James only just flagged this thread up for me, but its interesting for sure. Sometihng thats pretty clear to me is that all this talk of 240bhp, 260 bhp...it could be 1000 bloody bhp and youd still only clock a 4.5 second 0-60 in a Clio. It is a front wheel drive car and the bottom line is, it limits traction. My Clio is supposed to be running around 250bhp and the same lbft of torque. But if someone said to me, your cars sh*t, it only makes 220bhp, Id say bobbins to them cos it still wheelspins in 3rd gear so who needs any more power?
The turbo conversion, if its built right, will be reliable and strong. Plus you avoid the problems of highly tuned NA engines whereby the more power you get out of them, the further up the revs you are pushing the power band and the less of a handy (for everyday driving) flat torque spread you are seeing across the low-mid parts of the revs. A turbo conversion of an already good engine will be quality in every department, my valver certainly responded very well to it.
As far as the rest of it goes, youd need a whacking great exhaust, basically as big as you want, probably 2.5" to 3" diameter all the way through from the turbo to the tailpipe would be about right. Any less and youd choke the turbo and not see the bhp you wanted. Standard clutch would die as soon as you were harsh with it, something like kevlar semi-paddle clutch is what you need. Brakes would need upgrading by the same amount that youve made the car quicker. You can never have too much braking though. As a guide, Ive got 325mm 4 pots on mine and it stops it like youve thrown out an anchor. But it needs 17s and 5mm less offset than normal just to fit them in, and you seriously couldnt get a fag paper in the gap between rim and caliper LOL. Clios arent that heavy so an upgrade to 300-310mm 4- pots on the front would do the trick easily.