|
|
The exhaust ports of the 215 HP S14 cylinder head appear to be identical in specification to those of the Evolution 3 cylinder head. They both have the same 32.0 mm valves. Yet, the two heads do not flow exactly the same, as shown on the chart above. The difference in the two curves is a little larger than one would associate with simple measurement variation. The two exhaust port configurations may be different in a way that is difficult to distinguish through simple visual inspection. Subtle variations in the length and angle of the valve seat cuts can have a big impact on flow capacity, and it is not clear whether these two cylinder heads are *exactly* identical in this respect. Note that the pressure acting to push exhaust gases out of the cylinder can be as much as 5 times higher than the pressure pushing gases in. Therefore, even a modest flowing exhaust port is quite suitable for making power (when compared to its intake partner). The exhaust ports on all of the factory S14 cylinder heads are generally considered to be identical, since there was no real need for improvement. It's the intake ports that needed help. |
| « Back |