Anyone running unorthodox s pulley for a vg? What are some of the significants of this pulley and also what are the appropiate belt corrective sizes that are ran.

 

I run the unorthodox pulley. I personally notice big performance gain after 3k rpms and if you run the A/C a lot there isn’t much power loss with the compressor running as with the stock pulley. I don’t remember the belt sizes but if your thinking about it IMO its with it. But that is just my preference

 

http://www.4dsc.com/articles/drivetrain/udp/udp.shtml

as is the point of any mod, the pulley (in layman's terms) gives you more power - yes this is a very gross oversimplification.

as far as seat-of-the-pants feel, there's greater acceleration response and launch form a stop. since the pulley is smaller and thus turning the belts slower, you may notice a decrease in perfomance form the p/s pump, alternator and a/c compressor at lower speeds or at a stop.

hth

 

hey 2legal i thought you had a VE-5 swapped in that

 

I have one and agree that the engine revs more freely. The UDP is WAY lighter than the stock part. Some people claim that it will wear out your engine bearings faster because of the lack of a harmonic balancer, but I hav run mine for over 25000 miles with no issues.

The general concensus is that our engines are better balanced and more refined than others, so a harmonic balancer isn't really necessary.

Right guys???

 

Ive had mine on for about 35k still runs fine so idk?

 

On an unbalanced engine its pretty much required. The old L24/26/28's really needed them but the VG is very balanced. And V8's usually need them because domestic company's cheapen out in the balancing department.

Id have one but I have to do more maintenance before modding begins.

~Alex

 

Alex do you mean pay me back be for you start modding?

 

Yep thats first thing. Modding has been pushed back quite a bit.....

Quick Q, any one notice MPG change before/after UDP?

~Alex

 

I have been happy with the UR UDP for almost two years. I know the pulley comes with the correct belt numbers. I will look tomorrow and see if I can find the parts number list

 

That should only be affected if your foot meets the firewall often, if you get my drift.

 

Got those belts for ya.
First they recommend Gates belts

Alternator belt - Gates #K040292 (29.34" or 755mm) alternate belt size use Gates #K040300 (30.75" or 780mm)

Water Pump belt - Gates #K040395 (40.25" or 1020mm)

Air Conditioning belt - Gates #K040460 (46.625" or 1185mm) alternate belt size Gates #K040450 ( 45.75" or 1160mm)

 

Nah It's a vg i swapped in a 5 speed. I was half way done with my turbo swap then i sold another car of mine and so i decided to put back my vg30e and take out the vg30et to be able to use as a daily driver.


Ps@ It's 110 degrees out here in az

 

thank alot im gonna order that pulley then since i have the corrective size thanks .ORG

 

what about off the line performance is there any changes there also?

 

How much of a difference is notice? I mean is there a stiffiness in the sterring wheel, or is my lights gonna dime out when night driving at a stop light, or is my a/c not going to blow cold when at a stop light when all the others accessories are in use.

 

I have never noticed a difference in the performance of accessories.

 

so they still operate in oem standards?

 

Do Your rpm fluxuate when the accessories ar on at a light.

 

My accessory lights (headlights, dash, dome) all dim down at stops but that is mostly because of my subs and amp.

 

well the amps i have are the oe bose ones. i dont really have any high draw items on my car. My headlights are only 35w, and most of the other lights are l.e.d's so most of the draw for power is eliminated. (Except A/C, Cooling Fans, Windows and Sunroof) Most of the other stuff i dont use due to cllimate issues

 

Just set the idle a bit higher if you're worried

 

The only mods that make me notice a differance is boost and good ole motion poition

 

No disrespect, but a UDP doesn't give you any horsepower gains, just frees up horsepower that your engine is already making. Essentially, when your AC is on, and accessories are running, they take power away from the engine. Having them spin slower, with the different pulley ratios, will free up some horsepower that the engine is wasting on keeping you frosty in the summer sun. So, you won't see gains in terms of horsepower really...but you will get a quicker response time and should have smoother idle and less draw if the AC kicks on or whatever....

To give dawifey some credit....he DID say it was a very gross oversimplification.

Also, yes it's been said that our engines are balanced so well that the harmonic balancer is not needed. I'm still not too sure about an engine that is as old as ours. I don't know if I'm personally willing to take the risk of putting on the UDP on a 13 year old engine. Consider it this way...the VG engine was quite balanced at 50,000 miles, but add another 100,000 miles to that number and little specks of metal might have been pitted away, build up gets in the passageways and on the valves, and other things that could throw off balancea slight bit. However, what may seem like a little thing, becomes a big thing at 4000 rpm. So, while you might not see any knocking or huge engine shakes right away, that harmonic balancer might be the only thing keeping a piston ring seated right. You'll have to look at the overall quality of your engine and how it's running before you decide to add a UDP, that could throw some things off inside the engine. It's not probable, but it is possible. Nissan didn't add that balancer just for weight...I'm sure it serves a purpose as to why our engines last as long as they do. Just a thought....

 

what about if the harmonic balancer is on crooked and has enough runout to be visible to the naked eye? is it still doing its job?

 

Harmonic balancers really aren't neccesary below 7-8000Rpm. At higher RPMs the damage can happen to the crank. For the use a daily driven car gets you aren't going to cause the damage everyone is worrying about.

As far as HP, the "gains" you get from UDPs is partly from driving the accessories slower so they rob less from the engine. Most of your gains come from less rotating mass. The UDP weighs considerably less than a Harmonic balancer.

You will not see any difference in accessory performance while driving. I do, however, notice that at idle the lights will dim...but only at idle.

 

bah...that would just be user error!! Considering that they're probably put on by machines would mean that they're about as close to perfect as they could ever be. That is true though...If you took it off and put it back on wrong it would be pointless to have it in the first place. I didn't know they werent necessary below 7-8000 rpm's though. For such a common item on engines, you'd think it would be usefull BELOW the redline, lol.

There's plenty of things that could throw off the balance of an engine on a small level....I was just saying that putting a UDP on a 13 year old engine that hasn't has any modifications done to it for the first 10 or so years of its life might be the "straw that breaks the camels back." Probable...no, Possible...yes.

Plus I'm not gonna lie I really want one.....

An entire discussion on the pros and cons of a pulley can be found here:

http://forum.e46fanatics.com/showthr...t=85613&page=1

 

I'm getting it taken off soon anyways when i get my timing belt done, since i'm going to go ahead with the crank and cam seals too.

 

I just cleaned out my engine, and did the seals. I was thinking about putting a pulley on, myself. You have pm.

 

When the discussion is about harmonic balancers being necessary, we always should remember that auto makers try over-build everything to the weekest link so the cars are more reliable even after much abuse.

Harmonic balancers do serve a purpose, they minimize vibrations in the rotating assembly. Basically, at lower RPMs this makes for a smoother running engine, it doesn't prevent damage. The vibrations at lower RPMs are not severe enough to cause damage to a forged crank (which Nissan engines have). These vibrations are intensified many times with each 100 RPM. HBs are used on performance engines because they see high RPMs on a regular basis. Street driven engines rarely see RPMs above even 3500. And with the VG and VE engines redlining below 7000, the HB can be removed with little risk of serious damage to the crank.

 

I'm going to take the side that the power release comes from the different pulley ratios, not the reduced mass. Technically, moment of inertia is the correct term to consider, it factors in the reduction and redistribution of mass as well as the reduced radius.

If you consider the inertia of everything else: the crank itself, tranny, axles, discs, wheels, the difference a lower UDP inertia makes should be marginal.

Continuing with the pulley ratio argument, a good alternative may be to get larger pulleys on the accessories and pumps instead of changing the UDP. No more harmonic balancer concerns, and the same performance effect.

 

Right....the same concept applies to why the rear BBK is so effective, even though it uses the same caliper...by moving it out by only an inch, you see a big improvement in braking power...simply because of the longer moment arm, or distance from the center of the wheel to the applied point of force on the rotor.

Similarly, on a smaller pulley, it takes less force for get it going and to stop it, and less horsepower is wasted on accessories. (I'm not sure if I worded that right.)

 

Close, but I think this point actually contradicts your first point. When a smaller pulley is increased to be closer in size to the bigger one driving it, or the driver itself is reduced in size relative to what its powering, the radius ratio between them changes.


Each accessory consumes a certain amount of torque on its pulley so that it can do its job. The belts are just an intermediary torque transfer mechanism. A smaller UDP results in less revolutions on the accessories per complete engine revolution. So if the accessories turn less, they consume less engine torque per complete engine revolution, leaving more to be distributed for the rest of the drivetrain.

 

Right right....that makes sense. Don't see how it contradicts though. Either way....you're an engineer eh? What college if I may ask?? A 23 year old that knows about moments, inertia, and mass distribution HAS to be taking some statics or engineering courses.

 

I just finished at the University of Texas at Austin last Dec., in Physics though.

And now that I re-read your statement, you're right, its not a contradiction... I just hadnt had my coffee yet when I was reading the first time

 

just to clarify / simplify

the UDP isnt really worth its buck probably...

a lightened pulley would be better, instead of a smaller one?