I just picked up a 2003 mini S for a daily and the first thing I wanted to do was change all the fluids (including the S/C oil) so i figured while the supercharger was off I would change the pulley. I am stuck between the 15 and 17 percent pulleys. What is better for a daily? the car has 112,000 miles on it and I want to make it more fun but keep it reliable.

 

IMO the 17% is great for a daily driver, with mid level rpm's, with an occasional excursion to the redline. If you plan on doing auto-x, then get the 15% because you will be riding the red line much more. Either way, plan on yearly belt changes IMO.

 

I have a 17% on my daily driver with 98k miles no problems I love it!

 

There are tons of cars with 17% pulleys on them, its pretty established that it's within the safe range. I wouldn't go higher, that's all.

I wanted the 15%, but because of a miscommunication, my mechanic ended up putting in a 16% -- felix culpa. If you're on the fence, consider 16%. I'm happy with it.

I like the idea of the 15%, but then again, I was almost inclined at one point to get a 12% to be as close to "stock" jcw as possible. If you're not like that, and just want the biggest gain, go for the 17%. I'm not sure what difference you will feel, it may just be a mental thing, but others with more experience on pullied cars can speak to that.

 

In my opinion if you do the 17 percent I would also get the 380 JCW injectors.

 

I have a 17%, Alta CAI, and Invidia N1 exhaust. Perfect in a 121k mile 03 MCS I have. No problems at all

 

Food for thought.

 

Or just buy 450's, they're cheaper than the JCW's (warranty doesn't apply here anyway), and apply the money saved for a tune. Biggest bang for the buck.

Daily driver, 17% makes sense. For the track, 15% is your best compromise, like stated earlier.

 

What if the car only saw the track once, maybe twice a year? 17% ok or still go 15%? What's the power gain difference between the two?

 

You don't make more power with a 17, just more torque down low, which is great for around town. But at high rpms, you're spinning the SC faster, past the point where it's making power, generating a bunch of heat, which you really don't want. Doing a single track day, you'll be fine. Just don't hang at the redline all day and you'll be fine.

 

He won't be able to use them until the tune. So unless you are doing the tune at the same time they won't perform.

 

Running 440 injectors on a stock tune, you'll be running very rich. The amount of fuel getting to the engine is controlled by the on/off duty cycle of the injectors. With slightly larger than stock injectors and a stock tune, the car's ECU can compensate by using the "fuel trim" to shorten the injectors' "on" cycle to deliver less fuel. 440 cc injectors flow more fuel than stock injectors. So even with the fuel trim at its limit, you'll be flowing too much fuel.

 

That's why I said get the 450's with a tune...

I wouldn't waste my time or money on the jcw injectors, it's a pretty marginal bang for the buck, they won't be optimized without a tune anyway either. More trouble than its worth on the stock ECU. When they used to do the after purchase JCW package (installed at the dealer), with the 380's, the first thing they do is reflash the ECU with setting appropriate to the 380's. Personally I'd rather have a 17% with a tune on stock injectors, rather than a 17% with JCW 380's without a tune.

I'd either stick with the 17 on the stock ECU, or go with 450's and a tune. Also, 450's will allow you the flexibility to mod further if you so desire, the 380's will max out quick. 450's are easy to scale.

 

I did a 17%,and later added jcw380's and a tune...ran them untuned for a bit
...heck many dealers a installing jcw tunes on cars...makes for a cheap tune..
I am happy...car runs great.but ran good, 17% no tune,no injectors....just got 380's out pf an abundance of caution....then a tune...same thing...did not want to kill a $$$$cat.....
With a tune,i have 200+hp,morr tq down low, and better mpg!! And i KNOW the fuel/air mixture is good....so no stress or worries.
I do know many folks running 17% in newengland,no tune, no injectors....fine.but we do have 92-93 octane...94is mostly gonr due to sonoco shutting downtheir refinery.

 

Seriously though, in retrospect, I'd have used stock injectors until you could the tune, and then add 450's and a tune at the same time. The 450's are cheaper than the 380's and allow you room to grow. I don't thing you're gaining anything by running 380's untuned over stock injectors if the only other variable is a 17% pulley, at least not enough to justify the cost.

I don't want to sound critical--when I initially started modding my car, I went with 380's, with the JCW dealer ecu flash, and in retrospect I wish I'd done the 450's tuned, off the bat (which is what 's on my car now). But my car also has a BVH, header, and cam, and 380's won't cut it for that.

Just my 2 cents.

 

I met a guy at the Dragon who did the 17% pulley on an 06 MCS with 28k on it. He kept the stock injectors and stock tune and his MINI ran lean, blew a head gasket, warped his head and blew up his expansion tank. He sat in his rental car all weekend and had to pay to have his car towed to Helix in NJ. When I say it's cheaper to go with the 450 cc injectors and a tune it is this his experience I refer to. It was a sad and expensive trip for Ben. He is now getting a new RMW head, Cam, Injectors, Header and RMW tune. Not cheap but at least he is going to end up with a sweet ride in the end but I am sure he broke his budget.

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so then i guess i should stick with the 15%! I want to get a tune but later after i get the intake and exhaust and stuff on. I want to be able to run it safetly without a tune for a little so I dont think I am going to risk it with the 17%

 

Im pulling the supercharger off to refill all the fluids, should I be scared? Is there anywhere I can get new seals for it? The car has 112,453 miles on it

 

In all fairness, that car that had problems with the 17% pulley had more issues than just the pulley. There are many cars that run a 17% pulley, no tune, and get along just fine.

That being said, I'd do the 15% too, if you're planning on getting near the redline frequently. The 17's are also more prone to squealing and belt slippage, which you really don't hear much about on the 15%.

 

I have the 17%, untuned, and love it. I think it's fine as long as you don't get too many other mods in the mix. Then I'd get a tune. (I only have an intake besides.)

By the way, DTMR, I have a thread going on changing S/C oil. https://www.northamericanmotoring.co...y-s-c-oil.html

 

I ran a 17% with exhaust and intake for over a year. On stock injectors, tune and plugs. The car ran fine with no issues. You will be fine with the 17%.

 

Installed a ton of 17's with no tune and no injectors and they've been fine. If you do the math the boost isn't much different from a 15% pulley untill you get the RPMs up, and during normal driving the rpms most people don't rap the car out.
I would not blame the broken car at the dragon on the 17% pulley. I've seen blown head gaskets on stock S, and 15% pulley cars.

 

damn that is a lot of stuff i should consider changing!!!

 

Yeah, but keep in mind I'm trying to be as thorough as possible. I'm trying to get my car ready to be left alone with my girlfriend for 7 months while I'm away with the army. For someone who has the time to fix things as they come up, you might not need to be as forward thinking.

 

How much boost are you guys making at WOT with the 17% pulleys? I’m going to change the SC oil pretty soon, so I’ve been thinking about swamping the JCW pulley for a 17% pulley while I’ve got the SC off of the motor. Not sure the upgrade would be worth the trouble or money though. It’s making about 13psi boost right now….just wondering how much more boost and HP the 17% pulley will make. The JCW head is a little different than the stock MCS head, so the boost numbers will be a little lower since it flows a little better.



Also, with the 17% pulley are any of you guys getting any engine "pinging" on 91 fuel when the weather is hot and humid??