Q: I plan on getting a 240sx and doing a sr20det swap. however i was told that i can put a turbo kit on the stock engine and that will be way faster then the sr20det. plus the turbo kit cost less then the sr20det, what should i do?
A: Turbo the stock engine. The only reason the SR20DET is faster than a KA24DE is it's got factory turbos. An SR20 with no turbo gets 140 at most unless it has Variable Valve Timing which brings it up to 165hp which is still only slightly more than the naturally aspirated KA24DE. Nissan's Variable Valve Timing had problems (the VTCs "clack" and can lead to other more serious problems) on the 92-94 Nissan Maxima SE, I believe it had problems on the 300ZX and I'd expect that any engine with a similar system by Nissan would have the same problems. The stock SR20DET turbos can't make more than around 250hp and if you pick your own turbos for a KA24DE you can get the same sized ones with around the same horsepower or bigger ones that can make even more.