RODS aluminium FORGED vs aluminium BILLET

wich have more resistence rods, aluminium forged or aluminium billet ?

 

Resistance to what? Stretch? Breaking? Twisting? Forged have always been considered to be the stronger version,(i.e. have a conversation with Bill Miller on forging, grain structure, flow, and elongation and you'll be convinced). However, there is a little known person called Mike, who owns
R & R rods, who has worked with Alcoa for many years, who will tell you different. We think of the grain structure of a piece of metal in lay terms. It's like I made a rod out of a piece of yellow southern pine. If the grain goes lengthwise, it will break at the yoke of the bearing on the leeward side of rotation. If the grain goes crosswise, it will snap at the place where the rod necks down to the beam. None of this is actually true. Alcoa has extruded
1 1/2 inch stuff for Mike that is stronger than Bill Miller's forgings. He merely band saws out the blank sizes and then puts them in the old C&C and "wala", a rod is born. You can freeze 'em or shake 'em to make them even stronger. The most important thing is the specific aluminum alloy that they are machined from: contact Alcoa for engineering data on that or maybe Mike can provide you with some specifics without tipping you off to any of his secrets. We once had a crew guy who didn't torque one rod: it made the run without breaking; the rod cap had a .090 gap to the rod when pan was removed; the piston had ghosted the head pretty good; the bearing was mangled by the crank cheek; we measured the crank pin, polished off some brass from the bearing locator pin, stuck in a new assembly and made next round. We are still running that crank today. Mike's rods saved us $40K in damages and made us customers for life. You don't always have to buy the Cadillac Northstar; Volvo makes some pretty good stuff, too.
Our experience has been excellent with Mike's rods.....be careful to ask him about the "bad bolt" thing from ARP, which has been resolved for some time now. We ck. big and small bores for roundness and c/c after every meet. Replace when they go out of spec. Some of his rods have gone 20 passes.

 

bobbyblue,
Other than distortion why is it necessary to change the rods after so many runs? Do you think the rod actualy gets fatigued?

 

I am a chicken $--t. We've blasted so many blocks in the past thirty years that I could be retired now instead of having to go to work to get my next meal. We run cautiously. Just check the rods to see when they start to move and then get them out of there before they hurt my wallet. Fred Mandolini showed me how much a rod stretches at 10,300 rpm and it scared the living bejesus out of me. Yes aluminum does work harden or "fatigue"; I want it to get tired outside of my motor rather than inside. Engraving an autograph on a used rod is lots more fun than trying to sell them to the junk man at $1.00 a lb. Hope your holidays were nice.