Who said anything about having an engine bay?

Anyone with input on turbo sizing per rotor?

 

If you get the sizes right 3 turbos will give you better responce and more flow than on large single.

 

Do you have the cad plot of the header flange to the engine you can e-mail? I need to get a flange cut for Tuesday and am in the UK!!!

 

This is completely wrong.

Multiple turbos are always less efficient than single turbos, because the ratio of working area to drag is better for a bigger turbo. This is partly because the mechanical drag on the bearings is not proportional to wheel size: ie, a larger turbo will flow much more than a smaller turbo, but only have slightly more mechanical drag on the shaft. When compared with double the drag from 2 smaller turbos, this only gets worse.

Aerodynamic drag is similar: all turbos will have similar maximum airspeeds, and thus drag is proportional to the surface area that is exposed to flowing air. A larger turbo will have a greater ratio of working surface area to nonworking surface area than smaller ones, thus more efficiency.

A more simple analogy is to consider flow through a pipe: A 4" pipe will flow MUCH more than two 2.8" pipes (equivalent cross section), because although the flow area is the same, air velocity at the surface of the pipe is zero by definition, therefore the 2 pipes have a much higher percentage of slow-moving air than the 4" pipe. The same thing is true with turbos to an even greater extent, because of the additional variables of shaft drag and the more complex shape of the flow area.

 

I think HErblenny's idea with 3 'overhead' runners joining into a 3 to 1 with a90° bend pointing downwards is one of the best idea's I've seen so far. True... not divided but a trully fresh idea with excellent access to the wastegate, low position of exhaust (positive I think)