How do you KNOW this????

It's heavy, same size = no power gains at all.

I have talked to people on all the forums that relate to the Nissan VQ35 powered cars. The concensus and lack of proof of lightened crank pulley causing premature engine failures in the internally balanced VQ says this is not needed and will do nothing for you. The stock pulley is not a dampener or balancer. The elastomer in it is for noise control based on the info found all over the net not for dampening. If the elastomer in the stock unit were a dampener, then aftermarket units would probably be useless as well since in cars that do have a dampening material have the material tuned to the harmonic frequencies of the engine they are installed in. Most aftermarket companies would not have the resources to tune the product for every engine they sell for.

Do your own research and searching. I don't proport to be an expert but have done a lot of searching and reading on the topic. Before you shell out money to fix something that is not broken, be sure you need it.

 

When you're talking rotational inertia, the mass farthest from the center of rotation (crank in this case) has the greatest effect. So even though this part might be the same size and weight as stock, if it is designed with most of the mass on the inside then it will still have some weight reduction benefits. I highly doubt it would be as much as the UR because the UR is a very light piece throughout, but it will still make a slight difference.

 

This is what I know. My car sure likes it and I can feel it working. IM glad I installed it.
The UD pulleys are a good item and have one of the best bang for the bucks.
And for me I prefer more flywheel mass in a stick shift car.

 

How many times do have to go over this Sure, the assembly may be "balanced", but that does not take into effect the torsional vibration generated by the explosions occuring on the pistons and the massive loads placed on the crank. I can assure that the OEM crank pulley is in fact TWO peices that are bonded together with an elastomer ring which is in fact a crank damper. The rubber is not there "to quiet the accessories" as Unorthodox and other misinformed people will try and tell you. The ring is there the dampen crank certain order vibrations in the crank.

What I find amazing is how many of us, including me bought into the reduced rotational inertia of a light crank pulley. Let's think about this for a second, how much rotational inertia advantage do you think 6" 2lb pulley really has over an OEM 7" 6lb pulley? Seriously, think about it and do some research like I did years ago. I've learned that rotating assemblys that are driven by the engine and are further away from the engine have the most effect. These items would include brakes, wheels, axles, and driveshafts. Small and light items mounted to the engine have far less of an effect in terms of power. It takes a lot more power to try and turn a 19" rim/tire vs trying to turn a 16"/tire because:

1) The 19" combo has a lot more weight further from the hub
2) The 19" combo will typically be 5-15lb heavier
3) The wheels are far away from the engine.

A 40lb driveshaft, a 50lb wheel combo, a 25lb halfshaft requires a lot more power than a 6lb pulley mounted directly to the engine.

On my VQ30 Maxima, I had an UDP. It weighed 1.5lbs vs the 5lb stock pulley. I made 40 passes before and after the pulley. There was absolutely no change in 60', 1/8 mile, and 1/4 mile performance. The only thing my VQ gained was increased engine vibration, jerky entry into gears (5 speed manual), and a strained engine noise in the upper rpms.


Concerning fluid-style dampers:

Functioning along the lines of a viscous-couple all-wheel-drive system, vibration causes the silicone fluid to shear, thus achieving damping by converting mechanical energy to heat energy. Other manufacturer-claimed performance advantages are that fluid dampers can absorb vibration at any engine speed, can dissipate more heat than same-sized elastomer units and are more durable because the silicone is less likely to deteriorate than elastomer rings.

Regardless of style, performance aftermarket dampers offer many benefits. A reduction in torsional vibration increases engine power output. A functional damper removes the twist from the crankshaft and stabilizes camshaft and ignition timing. A reduction in twist at the end of the crank also stabilizes the valvetrain. The bottom line is more power and more reliability.

 

I guess there are going to be 2 camps on this for all eternity. It's a matter of which side's explanation makes sense to you. For every pro you can find a con and viceversa.

I have yet to find any 100% conclusive data of actual engine destruction due to lightened pullies. If anyone has it please post away. I would rather find the proven truth either way.

DaveB, please explain what you mean by your first paragraph. How can you assure us. Did you take a stock pulley apart? Do you have data from a Nissan engineer. I am not trying to pick a fight or be rude, I am just searching for the truth about this issue. I have a UR pulley set waiting to be installed so I want to use every available time until then to make the right decision on this.

 

Unfortunately we aren't talking about a Maxima here. It also sounds like you botched the install, because so few people report any problems with pulleys so that's strong evidence there was a problem somewhere with your setup, probably your belt tension was out of spec.

Mine works great, smooth as ever, and definitely increased responsiveness. I can especially tell the difference while engine braking and rev matching.

 

Botch the install There's nothing to mess up. The pulley is keyed, getting the torque on the crank bolt is easy, and tensioning the belts is cake. I had the Nissan FSM and all the belts were at the correct deflection. If the belts aren't tight enough, it's not going to make an engine feel grainy. Instead, the belts will squeal like a stuck pig. The vibration and graininess is related directly to certain order vibrations of the crank. It's as simple as that.

The reason you don't notice the increased vibration is because the VQ35 lacks all the smoothness of the VQ30. The VQ35 is a jewel of an engine, but when Nissan increased the bores slightly and extended the rods .5", the VQ lost all the smoothness it was known for. All the mags have noted that the VQ35 is much more powerful, but gone is it's velvetly smoothness it was known for in the VQ30.

 

I know you're not trying to be rude or the such.

All late model Nissan motors have crank dampers and they all look very much alike. The VG30, VG30T, VG30TT, VE30, VQ30, VQ35, SR20, and QR25 all use dampers. I constantly get badgered by people saying "The VQ35 G35 isn't a VQ30 Maxima therefore you can't compare the two when it comes to their pulleys". Well guess what people, there is such a thing as a VQ35 powered Maxima (02+) and it uses the same exact style damper (looks the same too) as my 96 Maxima had. And guess what? The VQ35 block, crank, rods, pistons, and heads are shared between the all VQ35 powered cars. The only difference is the ortientation of the drivewheels and the way the accessories are lined up on the engine therefore the pulleys may look at little different, but internally they're all the same with a sandwiched elastomer ring that goes through the whole pulley. The pulleys are in fact two peices and here's a picture of a failed elastomer ring off of a 95 Maxima:

http://forums.maxima.org/showthread....t=crank+pulley

 

Guys

Understand that the more balanced an engine the more power it makes.
The fluidampr does what it says it will do. I have a real problem right now telling you what has helped the most. I just installed Crawford headers, Cats, Invidia exhausts and of course the fluidampr. This I can say. I have a new car with all the low end power problems taken care of. The low end power is up to the point where I can just drop the clutch at Idle and the car moves. The installs have in my mind been a win win deal here. This car has *****" down low and it will start pulling hard at 3500 rpms and at 5500 rpms hang on. It is so smooth You better be watching the tach. At redline and speed shifting into second -Well- it just fell in to gear.
I know the fluidampr is working. Im happy

 

pretty cool

 

Thanks for the followup DaveB. That pic of a failed pulley does give one cause to rethink ones position on the pulley debate. Of course I've already heard one rebutal that the elastomer is there to cut down vibtations/noise cause by the connected accessories not crank related at all.

This is tough because both camps have convincing arguments. I guess I will keep searching until I am sure one way or another. My UR pulleys can wait a bit until I am completely comfortable.

 

The chances of your VQ blowing up with an UDP is basically nill. The VQ is overengineered from an NA standpoint assuming you keep the revs below 7000rpms.

My whole argument is that driveability and overall vehicle refinement diminishes when you add an UDP and that there is very little and mostly no performance gain associated with the UDP. Don't you find it interesting that no one on the 350Z or G35 websites has neither dyno or track proof of this thing really working? The only dynos I've found are from Nissan Performance Mag which is a paid aftermarket mag. I've read articles about installing UDPs on the 350Zs, Altima V6s, and Sentra QR25s with the gains showing any where from 2-6whp. When you look at the dyno graphs you'll see that they're claiming little 400-500rpm spikes in power as these gains. Unfortunately on the track, a little spike in power that lasts a few hundred rpms isn't going to make any difference.

 

Well, I installed the Fluidampr though I decided not to do a full up dyno on it. I don't know that it makes HP and to be quite honest I don't want to be in the middle of the debate. Having said that here is my initial impression.

Anyone with a Stillen engine dampener brace knows that it transfers a considerable amount of vibration into the cockpit most noticeable through the steering wheel. After installing the Fluidampr I can say that the vibration has slightly diminished. Still noticeable, but noticeably reduced from before it was installed. The engine now seems to have a "silkier" quality to it.

If you haven't been driving with a Stillen dampener in your car for more than a few months, or if your G is near stock form, I think that the difference would be imperceptible.

I'm definitely going to leave it in, as far as gains go I just can't say. I don't trust my butt dyno and my track times will be thrown off by my new track rims and tires. So I can't give an honest comparison.

My $.02.

 

I can also say I dont feel much difference with my UDP pulley as far as performance goes. But I also have the stillen dampener and the vibration in the steering wheel i think overwhelms any smoothness the UDP may have created (if any). I know alot of people like to justify their money spent on aftermarket parts by convincing themselves of any change in performance, but im not one. I simply want something that works meanwhile retaining everyday driveablilty and reliability.

I only wish the UDP pulley had the affect the spacer had on the car after installation.......