The chassis of the 1.4tsi cars are not designed for the 2l t fsi power you could potentially make.....350bhp, the gear box 100% couldnt handle that and then theres the
problem of getting a 6 speed dsg to fit. Wheel spin would be savage, and the car is already light at the back, heavy at the front. The extra weight alone would make it a handfull if you were to do some hard driving.
The standard steering rack is weak on these cars, si who has the fabia hybrid mapped by apr did nine trackdays before his rack broke and hence is getting rid.
You would have to look at trying to get suspension and a steering rack replacements aswell.
The
ibiza is designed to be lightweight, very good power/weight ratio and quick instant power. Th only advantage of putting the s3 engine in is that it woud have a better power to weight ratio.....usable power on the other hand? not a chance.
I was looking into other egnines to fit over doing a rebuild............3.2l v6, 2.0tfsi,1.8t, 2.0l 16v, the latter being probably the best. Simple, robust, not too heavy, easily 200bhp with intake kit, full exhaust, cams, remap. If you rebuilt the engine before fitting you could get a gas flowed head, throttle bodies etc............220bhp is possible i think. A proper old school no nonsense drivers car. The 1.8t is a stong highly tunable engine but again easily more than the little
ibiza could handle
I would just buy an old high milage s3 and spend your money rebuilding the engine and adding performance mods.
As a technical exercise though I would love to see it done, if you could somehow get a 4wd transmission chain fitted it would be a monster in a straight line