So im going to order an sos stage 2 kit for my 05 and have everything in order but im not sure which pulley to go with. i want something smaller than the 4.2 that it comes with and im stuck between 3.6 and 3.8. so i would like to know what you guys are running and what your numbers are. im going to run stock motor stock header berk tp and greddy SE exhaust. oh also i would like to be in the high 300hp area, 400 would be awsome but not sure if thats possible with a stock motor. anyway any experiance/knowledge on this is ver helpful. thanks in advance

 

I don't have an SOS supercharger. Centrifugal superchargers share attributes and problems.

I suggest go for the smaller pulley. Boost is hard to get so the more you can make the better. The big plus of the smaller pulley is greater boost down low so more torque all the way. You always want more torque.

I went so small on the supercharger pulley my engine red line needed to be reduced from 9600 to 8000 rpm to keep from over spinning the impeller. I missed the thrill of the top end red line but the power at low rpms was beyond amazing. I would do this again if running autocross.

You need to know the impeller rpm limits. That and the gear ratio in the supercharger and you can calculate the impeller speed from the engine RPM. Get the pulley that does not put you over the max impeller rpm.

The big negative of smaller pulleys is belt traction. There are aftermarket pulleys that treat the surface to be grabby by various means. I do not know what SOS offers. They are known for being on top of things so their pulleys should be good.

 

Buy mine. It's in the for sale section and has the 3.8 and 3.2 pulleys.

 

The Stage 2 comes with a 4.2" pulley (for 1200 blower) as the default setup, which is 9psi. You should be able to make high 300 whp with a good tune.

I just ordered my kit last week (9psi/4.2" pulley). I was also stuck between the 4.2 or something smaller. I decided to stick with the 9psi for several reasons:

9psi will yield high 300whp (around 375)
Option for 4.0" pulley would only yield marginal gains
Higher boost levels would place yet more strain on engine and transmission. Not worth the hp gains IMO
Clutch may start slipping on smaller pulley size. I'm currently running an Excedy stock replacement clutch

It's easy to get greedy with more power. My main driver was the clutch. I didn't want to replace the clutch again just for the additional power. Also, I feel peace of mind that I have much more safety margin (to engine destruction) at 9psi than something higher. If I can get 375whp at 9psi, I'd be very happy. I road race my car, any more power would be diminishing returns.

 

Don't expect your stock clutch to last too long.

Sent using free Tapatalk - Android FTW

 

Here is my opinion, for what it's worth.

The 3.8" pulley made my AP1 noticeably quicker than stock, but only once VTEC kicked in. I barely noticed any difference below 6k.
I switched to the 3.6" pulley and it was a nice bump. I'd never go back to the 3.8" personally. Top end was stronger, midrange was better, and low end wasn't as bad as before.

Neither of those made the car truly fast, in terms of other cars like Vettes / Vipers / 911's / GT-Rs. But it was still a lot better than stock once you stomped it.

Then I went to the 3.2" pulley and holy guacamole Batman, somebody engaged the warp drive! The car became crazy fast and totally addictive to romp on. It finally made a healthy improvement at low rpm, and the midrange was nice and strong. It wasn't a 'quick S2000' anymore; it was a seriously fast car.

To summarize, buying a SOS setup with a Novi 1200 blower and thinking that a 3.8" or 3.6" pulley is plenty is like getting your first blowjob and then assuming sex can't possibly be better... WRONG!

 

 

thanks for your help guys i think im going to go with a 3.6 cuz i want to run about 12psi and i want the car to be reliable. im getting the heat exchanger and the 1200blower and ive got an upgraded clutch and pressure plate and a 13lbs flywheels.

 

yeah but BJ's are nice because you don't have to do anything

 

Lol so true