I had my rotor housings shot peened by a buddy of mine (govermnent job at a place that makes boinger valve-train components of all things hehe shhhhhh)
The peening was strictly for cosmetic purposes and I think it did the trick. I spent a good couple hours with a wire wheel and this looks 10X better, that's like what 50 extra rwhp... right? There are a few coats of high temp clear engine paint on there as well.
here's a pic of my shot peening buddys PT (yeah I know it's not a rotary but hes put a hell of a lot of good work into it and a turbo is on it's way in)
http://grovelandfire.org/lowpt/low2.jpg

 

Wow... Pretty sweet.

 

Doesn't shotpeening compress the surfaces just a tad?
I'd worry about getting those edges shotpeened, since it'll screw up all the mating tolerances.


-Ted

 

Yes it does deform the aluminum surface a bit, this is why I maksed the hell out of everything. Bolts and washers on the oil injection holes, both housings doweled together with plywood end-caps with all-thread to hold the sandwich together. I am in the process of making a turbo manifold so I bolted the flanges over the exhaust ports with sheetmetal behind them. Basicaly the only thing that got peened was the outside surface. I miced the housing width before/after, no change.