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Well, you all have good points, here's what I have observed. My SHO motor, 3 liter 8000 rpm engine, was designed by Yamaha to take at least 300 hp. It has a really solid cast iron block. It ALSO has a main cap girdle, in this case it's cast iron and only ties the main caps together fore and aft.

I have a lot of respect for Yamaha engines, they are usually pretty tough. So when I see a factory main cap girdle from them I have to believe it adds strength to the engine.

The block for this motor which is only 183 cubic inch V6, weighs almost exactly 100 lb. So in pounds per cubic inch it is ahead of a 500 cubic inch bigblock on which the stock bare block weighs around 230 lb.
So if a main cap girdle helps the stouter block, what makes you think it wouldn't help the weaker block?

I am not trying to explain what it does, it's kind of a mystery to me. But it seems to do something.

R.



Is that Yamaha set-up not more of a bed plate than a girdle, as in the mains are all one piece? If so I would think it would be structurally superior to the girdle in that it is designed to handle the vertical force that the flat plate girdle can't.

Kevin