Hi guys, I was wondering if anyone had any feedback regarding the fitment of an underdrive pulley kit to an n/a. Is it worth doing or does it make the car less drivable? I know i'm not going to see much power back from it but im hoping between all of the mods im doing i can gain 30-40hp in total. So far i'm planning on a lightweight flywheel, 1 piece tailshaft, full 2.5in exhaust (headers and everything behind them), ram air intake and possibly a lumpy cam with an ecu upgrade. Would there be any point to an underdrive pulley on the VG and if so would there be any side effects?
Creates an extra 25 dope points and allows for better fitment of one said gentleman bar.... Apart from that, it releaves the crank from a small amount of unsprung weight. Coupled with your suggested mods, it would maybe improve throttle responce marginally. Note you will also need resized drive belts to work with them.
Yeah i knew i would need to add resized belts as you're changing the total length that the belt needs to run. I've heard mixxed opinions about Underdrive pulleys as some people say at low rpm/idle the headlights and such don't really work very well as they're spinning at a lower speed. I've also heard stories of bad ones causing the keyway to give and let the timing go destroying the engine. But i've also heard stories of as much as 10-15hp gains at the wheels... I was more curious to see if anyone on this forum was running one or has had experience with them on the VG specifically.
Your best to fit an under drive pulley set, not just the harmonic balancer on its own. If you only do the harmonic balancer, the water pump and alternator will turn slower Make sure you get the NA set as the alternator pulley is different from the TT. You'll not gain a massive amount of HP from an NA. Chasing HP on an NA is an expensive process and is not cost effective, I know as I own 2x NA's. You'll still have fun with them, just don't race them.
Personally I would not run an alloy pulley on the crank, the crank requires a harmonic balancer, I know there are people who say it's not needed, but it's there for a reason. ATI and others make aftermarket harmonic balancers but they're not cheap. As far as underdrive alloy pulleys for the peripherals (alternator, power steering, etc), generally only warranted when racing. ie at constant high revs this reduces the stress on these components. For daily driving however it means your alternator for example may not get enough rpm's to keep your battery correctly charged and maintained. IMHO. Bad idea...
Oh i understand that. I've built a couple N/A cars in the past and i've built a few turbos. I'm not looking to go overboard. The stuff i listed previously is all pretty basic anyways. When i do the manual conversion the clutch kit im using has a 12lb flywheel in it, figured that would be a good little gain. I'd like a one piece tailshaft when i do the conversion, if not ill settle for a 2 piece till i can get a 1 piece. As for the other stuff, intakes aren't hard to make, since its non turbo i can run intakes down where the sidemounts would normally be. Exhaust headers are pretty inexpensive and other than offering a nicer note you get the obvious better flow. ECU allows me to change a few things really, It allows me to change the way the car injects fuel resulting in better fuel economy, it allows me to milk a little more performance from the car and will give me better diagnostics. Cams are a Maybe kinda thing, I want them but they're not high on the priority list. The N/A is going to be my daily, Occasionally i would like to take it to QR/Lakeside for a bit of a bash and maybe the skids at archy every now and again. But i would like to get what gains i can from it without exceeding a 2.5-3k budget.
This is the set I run, and the crank pulley is a bit smaller in diameter than the GFB one. http://www.ebay.com.au/itm/221224471186?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649 Also make sure you tighten the crank bolt up to spec.
Theres 2 keyways on the nose, one for the lower crank timing cog and the other for the harmonic ballancer. So not sure where the timing fault would occur if the pulley fell off. But each to their own in respects to using them.
Its not the pulley falling off is the bolt coming loose and the crank sprocket allowed to move on the crank shaft. That is why its so important to do that bolt up tight, as per specs, and even check it a day or two later.
I've been running a GFB underdrive pulley for years. Worthwhile mod imo and plenty of threads on the topic. Personally, I found quicker response throughout the rev range. It's like driving downhill but all the time. No noticeable vibration even up to 7k rpm.
I've had an UD pulley on my TT for around ten years now, zero issues that could be attributed to not running a damper. One of the most plausible stories I have heard in the argument for using a damper was in regards to the IMSA cars built all those years ago. in one of the endurance races one of the engines was limited to lower revs to make it last longer (in theory). That engine blew up, the story goes they figured out it was due to harmonics & they then fitted dampers back on the engines. Sounds great - until you see just how different those engines are to the engines we run, combined with running a transaxle rather than a gearbox mounted on the engine, solid engine mounts rather than rubber mounts, much more boost, really primitive ECU technology etc. Sort of relevant, sort of not. One side will say better power & no issues, the other side will say minimal gain & potential to ruin bearings etc. The truth lies in between.
Pretty well summed up Mungyz. I guess my approach is, for the small gains to be had, is it worth the risk? There will be a specific rev range where damage can be done. Passing through this point won't cause major problems. But if you happen to be maintaining load in this range for extended periods damage can be done pretty quickly.
I'm still learning a great deal about the Z32 but judging by my previous experience with other cars I will end up installing fully adjustable coilovers, upper and lower control arms, camber and castor arms, front and rear swaybars, front and rear strut braces, fender braces, replacing old flogged out bushings with poly bushes, solid engine mounts and so on as things need replacing and as money allows. Although it will be my daily driver I still like to have fun with it.
Since you are turning this thread into an 'improve the NoTurbo' I have been told that a NoTurbo Z32 can be drastically improved in the way it feels to drive by minor improvements in many areas. + extractors + light weight wheels and tyres (so 18" or 19") + lighter weight seats + synthetic engine oil (5W40) + basic bracing + minor suspension and bush upgrades + japspec ECU and 98RON fuel + higher flow exhaust + manual gearbox + full electric cooling fans. I am only doing 3 or 4 of those things because it is more cost effective to buy a TT of any spec. I did drive around without passenger or rear seats, no space saver tyre and empty boot. I was only using an electric fan and the synthetic 5W40 engine oil. The car felt almost zippy compared to how it is in full OEM configuration. PS: I am going to do the FOAM thing to stiffen the chassis.
Buy a Twin Turbo! Save your money & buy a TT. You're hoping for another 30-40hp, a stock Twin Turbo will give you 78bhp over the NA. You won't get any extra horse power from an underdrive pulley kit. Nor will you get any additional horse power from a lightwheel flywheel or a one piece tailshaft. The Z32 comes standard with ram air intakes.
First of all, I already have a TT - Im parting it. Second, If i wanted a TT i would have bought a TT. My RX7 Turbo is my track car, however im buying the NA as a daily. I'm not looking to spend a whole heap of money on it straight away aside from the manual conversion and a few basic things like coilovers. I will gain back slight marginal bits of power and response by swapping for a lighter fly and depending on how much parasitic leech the accessories pull an underdrive pulley kit MAY help (this is the point of this post). A tailshaft depending on what it is made of and the diameter of it will infact have a lower rotational weight and result in better power translation to the wheels in addition to being a fair bit lighter than the stock standard component (and the lack of having to do the center bearing). The Z32 has A ram air intake, on a non turbo it would probably be better to run 2 seperate intakes under the headlights where the sidemounts would normally be.
This is totally incorrect. A edited quote from the almighty internet (do your own search to back it up): Lightened flywheels reduce the amount of energy produced by an engine that's spent in moving its components (parasitic loss). Since flywheels are solid, unsprung components of a vehicle's driveline, a lightweight flywheel will decrease parasitic loss at a constant rate, improving a vehicle's horsepower and torque output (measured after the flywheel) throughout it's entire rev range.
If you overdrive your other accessories you're negating half the benefit of the underdrive pulley. Plenty of people have been running udp's for years with no ill effects. Even nissan revised the harmonic balancer design on later zeds which removed a lot of the dampening rubber and made the pulley a fair bit lighter.
