balancer shaft elimination????
balancer shaft elimination????
has anybody done a balancer shaft elimination yet on an evo? i know it was pretty popular on the eclipses, but not sure about the evo.
currently building a motor for my MR and wanting to get rid of the balancer shafts if it is a good idea.
currently building a motor for my MR and wanting to get rid of the balancer shafts if it is a good idea.
I'm building an engine that eliminates it, but I haven't run it yet.. Unless you plan on tearing down the motor, don't bother removing them, I doubt the gains are worth the effort.
(Sorry it was a generic reply, since your building an engine, you won't miss 'em)
(Sorry it was a generic reply, since your building an engine, you won't miss 'em)
if you have the motor out of the car, for rebuild or not... remove them. Your hp gains are negligable, even though you're pulling 12 lbs of rotating weight off the motor...
the real gains are in reliability. no worrying about a balance shaft belt taking out the timing belt, and even more importantly, a big increase in oil pressure. People haven't put enough miles on thier evo's yet to appreciate these benefits.
don't try an take them out with the motor still in the car... not that it can't/hasn't been done... but even those people curse that day and reccommend doing it with the motor pulled.
the real gains are in reliability. no worrying about a balance shaft belt taking out the timing belt, and even more importantly, a big increase in oil pressure. People haven't put enough miles on thier evo's yet to appreciate these benefits.
don't try an take them out with the motor still in the car... not that it can't/hasn't been done... but even those people curse that day and reccommend doing it with the motor pulled.
Evolving Member
Joined: Jun 2003
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For much higher than stock redlines, the balance shafts can possibly seize and/or their belts can be thrown or bunched up causing the timing belt to skip = big problems. If that wasn't bad enough, the "front" (right) balance shaft pulley also drives the oil pump and can cause an oil starvation issue if that one seizes.
I don't remember the exact ratio, but I think the balance shafts spin somewhere along the lines of 2x per crank rev, so those things are movin' at 9000 RPM. Removing them also removes rotational mass. As mentioned, HP gains will be negligible...improved throttle response might be the larger benefit. You will notice little, if any, more vibration with them out and if your rotating assembly is zero-balanced, you won't miss them at all in that department.
In DSMs, pretty much if you want to rev 8000 RPM+, the balance shafts should be removed for engine safety, but I have seen them (or at least their belts) fail at RPM lower than that.
I am not sure I am a real big fan of the short-shaft eliminators since you remove a lot of the stability gained with a long shaft and 2 bearing locations spread far apart. I suppose oil pump failures from it aren't widespread or even common, but the only thing holding the load with the short shaft is the single journal right next to the oil pump gear. When I pulled the shafts out of my 2G, instead of replacing the oil pump side balance shaft with the usual short Mirage shaft, I had the counter weight machined off the stocker and reinstalled the entire shaft to maintain the 2 holding points. It still weighs a pound or 2, but it's much easier for the engine to turn without the counterweight and offers more stability to the oil pump gearing.
On a caveat, I rarely ran it >8000RPM, but had 0 problems nonetheless...and I slept better at night
I don't remember the exact ratio, but I think the balance shafts spin somewhere along the lines of 2x per crank rev, so those things are movin' at 9000 RPM. Removing them also removes rotational mass. As mentioned, HP gains will be negligible...improved throttle response might be the larger benefit. You will notice little, if any, more vibration with them out and if your rotating assembly is zero-balanced, you won't miss them at all in that department.
In DSMs, pretty much if you want to rev 8000 RPM+, the balance shafts should be removed for engine safety, but I have seen them (or at least their belts) fail at RPM lower than that.
I am not sure I am a real big fan of the short-shaft eliminators since you remove a lot of the stability gained with a long shaft and 2 bearing locations spread far apart. I suppose oil pump failures from it aren't widespread or even common, but the only thing holding the load with the short shaft is the single journal right next to the oil pump gear. When I pulled the shafts out of my 2G, instead of replacing the oil pump side balance shaft with the usual short Mirage shaft, I had the counter weight machined off the stocker and reinstalled the entire shaft to maintain the 2 holding points. It still weighs a pound or 2, but it's much easier for the engine to turn without the counterweight and offers more stability to the oil pump gearing.
On a caveat, I rarely ran it >8000RPM, but had 0 problems nonetheless...and I slept better at night
Last edited by BlackEVO; Nov 23, 2004 at 04:09 PM.
i ended up getting one from AMS in chicago
the only parts i need now are to decide on pistons and rods, gaskets, intake manifold TB and injectors,
after that the motor is done, just need an AEM and probably the AMS turbo kit.
the only parts i need now are to decide on pistons and rods, gaskets, intake manifold TB and injectors,
after that the motor is done, just need an AEM and probably the AMS turbo kit.