so i did the money shift (from 3rd to 2nd) and revved my engine up to about 9k rpms. i bent some valves, which have already been fixed/replaced. but now something else has been brought to my attention. i removed my balance shafts 15k miles ago (150k miles total on the engine), and my buddy thinks that it could have caused damage to the bottom end since its not weight balanced anymore. so, does anyone know or have any educated insight if there is truth to this theory? TIA.

 

Balance-shafts are only there two eliminate second-order vibrations inherent to 4cyl engines. It's a premium feature that the H motors have them, to reduce nvh.

At 9k+ more, I'd worry about spinning a rod bearing. Not entirely sure what the physical rev limits are of the H22 bottom end. An H23 bottom end would be toast if it saw 9k.

 

I don't know about the h23 part vig....john's engine is 95mm

Then again, a stock h23 bottom end would definitely be toast.

 

I'm sure it's fine unless there is evidence such as noise or something coming from the bottom end.