Date: 16 Feb 2005 17:07:59 GMT From: Dave Hinz <DaveHinznospamcop.net> Subject: Re: new saab motor for 9-3 series
On Wed, 16 Feb 2005 08:37:58 PST, Everett M. Greene <mojavegnospamveg.iwvisp.com> wrote: > Dave Hinz <DaveHinznospamcop.net> writes: > >> And the dual balance-shaft design of the I4 is very >> vibration free. > > So that's how they do it. > > I read somewhere many, many years ago that a 6-cylinder > engine (in what configuration, I don't recall) is > inherently balanced whereas a 4-cylinder engine is one > of the worst, if not the worst, in trying to get it to > run smoothly. Odd, and I've heard exactly the opposite. Even in a non-balance shafted I4, there are two pistons up, two pistons down, at any given time. > My experience over the years has found > this to be at least approximately true in that, other > than the Saab, the 4s have been rather rough running > while the old Corvair and the 6-cylinder Porsches > run quite smoothly. Well, sure, but the Corvair and Porsche engines are flat-6 boxer configuration engines, right? So, any out of balance is in the same plane and cancels itself out. It's having the balance differences on two intersecting planes that make the forces get "interesting". Dave Hinz