Originally Posted by GTREVO View Post
I have been an early user of underdrive pulleys for many years now but only learnt about the detrimental effects of harmonics in the 4G63 engine not too long ago.
Try replacing bearings every single race like I do and you will know that the problem lies more than just tolerances and balancing. Have been building 2.0 on the DSM's for years now and the inherent bearing problems but thank god I nitrided my cranks ( thus am able to save cranks even with worn out mains) and 2.3 strokers in my Evo 6 which kills absolutely every single mains running only 6 to 7 passes on a single event. And both makes over 700WHP. Both have not run harmonic balancers and without balance shafts. And yes, the engine DOES make a little more vibration without the balance shafts. Funny thing is that while the main bearings are worn out badly, the conrod bearings remain perfect, almost untouched....
Have recently completed a race on the stroker and will remove the main bearings shortly to compare previously on which I have ran no dampener and this time with the dampener. This will at least confirm some how on the effects of the dampener.
Am only relating my experiences with the harmonics that are killing the engine and I don't think Mitsubishi would be putting one on if it didn't need one...
If I recall in one of many early forums some long time ago, even Bushur runs the stock dampener and doesn't use pulleys....
Read more at
Lightweight crank pulleys? - evolutionm.net