udp worth it or not

**02kyle** · 6-16-07, 20:59

well I was just looking for something new for the 6 and I saw some udp's for like 50 bucks online. is that a mod that is really worth it? I see they say 10-15 hp gain's? is this true from just a pully? I have to chance out my alt and alt belt so if I got to get a new belt might as well do the pully and everything all at once. any advice on this? I hear that they are a waste from some and great from others. I hear the same thing about the light flywheels. I am sure they are each good for a type of racing. this is for my dd car that does hit the track some. so more power is nice

so lets hear what you think! also wasnt there a udp deal that was on here from obx? or some company?

td435br · 6-30-07, 19:40

i have experienced charging system problems from these pulleys. those big horse power gains are from modified cars with all the usual bolt ons. usually you see 2-5 hp gain, some times none. the theory behind the pulleys is very sound. ive seen them work on some cars. and ive seen them screw up others. try it, its up to you. one thing i will say is that they do look nice

**skiingman** · 6-30-07, 22:04

I think you'll find a light flywheel will make a more noticeable difference. Definitely not 15hp gains on a typical KL from just this pulley.

Also, it might make your A/C and charging system work a bit more poorly at idle, which might annoy you or might not.

**Goatcrapp** · 7-1-07, 0:15

udp's are worthless

i didn't notice a single difference AND it removes the harmonic balancer... if you get some wierd resonant vibrations, they'd now be transferred directly to the crank.

**02kyle** · 7-1-07, 0:36

well as far as all the bolt on stuff I have that and I 75 wet kit and I am building my turbo kit as we speak. I just didnt know if it would be worth anything or just a waste of money

if I got some power gains I guess that would be nice but 80 bucks for 1 whp is retarded. that will get me more turbo stuff!

thanks for the advice

**skiingman** · 7-1-07, 0:54

If you use serious power mods I would encourage you not to use a UDP of any sort.

V6 (and other) engines produce large torsional vibration modes in the crankshaft. This gets worse as you add a lot of power and change the factory design. The OEM bonded rubber harmonic damper is important because it reduces the chances of those torsional excitations from becoming resonant as Steve mentioned. IOW, UDP plus power equals broken motor.

**02kyle** · 7-1-07, 1:13

ok then stay away from the udp since I am boosting then! gotcha!

thank god I didnt order that thing

lol

**Panther37** · 7-1-07, 6:46

This thread does not belong in the General Automotive forum.
Please read this thread (If You Are Posting About an MX-6, 626 or Probe...).

MOVED

I know there was a HUGE debate on this in the 1gen forums. I just bought a LIGHTENED pulley that is not under drive. It weighs less at the crank but does the same thing as the original so that should be a few extra HP.

**skiingman** · 7-1-07, 6:56

Quote:

Originally Posted by Panther37

I know there was a HUGE debate on this in the 1gen forums. I just bought a LIGHTENED pulley that is not under drive. It weighs less at the crank but does the same thing as the original so that should be a few extra HP.

Given that the original is a tuned mass damper, I highly doubt that a "lightened" version does the same thing as the original.

Did the people you bought it from have the engineering expertise to back up that claim?

**Panther37** · 7-1-07, 10:49

You can find why I needed a new accessory belt pulley here.
The OEM part is $350. The light weight pulley I bought off of ECS tuning was only $150. I like to save $200 when I can.

**chris_y2k_r1** · 7-3-07, 15:29

I love these cats that run an UDP and heavily amped sound systems.

Under those conditions you could actually loose power. Why you ask...?

The alternator begins to work extremely hard to try and charge the battery due to the heavy load that amplifiers put on the charging system that it actually acts like a brake against the motor. Aside from that, the additional charging demand will either smoke the alternator's bearings or the internal voltage regulator/rectifier.

If you have a sound system or any other type of heavy electrical demand installed on your car - an underdrive pulley is definitely not a good idea. Essentially, you can't get something from nothing. It's that simple. The factory wants to post high horse numbers at the wheel too - it sells more cars. You can bet the factory chose that (the OEM) pulley size for a damn good reason.

**jarnold** · 7-5-07, 10:24

From one who has had both an Unorthodox and a eBay underdrive pulley. 3 LS's and 3 with Underdrive pulleys. Total of 203000 miles running them.
First of all your stock pulley is not a Harmonic Balancer. It is Vibration Dampner. Harmonic Balancers are used on non-internally balanced engines. Vibration Dampners are used to smooth out accessory vibration and used on internally balanced engines like ours. Not using a Dampner will not destroy your engine. I put a UDP brand on a 94 LS at 40000 and that car now has 194000 and still runs well for the kid who I sold it too. He routinely runs the crap out of it turning 7000rpm as he tells me. So this may tell you not to worry.

UDP versus OBX eBay unit. UDP is a lighter and better machined piece. the OBX weighs maybe 1 lb. versus the UDP at like nothing. Weight plays a big part in their performance. Sport compact did a Probe build a few years ago and the UDP pulley put about 4-5 hp to the wheels and with drive line loss of about 15% that is close to what they say of 1 hp per pound of weight loss. I think they say like 7hp at the flywheel? My UDP cost me 179.00 at the time. Compare that to a cat back at 400.00 + that guys pay for and net less.
This is a noticeable gain in seat of the pants power at the midrange mostly. I think the Automatic guys are probably the ones who don't feel a power difference. This or the UDP works better. I put the eBay pulley on my KLZE when I swapped the motor so I can't give you an idea if it works. I can tell you that the KLZE runs very good. Revs like hell. Out runs S2000 Hondas too.

Charging is not a problem unless you have a weak alternator. I replaced alternators on all these cars at about 100000 miles which is most likely pretty good? By the way change yours out if it getting close to this. You get a little less juice with them at idle and can effect the air con but not a ton. If all your accessories are working good you should not worry. I ran 2 small amps (125's) and had no problems. Weh you race it just turn off the radio. Capacitors help though. Besides i truly believe people go over board there as well. If you are a performance guy that is just excessive weight any way. Wait till you are 50 like me and start getting the effects of loud everything.

**02kyle** · 7-6-07, 21:24

wow and here are more different thoughts

and I have way more electronic stuff in my car than anyone would ever need really. I have a few tv's soon to have a few more. lots of light, subs amps blah blah blah. I am going to get a strong amp and a yellow top maybe even 2 yellow tops

I mean for the power gain ehhhhh money not that well spend I dont think. I mean with my spray that is good bang for the buck and when I get my turbo on then I will be happy. but I just wanted to see if this is a good deal with power and money spent. I really dont want to run the risk of messing my car up. and from the sounds of it there is? I dono? everyone has there thoughts I was hopen someone knew that it was good or bad and can back it with some real proof..

**ZygonsPGT** · 7-6-07, 23:58

There is a before and after dyno on PT if I remember correctly. The difference at the wheels was basically nothing. But you never know what condition his alternator was in or how much load it was operating under, same with the other accessories. Thats as much proof that I have seen for the KL, so thats really all I can go by other than peoples theories.

SupaDoopa · 7-7-07, 14:16

I'd trust the guys that have had most experience with these things. If he's done it on multiple cars versus people working on a single car, I'd rather go with his opinion. It's not just a luck install but a proven fact.