STILLEN lightweight crank pulley
 

I saw STILLEN added one of these to there website. What is the consensus on the value of these for non-supercharged applications?

+1 I want to know because I might get a set.

Actually these have nothing to do with supercharged or non-supercharged applications.

Lightweight pulleys work the same way as a lightweight flywheel or lighter wheels and tires, lighter brakes...Any time you can free up some rotating mass you are freeing up horsepower. By reducing the weight of the pulleys you are reducing the energy or horsepower required to spin them. It makes your engine much more efficient.

If you plan on getting a supercharger sometime down the line we do not recommend getting an underdrive pulley. An underdrive pulley will underdrive everything that is powered by your engine...Basically meaning your supercharger will be underdriven. Lightweight pullies are great for superchargers, but we don't recommend installing underdrive pullies for supercharged vehicles.

Turbo vehicle's will benefit from either light weight or underdrive pullies.

^ thank you

Kyle, you guys have any numbers on how much gain these yield?

Kyle, that reminds me about the all-plastic engines they've been working on... Crank, pullies, connecting rods, and flex plate are all supposed to be made out of some super-strong lightweight plastic... I imagine some sort of aluminum/carbon alloy, but I can't really see that as cost effective. Heard anything about this?

eh, I knew all that. I was more interested in how it affects the SRM system. I figure if this doesn't mess with it, nor will the flywheels...

We don't like to say that lightweight pullies "make" horsepower because they really don't. They do FIND lost horsepower though. Typically we've seen gains of around 10-12 HP on an underdrive pulley and a little less on a lightweight pulley.

This is news to me but what you're describing doesn't surprise me. With the new technologies they're constantly developing and the new materials being produced every day I truly believe that anything is possible.

Like you pointed out, I have a hard time imagining that it could be produce in a cost effective way but could you imagine how much higher you could rev an engine with lighter internals. It'd be pretty awesome to learn more about this stuff. Sounds too exotic to be in most production cars for awhile though.

I have to be honest. I am HORRIBLE at figuring out acronym's. What does SRM mean?

do you sell lightweight pulleys also ( those the same size just lighter - so you can use the same belt ) ?

Josh just gave me a little edumacation and informed me that SRM stands for "synchro-rev match." With that in mind. The lightweight pullies won't affect that system at all. The Synchro Rev Match system will basically have a set RPM point that it takes the engine to upon downshift. That won't change it'll just allow the engine to achieve that RPM point faster.

Yes we do.

STILLEN : STILLEN Performance Lightweight Pulleys

Part # 400338

Fifth one down. It doesn't show 370Z yet but that's because we JUST did the test fit the other day and haven't updated the site yet.

Very good, sorry if I keep beating a dead horse. We arrived at the same conclusion in another thread, however you can't be sure until someone comes over and says it is one way or another 100%. Some argued that the SRM system took the mass of the factory driveline into account. That makes very little sense to us from a practical standpoint, however it's better to be safe than sorry. (This was more about light weight flywheels than pulleys, but they have similar effects, so I was seeing if you could shed more light on the subject) Anyhow, thanks again Kyle!

Now the question becomes...will a lighter flywheel AND a lightweight pulley be too much lightening for a daily driver?

^^sorry for my ignorance, but why would a lighter flywheel and/or underdrive pulley make it a worse daily driver?...or any different different driver for that matter. any past experiences would help... thanks

Its all good ssqpolo - The reason that it may become a problem is because of the clutch engagement. The mass of the stock flywheel allows you to engage the clutch at low RPM's and without much jerkiness. The inertia of the spinning mass (flywheel) counteracts the clutch as it tries to clamp down, therefore allowing for smoother, gradual engagement. If you get rid of that mass, then the flywheel will slow down to match shaft speed much faster (jerkier) and you may sometimes stall if you aren't being careful or giving it enough revs. This is a common issue with the Carrera GT, the drivetrain / flywheel is so light that engaging first gear can be a tricky endeavor. Often people don't give it enough revs...or too many.

By lightening the flywheel AND the pulley, you are making it even worst. Some people would advice that you do one or the other. Usually it is better to go with the flywheel because there's more performance to be gained there...However, on some cars, it is OK to do both...Hence my question :)

tks man. good to know.

I couldn't find the info on the newer plastic engines I was hearing about, but found this:
Plastic engine - Wikipedia, the free encyclopedia

300+ HP revving up to 14,000 RPM! Pretty cool for old technology.

way to kill the thread crash ;)

That would be pretty neat. I wonder how long it can survive everything.

Hey, if they can make gun barrels out of polymers and plastics that can stand up to those explosions...anything is possible!

RCZ- Excellent explanation of the flywheel.

I actually have a phone call in to the Nissan engineers right now to get a solid, definitive answer regarding the SRM system. His initial thoughts were the same as mine and that the minor adjustment in weight would only be beneificial to the drivetrain and wouldn't hurt anything. However, the 370Z was apparently a 100% Japan project and no one from Tennessee was involved so he's going to have to check with his counterparts in Japan for confirmation.

That was 80's technology too. Today's technology? Who knows. I personally would build the connecting rods out of an aluminum/plastic alloy for extra strength, but 300+HP from a motor that weighs less than 200Lbs wet is a VERY impressive feat.

I put lightened flywheels in both my RSA and 993. In both cases I had to adjust my driving style on the street. A chip helped in both case but did not completely eliminate the stalling when abruptly coming of throttle.

I can't imagine a light weight pulley by itself would have the same effect. I do like the idea of an under-drive setup.

I am very interested in the results of the call Kyle. I have a feeling that we are just waiting to confirm that our theory is correct and the SRM system uses a pre-set continuous table of target RPM (wheel speed vs gear) to calculate and hold RPM. In this case, a lighter flywheel will actually help the system match gears faster thereby getting us a few 10ths on the track :)

Bah, great job everyone, now I want a flywheel too:shakes head:

I had a JWT flywheel on my 350. My only complaint is that it sounded awful, especially from the outside. It sounded like something was broke at times.

chatter?

The other aspect that people should be aware of is the fact that the infamous "off-throttle lurch" in first gear will get worst. If you can deal with that and the chatter/sensitivity, then this one is a key mod.

You bring up an excellent point.

The factory flywheels are a dual mass flywheel which keeps the noise down. All of the aftermarket lightweight flywheels are only single mass which has a tendency to rattle a little bit more.

Personally, I love that sound. It means that you have high performance parts on your car and you're not messing around. For example, the very first thing everyone with a Ducati does is purchase the open clutch cover. Because they run a dry clutch system you can run clutch covers that are open to the elements. It rattles away and to the lay-man sounds like something is rattling inside the engine. To those who know, you just see a little grin form on their face and the look of "yea...That sounds AWESOME!!!"

waiting to know about SRM and if changing the flywheel will effect the SRM

Ah yes beautiful sounds..like straight cut gears whining or sequential gearboxes slamming through gears..or brake squeals in the paddock..

To think I just got home from the Koni Challenge haha, never going to get tired of this...hell Im going back tomorrow for day 2.

Hey I actually met Mag from Performance Friction today, he said he used to work with your brakes department for development...

We have worked with so many different manufacturer's over the years in the pursuit of finding the best brakes that I could definitely see working with Performance Friction. They make a nice product.

An old car of mine had a great gearbox whine (like a rally car) and I really enjoyed until I got a phone call to say they forgot to put any oil in it when they replaced it...

Brake squeels and exhaust popping are my favourite :)

What's the status of testing lightened pullies [from Stillen] for the 370Z?

Does the lightweight crank pulley bolt on to the front of the factory dampener or is it completely replacing the factory dampener?

From what I read here before, there is no real harmonic dampener on our engine, it's internally damped/balanced. Our stock pulley has an integrated NVH (noise/vibration-something) that reduces noise, which the replacement doesn't have.

All internal zero balance engines still need a harmonic dampener. You still have harmonics in any reciprocating assembly. The pictures I have seen of the factory crank pulley show it has an inertia ring, so it is a dampener like its supposed to be.

I would never replace the crank pulley on my car with a pulley not built as a dampener.

Can you elaborate on the above? The service manual doesn't really go into this sort of detail, although it does call the ring a "damper", when it says "Never put suitable puller tab on crankshaft pulley periphery, because this damages internal damper." (by which they mean, attach the puller to the insides of the pulley, not the outsides).

Wikipedia has this to say, although I wouldn't consider them very authoritative on the subject: Harmonic balancer - Wikipedia, the free encyclopedia.

Have people actually seen crankshaft failure from this sort of thing?

As long as you are going with a reputable pulley manufacturer who understands how to build a perfectly balanced pulley, there have been zero problems. We've been producing pulleys for superchargers on down for years, and have never had a failure.

There are thousands and thousands of pulley sets being run on 350Z's, G35's, G37's and now 370Z with no problems at all. The factory crank pulley does NOT have a harmonic balancer, the engines are internally balanced.

Again, this is not the type of item you want to take a risk on ebay by just anyone who thinks they can cut a pulley, but have been a proven power-adding modification that provides great results.

Quick question - have there been dyno results for the Stillen lightweight pulley? Not the underdrive, just the lightweight one. I'd appreciate the info or a link to the thread with it - I can't seem to find any.

I believe RCZ has the light, non-underdrive pulley, but hasn't installed it yet.

Yes he does. He will get it installed soon. We ran into some difficulties and decided to leave it for another day.

Back on this subject of harmonic balancers and all that jazz, here's a better wiki link: Underdrive pulleys - Wikipedia, the free encyclopedia. To quote from the end of that article:

Again, it's wikipedia and with no citation, so take it for what it's worth.

You are missing the point. I've had machine shops zero balance engines I have had built in the past. This does not mean you still do not need a harmonic dampener. A rotating assembly will always have harmonics that need to be dampened.

That is great that the pulley itself is perfectly balanced. That means the pulley itself will not introduce any additional harmonics. However it does nothing to absorb the harmonics that are inherent to the rotating assembly.

As the engine turns, the changes in direction from the pistons moving up and down and the forces exerted on the crankshaft by combustion force pushing the piston/rod down on the crankshaft produce torsional vibration. The crankshaft itself being perfectly balanced as it rotates is not where the harmonics come from. Sure an out of balance crankshaft will make things worse, but once the crankshaft is balanced, the forces at work on the pistons and rods exert their own forces which produce the harmonics in all engine rotating assemblies. That is why you need a dampener to absorb those harmonics.

If you look at this picture of the engine http://www.seriouswheels.com/pics-20...-1920x1440.jpg

You can see the ring bonding the inertia ring to the inner hub. It is a dampener and it needs to be there.

The reference to the shop manual that Wstar quoted further proves my point. You want to pull the dampener off from the center hub, not the outer ring because you could break the bonding and separate the outer inertia ring from the center hub.

I am a bit surprised at something like this from Stillen as I've always held your parts in high regard, but when it comes to this part, you wont be seeing my money for it. I don't believe its right.