt. pulley size does not affect the underdriving of the crank pulley as it is a slave device, and not a master. The crank pulley is the master.
03-07-2006, 03:49 PM
#32
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Originally Posted by tCtuner
Ok.... this is good...
So what you are saying is that there it isn't a linear effect on the pulleys... I am taking that to mean the NST alt pulley (an overdrive pulley) does not 'compensate' for the reduction in diameter of the crank underdrive pulley.
Am I off here?
So what you are saying is that there it isn't a linear effect on the pulleys... I am taking that to mean the NST alt pulley (an overdrive pulley) does not 'compensate' for the reduction in diameter of the crank underdrive pulley.
Am I off here?
The underdrive crank pulley will underdrive everything, including the alternator, by 20%. This means if the alternator were to charge at 1,000 RPM with a stock crank pulley, it would now need to charge a bit later at 1.200 RPM. This is absolutely ok for daily driven cars. The only time it becomes a problem is if you have a HUUUUGE audio system and lots of ricer lights and neons!
Now, if you put on the 20% OVERDRIVE alternator pulley that NST supplies, your alternator will charge 20% sooner. So instead of needing to charge at 1,200 RPM you are now back to 1,000 RPM. You could even throw one of these bad boys on your alternator if you have a stock crank pulley and now you would be charging at 800 RPM instead. A lot of MR2 guys have been doing this in the past few years and they like the results.
03-07-2006, 04:13 PM
#34
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hPower, thanks. I was off, but am on track with that. 
ZPIracing....
I would really like to see how the weight of the V2 compares to that of the NST underdrive. Stock pulley is 55 ounces, NST is 20 ounces, maybe one of us can find out the V2...
03-07-2006, 09:23 PM
#37
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For a well informed post on the cons of lightweight crank pullies, see:
http://www.yoursciontc.com/forums/in...showtopic=6923
If Steve Dinan says you'll screw your engine, I'm inclined to believe him.
http://www.yoursciontc.com/forums/in...showtopic=6923
If Steve Dinan says you'll screw your engine, I'm inclined to believe him.
03-07-2006, 10:13 PM
#38
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pulleys have been used forever and unless you going to keep your car for 4+ years i would advise against that...as far as zpi vs NST sorry but NST is better have had it on for about 3 weeks no problems yet....
03-07-2006, 10:25 PM
#39
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as long as we dont go icreasing our rev limit, we will be fine. The stock pulley dampens those vibrations sure, but it by no means removes them. Just reduces them, so the diffrence isnt really that great. The people that argue bout the whole damage thing, most the time have never really owned one of these pullies and dont have any arguments towards the people that have had their pullies for years. Well other than ITS ONLY A MATTER OFF TIME, except that time never comes.
03-08-2006, 12:17 AM
#40
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^ Good point! And even with the stock pulley its still only a matter of time.
Ohhh Sensay vewwy wise for young pup!
As far as overdriving your alternator-I'm not sure it will make any more power-maybe?
Ohhh Sensay vewwy wise for young pup!
As far as overdriving your alternator-I'm not sure it will make any more power-maybe?