Mythbuster: continuing project thread of my 1303 '75

[70Turbobug]

For an even bigger engine like your comming 2413cc, I would surely get the 0,82 A/R if you had free choice. You may loose some spool as opposed to the 0,63, but you already got that covered by the 200cc's more you have over mine...

I agree 100%. The .63 Housing will be too small for a 2.4 L engine.It would spol extremely quick,but I don´t think you would be happy with it.Our Boxer engines make torque really quick and spool turbos usually quicker than other engines,especially as soon as the engine is under load.IMHO due to the 2 valve design and "uncluttered" chamber and realtively short intake and exhaust ports and the large amounts of air volume and air speed generated at lower rpms.Maybe the Subaru guys have to choose a smaller housing to "dial in" their spool up time due to the central/single throtlebody and long intake runners? Just a hunch though on my part,I don´t know enough about the suby for a better argument.
Another thought of mine is,that Wally may need a larger housing because the core engine is more that of a high rpm engine with the large bore and short stroke.So maybe his "power range" is much higher in the rpm band and out of the optimum efficiency range of the current turbine housing.Also the cam (here we go again..) has enough duration and lift to deliver higher rpms and with the 114° (?) LC more stability and valve control and longer off seat time.