I really wish I didn't have to write this.

First of all, I want to thank Evo Joe and RRM. Anybody who goes out of their way to produce high quality products for the Ralliart has my utmost repsect. I'll be putting on my RRM rear sway next week so theres much love there.

I spoke to the owner of a reputable EVO performance shop yesterday (I wont I dentify him unless he wants to be identified) about installing one of Joe's pulleys. He told me that he was extremely against any underdrive pulley because they can damage your engine. They never use them on the EVOs. He said the performance gain is not worth a blown engine as he's seen them blow before because of aftermarket pulleys. Now, I'm not a gearhead but I'm not afraid to search, so I started looking around the net for articles on underdrive pulleys. After reading several articles, heres what I found.

Theres a harmonic dampener on there for a reason. Underdrive pulleys have been an age old hot rodder's trick. In the 70's for drag racing, they banned an old style pulley because it was dangerous when it broke. People actually got killed by it. So they mandated a solid pulley which we would call an underdrive pulley now. Techs started noticing that they were only getting about 10 runs before the crankshaft shattered. After that, the harmonic dampener was created, and they are now used as the standard.

Now I don't drive a 700 hp dragster, nor a 300 hp evo. I drive a 162 hp ralliart for crying out loud. So I searched around some more for a more relevant article.

A guy did a writeup about installing an underdrive pulley on a Prelude. Preludes are close to us in N/A power and 1/4 mile times so I thought it might be more relevant to our engine conditions. The guy was very excited about his new pulley. He put it on and instantly noticed gains and was very happy with his purchase. He did however do an update about a year later. When he started the mod he had 25K miles on his car. A year later, he had 45K miles, just 20K miles later. They took apart the engine to check for wear. The tech found that the bearings that rotate the crank shaft had a "hard life" and were heavily scratched and damaged.

So, here are my conclusions about the underdrive pulley. Its a terrific mod for the money and the HP and torque gains are real. However, long term use of a light weight pulley forces the drive shaft to take the brunt of all the engine vibrations and in turn, passes it on to the bearings. The result? Premature engine death.
As for how long until that happens, I don't know. I just know that it does wear the engine down alot quicker. I put a ton of miles on my car from my work day commute so at high speeds, I woudn't see the benefit of the pulley at high speeds and the way I put miles on, I would be just hurting the engine. Now, if I start to do autocross or drag racing, I might buy one and put it on for the summer and then take it off when I'm done. Luckily its an easy mod with good instructions and isn't very time consuming.

I made this post, not to be a naysayer or to hurt someone's sales, but to bring to light some of the information I've found and since nobody else has said boo about it, I thought I'd bring it to everyone's attention so that we can all make educated decisions on if it is worth it or not. Thanks for your time.


-shiroboi

 

interesting. I'd like to hear Joe's comment on this, but then again the modding business/hobby for a car is by the owner's own risk. obviously the stock car is made to last the longest etc, and i wouldn't expect modding a car would extent the life of the engine. I think i might take a look around and see what i can find for research for more of a selection of opinions. I too want to know the general consensus for the long term effects of the pulley, but i gotta say, though i haven't installed it yet, the product looks amazing and from what i hear it works amazing too.

 

No doubt, the results speak for itself and it looks like it is an extremely high quality product thats been machine balanced. I imagine that many pulley owners will have long lives of their engine but nobody knows for sure until it is long term tested and then inspected. I'm mainly trying to give everybody a heads up and maybe an early warning to heed before everyone goes gung-ho and adds a pulley to their ralliart and then we have massive site wide failure of engines in 3 years. Just wanted to point out that its not all positive gains and that yes, there is a price to pay for the extra speed.

 

Sorry for the double post but I refound a good link that I came across yesterday from a VR4 owner talking about underdrive pulleys.

http://www.3000gtvr4.com/pages/underdrivepully.html

 

isnt there a different between a lightened crank pulley, and an underdrive crank pulley?

people have been saying this forever, btw. why is it that there are no evos with underdriven crank pulleys. i know why.

 

I imagine that a lightened crank pulley would be like stock but probably drilled out for less rotational mass. This woudln't be so bad since its still technically a harmonic dampener. It does hurt at little having less rotational mass but I imagine any engine damage would be so minor as not to affect you at all. You wouldn't get the full benefit of an underdriven crank pulley though.

 

this has been debated on here many times (regarding evos tho, not ra's). The conclusion has been... dont use them on your evo.

 

Something to keep in mind - the UD pulley that RRM sells is balanced, on its own it contributes no additional vibration to the balanced crankshaft. Even in stock form, with the stock dampener, there are still vibrations going through the shaft. With a balanced UD pulley, I really don't see how the vibrations can be amplified to damaging levels.

 

Balanced just means that it doesn't add vibrations due to rotation which is fantastic but dosen't elimiate vibrations already coming from the engine like the stock pulley does. Damage is not caused by the pulley creating its own vibrations but rather the other way around.

So we know not to use them on your evo, but I'm not sure about the ralliart or how it works or what the function is of the stock pulley. I'd just like to get some discussion about it since there hasn't been any.

 

i dont see the problem until you eliminate the balance shafts....

 

I realize the arguement has valid points but I still think it will be 10s of thousands of miles before any kind of issue could arise. These same pulleys are used on v-8s where balancing is critical. I'm keeping it on our RA. I am not worried at all.

ROAD/RACE

 

OK. I have 103K miles on my 2003 EVO VIII. I'm putting down about 330(AWHP) I have been running an underdrive pulley since I was at about 30K miles. I have had ZERO issues and don't plan to remove the pulley anytime soon. You need to research balance shafts!
The only thing you have to worry about when using an underdrive pulley is overheating at idle due to the water pump not turning fast enough to keep the engine cool, and that is just in improper applications when the crank pulley is to small for the engine.
I am not an engine builder but my step-dad builds NASCAR Engines and they use underdrive pulleys too. I know that is a different application but he did tell me that as long as the engine stays cool at idle and the battery is charging properly you are good. (This is simplifing his statement as it was pretty technical for me)
I think it all comes down to using a quality pulley that was CAD designed for your engine application not just half-assed fabricated in some "race shop".
I have this pulley:

 

I went with the perrin lightened crank pulley instead of an underdrive pulley for those reasons. The perrin is just lighter but is the exact same size as the stock and uses the same stock belt. I hope i did the right thing. I'll let you guys know when it breaks.

 

I got one....no installed because I send it to anodize in good old black finish. I plan to use it only for Auto-X. But I found this info:

http://www.machv.com/tip11cranpul.html


to do...or not to do....

 

That was a great article ThyPunko, thanks for posting it. Redcloud, you're lucky. Unfortunately for me I drive 20-25K miles per year and I need to know i can get to 150K without having engine problems. I can't afford to sacrifice reliablility.