Adam,
The torque and power curves are derived from the turbo / cam / and headwork specification of the engine. Mine was built "down" to a specific output, as I wanted the whole package to be reasonably reliable (torque kills diffs / gearboxes). However despite this, the original gearbox lasted 1k miles of 500bhp before it died. the new one has so far done 16k+ miles, but is getting noisey and will need replacing soon.

This is what happens to the planet gears in the diff with anything over 400bhp...




Which is why this bit of equipment has been replaced for a Quaife item. However, the engine always has a way of finding the weakest link, and as the clutch is a six plate paddle, this is what happens to the nose cone that connects the prop to the gearbox when you fit slicks (as the power would normally be spun away with 2wd)...






The Cosse lump can produce 325bhp / 450lbft in WRC format, using the right turbo / cam and head spec, but this engine doesn't like to rev because of the restrictor. You can also have 500lb ft of torque, but trying to find a gearbox that doesn't belong in a tractor to cope would be a different matter. It is all about a reliable package / compromise. My next engine will have more torque, as I have a reliable gearbox / diff package in the pipeline which will allow such an increase. The only limiting factors are the ancilliries and your wallet, as 670bhp is available if you have a £15k budget for an engine of this spec (turbo is £3k alone and requires special exhaust and manifold etc to be made up for it to fit). That engine would have well over 500lb ft of torque as well (I'll tell you the amount as soon as it has been dynoed...).

To give you some idea of the acceleration a 500bhp Cossie has, I am also a biker and have a 140bhp ZZR1100. This is not exactly cutting edge technology, but is quite quick (doesn't do corners - bit like a Cossie then). The Cossie annialates it from 100mph onwards (no 2wd car can live with a bike from a standing start).....
Best regards
Mike R