It's funny you bring this up, as it's something that we are constantly battling on a daily basis with our new wheel technology. When it comes to cast vs billet material, you are absolutely correct, not much performance difference at all if the blades and the design are identical. However, this is not the case with our new CEA technology compressor wheels. CEA = Competition Engineered Aerodynamics.
Our head engineer Dan Barlog, has spent numerous hours upon hours designing these new wheels. Utilizing the latest CFD computational fluid dynamic software with each new wheel design. Everything you can think of to make these wheels better has been done, blade lengths, pitch, angles, everything, including boundary layer and direction of flow technology has been put into the designs.
Maybe this picture can better illustrate what I'm talking about.
Billet 67mm CEA compressor wheel.
One other thing, we have always brought the best technology to the table with our turbo designs. With regards to these new compressor wheels, we wouldn't have created a new turbo if it had not shown significant gains over it's cast compressor wheel cousin. We have seen very nice gains of anywhere from 25hp upwards of 100hp. This has been proven throughout the country with these new wheels on everything from 1.6L Honda motors to 600+ CI twin turbo motors.
Even our tractor pulling turbos have been setting records and turning that world upside down since we got into that market. We have been battling this billet vs cast debate for awhile now, and thankfully, with the cnc machine technology that's available to us, we can now pull out all the stops with our designs and bring the very best to the table.
Hope this helps and sorry I get so long winded sometimes.
Patrick