It all depends on if the engine is Normally aspirated or forced induction.
The bench mark for production NA cars is 100BHP per litre, there’s not alot out there in gneral car world than can achieve this and still have enough tourque at low enough revs to make the car truly driveable, one example as stated above is the Honda S2000.
It’s nigh on impossible to achieve this kind of output without some very clever variable cam timing. the previos incarnation of the BMW M3 was also pretty damm good at this, also with clever variable cam timing and AFAIK variable inlet manifold lenght allowing both low down torue and top end power.
Turbo cars, with the right tuning are very easy to generate high specific outputs of both torque and horsepower. However they can become very very laggy and no fun to drive unless flat out.
coffeeking I’d be very interested to hear of the modifications to your engine/breathing/ecu that have allowed to to achieve 150BHP/litre from a NA (presumably VVTi) Toyota engine, whats the power & torque curve like?
Just to blow my own trumpet my last project NA car was a 1993 Honda Civic running a very heavily modified 1796cc DOHC VTEC engine, in it’s upper most state of tune this was giving 234BHP & 165lbs/ft of torque. That was an expensive engine completly built from the sump up – stood me at over 3k inc inlet/outlet manifolds & transmission.
