I know this thread is rather old but I have just stumbled upon it and found it quite fascinating. Someone touched on a MerCruiser 4 cylinder being half a v8 - well the MerCruiser 470, which was 3.7 litres and produced 170HP used a Ford big block head, I think Ford pistons, a Ford flywheel and as pointed out a flat plane crank. I have had several to bits years ago and I seem to remember the crank being a big heavy thing. I think it was MerCruisers own block which was made out of aluminium but I have heard it being attributed to a Renault truck. Must have been a custom crank and even if you could re machine it into a V8 then presumably it would be a Ford big block - stroke appears to be pretty much the same, 2 x 3.7litres = 7.4 litres, is that not what the Ford big block is? Incidentally it was a horrid thing..
Want an engine noise to make the hairs on the back of your neck stand up? BMW M5 V10 with special exhausts. 500+ HP and a scream to match. If only I had the budget to firstly buy one and then invest in the sophisticated electronics needed to control the damn thing, find a way of ditching the silly semi automatic gearbox (no manual option in the UK) so I could stick one in my 72 HS30. Hope one of you guys managed to achieve the flat plane sbc!