I've been using NST stuff for years with no problems to speak of. All my friends who drive different makes and models are also happy with their products. These guys are experts and their selection seems to be growing.

www.NonStopTuning.com
They have a factory backed NASA race car using their stuff

 

Sure, throttle response in neutral maybe.

 

Nope. In gear too and obviously more pronounced in the lower gears Initial throttle was better (nothing very significant), but noticable (more snappy). Guy with lightened flywheels notice the same exact thing, but to a larger degree. One major issue is the lack of rotational inertia. It feels responsive initially, but is FAR more prone to bogging in the lower rpms.

 

The VQ30 is VERY much like the VQ35. Nearly the same heads, same block design, same general accessory layout, same lower block design, very similiar crank pulley design which is a two peice pulley with a sandwiched elastomer ring to quell certain order crank vibrations. The VQ30 pulley weighs 5.9lbs and the FM VQ35 pulley weighs 6.2lbs due it's second pulley rib. Both VQ UDPs show a solid 0-2hp gain on dyno. I also know for a fact my VQ30 was harder to drive smoothly at low rpms with the UDP, it was harder to launch consistently, was no quicker/faster, showed no gains on the dyno, and there was a bit more NVH because of the lack of the crank damper. To say that a UDP isn't going to perform the same way on the VQ35 is completely ignorant because the VQ35 Maxima/Altima crew see the same exact results as I have with the VQ30. Just because the VQ is in the FWD layout doesn't means it magically performs differently on the track or dyno. The only real difference is the reduced drivetrain drag with FWD.

For those considering UDPs:
If UDPs were so great, then you'd see them on race cars and race VQs. The reality is these crews wouldn't touch UDPs with a 10-foot pole because of the lack of the crack damper. Most race VQs, and most any race focused motor for that matter, use crank pulley dampers which use a fluid gel in the crank pulley which reduce crank vibrations far better than even the OEM pulley. These are called fluid dampers and they'e actually heavier than the stock crank pulley, but they actually make some power because the reduced crank vibrations allows the valvetrain to operate more efficently. You also get extended life out of the motor and a smoother revving engine.

 

DaveD,

You bring out some really good points. You definately seem to know what you're talking about. BUT, as far as how it negatively affects the VQ35, no one really seems to have a clue.

Most of the few failures caused by a UDP pulley seem to be due to a bad installation; usually leaving something loose.

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Henry, as mentioned previously - the pulley debate is the greatest controversy out here bar none. Without a doubt there is no other mod that has had as much debate... and the verdict is no stronger one side than the other.

The bottom line is there has not been any reported detrimental effect from a properly installed UR crank pulley... there have been some poorly made pullies that have failed and some install issues that caused problems... but nothing anywhere negative regarding a quality unit like UR.

Now, some people will say this is because no one has enough miles yet... and that after 100K or more is when you will notice probs... well, to that the response is MANY people have been monitoring via oil testing and no one has reported anything negative, not even the slightest... Additionally you need to consider the "benefits" being reported – set aside the terminology being used (such as throttle response) the unit will make your motor rev easier and quicker... any benefit it's subjective at best. People that have it say it's great and they feel results. People that don’t have it only have theories as to why it's not worth it.

So... IMHO since you are very interested in this reasonably priced mod, there is nothing detrimental about giving it a try. Go for it bro! It is the only way you will know for yourself if it's worth it. It will not hurt you motor (it hasn’t hurt anyone else’s). You will probably feel the same thing everyone else does in terms of characteristics – but will it give you more horsepower or faster ETs?… hmmmm…

 

Well put Mike.

That's actually exactly how I feel. I thought about installing it myself; it seems pretty easy, but the slightest mistake can make your engine say bye to you.

I'll give it a try, only after I have completed all NA mods in my list.

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I was hoping I wouldn't have to type a novel on this, but here it goes anyway. Some will read it and agree, others will think im full of crap because it doesn't meet the recent "internet scientist" style of arguments.

On a relatively understressed near stock motor with bolt ons or low amounts of boost like what what most of the people on this forum probably run, an underdrive pulley will not have any life treatening consiquences. The factory pulley with a 2mm (less than a 1/8th inch) damper is primarily for wide band NVH (noise vibration harshness) supression from the engine and driveline. Removing the damper and replacing it with a solid hub underdrive pulley will cause minor addtional NVH but not harm the engine. In fact, most people claim their engines seem to run smoother with aftermarket pulleys.

The engineering reasons are that most modern engine have a short, strong crank with, a relativly high natural frequency. The dangerous second harmonic that can cause damage occurs at an rpm that this sort of engine will never see, in the area of 10,000 rpm. Now the stock harmonic balancer is not tuned for attinuation at this sort of rpm either so the argument is somewhat of a moot point.

Now small engines that are pushing the limit with lots of revs, wimpy cranks, super long strokes, lots of boost and dwelling in the upper rpm ranges for long periods of time can benefit from a damper designed to deal with this sort of operation but our engine is not like this, and probably very few people with this motor on this forum push the envelope that hard.

As far as I can tell, our engine has a strong and stiff bottom end that is overbuilt if anything for our intended use. It has an internaly balanced crankshaft which is less like to break due to torsional vibration.

There are a lot of Nissan guys who use underdrive crank pulleys in road racing series like NASA or SCCA. Road racing is much more punishing on an engine than other motorsports. The engine is subjected to run times lasting anywhere from 20 to 45 minutes with the engine always in the upper ranges of its rpm limit. One race weekend is the equivlent of hundreds of 1/4 mile passes.

Some engines like the Nissan SR20 have to have an underdrive pulley to live at all under race condtions as the water pump cavitates at a low rpm. All SE-R Cup cars and most professional drift S chassis cars run underdrive pulleys. SE-R Cup cars are very relaible with engines lasting several seasons sometimes. I have heard of guys that have had them for 200,000 miles.
The same goes for the VG, VQ, QR and GA engines. Many World Challange race cars use underdrive pulleys.

Is a solid crank pulley harmless to all engines? No it is not. Small, super high reving engines, when modified way past the simple bolt on stages may have problems. These engines reach critcal harmonics, past the 10,000 rpm range, an rpm often reached by real race engines.

A mildly modded inline six will most likely be fine but one subjected to high rpm for long periods of time (90% of its life) with lots of boost will probably suffer. In this case , the stock balancer is probably not adequate either.

American V8 engines are often externaly balanced and it is critcal not to use a solid hub pulley not designed for this applcation or damage to the engine will result.

Our engine and most people's here have motors that do not fall into the above catagory. Rest assured that your engine will not blow up and die or have a reduced life in street and even racing use with these parts.

I would bet that every "expert" that tells you otherwise here has little personal practical expericance with the subject.

To close out, most of this information is from Mike of NST. You can chat with him yourself on AIM. His screen name is NSTonAIM and he is very easy to talk to. I plan to run NST pulleys for life!

 

^^^ Excellent post!

 

Wow, you could feel the <1% decrease in effective inertia accelerated by the motor? That's very impressive. Have you considered working on the side as a dyno?

 

There are those who actually DO and speak from experience.

Then there are those who sit on the bench and type theories on the internet.

 

Clearly those two are mutually exclusive. That is why the engineers who actually designed the car in the first place don't use stupid things like "theory" or "basic physics" to narrow down any design trade-offs... they simply build an infinite number of combinations of every part and car combination and try them all out. The world's not flat until I can see that it's round with my own eyes. You make an excellent point.

 

Ever had on installed on your VQ? Didn't think so.

Look, I'm on your side with this one, it's a pointless mod that shows no gains on and off the strip. But it does make the VQ rev quicker, even when in gear. Is it real noticeable? No, but it was even noticable to my highly critical butt dyno.

 

I understand your viewpoint. But use some common sense on this one. To make the engine rev noticeably more quickly in gear, it has to be making enough power to noticeably increase the acceleration of the vehicle (engine's linked to the tires through the trans, right?). And if that were the case, it should be noticeable on the inertial dyno and on the strip.

But from the mass change numbers alone, we know that it's not giving a noticeable increase in acceleration simply because it doesn't give a significant change in effective inertia working against the motor. Thus it certainly isn't making the motor rev noticeably more quickly in gear.

However there is an explanation for your viewpoint that is more plausible (IMO), and that is that the noticeably quicker revs in neutral trick you to think that it's also moving more quickly in gear (placebo).

 

Everyone is brining up good points...

But once again, all of these fall under the opinion or theory catagory.

No proof, no evidence? No facts.

It certainly might be true in SOME certain engines; but for an accurate assumption & conclusion, the proof has to be shown on our VQ's, which no has yet accomplished.

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