Could i just take a ej25 short block and bolt my sti2 heads and manifolds to it? And use the same sensors and wiring loom ecu etc and put it back in? Or is there more to it?
Anyone done this before?

 

That's prity much it, in Theory.

You need to work put your CR with correct gaskets and or carry out a small modification to the cylinder heads combusion area. Also address fueling etc with a aftermarket ecu hey presto.

2.5 conversions are more that common place these days.

 

thanks mate... Could you explain that first part though? Are you saying i need to modify the head or dont have to if i use the right gasket? And i kind of figured about the ecu part but would it still run ok with the standard one? Untill i get the mpney for an apexi. Thanks again mate

 

No, it won't run OK with the standard ECU map. By going from 2.0 to 2.5 you've increased the amount of air sucked in per revolution by 25% - unless you increase the fuelling to match, it'll run lean and go bang. Perhaps surprisingly quickly.

 

You'll also need a different water cross feed pipe that sits on top of the block, to clear the extra breather the 2.5 has.
As for the ecu, i ran a 2.5 with standard ecu/injectors, for the run in period, but delayed the upgrade to long, and the engine lasted 3000miles