I originally said that 3 cylinder radial engines were inherently balanced but upon reconsidering it and drawing diagrams on a piece of paper, it appears that the second harmonics are additive rather than cancelling. So, original post deleted.
Twenty years ago Yamaha invented (?) âOmniphase Balancingâ for their big 500cc single cylinder motorcycles. It was revolutionary. Today, many engine manufactures are using counter-rotating balance shafts in their engines to make them butter smoothâŠ
If you have ever seen a I-6 or I-8 crankshaft on the floor waiting to be machined, you would understand why they are no longer in favor. A V6 crank can be made for half the price.
Caddyman, can you name a few? I was not aware that anyone did anymore. I know that Chrysler used to have one in a 2.6 liter 4 cylinder, but I thot it was a Mitsubishi.
Wouldnât an O-4 be unbalanced due to the fact that opposing banks of cylinders arenât directly opposite one another, thus producing a rocking moment?
(I mean, I see how you could design an engine with perfectly-opposed cylinders, but I didnât believe it was done that way.)
When the front pistons are at top dead center, the rear cylinders are at bottom dead center. This causes opposing rocking moments that cancel each other out. Two cylinder opposed engines do have a rocking couple problem.
Everyone thought that the inline four cylinder motorcycles that came into being around 1969 were buttery smoothâŠuntil Honda unveiled their original Gold Wing with a opposed four which totally redefined the term buttery smooth.
I think many/most of the large-displacement 4s have balance shafts. Most every I4 2l and up vibrate quite a bit without a balance shaft.
Wasnât produced by Suzuki either,according to my recollection-Kevin
I donât believe many have balance shafts. But I havenât kept track of them lately.
My 2004 2.4L 4-cyl Hyundai Sonata has a dedicated balance shaft run off a small timing belt. Even the oil pump shaft on that engine needs to be balanced otherwise youâll get a vibration.
Wikipedia (for Balance Shaft) has a good list of manufacturers who use balance shafts.
Not sure about truck or farm use, but those 2 stroke Detroits were used in the marine industry through the 80s, even into the early 90s⊠Coincidentally, one of those was the 671, an inline 6. And yes, the 6V92, 8V92 (V6 and V8, respectively) and others were still available through that era.
My '02 Wrangler has 159,000 on it. Nothing but good things to say about it. That old AMC block was a perfect engine for those vehicles.
Doesnât Ford have a balance shaft in their 4.0L V6?