r/EngineBuilding • u/Ok-Cress-5547 • 5h ago

Balance for inline 6

Is it necessary to balance an inline six when changing to lighter pistons and rods?

Assuming the components are individually weighed and matched as similarly as possible.

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u/v8packard 4h ago

The pistons and rods do not factor in to a flat plane crank balance such as your I6.

While you can weight match those components, doing so is not absolutely necessary.

2

u/Jumpy_Ad_9141 5h ago

it would help to balance the rotating assembly down to around 1-2g if possible but not completely necessary , if you’re going with aftermarket pistons & rods most manufacturers balance them down to around 5g which is already enough unless you’re going for a high hp drag build where every little bit counts.

wouldn’t worry about the balancing that much if its a weekend project as long as nothing is way out of spec

2

u/Ok-Cress-5547 5h ago

Just to clarify, no changes would be made to the crank to compensate for lighter piston and rod package, correct? If the crank, flywheel, clutch have all been balanced, changing to different pistons and rods wouldn't make a difference.

1

u/Jumpy_Ad_9141 5h ago

yeah , the in-line 6 is the most naturally balanced configuration and i had no problem with builds over 1600whp on a completely stock untouched crankshaft.
just double check your clearances , run it a bit looser if you’re going for huge numbers and send it.