... well wonder no more. The Vincent Foucart 205 V16 is your answer:

It's based on a tubular chassis and uses four de-stroked CBR600 engines put together

The whole car:


A shame there's no word on power output...
EDIT: there is. According to one of their competitors, power output would be 437hp. That's twice the specific output of a Honda S2000!

That power is channeled through all four wheels and a 6-speed sequential gearbox.


Photo credit: Rallye TT