ok im just curious, what are you people smoking? sr20 over rb25? and an rb20 over an rb25? WTF?! ok let me drop some knowledge on you.

the rb25 is almost identicle to the rb26 aside from a slightly smaller stroke, and a single turbo as well as no independent throttle bodies and a less agressive cam profile. the rb25det NEO (post 98 model years) used the same head design including same cams as the rb26, boasting a whopping 280hp.

the rb25 (pre 98) with out the NEO system boasts 250 hp stock on a lovely 8lbs of boost.

the going rate for an rb25 right now is around 2500 to 3gs, wait? the going rate for an SR is 2500 to 3gs as well and is an aluminum block 205 hp 4cyl vs an iron block 250hp inline 6?.

I would choose an rb25 over a 26 myelf simply cause you dont have to fab anything but mounts, VS a 26 where you have to scrap the twin turbos, or completely redisgn your steering input, or make the car right hand drive to get everything to clear properly.

yes the wiring is a bitch, but at the same time, ANY engine short of a carbed v8 will have a painfull ammount of wiring except for an sr, which is mostly plug and play aside from a little bit of splicing, but at the same time, you sacrifice max hp capability.

Now SR20s vs Rb25s max power wise.

both egnines can take and produce 400hp on the stock internals, though the rb would be way more reliable in this respect and need fewer upgrades to accomplish this.

injectors, a bigger turbo, and fuel control and 400hp is perfectly capable in either engine, though because of the SR20s aluminum block, a LOT of extra cooling systems would be needed to sustain the power reliably. (SRs are KNOWN for having cooling issues).

to get either of these engines in a 240sx, your going to need exh, a radiator (if you dont want to have overheating issues in stop and go traffic), wiring, intercooler piping, an intercooler, and a BOV. in both cases youd be gaining a bit more power simply from the intercooler and exh alone. in the case of the sr20, youd be gaining about 10% power. same with the rb25.

so SR20 in 240sx = 225hp with those listed parts (still not even close to an rb25 stock rated power)
rb25 in 240sx = 275 hp (now we are talking)

personally an rb26 is nice, but way to expensive at double the price of an rb25, for the price of an rb26 you could have the rb25 in the car, running driving, with about 400hp.