My mechanic called me up saying he thinks it would not be safe to install the ud pulley due to having to remove the rubber grommet on the original pulley which acts as a dampner.I said to him go ahead because there are heaps of z's out there with the ud pulley on and it is a standard upgrade and for all the who-har about its potential problems I have not heard of one failure that could be directly related to the installation of a ud pulley.Just for piece of mind who here has one on? and how long have you had it on for without any problems?
No probs, if anything my idle is as good>>> >>> as ever, despite IAA being screwed right down to get 750rpm.The Z32 is so well balanced there should be no problem - certainly none ever reported that I'm aware of.
Who installed it? Funny you know...Gavin Wood gave me a big lecture a couple of years ago about my UD pulley... Told me to remove it before it snaps my crank and went on to tell me about all the damage to RB25 and RB26 motors he's seen as a direct result of UD pulleys and said he'd NEVER install one again.Yes there can be problems, but the VG30 seems to cope very well with any issues having a strong/stout crankshaft, crank-girdle, and tri-mateal bearings as stock and very well balanced motor to start with.As a side thought, maybe an UD pulley will highlight any balancing issues you may already have? if you've got a bottom end wobble it may make it worse.I wouldn't be putting one on a straight six, but the VG30 seems fine.Cheers,
Yes Gavin said something similar to me but > >>> only had probs with Marcus's race car which had massive hp and the consequent lumpy idle.
*nods* I just agreed with him and said the Z has had thousands of them fitted without any problems. I agree though, wouldn't be fitting them to M3's and Supras and skylines. Not sure about WRX's though, they seem to cope with them very well. *shrugs* Take care,
Fitted mine last month Only one minor change and that is at 4thou revs there is a bit of vibration but other than that, smooth as especially at idle.... plus the power gain which is very noticable, 20 more horses they say, though I haven't done before and after dyno.:YD
Just picked mine up a few hours ago... New 6 button clutch and fark me I never realised how much my old clutch was slipping, it is an absolute beast now. I keep getting out of the car shaking after I boot it, scares the sh*t out of me. It holds the power that well now I can screetch the tires all the way to peak power in 2nd gear (about 5,500rpm)... haha i reckon that's a pisser.Plus now the underdrive pulley is in it makes it heaps more responsive, I hardly have to touch the throttle now and it goes...Geez its been a while since I've driven it but holy sh*t I forgot how bloody quick it was. Now I have a non slipping clutch I can really feel what 17 pound boost is supposed to be.My mechanic took it for a spin and he goes fark that thing is an animal... how the hell haven't you lost your license yet?As my mates say... I've got a horse shoe up my arse.
WARNING: You may not have problems, BUT! UD pulleys are discouraged by most engineers because of the physics behind them. Manufacturers know what they are doing when they design engines, the only reason why not all performance enhancements are made is because Nissan have a budget and reliability they must keep to (otherwise they would develop a supercar). The UD is heavy and quite large due to the physics of the rotating mass of the crankshaft. It is true that the crank is already internally balanced in the ZED, however that does not mean the crank is not phsyically bending and moving on each rotation. The bends in the crank actaully become larger as they travel down the crank and at higher RPM. A UD that is heavy basically places a counter weight on the end of the crank to absorb and minismise this movement in the crank. The rubber ring however on the ZED UD is not there to absorb these movements (but rather the weight is and not the rubber ring). The rubber ring is there to absorb engine and auxillery niose and keep the engine running quietly. There are quite a few articles about lightened UD's and there possible consequences. That said I have never heard of anyone reporting a broken crank with a lightened UD on a ZED VG30DETT - and there are plenty of people instaling these things. I'm currently in the process of upgrading my ZED and currently don't have my car to drive (John Hill from JHH engineering in QLD is doing this). He has strongly advised not to install it, and said you may get a way with it, but if it were his race car he wouldn't do it. The ZED crank is known to be particulary strong (also due to the fact that it is shorter than most cranks as it is V6, rather than straight 6). Personally I've taken John's advise not to install one. I don't believe it is worth it for 10+ HP. I believe on this case manufacturers have made it that way for a reason and not to save cash. Yes in most repects the ZED engine is over-engineered, so removing the stock UD you may not ever have a problem, but if I'm going to be looking at 8500 RPM redline I'm not going to risk it. I've actually already bought an UD pulley from orthodox racing before I did all this research. I'm now trying to sell it, so if you want one cheap I'm selling one. Let me know if you are still interested after all I've said. The pulley is brand new and has not been opened. Its anodised silver. asking for $300.00 + postage. www.nismo.com.au sell one for 375.00. so u save your self $75.00 due to my misfortune. You can email me on Jonathan.Hirtler@qr.com.au if interested. I am also selling LOTS of other stuff (mostly from my car's upgrade, including an AUTO box and all kit in good nik (doing a manual conversion, bored of AUTO box)), stock intercoolers, stock rad (was re-cored 2 years ago), good stock injectors, stock turbos (need rebuilding), and others.
Hehe I'd be speaking for quite a few zed... owners on the subject of underdrive pulleys. The opinion that an UD is a detrimate to the engine are noted...but the bang for buck that is gained aswell as the fact that everyone has used them on the vg30 for years and no problems have ever presented themselves have lead many of us to purchase one. And we're all happy with the response and power for the few dollars spent!John :-Z
Yeah I got told all that as well... but facts speak louder in this case a lot more so than potential or theoretical problems... whilst it all may be true, the proof is in the pudding and as no body I have heard of has had problems, the track record says they are 99.99% safe.Good enough for me.
Agreed....this theoretically problem is... discussed over and over on ttnet to death. At the end of the day its just theoretical and completely unproven. There must be millions of kms done on zeds with US pulleys and no one has ever reported any ill effects. About the closest Ive seen is someone lose the back end on a corner due to the extra HP
Only thing I found... which I always say is make sure you adjust your idle when shes warm. My idle was slightly on the low side initially. The voltage at the lights would start plumetting as the alternator is being underdriven. I adjusted my idle so it was within normal specs and it holds charge perfectly.
The only problem I have found..>> with my UD pulley is that when at idle and I have the heater ON, lights ON, stereo ON and wipers ON then the alternator will not charge the battery! That is, the battery will drain until the revs pick up to above 900 rpm then all is well again (until the next set of lights).Cheers
What about.... the UAS Type II Crank Pulley. Its got the rubber to absorb vibrations etc. Its still much lighter than the stock pulley (1.32kg)A lighter pulley is definatly a worthwhile mod. Most NA's will notice a big improvement, especially when driving uphill Before this steep hill, mine refused to accelerate up it. (yeah I know, its an NA, but it was pretty steep). I Was even flooring it in 2nd. After getting the pulley installed it went up it real fast!!
put it on yesterday It ran like a pig for about 10 minutes and ever since it's been beautiful. I thought it was great value for money. PLus it's knocked a few tenths of my times.
Fisher Concepts Crank Pulley >> If you are concerned about the UR underdrive pulley then this underdrive pulley may be for you as it still retains most of the dampening characteristics. [image]http://www.splparts.com/Parts/_Z32/engine/FisherPulley.jpg[/image]
Luig - I'd be interested to hear what you have to say on this subject (before I install mine on the TT).
An Under drive pulley broke my ...>> timing belt auto tensioner}D Just scare mongering:-Z How would you be able to tell if an UD pulley did damage your crank:?) If you did damage a cranksaft and had a pulley fitted, how would you know the damage was caused by the pulley:?) I just don't think they're as bigger bang for buck as an ECU with raised boost:-Z
About the only time you'd know if an UD pulley caused damage or not is if the crank breaks in half. Having seen a Zed crank, I don't think that's very likely, but as I've said before, fitting an UD pulley will increase the risk, but by how little, who knows?Fitting UD pulleys is a perfectly acceptable mod as long as the owner knows of the potential risks, just like raising the boost or advancing the timing. There are a few other minor risks, such as potentially running the alternator harder thus shortening its life, and transferring more combustion 'shock' to the timing belts and engine driven accessories like the power steering pump, A/C compressor and alternator, but once again, they're minor, and problems may never surface throughout the life of the car. Some people have mentioned that they might shorten bearing life, but I can't see how. That's got more to do with rotational imbalance than torsional deflection. I'm just a bit concerned that some Zed owners think it's free power at no cost, and no risk, 'cos Nissan must have got it wrong'. I'm not against UDPs, but I'd like to think that everyone understood them a little better (and that includes me!)
