These Y-pipes are more complex in their operation than you would think, they are designed to provide a good restriction at the top end of the rev range and not impede flow low down too much but just enough to provide good torque.
The only design that works is the half helix design, just clearing its throat will screw the low down torque and you feel that more than the top end benefit.
To use the simple designs I've seen you would need to have a huge increase in top end so that the 'trickle down' effect just makes up for the low end failings, to obtain the torque and the top end you need distance references for torque generation, the distance to the turbine×the flow restriction from the turbine (around 0.7)peak torque ristriction point (around 2000rpm) as a factor of flow design rate (Froud number 1.6)
85×0.7×2(k)×1.6 around 190mm from the valve head or 95mm for each 1000rpm step in the 'boost point'.
Thu, 18 July 2002 22:33
