Here's the deal: I want to get a bit more power from the engine without making the car any louder. I have a K&N panel filter and my timing advanced and was wondering if I would notice a difference if I got a UDP for my 03 auto. If there is a notable difference, do you think that it is worth the money? Thanks guys.

 

i hear its worth the money it frees up a couple horsepower

 

yea, its pretty inexpensive and gives you a few hp and every little hp you can squeeze out is worth the money

 

what does the udp do and how does the udp work?

 

It spins ...

 

I slows the speed of the accessories thereby reducing engine load. The extra power saved goes to the tires.

...oh ya, it spins too!

 

http://www.greghome.com/Greg%27s%20G...xSE/2K2UDP.htm

Smaller pulley, revs higher, weighs less, etc.

 

Theoretically.

fixed ..

 

Right, my bad.

 

I say save your money...the gains are minimal at best....FYI the two current fastest auto 5th gens (Jime and myself) do not have an aftermarket UDP. When I had one installed my times in the 1/4 mile were identical to without it.

 

I was not going to get a UDP but I got in on the group deal for 70 buck awhile back. I am getting it installed tomorrow. I have an auto with a Berk intake. I will get back with you and let you know the differents. (butt differents)

 

I doubt you'll see much gains with an auto.... I think they really only help if you've a manual and have a lightened flywheel, since I'd think that whatever ya gain at the crank from the UDP will still be lost at the flywheel anyways. But then again, I've no proof of this either...

 

Btw, look at the dyno posted in this thread:

http://forums.maxima.org/showthread.php?t=406402

The numbers look pretty stock (low) considering he has a UDP and intake on his car, which is a 6 speed. There could be other issues at hand of course, so if you're interested, you can follow up with him to see what's up.

 

I saw that but I was wondering if the autos benefited from this as well. Looks like it is probably not worth the time and effort of installing it. Oh well.

 

I noticed a bit of torque difference after I put in my UDP. Shows up as more torque steer. Not a major gain but a gain. I measure the gain from my CAI and UDP by the .21 drop in my 1/4 ET.

 

This website has some information on the UDP: http://www.motorvate.ca/mvp.php/521

 

heh, speaking of this, i'm finally going to throw the unorthodox udp i snagged on the for sale forums here on tommorow.


Lets see if i notice anything : ]

 

I Noticed It Right Away Engine Revs Much Faster 9hp 11lbs Torque According To U/r Dyno I Have 6speed

 

Is it correct that the UDP doesn't do anything for a 4th Gen Maxima? If, so I don't know why the guy in the dyno installed one on his 99.

 

The UDP will not do anything once the car is in gear. Just because it revs faster in neutral doesn't mean that the car will accelerate any faster. In neutral (where only the engine, flywheel, and accessories are being accelerated) an UDP offers a significant reduction in rotational inertia. But when the car is in gear (where the engine, flywheel, accessories, transmission, rotors, and wheels are being accelerated) the UDP makes little to no difference. Don't confuse the two and save your money.

edit: To clarify, in theory the UDP reduces some inertia in the driveline. But for practical purposes, the gains are negligible.

 

it helps with the lag from the AC in the summertime I found as well - not a big deal, but I found the car accelerated more normally when using the AC.

 

Does anyone see the irony here?


Smaller pulleys only show gains in s/cd vehicles

 

A guy is entitled to a typo now and again.

 

I know, I have more than my share of fukc ups .. just paranoid and was happy to see I'm not alone ...

 

NmexMAX = Typo Police

 

Shush!!!! LOL

You got the point...hehehehe...

 

Just got mine install. The only gain I see is that it does rev faster.

 

all i took into account was the weight and size of the stock crankshaft pulley when i got my unorthodox udp. i have dynoed my car but it was not a baseline then udp pulley so i do have not have back to back info. as far as what i felt, i noticed i had less low end hesistation with my auto. not saying it changed the transmission, i am stating which tranny i have and describing the typical hesitation occuring in most automatic trannys. after i bypassed the ac compressor and used a 4 rib belt, i felt more of the same positive feeling as when i had the udp originally put on.

 

I had the same problem with my auto. The low end hesistation is not there with the udp. I guess that is why I say it revs faster.

 

i noticed no difference with udp on my maxima. however with my 05 3.5 alti i noticed big gains. It could be that i added the 350z wheels like the same week too. which are heavier and offset the power increase.

 

smaller and less mass. Requires less torque to spin, wastes less power powering your accessories and leaves more power available to the wheels? What is so hard to understand?


Some guys notice it, some guys don't... Yet without a doubt it does offer gains, how much is arguable.
edit in:

I already have a JWT flywheel installed, didn't get the pulley on yet (waiting to get the impact wrench and a lift next weekend) yet i'll post my impressions on how they react together.

 

Nobody here isn't understanding the theory. That's not the point. Actual gains > theoretical gains. Cross-drilled rotors have less mass than blank rotors. They should help a car be quicker in the 1/4 mile too right??

 

I have dynoed before and after....there was no significant difference (.1hp/tq). These things dont add any power...they simply reduce inertia. Basically, only those who race their vehicles (more specifically situations with alot of revving up and down, aka road racing) will notice the difference. Otherwise, save your time and money.

 

this isn't a theory man... That's the confusion.

Proof isn't in quarter mile times.

Here is a theory: Not everyone knows how to drive the perfect time, is it possible?

(sarcasm off)

Since when is quarter mile times the reference standard of performance? According to you maybe... Even so, it does improve acceleration.

Oh and, rotational mass (momment of inertia) is not the same thing as regular mass, you clearly didn't understand my comment. It will help with revving which is what i want, that's why i went and got a lightened flywheel : ].

 

How else could you quantify an increase in acceleration other than the 1/4 mile? I'm not necessarily talking about 1/4 mile times as much as trap speeds. No increase in trap speeds = no appreciable increase in power. Period.
The lightened flywheel helps acceleration because it's so wide. Mass staying constant, the wider the diameter of a rotating object the more inertia it has. Which means the wider the diameter of that object the more of an effect lightening it will have. This is why lightened flywheels do so much and UDP's do so little.

And i do understand that rotational mass is not the same as static mass. That's why i used the rotors as an example.

 

"How else could you quantify an increase in acceleration other than the 1/4 mile? I'm not necessarily talking about 1/4 mile times as much as trap speeds. No increase in trap speeds = no appreciable increase in power. Period."


We aren't really arguing the same point. I'm talking performance man, trying to race on a track that isn't straight etc, not everyone is interested in time slips man. I won't argue if we aren't even talking about the same thing.


"The lightened flywheel helps acceleration because it's so wide. Mass staying constant, the wider the diameter of a rotating object the more inertia it has. Which means the wider the diameter of that object the more of an effect lightening it will have. This is why lightened flywheels do so much and UDP's do so little."


What are you talking about? The flywheels are absolutely the same diamater.
Now your talking about acceleration (which was what i was talking about from the get-go). lowering the mass of the flywheel makes it easier to spin, at the same diamater, is that what you are saying?


I have not compared what does more then the other in a quarter mile... I'm not really interested in that anyways. Your trying to say the UDP does nothing because you can't see the difference in the quarter mille... The flywheel wasn't intended as a power mod, and though it might improve power since less work is needed to spin the thing, it changes the characteristic of how the car drives drives.

Anyways the rotor example still doesn't make sense, and they slot and cross drill them to improve heat dissipation, not really to make them lighter.

 

MJG: The UDP advantages are indeed for road racing, and road racing only. However, it only serves to make it easier to match revs properly. Thats it, no power gains, just ease of rev matching. Anyone who tells you they are feeling better acceleration probably has an engine that is making so little power/torque that the weight reduction does matter.