Perhaps this has been covered, but why doesn't Vishnu offer a pulley similar to the WRX one for the evo?

 

two words : "harmonic balance"

 

Pretty much sums it up. I'm not going to say they will damage the evo engine, but the jury is still out, imho, about the long term consequences. They will, however, be worth 10-15whp which is pretty significant and can be a worthwhile risk for some individuals who have reached the limit of their stock turbo and need more power with a lot of extra expense.

Shiv

 

Im sorry for this, but I must know. What is a pulley in terms of an engine? Ive heard it thrown around but never understood it.

 

IMO..with the balance shaft in the 4g motor, an underdrive pulley is'nt going to hurt anything. I know everyone has their own opinions about it, just like with the WRX a few years back, but I think it would be pretty safe.

 

So basically a case of what is good for the Subaru isn't good for the Mitsubishi?

 

BTW that is the generic excuse posted on every forum about every car on this topic.

 

Sounds like you're not happy with the answer. If so, then why bother asking?

FWIW, it's not a harmonic balancer, it's a torsional balancer. Our engines are decent when it comes to harmonics, due to the balance shafts and factory balancing. A torsional balancer helps absorb crank wind-up stress.

 

Good point mhgsx. I pulled up this article about dampers that I thought was interesting. http://www.vibratechtvd.com/the_facts.htm#

And if that doesn't hurt your head, they give the following reference at the bottom for more in depth information.

"a good technical paper to read from the Society of Automotive Engineers is "A Practical Treatise on Engine Crankshaft Torsional Vibration Control" by Robert C. Bremer Jr. (SAE Paper SP-445, June 1979)."

 

so the real question would be, if I installed a pulley (let's say the UR pulley), is there a way to occasionally take a look at the engine to see if it is causing harm (ie. look at the crank, etc)?

also...

Shiv, did you guys ever determine what happened to the Thunderhill 25hr race car?

l8r)

 

Actually, this is the link that you want to get a clear idea of torsional vibration:

http://www.vibratechtvd.com/torsional_vibration.htm

- Rob

 

if it's worth anything i have an UR crank pulley on one of my TSI's and haven't had any problems. i also still have my balance shafts in.

 

I havea full set and intend on putting in the accesory and power steering pulley.. but i think i leave the crank pulley as is. The Harmonic dampener theory is only partial true since there would really only be harmonics at a certain rpm/frequency.

 

if you guys want a pulley, get the perrin. It is harmonically balanced and is not underdrive.

 

what tune did they play while they balanced it ?