i have a stock supercharger, and i heard when you have a supersharger, if you change the pulley you get more power. Is this true with the stock supercharger? Can i Change the pulley and get more power? if so, what size should i change it to and how much more power should i expect to recieve? I checked the search thing and all i found was info on how much PSI you gain, but i don't understand the psi thing!!!

More PSI = more air into engine = more power. PSI actually means "Pounds per Square Inch".

The only way you'll truly know how much more HP/Torque that a smaller S/C pulley will give you is if you go get some time on the dyno.

Be wary that doing so will add more stress to all the internals of your engine. You may want to set aside some extra money for a stronger crank, bearings, pistons, con rods, and new valve springs too.

Might not be a bad idea to have a more free flowing exhaust too.

I know it's pretty commonly done (adding a smaller pulley) - I think you have to have a special tool to swap them out.

If you can't find what you need here, try some other Nissan websites... texasnissanoffroad, nissan4wheelers, nissanoffroad, npora etc

i was also going to put a smaller pulley on my 2004, i found the pulley and the tool on southfloridapulleyhq.com. i think the pulley was $110.00 and it added a minimum of 26 hp.

A little cheaper- LINK
I have a 2.4", I just haven't got around to putting it in. There are a few people on here that have had smaller pulleys for years with no problems. I wouldn't rev the hell out of the engine though. Enjoy your X!

Did Nissan not use better internals on the supercharged motor? That's usually typical for any manufacturer to use stronger internal components to handle boost.

Isn't there issues where the ECU detects too much boost and goes into safe mode?

The smaller pulley must be nice, not only for the power increase but it boost sooner too, right?

Yes nissan used upgraded internals on the S/C engine.

In early engines there was a recal that adressed the MAF sensor reading going over it's limit, and illuminating the SES and limiting the engine to 3500RPM. After that there is still a boost control electronic bypass controller that the ECU does control to limit boost to 5psi under certain circumstances. The bypass controller can be bypassed.

Yes the smaller pulley will boost sooner.

IIRC on my 02 Supercharged Xterra I would get the following readings:

Stock: 5psi@3000RPM, 8psi@5900RPM
2.3" Pullley: 9psi@3000RPM, 12PSI@5900RPM

The truck pulled 199RWHP on the dyno with the smaller pulley, K&N cold air intake, bypassed electronic bypass controller, and a free-flowing exhaust. That equals about 40hp over stock.

On a final note, I blew up the original engine at 70K miles, running 50K of that with the 2.3" pulley. After replacing the engine I didn't like it with the stock pulley, so I changed the pulley back to a 2.3", and proceeded to dyno it after break-in.

That's when I overheated the exhaust and killed the catalytic convertors which caused high backpressure and overheating of a piston (or two) and resulting in rod knock.

Ummmm, I think you told me that you didn't have any problems.

Do you happen to remember what air/fuel ratios the stock ECU was getting with the smaller puley?

I didn't have any problems until I ABUSED it!

The original engine failed after I used the truck to move from California to Washington...four round trips, each time towing and having the GCVW over the GCVWR. Did I mention there are about 300 miles of mountain passes between California and Washington.

The second engine failed due to me overheating the exhaust on the dyno.

As well, I really drove it too hard all the time...I mean really hard.

If you drive like a person with a normal IQ you shouldn't have the same problems that I did.

Drewfusss: As far as the AFR's go I mever checked with a wideband O2. Through the stock computer it was always able to keep it within spec's enough to keep the SES off, and not excessively ping. The only scanner I had at the time was too slow on refresh rate to get a good real time measure of AFR's. The interesting side note on pinging is that on the original engine it would ping if you went over 7psi under 3000rpm. With the replacement engine that problem never arose. It was too bad that I killed it before seeing how it would run in the long term without so much boost. I really feel that the pinging issue on the original engine, which got excasserbated by towing heavy (5000Lb) caused its early demise.

FWIW the VQ40 in the new truck just turned 60K and I tow more weight and longer distances than I did with the VG33ER powered truck...no problems whatsoever and better towing fuel economy.

The only thing I liked about the VG33ER truck was the abount of torque avaialable instantly off idle...however I am sure again that really helped the longevity of the engine

Thanks, I was just curious if the stock computer could compensate for the added boost.

hey all-- sorry for the ignorance, but could someone tell me how to bypass the boost limiter?

I have a 2002 supercharger--I rarely tow, Im looking for more HP and low end torque (I drive fast), I would love to change the rear end gearing, but (I assume) that is a little over my pay grade

Low end torque and driving fast don't work....you need high rpm torque to go fast.

If by "Fast" you really mean you like to accelerate quickly, THEN low speed torque might help.



Go to a speed shop with a dyno, and have them reprogram the ECU to get a new ramp to handle the new flow, etc....JUST by passing the boost just means you can blow the engine more easily, etc.



The above will be above your pay grade if new gears are above your pay grade.

www.4x4parts.com has lower diff gears if you want to increase power that way.

yes I mean acceleration- top speed is not that important to me