Limits of stock 1nzfe found once and for all.

[pimp my yaris]

Originally Posted by TURBO YARIS

Was the shop you spoke to a machine shop? Or a performance shop?

There are numerous advantages to balancing a motor. Balancing goes hand-in-hand with performance engine building. Balancing reduces internal loads and vibrations that stress metal and may eventually lead to component failure. But is it worth the time and effort for mild performance applications, everyday passenger car engines or low-buck rebuilds?

From a technical point of view, every engine regardless of the application or its selling price can benefit from balancing. A smoother-running engine is also a more powerful engine. Less energy is wasted by the crank as it thrashes about in its bearings, which translates into a little more usable power at the flywheel. Reducing engine vibration also reduces stress on motor mounts and

Though all engines are balanced from the factory (some to a better degree than others), the original balance is lost when the pistons, connecting rods or crankshaft are replaced or interchanged with those from other engines. The factory balance job is based on the reciprocating weight of the OE pistons and rods. If any replacements or substitutions are made, there’s no guarantee the new parts will match the weights of the original parts closely enough to retain the original balance. Most aftermarket replacement parts are "balanced" to the average weight of the OEM parts, which may or may not be close enough to maintain a reasonable degree of balance inside the engine.

This was a very reputable machine shop in the Chicago burbs. He told me that quality after market rods and pistons will be balanced to within a tenth of a gram. I assembled my engine and it runs perfect. No vibration.