So I've read a little here and there about the whole pulley debate. I'm looking at the AMS lightweight pulley set. It's saying they're balanced but how much compared to stock? I would like to hear some opinions on if it would be worth buying the kit of 3 pulleys for $225 plus s/h. Any comments, knowledge, or opinions would be greatly appreciated.

 

even if it is balanced I doubt you'll gain any real HP

 

With lighter rotating mass you will rev much faster and will also free up a few extra HP of parasitic loss.

I have been running the UR lightweight stock sized pulley for about 50K miles now. Its great.

 

So if I wouldn't see or feel any gain, which I have my doubts that the gains would be noticeable. If the engine rev's faster is it possible to see a tiny bit better drag time??? Also, later on down the road I plan on going FI. Would the pulleys have a bigger effect on the engine then? Sorry for all the questions, I just want to make sure I'm not going to waste some money on something that won't benefit my G now or later.

 

So I ended up buying the pulleys form Z1. With the FB black Friday discount I saved like 27 and some change so I figured why not. Should be here beginning of next week and depending on the weather I'll install them shortly after. I will post something about my first thoughts after they are on.

 

you have any dyno results confirming your claim? I have yet to see any dyno showing an increase in HP

 

No I don't have dyne to back the claim....others have though. It's physics. Weight reduction in rotating mass = saving power that was lost previously as parasitic loss. I'm not claiming that it's drastic but only that it's there.

I think it's worthwhile...you may not. But if you haven't done it and don't understand it research it some more.

Stock pulley weighed like 9 or 10 lbs, the UR pulley was like 2

 

^ incorrect my friend

1) feel free to show me anyone's dyno charts showing an increase in HP
2) Once an object is rotating it takes less energy to keep it in motion so any parasitic loss you're referring to is marginal
3) if you're going to get an ultra light pulley at least get one that's dampened and don't get the UR pulley

I'm hoping you can show me any dyno chart disproving me. I have researched this topic in the past so im just relying on my past research which has failed to show any actual improvement in HP. I hope you're right, I'll be the first to by a set if you are

 

The main reason I bought the one's I did is because they're supposed to be balanced and the thought of a somewhat "faster" revving engine is good. If I can get though gears faster than that's a plus for me. If I just gain a little better throttle response, that's also fine with me. I just figured I'd try it for myself just to see. Trial and error is how you learn what not to do in the future. When it comes to parasitic drag I think of a tranny and a lightweight flywheel. There is a big difference between a transmission and accessory pulleys though as the tranny is what puts the power to the wheels. With that being said, I dont expect any gains in hp or tq. I'm just hopping for even better throttle response than what I already have.

 

A waste of time and money, zero measurable gains have ever been proven? You just spent $300 so you will tell yourself it revs faster but it dosent not enough to notice not enough for a dyno to see. Stock pulleys are harmonically dampened as are high end pulleys for the G. The light weight ones are not so it will not prevent engine harmonics from damaging your crank! I have never heard of anyone that had a crank failure due to these pulleys but I have also never seen any prove an advantage to them either aside from astecics.

 

The shiney ones sure are purrdyyy tho

 

Ok, let me start off by saying thanks for all your input and opinions on this subject. I decided to do a little more research on the subject and came across this.
http://www.the370z.com/engine-drivet...no-charts.html
Now these are somewhat underdrive and lightweight pulley sets for the 370z. Yes, I know their is a difference in the engines but everyone is saying there are no results...here they are and there is some info in the reading at the end. I found it somewhat interesting. My pulley set is not underdrive and I would rather it not be but here is some proof in dyno results that some pulleys do in fact do "something". I did not post this to prove anyone wrong. I posted this as an informative purpose.

 

Underdrive pulleys are totally different than what you are talking about, thats like one person saying a Kinetix intake makes no horse power and posting dyno graphs of a Motordyne intake spacer... not the same.

Underdrive pulleys have a smaller crank pulley and larger accessory pulleys causing the accessories to spin slower therefor reducing the parasitic drag the down side is your alternator may not spin fast enough to charge your battery so your battery can go dead once a week, power steering takes more effort to turn, the water pump spins slower reducing cooling capabilities ect ect. I have run underdrive pulleys before a royal PITA.

Another note that is not an independent dyno it is the manufacture/company selling them dynos they often manipulate the dyno to make things appear better than they are, so if you really want a dyno to put faith in look for an independent dyno buy someone that actually bought them....not someone trying to sell them to you. There are no ambient temps no intake temperatures all things that can manipulate dynos 2-5whp easily hell dynos can very 5whp from one run to the next due to the engine temp ect usually you want to see at least 3 pulls with and with out the mod or at least an average. they could have take the lowest number with out the pulley and the highest number with the pulley that could very easily be a 5whp difference alone. One of my close friends owns a tuning shop and I see it all of the time on 3 base line pulls in is ordinary to have 5whp changes from the 1st to the 3rd pull.

Not to mention 5whp is not even close to noticeable I would invest a uprev dyno tune before I dropped $250+ $200 install on something the people selling the product can only make 5hp on the dyno with.

 

Incorrect, on a VQ35 the water pump is driven by the timing chain. Coolant flow is in no way affected by underdrive pulleys. However I have experienced the sluggish power steering when I was running UD pulleys, but after a tune and +200rpm idle bump it went away.

I agree, I highly doubt a pulley makes power on a dyno, but I can say my car felt a little more responsive from a dig. I may try to do some testing when I get a chance and finish up the plenum testing to confirm this.

-Rob

 

Yes that is right our water pump is spun by the timing chain not the belts. Alternator, powersteering and AC are the only accessories our belts spin.