Tech Tip "Radii' and "chamfers" on M96

It's well known by Racers and engine builders and educated Techs that Radii and Chamfers are very useful in creating a stronger and more reliable engine. Factory production mass produced engine have many sharp edges and 90* corners are where stress cracks can form and also can impede oil flow and cause high friction and wear areas on critical highly stressed components. Sharp edges and 90* corners should be avoided at all cost on Race/ High Performance engines. These details are hardly ever done on factory engines due to more cost in time and machining and the reason hand built detail oriented engines are superior. Fatigue cracks always start at sharp edges (the weakest point of the material) in microscopic cracks and grow on very cycle of temperature or mechanical loading. Once the cracks grow large enough to be dangerous they will take off like a lightening bolt across the material and failure has occurred. Even if microscopic cracks have formed, they can be eliminated by Chamfering or Radii of the sharp edges if caught before they have reached the dangerous size.. This stops the crack growth and strengthens the area greatly. A Chamfer basically takes a 90* edge and makes two 45* edges out of it for better transition of sliding and/or more fatigue/crack prevention. A Radii basically makes a curved edge with no angle points and is much much better for transitional sliding surfaces and or fatigue/crack prevention, but is much harder/costly to achieve.. The larger the Radii the better but the maximum will be determined by the surrounding area. Chamfers or Radii also can help oil flow from oil holes with sharp edges in passages in the crankcase or in the crankshaft. Most machine shops will do a Chamfer or Radii on oil holes in the crankshaft when polishing. Chamfers or Radii can also keep from scuffing or wearing of lifter/bores and cylinder bores/pistons. First look at the heads on an M96 and I wondered how they hell they keep from cracking, they don't..Keeping from overheating is the only thing you can do..Take a look at this cracked head at all the sharp edges, some time with a dremel ofrdie-grinder with polishing rolls will greatly improve this area. How many sharp edges do you see? Chamfer/Radii oil holes will help oil flow Smoothing the sharp edges of the lifter bore will keep down wear The piston on M96 engine actually come out of the bore at the bottom on BDC, and the wrist pin is offset adversely on bank 2 causing a lot more side thrust, this one has a small chamfer but a Radii would help keep scuffing/scoring down Lots of sharp edges in this pic,smoothing them would take lots of time, but every little bit helps

So true. Lots of sharp edges. Anyone who has handled M96 blocks or heads know that most every surface is razor blade and we all have the scars from being sliced open from handling them. We do make our Nickies sleeves longer have also worked with JE to come up with custom cam skirt profiles for the piston skirts to improve the thrust side loading. Every little bit helps like you said.

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OMG Charles, yes sir !!! Those cuts from aluminum (for me anyway) hurt much more pain-wise and throbbing, than any other cuts !!!