if we install a pulley?
http://www.sr20forum.com/showthread....ht=pullies+rod

in short, quoted from the forum
"See Rocco, I was right, the rod did not break. The bottom half of the rod or the rod cap came loose. This happens when you install UR pullies. They cause alot of vibration at higher RPMs and which casue the rod bolts to come loose.

Many a car that has had this happen has had the rod blamed for breaking which was never the case. If you got UR pullies this rod bolts coming loose will happen sooner or later."

can this happen with any pulley including ebay ones?

btw, what was the problem with the ebay ones, they were tearing up belts or something? thanks.

 

Our pulley is not a harmonic dampener so I don't believe it is an issue for us. Some cars have harmonic dampener crank pulleys which are used to reduce vibrations but ours does not, so you aren't introducing any more vibrations with a pulley, unless there is something actually wrong with the particular pulley you install.

 

A well built pully is precision balanced so they do not vibrate...

Thats why you dont trust just anyone. I just installed my Motostorm UDP today

The only reason I got the one I did is because no one has had a problem with them and I know they are concerned with quality. They were slightly delayed because they wanted to make sure they were balanced perfectly for this exact reason.

 

If it hasn't happend to me I don't really see it happening to any VQ.

 

thanks fellas

 

I'd think that if the pulley was causing enough vibration to loosen the rod caps loose you'd notice it. The VQ is one of the world's smoothest engines and I'd think it would be readily noticable if something was out of balance. I'm not heavily experienced with the SR20 but from the friend's cars I've ridden in and worked on, it doesn't impress me as any dramatically more noisy or harsh.

Come to think of it, does the SR have a balance shaft? I don't think it does. I'd think that the removal of balance shaft would be more serious over the life of the engine than a machining error on a UDP. This seems to be gaining popularity among some 4 banger groups, such as with the Mazda 3 and Ford Focus guys, and I've heard of it gaining popularity with the Nissan QR powered cars as well.

 

i read an article about the removal of the balance shaft in the qr and it gained like 8 whp or something. Supposedly it makes the engine more reliable because the balance shaft itself spins twice the RPMS as the engine, according to the article.

 

I hope you are right ....because that would really suck!!!!

 

I thought Dave B proved that it was by taking one apart. There is a very thin elastomer ring between the inner and outer portion. He posted pictures.

Whether or not replacing the crank pulley with an underdrive pulley will result in rods shaking loose is another matter, but I think it would have happened by now to somebody on the org.

 

Well, if it will happen to anyone, with my luck lately I will be the first one

 

I doubt the removal of the balance shaft would make an engine more reliable - Nissan's engineers put it there for a reason, to reduce vibration. Vibrations will increase engine component wear in addition to reducing ride comfort. Additionally, 8HP at the wheels sounds a little high, I'd be more inclined to believe 2-4HP at the wheels, maybe they meant 8HP at the crank.

Do you have a link to the article?

 

the article was in HCI, from like last year. It was a tech guide to the Stillen or JWT kit. It said that the only increased vibration was felt between 2500 to 3000 rpm, or somewhere there. Iunno, maybe I should check b15.net and do a little search there.

 

ive had the same pulley on my vq 30 for 180k and reved the **** out of it now its on my vq 35 ive put 5 k on it already and i rev that up to the sweet spot also .

Trust me if something bad happens to your engine it isnt from the pulley

 

its on nissanpermarncemag.com on one of their project vehicles.

http://nissanperformancemag.com/november04/specv/

 

good find, the articles are very similar.

here are the fallacies of the balance shaft according to the acrticle"
But why would we want to remove the balancer shafts in the first place? First, balancer shafts spin at twice the engine speeds; at 6,000 rpm, the balancer shafts are spinning at 12,000 rpm. At such a high rpm balancer shafts have a tendency to seize, something you do not want to happen to your performance car. Second, balancer shafts are operated via a short chain by the crank shaft so they basically consume some power from your engine. Removing the shafts should reduce power loss and divert it to the wheels. The power gained from balancer shafts removal (BSR) is not clear. Some have claimed a 7-8 hp increase. If you want to know how much hp the JWT BSR kit will net you, simply scroll down to the "dyno testing" section of this write-up.

 

btw, i found this link which was helpful...
http://www.greghome.com/Greg's%20Garage/1999%20Nissan%20Maxima%20SE/Underdrive%20pulley.htm

think the info is pretty accurate?

 

Greg is wrong about there not being any rubber ring.

 

I hope not. If I saw a hole in the side of my motor I would shoot myself!

 

that's pretty bad, i don't know why anyone want to tweak with the pulley. I just leave it alone

 

ChromeSE5, I sent you a pm a few weeks ago, get back at me, thanks.

 

Yeah, bad for BMW's. Apparently not for VQ's, though.

 

Does that tiny rubber ring actually do any dampening? It's certainly not a balancer right?

I think a 4 cyl is naturally more unbalanced than a V6. But I don't know why the BMW I-6 needs a balancer on the crank. It's probably the most naturally balanced configuration this side of a I-8.

 

wow i remember this topic came up back in 01-02 and had everyone scared to buy UDP's..

 

Just about every car manufacturer uses a thin rubber ring between two concentric pieces of a crankshaft pulley. The amount of damping can be varied by how thick the ring is.

The harmonic damper is for damping out torsional vibration. It has nothing to do with engine balance. Even a perfectly balanced engine will have torsional natural frequencies that are self-excited by engine rotation, and the longer crankshaft length of an I-6 will result in lower natural frequencies with higher amplitudes than a V6. There is a certain amount of torsional damping in the oil film in the main and rod bearings, but apparently not enough for the Beemers, hence the need for the damping provided by the rubber ring. Also, apparently it is not as critical for the VQ engine, since people seem to get by just fine without it.