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tech: engine balancing - why dont our engines have balancer shafts?



    As the topic states, why dont our engines use balancer shafts? To perfectally balance a 4
cylinder engine, you must eliminate the 2nd order force generated by the pistons unequal opposition
(piston near bottom moves less than piston near top - for a given crankshaft rotation).
    The big reason i am asking this is because our engines dont seem all too vibration prone as
compared to an engine that employs a balancing shaft (i.e. the 2.0 DSM engines).
    Now before some of you try to think up a way to add balancing shafts to our engines, realize
that to eliminate the 2nd order force, a balancing shaft must rotate at twice the speed of the
crank.
    Another wrench to throw in the works is that the balancer on my talon was 1:1 driven from the
crank, but had internal gearing such that the balancer spun at half the speed (i.e. just like the
cams).

Allyn Malventano, ETC(SS), USN
87 Rieger GTO Scirocco 16v (daily driver, 170k, rocco #6)
86 Kamei Twin 16V Turbo Scirocco GTX ('it has begun', rocco #7)
87 Jetta 8v Wolfsburg 2dr (daily driver, 260k, 0 rattles, original clutch, driveshafts, wheels :)