KA or SR?
As the never ending debate continues, I’ve decided to say my part. I am by no means an s-chassis expert, but I feel that I’ve been around them more than enough to be worthy of sharing my perspective.
For those that don’t know, Nissan owners around the country have been arguing about whether it is best to turbocharge the factory 240sx motor (KA24DE) or to simply swap in the already conveniently turbocharged (and pricier) Japanese alternative, the SR20DET. For the sake of transparency, let’s say your goal is to put down about 275whp.
Although KA-T supporters argue that there’s “no replacement for displacement,” naysayers contend that the KA simply doesn’t hold up to boost like a factory turbocharged motor (*cough* SR20 *cough*) does.
I’ll give the KA this much — its higher displacement allows the motor to flow with much less restriction, and when boosted, its torque numbers are impressive. That being said, you must also face the typical headache that slapping a turbo onto an previously naturally aspirated motor will leave you with — shaky reliability at best, a hole in your block at worst. Sure, you could throw some decent internals into your KA and it would probably last, but you’re losing that factory built reliability the SR possesses, and you’re just adding more zeros to the price of your KA-T build.
The SR was designed to handle boost, and the overall reliability of one (in unmolested form) is worth the extra cash in my opinion. I’m not naive enough to claim that a reliable KA-T setup cannot be achieved, but for the money it would take to get there, I still see the SR as the better option. Obviously once you start shooting for higher numbers, things change, as both motors would need to be built to withstand the abuse, but in this scenario, the SR certainly wins.