VROD motor.
Designed in no small part by Porsche
Still makes only 100hp per litre. (125hp, 1250cc) 85lb feet of torque.
Rotax 1000cc v twin, 138hp per litre. 67 lbft.
That's an old rotax too.
Why am I not impressed by the V Rod?
As far as 138 hp from an aircooled engine, that 138 CI engine is over 2.2 litres. thats 62 hp per litre.
The old bandit made 84hp per litre, and with minor mods makes well over 100hp per litre. It's air cooled. (well, with an oil cooler too, though.)