dont do it

 

not good for these cars bud, i wouldn't do it...

 

unless u need a excuse to buy a new motor

 

wow, i didn't expect what I'm reading. if i may ask the dumb Q of why(?), please let me know everything you guys know. thanks.

 

Forget that mod. Stick with your stock pulley. It is the best one for the car.

 

as somebody tells me, my crank turns my pulley which in turn is connected to my oil pump via the belt, and w/ the underdrive pully, i would not have enough oil provided to my engine and turbo. is that the concern? if so, doesn't it make sense that due to the smaller diameter of the underdrive pulley that i would be getting more rotations per engine rpm?

 

Just do a search for what happens if the underdrive pulley fails?I can't remember why but I know not too put one on.The underdrive pulley fails in some way and boom your motors toast.For the little performance gain its not worth it.Try too find one experienced member on the forums that has an underdrive pulley.You won't find one.Maybe if your lucky one.Someone who knows exactly why and what happens with the UD pulley will chime in soon.:thumbsup:

 

What's all this talk about the UDP causing problems... LOL.

I've had mine on since the same DAY I baught my car new in Oct. 2003. My car has over 65K miles on it already and not one problem caused by this mod. The many different dealerships that I've been to for service have never mentioned anything bad about me having it installed. They didn't even relate the UDP to any of the problems my car has had....(mostly transmission related other than a bad valve cover gasket).

I actually had my MPx UDP installed on my previous 2001 Neon R/T, and removed it so I could install it on my 2004 SRT-4. All I had to get was a new set of belts and my install went perfect. As long as you follow the instructions perfectly, you will not have any problems. My turbo/engine still gets plenty of oil.

As for my opinion on performance gain... I actually couldn't tell you since I really don't know how the car drove before I installed it. With the R/T the UDP helped alot with power going up hill with the A/C on. It seemed to have a slight performance increase. On the SRT-4, I'd say the performance increase does not justify the cost/time/effort to install the part.

 

as i'm reading other threads, a solution that somebody else has come up w/ was detonation causing the fuel pump to fail. any feedback is appreciated.

 

everybody must be tired of this thread... i still appreciate any feedback.

 

Hey we found someone with one.If the pulley is high quality and most important installed correctly then yes they are ok but like FYX193 said also its not worth the hassle and time for hardly any performance gain.Just my 2 cents.

 

thanks. i'll take your 2 cents.

 

I have that pulley installed on my 05. Havent had any problems yet, but Im starting to wonder if I should take it off based on what everyone is saying. I didnt notice any real performance gains that were worth the money/time either.

 

You will eventually sieze up the small gear type positive displacement gears inside the oil pump assembly from spinning they way faster then they are suposed to spin. Look in the Darrell Cox Racing thread and the products they offer. Don't waste your time with the product. When i was at DCR I saw 2 failed oil pumps. I held them, looked at them and tottaly see why it happened.

 

I had the MPx Underdrive pulley on my car for around 40,000+ miles on it...

I didnt feel any/if minimal power gain from it...all i can say is that the car doesnt drag as much with the a/c on as it did without it...

I would of spent my money on some shiney stickers instead now that i look at it....but no problems here, motor wise

:hi:


My car was 05' btw...

 

My guess is that the UDP weeds out the weaker factory oil pumps because some people have gone 40K+ miles on the UDP without issues.

What are the symptoms of a bad oil pump, just in case I've never noticed it.

 

The real reason for failure

I believe the reason the oil pump could fail would only be due to vibration since you are removing the Harmonic Balancer to replace it with a pulley that does nothing to control vibration.

The main purpose of an Underdrive Pulley is to change gears so to speak slowing down the accessories by changing the size of the drive pulley and taking some load off the crank. It's like shifting gears on a bicycle. It gets easier to pedal, but you are turning the tires slower.

 

I see SOOO much wrong in this thread I want to do a double face palm.

one, the oil pump is run by the crankshaft, it is behind the cam gear inside that housing bolted onto the front of the motor a UDP will NOT cause the gear to "spin faster" then they would with a regular engine with a regular puller revving up through the RPM range. and the harmonic vibrations FYI are controlled by the BALANCE SHAFT ASSEMBLY which is run by a CHAIN hooked to the crankshaft. cutting this chain and removing this assembly CAN cause vibration based damage, but is not likely. it can also cause the engine to spin faster causing a cavitation of the oil problem in the oil pump, but again, not likely as many have done this mod with the only issue being the faster rev up causes the rod bolts to stretch.

TWO the crankshaft pulley factory IS NOT A BALANCER OF ANY SORT which is exactly why it is NOT KEYED to go on only a certain way.

it DOES however have a rubber insulator to reduce vibrations from other components transferred through the belts. so if the UDP has a rubber insulator then it shouldn't be a problem.

Edit: just noticed oldness of thread that was bumped and then re-bumped by me, I apologize.

 

You are correct. I just noticed that our pulley is not balanced. I knew we had a balancer below but I didn't realize it was a replacement for the harmonic balancer. Thanks for the correction.

Now based on this new information, I see no reason an under drive pulley could damage our engine.

Funny, because I was doing a face palm when I read the misinformation above. (Underdrive pulley driving the oil pump via the timing belt slowing down the oil pump... lol) I just assumed it had a harmonic balancer like most other cars. I figured I would lead some of these people in the right direction. My mistake.

I am glad because I can save some money getting one of these now without worry. I was going to get the ATI, and still might, but I can run one of the MPx under drive pulleys for now and put my money on some fuel system upgrades.

 

On a somewhat related side note. I switched over to an ATI Fluid Damper when building my new engine, which is the only other pulley I'd recommend beyond the stock pulley.

I've never been a big fan of underdriving the accessories via a UDP (despite having run one on my Avenger for nearly 60k without issue), but one thing that can be beneficial would be if there was a stock sized, lighter weight pulley available. This would reduce rotating mass and in theory free up some horsepower.

On my Avenger/Sebring forum, we had a guy make some of these for the v6 and 420a cars. They were very nice, but in the end unfeasible to produce due to low demand. I believe they sold for $125 shipped and the guy had to produce 10 of each in order to sell them at that price. They were balanced pretty well and seemed to perform - and kept everything spinning just like stock.

I am a bit surprised that we don't see more light weight stock sized pulleys on the market, but it could be that it is cost prohibitive to do so.