butterfly valve???

[evotech240sx]

hey there guys. i was woundering about this butterfly valve that my friend spoke of. he told me that if i removed it it will at least give me 5 hp. is it true??? i asked him if he knew where it was at and he didnt know. im hoping that you guys can help me out here and tell me where it is at. will removing this hurt my smoging as well??? and what does this butterfly valve do???

[SMoKeM240]

i just did it to mine, but im not done building my motor so i cant tell u if it does anything.

[NateDogg]

I removed the Swirl Control Valves (SCV) also, known as the butterfly valves. The results in the emission test are in a thread here so do a search.

I have noticed a decrease in torque below 4000rpm for sure. I have not noticed an increase in horsepower. All in all, I would leave them in. Nissan designed the engine management parameters with the SCV in place. Unless you are going stand-alone, leave them where they are. You won't be missing anything.

[InsanityInc]

they're another hinderance to the high end, but you may as well replace the whole manifold. Just removing the valve isn't going to do a whole lot.

[p00t]

2-3hp at most... i would only do them if you are tearing down the engine for something. bit of a hassle.