Quote:
Originally Posted by serialk11r
Too many edits. Okay so the area that the wrist pin spreads the forces is much greater, that makes sense. Thanks. I see why it makes sense to use it in frequently rebuilt engines, you can cut down the mass significantly, and the aluminum rod will still survive a respectable amount of time, but if you want to increase the service life the aluminum rod needs significant strengthening which would not be worthwhile.
|
you've got the idea now. Also keep in mind that pistons are usually 2618 and they have a higher strength 'at temp' than 7075. But now you get the idea of the load area for the forces perpendicular to the crank axis (up and down). The big force that usually causes rods to fail (neck before bending) is pulling away from TDC on the intake stroke. It then folds on the following combustion if it doesn't actually tear through. In this case, the rod is now fighting the momentum that the piston had when approaching TDC on the exhaust stroke.
Edit: forgot to mention that you'd probably run into fitment issues with an aluminum rod in an FA case if building for lower power but longevity. I couldn't get them to fit without extensive case clearing for EJ applications.
Quote:
Originally Posted by serialk11r
|
Yup
billet 4340 rods are my budget rods and 300M are a $180 add on. L19 bolts standard and then I upgrade to 625 for my guys going after 4 digits.
Quote:
Originally Posted by Dimman
Serial, if you want to blow your mind on rods, there are currently some dirt-bikes that use an aluminum matrix composite rod. Also it's one-piece and has no bearings.
|
Perhaps I ought to bite my tongue on this but what fun would that be?!
My mind isn't blown...though I will say that rods are next on the list once piston testing starts in two months.
