Lightly modified S14 at 2.3L makes ~250hp (specific output of 110hp/litre) at around 7500 rpm.
Pure race S14 I4 at 2.3L makes ~320hp (specific output of 140hp/litre) at around 9000 rpm
Pure race S14 I4 2.0L variant makes ~300hp (specific output of 150hp/litre) at close to 11,000 rpm
Pure race M62 V8 at 4.4L makes ~620hp (specific output of 140hp/litre) at around 9500 rpm.
Pure race S54 I6 at 3.2L makes ~380hp (specific output of 120hp/litre) at around 8500rpm. Undersquare (stroke > bore) engine makes it tough to rev and flow.