Hey all I was reading the FAQ article on Underdrive pulleys, as a friend of mine told me I'd have to be a complete dickhead to get one on my car while it's having the 100,000k service done (if it needs it), as he firmly believes that there would be little to no power gain from installing one. In fact, he thinks I'd get more power just not running the aircon and sound system. However, the Tech Article on underdrive pulleys states that there should be a gain of around 20rwkw on a TT 300zx. Is that figure accurate? I just want to be able to Laugh in his face!
you won't get 20rwkw, do a search on my nick for this and you will find a thread i posted up about the actual comparison of the weight stripped from the rotating assembly vs weight stripped off the car. It will rev easier and slightly quicker and you may get a slight power gain.
Around 22HP or 15 kw at the wheels for a TT and Yes, it is noticeable, particularly while the car is accelerating, as the motor does not have as much mass to try and rotate on the end of the crankshaft (less inertia to overcome). So imagine the performance gain as if you were making the car 150KGs lighter, as in principle, that is also reducing the amount of inertia to get the car accelerating. That is also why the power gain is higher on a TT as opposed to an NA.
Ok, so 1 vote for very little power gain, 1 vote for 15rwkw gain Any other takers? How many people out there have actually done the change? What have you noticed when compared to the stock Pulley?
These engines were mass produced not hand made, so some are better ballanced than others, from new. Nissan were smart enough to know this, and made the crank pulley to dampen out any vibration from the rotating parts. When a u/d is fitted to an engine that is slightly less ballanced than most, or a high milage engine in that condition, you will get vibration. In that case the stock pulley should be reinstalled. Its the luck off the draw imo.
I think you will find that most of the Zedders who have fitted a 'good quality' UDP love it! There are some that have removed them due to vibration, but they are few and far between. Maybe as the years go on and the original engines are becoming older/wearing we may find a few more that are 'less balanced'.
My z is a n/a so its not very powerful does that make it safe to install a udp? Speaking of quality Caz1 i see alot udp on ebay for $50-$100 and i see others going for $200-$300+ what is the diffrence here am i missing something ? from my understanding a udp is a udp can someone help
Yes, a UDP is a UDP, just like a girl is a girl(some are cheap and nasty, and others are worth their weight in gold).:zlove::zlove:
Put it this way I noticed a good difference when my car was a non turbo. Especially lugging it up hills.
Am i correct in assuming that the pulley is neutrally balanced for correct operation. Not counterweighted which would cause engine vibration ata certain rev range With the cheaper ones not having a harmonic dampener to cancel out torsional vibration of the engine and the UDP's only benefit is less rotating mass for quicker revving engine much like a lightened flywheel.
Yes, pretty much a light weight flywheel for the other end... I have a Unorthodox Racing UDP, love it. Noticieble difference! Turning off your aircon also makes a big difference. No extra vibes, same as before.
Oooh...another UDP debate. How I've missed these..... Chili I gotta ask....where do you find women worth their weight in gold...I keep looking but no luck dude! On topic, I've been tossing over putting one on for years. Coming up on 100km service time in a few months....think I'm gonna do it.
Ive got one.... Ive got one and had no problems with it. When it was put on the car we noticed a difference.
weight Stock one is around 5-6kgs (cant remember which). The ones like GFB or UR are around 800ish grams
Not really. Yes it is lighter so less for your engine to turn, but it also makes your accessories (power steer, water pump, alternator, air-con) turn slower as they are turned by the UDP. Hence why it is called an underdrive pulley.
