The power is noticeable with a 15%. A couple years ago, when I was stock, I got left behind pretty badly against someone of my local club that had a 15% and a unichip...

 

Ya, i guess different people's experiences and expectations will vary, but after modifying many vehicles over many years, i have to say the pulley mod on this car has made the biggest performance change of any single mod ive even done. Cant wait to get the high flow intake and cat-back done!

 

Hello! I'm thinking about this mod as well and this thread is interesting. I assume the blower has a wastegate to bleed excess boost? If so, then the main difference with the underdrive pulley should be to increase low-RPM boost and thus torque, right? (Which would be a good thing with this engine.)

Is there any long-term risk to the engine, with more boost, or to the supercharger, spinning higher RPM? Is there any downside to this mod? Fuel mileage?

Related parts: Shorter belt makes sense. Colder plugs - is this highly recommended? Does it have any ill side effects, like fouling plugs over time? What is the purpose - avoid pinging? No ECU mods are necessary? Finally, please forgive my ignorance, but what's a CAI?

I'm also searching the archives. If you know of any old threads about this stuff, I'd love to get those links.

Thanks, Jeremy

 

CAI= cold air intake

As for your other questions, I went with the 15% pulley because that was recommended to me as the best size for long term durability and driveability on a daily driven street car. 17% probably would have been okay too, but I wanted to be as safe as possible as I plan to keep my car forever. 19% was described as track-use only.

Fuel mileage, I haven't noticed a difference. The only downside is the install is a bit labor intensive, but can be done with patience and the right tools.

 

the pulley has been a proven reliable mod, no excess boost waste gate, since a blower can only make so much at a given time, it spins at a relative speed with the engine. reducing the pulley size, spins the supercharger faster giving you more boost allong the whole rev range. when you start getting into the 19% pulleys they create heat in the upper RPMs and can create cavitation in the waterpump, since the water pump is driven by the supercharger.

17 is considered the street use, since you dont live in the high RPM

12-15 are considered track since your bouncing around rev limiter frequently, the heat created at higher rpms negates the boost since the ECU has to pull timing to have safe engine parameters

colder plugs are reconmended, but not neccecary, helps a bit, keeps intake temperatures down, pushing huge boost and needing a few steps colder would have more of an impact, just get plugs meant for a JCW, which is 1 step colder

no ecu mods are needed

fuel mileage will have a slight decrease since you have less torque on the supercharger, but its very minimal, the most youll loose is from the extra power cause youll have your foot in it

 

I've read that a few guys experience pinging in the engine with the higher boost caused by an under drive pulley. Is it true that by far, most people don't have this problem?

Is the process reversible, or does the old pulley get destroyed during removal?

 

Most likely you won't be able to reverse it, the 15 is a known reliable mod.

 

Old pulley (the oem) is destroyed..sometimes only deformed a bit..but it is HEAT set....new one is put on with a bolt and collet arrangement...heck MANY rebuilt SC are sold WITHOUT a pulley installed....

Pinging is possible....but seems to be more an issue with making a PRE-existing problem worse....the Cooler plugs are used to help prevent this..they "wick" heat away a bit faster...the Cooler Plugs are actually the same plugs used in the JCW version....which has a pulley also.....about a 13%....
IMO a pulley is a nobrainer, especially if you live in an area with 92-94 octane fuel.... the octane help deal with the extra heat from the SC running faster...in a VERY hot area, with 90 octane...like southern CA...might not be as much of a slam dunk...
There are about 10,000 posts about it....not a huge number of facts..mostly educated guesses,and personal experiences....do a search...have a read!! then decide!!

 

The only time I have had pinging is when I try running 87 octane fuel, but that happened with the stock pulley. MINI's don't like low octane gas, at least the forced induction ones don't. The wife's Clubbie doesn't seem to mind.

 

Installed a 15% WMW pulley & colder plugs on an '04 MCS w/ 135,000 miles this past week...and I love the results.

I had recently swapped to a K&N Typhoon CAI, MSD coil, Hypercoil Wires, Invidia cat back exhaust, and Team Dynamics wheels. Of those changes the wheels were the only mod I did that I could feel in the seat.

Didn't/haven't reset the ECU but probably driven 300 miles over the weekend. Not sure it's necessary at this point. Still considering tune.

Sidney

 

FOLLOW UP:
After a month or so with the 15% pulley (and it's my wife's car so I only drive it occasionally), I can say I notice the increased low-RPM grunt, which is mainly what I was after anyway. I'm sure it must pull harder revved up as well, but it was already plenty quick up there. I just didn't want it to be quite as dead below 3k RPM, and it is in fact better. It's less abrupt when the motor really comes on the boost than it was before. I call it a success.

I have not yet installed colder plugs, and no pinging noticed in the hot Tucson summer. However, I'm going to give them a try anyway - using the standard grade copper NGK BKR7E.

 

If you really wanna feel the extra boost you should look into replacing the bypass valve also. Might not be holding all the extra pressure.

 

There's a bypass valve? Like a wastegate?

 

I'm not a expert in it but it controls the boost and the spring gets weak and doesn't hold boost as well. $90 for a new one on Ecs tuning, or a performance version from Detroit tuned for $125.