The reason I'm asking is because I just put a H1C Holset off an LPG engine on to my 2nd gen and it sounds way different than the one on my 1st gen. Both trucks have the identical exhaust and intake but the 2nd gen has a loud shrill whistle out the exhaust at all rpm kinda like a 6.0 powerstroke and my 1st gen is more mellow sounding. Remember these are identical turbo's except for one is off an LPG and the other a diesel. Is the angle of the blades different between the two to compensate for velocity of the different fuels being burned or is it something else? I stay up and think about this stuff all night.

 

It's not only blade design, its also temperature and speed of the exhaust gasses.

Blade design is an art for itself. I visited a company next to my work- they produce one piece titan made turbo compressors.

 

You should upload a vid so we can hear the difference. Im curious

 

I'll try to get one up. The difference is clear though. One has a real high pitched whistle and the other is more to what we are used to hearing.