Excuse me but I dont believe 40mm webers & those figures add up even with ethanol
nitriding and snail sidetracking comments aside the revs required to get those figures
from 40mm carbs is close to 10k rpm for most 1.3-1.5 bike engines with much squarer
and suitable bore stroke ratios.

Sure development always keeps moving forward but when you are limited to A series
bore sizes, valve, ports and 2 valves Im sure Nissan reached its pinnacle.
The methanol E series heads you could compare to late Alfa & fiat heads and
Euros have only cracked 120hp per litre with quadruple the effort vs A series.


If A series were developed to be making close to ZX14r hp per litre then
people would be using them for 7k than 10k for a factory busa or kwacka donk.

Honda D15 all motors built by some of the best Honda engineers and tuners still
only manage 130hp at the front wheels with 48mm inlets and some of the best 16v
chambers available for any engine and 79mm sleeved bores.