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  • Another Flywheel question

    I was wasting time on a slow work day and found mention of a small flywheel weight and how it helped with the inertia in a smaller engine. I know that the article was written about a 4 cylinder engine. I don't remember where I saw it and have been unable to find it again. My question is a multiple part question. Will this also hold true for an I6 engine, what are the pros and cons, and finally if it is worth doing where can I find something that will do that for an I6? Please let me know.

  • #2
    A flywheel is a kind of battery and a kind of shock absorber all in one.

    The power output from your engine consists of a lot of pulses (one for each power stroke of the engine). The flywheel absorbs these pulses and by virtue of inertia smooths them out into a nice smooth power output. As you increase the mass of the flywheel the engine can store more energy in it because of its larger inertia, but it also takes longer for the engine to "charge" the flywheel so you loose some acceleration. If you are building a drag race engine, you can use a lightweight flywheel so the engine will "tach up" faster, but your idle and low end torque will suffer somewhat because the smaller flywheel mass can't smooth the pulses out. If you have a big diesel truck you are typically looking for torque so you have a large flywheel mass to smooth out the pulses and increase low end torque, but you don't get the same acceleration of a small mass flywheel.

    Bottom line, if the flywheel is too small, you get a "rice burner" that will tach up to 7K rpm, but you start rolling backward on a small hill. If the flywheel is too big, then your engine could be sluggish, but be able to pull stumps at idle.

    No clue where to find additional weights for the I6, maybe you can use a 401 flywheel and have it rebalanced for the I6?