Is the fundamental difference between the Mk2 and the K3 just the engine and subframes or are the cars totally different in their structure

Totally different beasts.

The K3 was the updated version that used Rover Metro donor parts The subframes are indeed different - which also means the suspension, brakes and steering are different so it's hardly "just" different subframes. The intended engines are the K-Series along with their associated gearboxes.

Iain

Thanks for the information Iain, the reason I asked was to confirm that if I built my own subframe to fit to a Mk2 then that would allow me to fit the engine and front running gear off a donor car be that a K series or a Vauxhall Corsa (given that the wheel track is suitable).

Didn't you take on board what Raymond said in your other thread

I've had a look at my mate's MkII Rossa and we reckon the same thing - different engines are going to be a challenge because of those big fibreglass butresses either side of the engine. Even looking at 3 cylinder engines we reckon it would still be a problem as they mostly have the gearbox stuck on the end of the engine so the tall bit (cylinders and head) are offset and therefore need to be where the structure is. The reason the Mini engine fits is that the gearbox is underslung so the engine itself is fairly central across the width of the car. My suggestion of an Austin Princess engine and box didn't go down too well.

Zcars have put a Vtec in one I think but from the pictures they have removed the butresses completely and added a steel frame but it goes quite a way forwards to form basically a roll-cage as you can't simply bolt it to the rear bulkhead to carry the loads.

I've even found with my Coupe when putting the Micra engine in that it's a different matter to fitting it to a Mini because the engine simply cannot overhang the front of the subframe whereas you've got a fair amount of room behind the grill in a Mini.

Iain

If you haven't already got a Rossa 2 then look for a K3 to play with. The removable rear clam gives you all the room you need to fit the majority of fwd engine/gearbox types. The standard fare is rover metro subframe with K series engine however with a little modding you can fit the 1.8VVC 160hp motor from MGTF. The subframe anchor points are easily accessible to make up your own subframe without too much difficulty so you would be able to fit vauhall or honda motors and get really lairy!
PEEPS.

Apologies I thought Raymond was talking about the subframe turrets.

I'm going to collect the Mk2 tomorrow and have a number of options on the engine side of things to get what
I'm looking for. If the GTM turns out to be the car I hope it will be then I will be looking for a K3 to add to the
'stable'.

Thanks to everyone for their help on this matter, sorry about the misunderstanding.

Pete