Originally Posted by sandys
That is a different league surely £8k work of mods versus a couple of hundred quid
far from massively fettled.
While I see your point, if I was playing devil's advocate I could suggest that taking say a 150bhp TDi to 200bhp is more of a hike percentage wise in bhp/performance terms than taking a 250bhp GTA 3.2 V6 to 314 or 324 bhp with a 3.7 litre conversion with/without Ferrari throttle bodies.
Yes, the normally aspirated route is expensive as so many engine internals are needed, but you should end up with an engine as reliable as the original, and also balanced and lightened and thus a rev-happy grin machine. If, like me, you like engines that rev cleanly and do their best work at high revs, but are also silky smooth at low revs and with a decent mid-range, this is heaven.
The TDi route may seem cheap, as it is for chipping any turbo engine beyond what the manufacturer thought would pass endurance testing. However the downside is that you can expect it to go pop at some stage, as it was not designed for such work. Properly sort it with a new turbo, intercooler, pistons, head, oil coolers etc and you'll spend as much or more as the NA route.
When I've occasionally ventured onto forums where people have run chipped TDi's to high mileages, rather than saying "it's fine because mine's been running 10k miles without trouble" or some such nonsense, you see that many turbos and other parts give up the ghost around 50-100k miles. BMW 3 litre diesels are renowned for this, the chipping removes a lot of the protection given to the engine.
Anyway, yesterday, one-up and thus without my wife acting as a speed limiter, normal service was resumed and an assortment of TDi's were overtaken while themselves accelerating at full pelt away from a roundabout or similar. Good