well, i'm glad you finally made an (educated) decision on that, neff...and i would come out, but i have other plans for fri night..thanks anyway!


03 6MT coupe, red/willow, premium, aero, splash guards, alum pedals, clear corners, double 15% tint

 

Neffster, I commend you.

You have just not only confirmed and explaned the science behind InfinitiTech's findings (of increased vibration) but did so in an objective and scientific way.

As you said yourself, I too have been torn between getting that relatively cheap ~6 hp gain and imposing long term damage to the engine.

People always say that many Z and G guys have been using the pulley without any problems. Define "problems" !!! The problem is not obvious and immediate, it is is subtle in the short term and can be devastating in the long term. Putting a lighter flywheel does not have the same effect as putting on a light pulley , as there are no belts connected to the flywheel to create harmonics.

I am convinced that it is NOT the mod for me.

Thanks again.

Gurgen

 

You're the man Neff. This has been an awesome thread. I love learning fact and making educated decisions with all the info possible. The bit about the rubber is interesting and makes sense. Thank goodness for engineers and physics. It's all about risk/reward and now we all have the info we need to weigh our individual risk/reward decisions and be informed consumers. Thanks Neff, Infiniti Tech, and Q45Tech. You guys are great resources.

2004.5 Coupe/5AT/Ivory/Everything but chin spoiler/Z Tube-Popcharger/Crawford V5 Plenum on the way

 

Excellent research into this topic. I do have some questions as to the harmonic effect of belt tension dynamics. If this were the reason for the rubber ring on the stock pulley, why wouldnt the other pulleys in the system (alternator, water pump, power steering pump) be fitted with dampening rings? If the harmonics of the changing load affects the crank, why not the bearings on the other loads? And the non-crank accessory bearings are FAR less lubricated and tend to last 100K miles or more without dampening.

And the stock crank pulley is not the "classic" harmonic dampener with the 2 piece steel with the rubber ring in the middle of the 2 pieces to isolate belt torsion variance. It is simply a keyed 1 piece unit with a tiny 0-ring glued on the front. If its doing any dampening, its not doing much. There simply isnt enough dampening surface area relative to the rotational mass. A testament to the inherent precision of the VQ. If anybody with the UR pulleys is worried, do the oil analysis at every change. That is the full spectum blood test for your motor. If anything is being worn prematurely, you will know.

 

" If the pulley has a rubber ring on it be careful. The rubber ring is used to dampen out the harmonics of the belts. Belts are not rigid bodies and they are constantly changing length and tension. They get a very slight amount of slack in them at one point in a single rotation and then they get more taunt a split second later. This happens on a constant, random basis depending on the engine loads and other variables. These variances cause loads to change, which translate into harmonics, which are bad for the bearings. The job of the rubber ring is to dampen out these harmonics (or unwanted frequencies). This ring is actually absorbing the vibrations caused by the belts and is not allowing those vibrations to be seen by the crank or the bearings (this is a very good thing). If the lighter weight pulley were designed to have this rubber ring, it would have to have a larger rubber piece than the stock pulley does, since the aftermarket pulley itself is lighter. The stock pulley, being heavier, also helps to dampen out the harmonics from the belts, which help preserve bearing life."

--- The rubber ring if it were for dampening would have nothing to do with dampening the belts. The belts themselves act as a damper because they offer cushion (their rubber and fiber construction) against an external pivot points (the accessories & idler pulleys). Prime example is that domestic V8 racers covert their chain drive cam system to a belt drive cam system to minimize valve train harmonics to the crankshaft because a belt will not transfer any harmonics. Based on this experts explanation the cankshaft would need another damper to reduce the harmonics caused by the timing belt conversion. So clearly there is no correlation between belts and bearing protection. Another important point to bring up is how most engines going back 10-15-20-30+ years had no rubber rings on them. This is simply because over the last 10-15 years the car manufacturers have gotten fanatical about NVH (Noise Vibration & Harshness) reductions for the occupants of the vehicles. This is plainly evident becaue of the poliferation of baffles and resonators in the intake and exhaust plus the advent of liquid filled engine mounts and other stantionary vibration dampers that are bolted to the engine or chassis. The factories want the cars super quiet because they make these cars, I know this will be a shock, for the non enthusiast and that includes cars you might might think are specifically enthusiast driven. Another great example of NVH reduction progression is the transition from stamped steel accessory brackets (for the alternator, p/s & a/c) to cast iron and now cast aluminum. This changed increased rigidity at the mounting points and dramatically reduced vibrations and resonances that were once common with stamped steel brackets.
Its real simple as was stated once before we have 7 years under our belt not including the 2 years of development that was done before we came to market. We have yet to have one call from a customer complaining about an engine problem. We've worked with some of the best engine people including OE engineers that have stated off the record that the OE pulleys are for NVH control and not engine protection. I also challenge anybody out there to find a modification (other than nitrous or forced induction) that offers anywhere as much performance improvement as our pulleys. Materials don't lie so when there is a problem it can be traced specifically to a failure point or cause of failure point. There are a ton of reasons why engines fail and most of the time its from abuse which can mean lack of proper maintenance to bouncing of the rev limiter too often to abusive launches to excessive engine reving when the engine is cold to improper weight oil. The facts I have presented speak for themselves and that is 9 years of facts which outweigh any conjured up physics or ideals.

Respectfully,
Shawn Baumgartner

 

"I also challenge anybody out there to find a modification (other than nitrous or forced induction) that offers anywhere as much performance improvement as our pulleys."

The Crawford or Kinetic plenum or high flow cats or a new y pipe.

Seriously though Shawn, thanks for the input. However, 9 years of "no one has complained yet" don't trump physics, which aren't conjured up. They are quite factual....whether the physics in this instance will ever cause a problem I tend to agree with you. I doubt your pulley every would, and like another poster said an oil analysis would catch the culprit pretty soon.

Main reason I'm not buying one is cost vs risk vs benefit. It's just not that much HP, and it does have a slight risk, and besides that, like Q45tech said, engineers had many choices of pulley size to use and they chose this size. Power steering, A/C, Alternator....I want my electronics on their very best behavior if I'm stuck in rush hour on a 105 degree day. My old *** also needs all the power steering boost I can get.

Respectfully,
Todd

2004.5 Coupe/5AT/Ivory/Everything but chin spoiler/Z Tube-Popcharger/Crawford V5 Plenum on the way

 

Shawn,

After reading your post I have a specific question. You stated, <font color=red>"We've worked with some of the best engine people including OE engineers that have stated off the record that the OE pulleys are for NVH control and not engine protection."</font color=red> I think by OE you mean Original Equipment (or the people who designed the stock configuration). Are these OE engineers the people who designed the VQ35DE? Could it be that the OE engineers you are referring to designed Honda Civic engines?

Also, what type of specific guarantee does the UR Underdrive Pulley come with? If my dealership says my engine is shot as a result of installing your pulley, do you have someone come to my rescue and help me diagnose the true problem and work things out with the dealership, or am I actually 100% on my own? I'm just trying to understand your statement that was made previously... <font color=red>“Needless to say we stand behind our products and guarantee that owners will not have any problems when using our pulleys or any of our products.”</font color=red> Also, if the pulley is determined to be the cause of engine problems, what does this guarantee do for me? For the record, I have the pulley with the very comprehensive installation instructions in my car and did not receive any written or implied warranty or guarantee with it.

As far as your other statement, <font color=red>“I also challenge anybody out there to find a modification (other than nitrous or forced induction) that offers anywhere as much performance improvement as our pulleys.”</font color=red> The answer to this is pretty easy. Any new plenum will give an average gain of 10-12 rwhp, dyno proven again and again. I would imagine that the Random Technology High Flow Cats would at least be an equivalent gain. I’ve also seen average exhausts on this car dyno between 5-8rwhp, so there’s another example. NONE of these mods are as affordable (or as “pretty”) as your pulley/belt combo; however, none of these mods could potentially do ANY damage to our cars.

Thanks for taking the time to answer these questions. I really hope you respond.

Sincerely,
Neffster

300bhp??? We'll see... 5-22-2004

 

I'm not up on those parts but how much do they cost? As compared to just our crank pulley. I respect your concern and your choice. That is the beauty of of capitalist system!

Cheers,
Shawn

 

WOW, impressive thread here, glad we got it all straightened out.........

Infiniti Gearhead

 

Not the VQ35 specifically but I think Mike Kojima is as close to a Nissan engineer as we can get. If you read that back of the instructions you will see our warranty but as far as guarantees go its real simple. Thats what we have product liablility for and if there is a problem and the components and materials show conclusive proof of that damage then the owners engine is covered under our policy. But as I've said before there are a million possibilities as to why an engine may fail and the materials don't lie when you inspect them. But as I've said before its been 7 years and nothing.
Actually technically any mod you do can be devastating to an engine because the factory never intended the engine to work under non-factory specs. Every change you make takes you further away from the factories intention and that includes things that seem simple like intake mods and exhaust mods. What are the consequences? Well for one the intake pulses change which changes the whole resonance characteristics of the engine. The same goes for the exhaust. Many factories use special oil during engine development and testing and although you can use whatever oil you want technically the engine now responds differently than the oil it was designed using. Again there are a million things that have an effect on engine durability and some of the simplest things can have the most dire consequences. As I replied to someone else I respect a consumers choice to do as they wish based on the information they can gather.

Respectfully,
Shawn

 

Shawn,

Thanks for the quick reply. Forgive me for not knowing, but who is Mike Kojima and who does (did) he work for and in what capacity?

To answer your questions:
1. The Crawford Plenum is $395 + shipping (about the aftermarket cost of your complete pulley set).
2. The RT Cats are $500 (plus shipping from Performance Nissan).
3. The exhausts start at around $600-ish and go up to about $1300. Borla, Injen, Stillen, Nismoand Fujitsubo are a few that come to mind.

Keep in mind that the performance oriented side of me really wants to install this pulley. Please convince me that there is no way a properly installed pulley can do damage and I'll have it installed tomorrow morning (I actually still have an 8am appointment that I have not canceled yet with a local mechanic).

Thanks again,
Neffster

300bhp??? We'll see... 5-22-2004

 

thanks to everyone that has reponded to this post, to clear things up for myself i will make these comments and please correct them if i'm wrong. Physics and some "experts" say that yes changing the pulley will/might cause problems. U/R says that problems can be caused by any mod, but if the pulley is the cause of the "damage" U/R will warranty the "engine"!??
I got the pulley and installed(by dealer) 2 weeks ago,where i bought the car, i have to take the car back today so they can tighten the belts because they are squeeking, i'm also having them check the A/C line because i have the Z tube and JWT A/I, and some G drivers have had issues with a/c line rubbing and causing a leak..

 

InfinitiTech...

I am going to throw another variable/question into the mix.

The G35 coupe and 350z have electric fans.
The G35 sedan has a crank driven fan.

Is there a difference on the balancing of these engines, crank vs. electric fans?

A crank driven fan would definitely have different harmonics and load on the engine over that of a non-crank driven fan, having "lightened" the load.

If so, then DaveO (and I in the future) will have specific issues with modying our crank driven-fans on our sedans to electric, as we would be "removing" the harmonics and vibrations created by the crank fan.

Does Nissan have a different mfg/balancing process between these two production setups? Would you be able to supply any electric vs. crank fan balancing details?

thanks, Ted


'03.5 Sedan 5a: BS/G, Prem, Aero/Body, Sport, Nav
Click for MODS or Vote at Online Showoff

 

First of all, I'd like to say that this is a great thread.

Qoute:
"The answer to this is pretty easy. Any new plenum will give an average gain of 10-12 rwhp, dyno proven again and again. I would imagine that the Random Technology High Flow Cats would at least be an equivalent gain. I’ve also seen average exhausts on this car dyno between 5-8rwhp, so there’s another example. NONE of these mods are as affordable (or as “pretty”) as your pulley/belt combo; however, none of these mods could potentially do ANY damage to our cars."

I have to disagree with you here, neff. The plenum could cause an engine failure if one of the internal bolts come loose and gets sucked into one of the intake runners. The loctite "should" take care of that but what if it doesn't? I can recall at least a couple of posts where the owners have mentioned loose bolts.

RT Cats: there has also been some mention of the RT cats with deteriorating converters that have been sucked back into the headers and into the engine. I know that this comes from a rich condition that breaks the cats down and it would probably happen to the stock cats. However, my $ would be on the tech blaming the RT's or Kinetix, or whoever built the cats for this problem. No arguments about the exhaust though.

In terms of gains, even though the plenum has more peak gains than a pulley, could one argue that the pulley offers more hp over the entire range of the RPM band? It's the same with the cats, most of the power comes in the upper rpms where the additional breathing helps.

We forgot the popcharger also. Any time you have an oiled filter element and your MAF malfunctions, my $ says the dealership will blame the filter, which I'm sure your mod unfriendly dealership (as well as mine) would do immediately.
<P ID="edit"><FONT class="small"><EM>Edited by al503 on 05/06/04 10:09 AM.</EM></FONT></P>

 

Thanks, Neff, you've made my decision for me...you're might, physics don't lie.

2 G or NOT 2 G, there is no question!