9 hp gain at 5500 RPM and up 6.1 peak...

Which leads to my question... isn't underdrive bad for your car?

 

I haven't seen it. This was on a 350z ? Nice.

 

Yeah 350Z Sport Ed.

 

good question....bump

 

Try a search for multiple lengthy explanations and conversations.

 

Actually there was a (at least 2 in fact in my 350Z) very loooong thread on this issue a while back. I heard very convincing arguments both pro and con on possible engine damage from the pulley set and I’ll be damned if I know what to think. And I would DEFINITELY get the pulley set if I were SURE it would not cause harmonic balance problems with the engine over time. If I understand it correctly, the argument is that – you’ve heard of perfectly balancing a racing engine for endurance under sustained high RPMs? Well, I think the con argument is that the ultra lightweight pulleys do the opposite of that. That lack of the extra mass (and the little crankshaft balancer thingy) is more prone to create excess vibrations as the engine spins that, over time, can damage the engine. Sort of like when I was in the Air Force many years ago in basic training. Well, generally, we had to march along in almost perfect step with one another or the TI comes up behind you and kicks you in the butt (or worse) till you do. But, when walking over bridges of some length, they made different small groups of our larger group break step or get out of step with one another as we marched across a long bridge. They said that if everyone were in step, the large group might slowly set up vibrations that get worse and worse (grow). (Breaking step results in the groups sort of canceling out each other and not allowing the shock wave to grow – kind of like a balancer on many crank shafts.) These vibrations could cause the bridge to shake, rattle, and roll. (I have actually felt mild cases of that before on small bridges in which they didn’t have us break step, it really happens.) Worst case it has caused bridges to crumble and fall. (Of course it would never be while the TI was on the part that fell, damn the luck!) Well imagine what excess vibrations would do to our Z engines over time in much the same way. I’m not saying that the pulleys for sure will do that to your engine, only telling you the con argument. Sad, cause I WANT those pulleys…Doh! Almost like free HP by using less hp to spin the mass of the engine. And there’s nothing I like better than More Power! But unless/until I’m sure they’re safe, I’m inclined to decline on the pulleys. (The pro pulley argument was something like the Z engine has other internal balancers or something, but that the pulleys don’t create significant vibrations that will damage the engine, in any case.)

 

yep, here's one that should answer/question your decision on pullies thread link

 

Has ANYONE seen or heard our engines fail due to the UR pulleys?

 

Interesting that they said most of the gains were from weight reduction and not underdriving.

 

Has ANYONE seen or heard our engines fail due to the UR pulleys?

 

i know i havent

 

Mine have been on for 10k and most of that is spirited/track driving.

 

Interesting conversation. Glad I found it! Was seriously considering UR pulleys, but now I'm reconsidering, considering I'm only @ 9k miles under a 3/36 warranty.

It's a Daytona Blue '04 TRACK, so I had to fork out 35k and had one trucked in from Ohio (only other one was in LA at the time). I first stuck to Nismo while testing the waters; CAI, CatBack, Flywheel. All dealer installed for liablilty sake (don't worry; i researched and found a good dealer recommended by a factory rep. that w/i and hour's drive). So far so good. So I braved the Kinetix v4 intake, and Kinetix high-flow cat's which not only got more into and out of the engine but also shaved many pounds off the curb weight as well, just like the Nismo mod's (well except the CAI maybe).

I'm trying to stay under the "Warranty Radar" so I'm approaching with reasonable caution, and the dealer who installed it agreed I was doing pretty good at that. After finding out that Nismo makes grounding wires (that come with Japanese instructions!), i also bought some (other) wires and had the dealer put them on, again, for the warranty.

Believe it or not, it was a FACTORY REP that encouraged me to do the Nismo mod's which my local dealer knew nothing about but just an hour away in Birmingham they were all up in it and even had put Nismo "packages" on reg. Z's brand new, sitting on their lot. ('')

Now, to address this discussion . . . .

I'm going with the pilot. why? For numerous reasons. I have a broad background to tap into here, and I'm telling you, he's not blowing smoke. You might be lucky and get by, or, you might have luck like mine and know where I'm coming from (the school of Murphy's Law!).

First, my life has primarily been about music (re: Harmonics) starting at age 4 on to a music arranging degree from the University of Alabama. In addition, my dad who's a surgeon loves and knows all about physics, electronics, etc., and had passed a lot along to me over the years. I also took physics for non-science majors in college and did very well because I enjoyed it. I even have a close friend of the family who's a pilot that's flown in the air force, for delta, pan am (JUST missed going down over Lockerbie!) and on, and is very intelligent as well on such subjects (also ownes a Viper which is the closest I've come yet to a ride in the space shuttle!).

IMHO, having this background to tap into plus a bad experience with a previous 300 zx turbo whereby an improperly installed harmonic balancer plus extra boost caused the crank to break right behind the balancer some 2 years and 35k miles later, well, this '04 Track is still too new to take that kind of chance when those kinds of serious issues are at stake if you ask me.

I realize that hammering on a harominic balancer (see what happens when you go to a BAD dealer?) is different than installing UR's, but it's all tied to the same physics: Torque increase and/or resonant frequencies and their harmonics or worse yet a combination of the two can spell diaster in time.

Actually, this brings up yet another dillema I just now thought of . . . If you install the UR's yourself, you'll have a lot harder time defending yourself in court over a broken motor. But on the other hand, if you take it to a bad dealer like my 300 turbo experience, you could "cut your nose off to spite your face."

All this complicated risk over 10 hp? On a 35k ride w/ 9k miles? I don't think so . . .


Now, when the warranty runs out . . .

This, one would assume, would also be a good reason to go with a Procharger vs turbos on the 350 which we all know is not at all set up for FI. Besides the much cooler intake temp. to avoid motor-eating detonation, it's got a more linear delivery as opposed to the turbo which can impose a huge surge in torque in the midrange rpm and then falls off at higher rpm's where ironically the energy could be more easily dissipated with the higher rpm's therefore making it safer on the engine. I have also heard of superchargers breaking cranks from too much boost at too low of an rpm.

If I'm going to risk something that serious (again ), it better be for more like 150 hp, not 10 . . .

PS- Guitar strings, piano strings, etc. which are made to resonate the most are made of . . . . Metal! So proceed with caution!

 

Up from the dead.

 

Will this discussion ever die?

The best "scientific" results on this matter that I have seen, the only one I believe that is based in fact and not opinion or theoretical science is the guy who had his engine oil analyzed. Some member on this board sent a sample of his oil in at like 10,000 miles to have it analyzed by a company that does it professionally. After you send the sample in, the company sends you a report back stating the perceived condition of your engine based on the samples contents and their findings of the oils condition. The report answers questions like did the oil break down or did they find metal particles or water in the oil etc. His report said there was no unusual wear. He had the lightweight pulleys. He said he was going to send it occasionally to keep track of it status. Search the forum its here somewhere.

 

I had no opinion on this matter, actually bought one, and our mechanic said he wouldn't even put it on... So I returned it.

In the end, you need to take the advice of you mechanic or someone you trust… Mine wasn't a fan of the potential long term problems that 'could' occur... He stated that the benefits of 5-6hp didn't warrant the risk.

Your mechanic may have a different opinion...

 

i have had mine on for 15K miles, and just recieved my oil analysis from blackstone labs. it was perfect. i don't think the pullies add any unnecessary wear on the bearings.

 

Ad nauseum.

If you're scared, don't use it.

There will always be some unlucky bastard who blames an engine failure on pullies, ground wires, intakes, oil, plenums, etc etc etc. To this date, there are no proven pulley failures...only "My buddy's friend's mechanic said he saw one" stories.

In my experience with 4 different cars with pullies I have had no ill effects. Take it for what it's worth....you can expect to take about .2 secs off your 1/4 with em.

 

For those of us who are in their Z's for the long haul...

If Nissan Motorsports does not offer a pulley for sale then don't put one on yer Z. I trust Nismo engineers more than I trust any other after market engineers that do not have the R&D time and money and reputation-at-stake of Nissan.

Stick with Nismo parts but if you do choose other brands, don't tinker with things that not even Nismo will tinker with.

I love my Z and plan on keeping it for 7-10 years at least. I want to mod the car but I want it to last, too.

 

Actually, Nismo is using other company's parts and paying to put their name on it. BTW, no mods void your warranty, there is a law that states if there is a problem, the dealer has to prove the modification caused the problem before they can legally void your warranty.