Under Drive Pulleys...?
 

I have read through a few threads here and I can't see a clear yes or no as to whether these things are ok to run. I don't have a huge system, and the car is stock. Just wanting to free up as many horses as possible. What are the negatives to running a UDP?

Bump...

I too am having trouble deciding on whether I'll be getting pulleys or not. It seems like they aren't very detrimental to the accessories, but I also haven't seen too many (if any?) dyno results posted along with each set of pulleys these companies are putting out. I'd like to see some hard data and hear people chime in who have them installed.

Yeah I wanna stay N/A and would like to get as much power as possible. So if these help without hurting anything I will be all over it.

I have a friend who is running the NST ones in his 350Z and convinced me to buy them after feeling gains throught the powerband with his butt dyno. Said it was night and day. Im just waiting for NST to get some in stock, then Ill try to get a before and after dyno.

As far as safeness, the NST thread explains that they have never had any issues with pullies getting welded to the crank and never had problems with harmonic balance issues.

Ok now we are getting somewhere! Any extra info?

Yep, NST :excited:... We have been waiting for a month now:happydance:.. Can't wait to get them on:driving:.

I looked at Stillen, also some pulleys on ebay Unorthodox Racing Crank Pulley Nissan 350z 370z GTR G37 | eBay GlockWorks put one on his car http://www.the370z.com/parts-sale-pr...nk-pulley.html

Stillen and NST R&D is top notch. I went with NST because they sell kits for a butt load of cars, they have long history in racing. :stirthepot:

I've read the threads here and researched at each vendor's site and at other links found on google. I have friends that have gone this way on other cars, e.g. dodge charger. I can't because I am in a lease.

When I buy out the lease I will definately buy as many of the lightweight pulleys as there are. Unorthodox has the crank, idler, and alternator pulleys for the 370z. NST has crank and alternator pulleys.

Unorthodox claims about 10-12 WHP gain for the underdrive crank pulley alone, with 15% of that being contributed to the 20% underdrive. So the OEM size lightweight crank pulley would be 8-10 vs. 10-12 WHP. They also claim another 1-2 WHP for each of the other pulleys, idler and alternator.

Did they have anything to back that up Kcquinn?

NST Pulleys are awesome. Better throttle response, gas mileage, rev matching is faster, it makes power ALL the way through the rev range, and it's inexpensive. It's one of my favorite mods. It's worth a good 7-10 whp everywhere. Pair it with a light flywheel and that's a slice of heaven.

BTW, no issues what so ever and that's with about 8k miles on them. The last couple pages of the NST pulley thread, I have A LOT of info on my experience with them.

I've had NST Pulleys on for over a year 10k+ mi, and have had zero problems.

Dyno feel doesn't really change, but I do notice the fact that the engine revs much faster and smoother... Like there's 'less' of a strain to do so. Granted changes are minute and can be attributed to seeing what you want to see, but it's noticeable to me.

The primary concern comes down to how they're installed. If they are installed correctly by a competent technician, then you'll be fine. If not, then you'll have problems. So trust your mechanic or don't get them.

I've seen dyno comparisons. I just can't locate them right now. Those were for NST pulleys. I can't access the unorthodox racing site for some reason. You have to google and find retailers that carry their products. There is an NST thread here that I believe has dyno charts.

For the accessory pulleys I've not seen any dynos, and who would expect a dyno to show a 1-2 WHP gain anyway? Maybe if all of them were changed you could see the difference.

I did a before after dyno on the NST. Gained 7-10 hp.

Here is the dyno results after the install

http://www.the370z.com/attachments/e...arts-dyno1.jpg

Was this the two pulley set with under drive crank pulley?