Speed Secret # 4

[Kevin Price]

Assume large exhaust valves and large, unhampered flow through exhaust ports through porting. By your description it would appear to be an ideal (well, close to ideal) situation with regards to minimizing dilution.

So as the exhaust valve just begins to open, the exhaust squirts throught the valve/valve seat space at very high velocity as it seeks to equalize into the low pressure area of the exhaust valve pocket and the primaries of your headers. Some of this initial exhaust movement is improved by the scavanging effect or inertia of the other cylinders exhaust flowing down the exhaust tubes and producing a vacume for this cylinder.

What about the velocity with which the exhaust exits through the exhaust itself? It would appear that you would need some resistance, in some cases that is, to increase the velocity and flow efficiency.

In short, by running an exhaust valve to large and/ or increasing the exhaust port to extensively thus decreasing the initial velocity that is created when the exhaust valve first begins to open might loss of torque be a result?