Pulley Issues!!
 

I have the NST Pulleys and I was gonna install them couple weeks ago but then saw the video Sam posted in the SC st2 press release!!! He didn't recommend the underdrive pulleys.
I know a guy that has a 350 and he's pulley is leaking some oil (don't know what brand). So these are making me a bit hesitated.

My question is did anyone have similar issues? How likely is it to happen?

Everything Sam said in detail I've also heard from a number of highly skilled tuners and engine builders, and that is why I do not have one on my car.

I say, sell it off to someone who laughs at the risk of engine rebuilds -- I'm sure someone will scoff and pony up.

Yes there are nay sayers, but also those that have had them on, and on boosted cars and have had no problems as well.

Most problems can be attributed to improper installs.

I had my NST pulleys installed almost a month ago and have had zero problems and zero oil loss and I've been checking it every week for this exact purpose. I held on to my stock pulleys in the event of something going wrong, or if I decide to swap them back out for TT.

Which people had them on there boosted cars?

Go on NST's website and you'll see.

Damn it!! you bought them a month ago, I hoped that you're the one that is gonna buy them from me lol

Hopefully you will be saying the same in a year... :ugh2:

It's the high revs that exacerbate the effects of undampened vibrations. If you never race it to redline, it may never break... then again, why take the risk?

if he doesnt say it after a year, i can just say it now

ive had mine a long long long while now.

Even had mine powdercoated before installing.

and zero issues.

People should be careful about what they read as "bad products" as i could find "horror" stories on just about every single aftermarket (and oem) parts sold for any car.

Like someone said, alot of times, the issues come from installer problems and or user being stupid (cant be stupid with pulleys, but for example going too much boost, or not tuning a boosted motor, etc etc etc)

I've had mine for over a year, and had the turbo kit on for a month. So far there are no issues. I can only imagine what it would be like to remove the pulleys, but I have no reason to do so at the moment.

could you try to see the results :stirthepot:

LOL... hopefully I'll never ever have to do so.

I've had my Stillen underdrive pulley (which is even lighter and more underdriven than NST's) on the car now for about 20,000 miles over the course of 2.3 years or so. I'm in the upper end of the RPM range often. Zero issues. I don't even get what some consider "normal" VHR oil consumption. My dipstick level stays virtually at the same level throughout an oil change cycle for me (but then again, keep in mind I'm a fan of changing oil early and often. What I take out of my engine often looks good enough for some people to put right back in theirs). I also haven't had any strange engine symptoms or noises of any kind.

All of that said, there are at least two things to take to heart from Sam@GTM's pulley info in that other thread:

1) Clearly, he has a point about the Aluminum pulleys partially welding themselves onto the crankshaft over time. It makes basic sense, and his video removal evidence is pretty compelling. They can still be removed, but don't expect to get them off at a later date with just a simple home garage impact wrench with the engine and radiator still installed like normal. I'm sure mine is pretty well glued on at this point, but I also don't see myself ever removing it.

2) Underdriven pulleys will throw off the pulley ratios for a supercharger kit. You can correct for this by also changing the pulley size on your SC kit, but it's probably far simpler to just leave the stock pulley in place with SC (not to mention, if there's *any* shred of truth to engine life concerns, which I doubt at least in the NA case, they'd be more important with FI). You're adding so much power with FI anyways that any gains from a pulley are too trivial to care about.

FWIW I look at mods in terms of bang for the buck as well as bang for the risk likelihood and bang for the magnitude of risk severity.

Bang for the buck, 5-6 whp for the cost of the pulley and install is relatively good value.

Bang for the risk likelihood is unknown, because the base rate for failure due to pulleys in not known, but lets say for sake of argument it's something to the tune of 5-6 whp for less than a 1% risk, which sounds very reasonable.

Bang for magnitude of risk severity... 5-6 whp for potentially catastrophic engine damage. That's not so great...

That last one has me convinced that although it's not exactly a terrible idea to run a pulley, it's not a really good idea either.

You can apply that same set of decision criteria to FI, which can also result in a destroyed engine or trans with a bit of bad luck (and probably a higher risk likelihood), but you get a lot more bang for the risk severity magnitude.

Not suggesting that everyone should adopt this overly cautious outlook, and of course individual results will vary anyway, but this is just how I try to decide what is and what is not worth doing.

OK so it's a debatable thing. like VVEL will never be cracked or they're still working on it :inoutroflpuke:

anyway I need the money for an oil cooler so decided to sell it if anyone is interested

http://www.the370z.com/parts-sale-pr...t-pulleys.html

This.

And let me ask yall this, how many people have yall known that have installed UD pulleys on vehicles (foreign and domestic) and have ever had any issues? Cause I know close to a dozen in the domestic world that in the last 10yrs have never had an issue with their UD pulleys and their engines.

the thing with pulley's.. dont install em right and your screwed.

With an intake, or exhaust, dont install em right you get to redo it. Thats where the risk comes in.

Pulley's themselves arent really rocket science fella's.

I wouldnt even compare these to FI. The risk is much much less. With Pulley's your not changing really anythinga bout the engine except for how much inertia is lost/used to turn it.

With intakes, exhausts, tunes, etc etc your changing the dynamics of how the car works internally. FI takes that to a different level altogether. If anything pulley's should be one of the lowest risk items. Unfortunately it attaches to a place where a wrong install could be bad.

You can compare a pulley system to a lightweight fly wheel. Good stuff unless again installed wrong.

This is why NST puts a Steel ring around the inner part of the pulley. To prevent the aluminum from welding itself in and providing a proper bearing.

Well... ok... yeah... but it's the undampened vibrations that ultimately cause fusion and extra wear and tear on the crank.

I think the real debate is whether or not a V6 is "naturally balanced" enough to not be overly concerned, and I think it's unknown at best, especially considering our motors rev pretty high, and high revs will greatly exacerbate the effects of undampenend harmonics.

Just sayin'...

On the other hand, aren't our cranks forged? I suppose it could be sturdy enough to withstand the extra vibrations, but again, it's not clear.

As to the FI compariosn, I just meant that I'd rather risk the motor's longevity for a 100+ whp increase in power than a 5-6 whp increase...

Really the light+underdrive pulley is more about throttle response than rwhp. Adding a few horses from underdriving is just a bonus. Also, if there were any harmonics issue, it doesn't increase linearly with RPM, making it worse the higher you rev. It would be at a specific RPM (or more than one specific RPM) that exhibited bad harmonics for the crank without a damper.

I had the Stillen UD pulley, it was installed wrong and within a day there was oil leakage. Next day I had the stocker reinstalled and the crank oil seal replaced, no issues since. I'm done with aftermarket pulleys now. I did get a lightweight flywheel however that I will be getting installed, I believe this will be better way to increase rev speed without the same potential risk.

Just out of curiosity, how are people getting these installed "wrong"? Seems like a pretty straight-forward job.

AFAIK they didn't get it torqued on well enough/properly, so it had some wobble that caused the issue.

That's correct, the purpose of my purchase was to improve throttle response.

My NST pulley needed to be filed a tiny bit for it to fit properly. I'm sure something would've broke if he forced it in without filing it down.

I'm assuming these have a woodruff key? Most common way to screw it up is to catch the key and push it out of the groove. You're pretty much blind on any install like that-you just have to hope it didn't happen.

On my kart clutch, it's keyed and I see a lot of people push the key out when installing a new clutch. Then the clutch jumps the key and a few seconds @ 16,000 RPM and your crank is toast.

IIRC (it's been a while since I installed mine), our crankshaft pulleys just use a straight key (as in, a notch along the inner side of the pulley, and a "key" that stands out from the side of the crankshaft near the end).

I've ordered the stillen lightweight pulleys and not the under drive ones..the same issue applies?:confused:

installation issues can apply to anyone installing the pulleys even if they were replacing the OEM pulley with another OEM pulley.

so its basically depends on the installer themselves? i mean if the get it right or did it wrong..

pretty much.

thanks for your help Dai! repped!:tiphat::tup:

I'd like to add that the harmonics remain undampened regardless of a smooth install and regardless of whether the pulley is OEM diameter or underdrives...

If you want an aftermarket pulley with a damper...

Fluidampr® Harmonic Dampers Made in U.S.A.

Nothing against NST -- they make great stuff, and I have bought supercharger pulleys from them before that fit perfectly and worked great. They make excellent products.

This is simply an engineering issue... undampened harmonics put more stress on the crank -- period. Whether or not that matters (or at least the extent to which matters) for our application is, I think, unclear.

I think GTM Sam's commentary was spot on in the 600 whp SC thread, and everyone considering an aftermarket crank pulley should read it and think on that before buying.

But again, I try to err on the side of caution...

everyone I've spoken to about pullies says that the damage is in the long run. By replacing the pullies you tweak the engines harmonic balancer which in the long run will be trouble. I've heard it from enough guys to stay away from it but if you aren't planning on keeping your car for a long time it shouldn't hurt.

its all about the installation, if there is a leak then most likely it wasn't installed right. Get it done once and get it done right, if the mechanic hasn't done it before then don't take the risk. Most of the dealers do it and its a 1.5 hour job at most. Get the crankshaft seal replaced at the same time and that should avoid any oil leak issues.
About the pulley being a harmonic balancer, wasn't it discussed that for this engine it was internally balanced !!!

Well, there's a lot of confusion on this issue about vibrations, dampening, and external vs internal balancing. I can't settle the matter for our engine, but I can clear a few things up to put the debate more on-point: Yes, our engine is "internally balanced", and that has virtually nothing to do with the debate about the pulleys.

An externally balanced engine means there's actually an asymmetrical counterweight system on the pulley, which balances against the otherwise-imbalanced crankshaft. You will definitely destroy an engine if you were to slap a random symmetrical pulley onto such an engine. Because our engine is internally balanced, there's no specific need for a balancing component on the pulley. The pulley itself is expected to have neutral balance (even weight distribution).

Even with an internally-balanced design like ours, the stock pulley includes a (neutrally-balanced) dampening ring to reduce vibrations. The debate is about whether replacing the stock pulley (poorly machined, crappy metal, with a dampener) with an aftermarket one (much lighter, machined to better tolerances, no dampener) is going to cause long term damage due to increased vibration.

On the "stock" side of the debate is the idea that the stock dampener serves to quiet important harmonic vibrations at specific RPMs, and that without it the engine will slowly tear itself apart (slowly wear out crankshaft bearings at the very least). On the "aftermarket" side of the debate is the idea that the (a) whatever vibrations the stock pulley dampens are relatively trivial and mostly about reducing engine noise heard by the user, and won't cause engine damage, and (b) the more-precisely machined aftermarket pulley is better-balanced to begin with.

There's little doubt that as you push an engine further beyond its design boundaries, you need to be more precise about balance and vibrational issues in general. The tricky question is whether our engine in basically-stock form needs that NVH ring for long-term health or not.