Oooooo, +1.1hp in 1st, that's good enough for me ^_^

 

And for most, apparently!

 

let me add, You just lost drivability ====== what did you gain?
Underdriving the VQ with loss of flywheel mass = no drivability = No gains

 

Damn....... someone better tell UR because they claim the oppsosite. Hmmmmmm Who's right???

 

Unorthodox makes an underdrive pulley, not just lightened. Any and all gains come from the underdrive, not the weight savings, despite what Unorthodox claims. They need to hire some real engineers to do some math for them rather than just the CAD monkeys that "design" the pullies. Don't forget that Unorthodox, and any pulley manufacturer, stands to earn money by claiming their hardware makes a lot of power. I, on the other hand, stand to lose nothing in either case.

 

Ok then their product makes gains???? They say by lightening, you say by underdriving. Why don't you write these guys and explain your point and we'd like to see what then have to say. Please post their response. But probably most here will say they don't care if it's from underdriving or reducing weight that gives them the gains, as long as they have gains. How much, I agree, is little but..........

 

I agree with MechEE's scientific analysis based on what I've seen in real life after installing my pulley. I believe the pulley helps most at the initial stages of acceleration. After a certain amount of speed is attained the "power" gain has to be pretty minimal from a "makes sense" point of view. It simply doesn't take that much less power to spin the smaller, lighter pulley vs the stock pulley once it's up and rotating. If you use the analogy of performers who spin those plates on sticks, the most resistance would be when you first start the plate spinning. A smaller, lighter plate would be easier to get going but once spinning requires very little additional force to keep it going. A larger plate would require more startup power but once rotating would require minimal incremental force vs the smaller plate to keep it spinning if any. The size and weight difference between the two pulleys isn't great enough to make a significant difference in how much power is needed to keep them going. Maybe one reason why you don't see improved times at the track with the pulley (at least I've not seen them posted).

My real world observation is after installing, the pulley, from a standing stop the car rolls forward or backward without applying the accelerator whereas prior to pulley install it did not. This was most evident when backing out of my garage. For the first year I didn't have the pulley I'd put it in reverse, apply accelerator and off I'd go. This is a scenario I repeated hundreds of times during the first year so I have MANY observations. After pulley install I put it in reverse and the car backs up without any accelerator input. True from a standing stop going forward as well. Maybe a simplistic view but it is consistent with MechEE's science.

 

........................................

 

Unorthodox claims that 85% of the gains comes from the lightening. If this is the case, then their pullies are completely worthless and make no power, since the lightening produces fractions of 1 hp in anything but 1st gear, and ( nothing / 0.85 ) = nothing. Simply point anyone technical at Unorthodox to my lightened component website and ask them to refute it. I guarantee you that all they will say is that they are dyno proven. Given that it is very hard to model the parasitic losses of accessories hanging off the engine, I can't really refute any small measured gains since they may come from the underdriving. But you CAN take the underdrive (say 10%), and estimate the power loss from accessories (say, 30 hp), and estimate an increase of ~3 hp from underdriving, for example.

 

The pullies "help" is directly proportional to acceleration. The more quickly the instantaneous acceleration rate of your motor, the more power or torque the pully has unleashed compared to stock. It takes the EXACT same amount of torque to accelerate the pulley from 1000 RPM to 3000 RPM in 1 second as it does to accelerate it from 5000 RPM to 7000 RPM in 1 second. Remember that acceleration is a change in speed over time, and does not depend on the absolute speed.

Regarding your observations of the car rolling, it has nothing to do with your newly installed pullies (unless you changed something like your alignment in between). Rolling resistance of your tires alone represent orders of magnitude greater forces on your car than accelerating your lightened pullies at such an incredibly low rate, not to mention all of the other inertias that you're accelerating when you do so (all four wheels, tires, driveline, etc).

 

so the question SHOULD be.. does anyone have a pulley-add dyno before & after? so we can see where if any gains were made.

 

it's like lightening a flywheel; you won't see it on the dyno

 

so then the theory is that it revs faster, therefore going through the gears faster?

 

They're lying. Everything MechEE is posting is true and legit. Someone also needs to tell the guys at UR that the VQ pulley is in fact a crank damper. It's actually a two peice pulley with a sandwiched elastomer ring that quells crank vibrations.

 

Do you know why it's there???? Is the OEM pulley cast or turned from solid material???? Do you know how much castings differ from part to part???? Do you know how "True" it runs from part to part??? That's why Nissan has that there!!!! So they can mass produce this part and hopefully rid the problem of vibrations.

Also people this is not really a HP mod. It only frees up the motor to rev a little quicker. How much????? I have always looked at this as an aid to get you "out of the hole" quicker. If you want real improvements, get a lightened flywheel otherwise it will be a so-so mod!!! Like MechEE said previously, you'll only really feel this mod's maximum effect in first gear. Damn I hate agreeing with him!!!