Please help! Heat treatment of die cast aluminum 1

[Willbriggs]

Hi, I'm new on this forum. Im currently working on a project trying to increase the horsepower on a old mini bike engine without using any aftermarket parts. I did a lot of work to get more power and rpm. Now I want to increase to tolerances of the internals.

The stock connecting rod is die casted aluminum alloy 380. On other forums I've researched that the stock rod usually breaks at RPMs above 4,500. Is there a way to increase the strength of the rod to keep it from breaking at higher RPMs. I thought about heat treating the rod, but I don't know the proper procedure for die cast aluminum. Also it is possible to weaken the metal If it were to be heat treated twice, because it may have been heat treated during the manufacturing processes. If you know of a good way to strengthen cast aluminum, or have any good ideas that may help me please let me know thanks.

 

[EdStainless]

Strength is only one of your problems. Being cast the conrod will have limited toughness and fatigue properties.
I don't believe that A380 is usually heat treated, and when it is it would be to assure uniform and stable properties, not max strength.

= = = = = = = = = = = = = = = = = = = =
P.E. Metallurgy, Plymouth Tube

 

[tbuelna]

Willbriggs,

Unfortunately, as EdStainless noted 380 aluminum alloy is not heat treatable, and die cast aluminum in general has limited fatigue capability. About the only thing you can do to your connecting rod to improve its fatigue capability is shot peening. Here is a MIL-S-13165 which provides guidance on shot peening of aluminum.

One thing you need to consider with any outside processing like heat treating or shot peening is cost. In your case where there is only a single part involved you will end up paying a minimum lot charge, which will likely be far more than the cost of a high-performance aftermarket component.

There is also something like this for a DIY approach to surface peening. It will allow you to peen most of the convex beam and cap surface areas, but may not work well on concave surfaces like fillets/pockets.

Good luck with your project.

 

[mfgenggear]

maybe make a new rod lost wax process with sand mold and cast an other rod. pick a new material. heat treat it and machine it.