I'm sure this has been talked about in the past but after doing some searching i found a couple answers to my question but they were not clear enough.

I have an 05 mcs w/ 65k miles on it. Well maintained with no issues. Currently im looking to buy either the 15% or the 17% pulley along with supporting mods including cold air intake, new plug wires, colder spark plugs, belt obviously, and doing that "oneball" mod on my stock exhaust.

From what i read the 15% pulley is the safest option while the 17% is not recommended for higher mileage engines... Now my question is will i have to purchase larger injectors/fuelpump/better intercooler in order to run the 17% pulley AND will it be harmful to the supercharger/engine/transmission if i do decide to go this route. Along with that is a retune MANDATORY with the 17% pulley or will the stock system be able to compensate fuel for the added air.

 

Either one is a safe mod. The 17% has a little more punch around town. It's not recommended if you do a lot if track time. It does cause a little more heatsoak than the 15%. I ran the 17% with CAI and exhaust on stock injectors, plugs and tune for more than a year with no issues. Any pulley will cause added wear on the supercharger but won't affect other drivetrain components. A better intercooler or meth injection will definetly help with heat soak but not a must do. And a custom tune will really help to pull all your mods together giving you the most performance from them. My mods with stock tune resulted in 175whp. Tuning it gave me 200whp.

 

I see, im leaning towards the 17% pulley now after doing a lot of reading...i am looking to change the intercooler for something better AND funnel the air to the IC a little better since i will be taking this little thing to the track quite a bit once all the mods are done.

 

There isn't really a better IC. the JCW is *slightly* better, but not enough to warrant choosing over water/meth, which will *significantly* lower your IAT, especially now that the JCW has doubled in cost.

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I was in the same boat as you..trying to figure out if I wanted to go from my stock JCW pulley up to a 15%, or 17% pulley. After some reading, I went for the 17% pulley. I don't track my car, and some extra boost down low and mid-range from the 17% pulley is what I'm looking for. I think a 15% or 17% pulley is good to go.

 

if you are going to track, id stay with the 15% the 17% will just create heat towards redline, then the ECU will pull timing since the intake charge is over 100 deg and youll lose power.

you will see more power out of the pulley if additional mods are done, such as a CAI and an exhaust, one ball is definently a cheap option, from what i have seen, doesnt flow much better. you will need the colder plugs, plug wires will be fine

for Intercooler upgrades, either get the GP, or the DOS coated, the DFIC doesnt work on the track nor does w2a. Meth injection will help the most, allowing running of the stock IC. The stock IC is one of the better IC's out there minus the GP. Easier to keep your money from upgrading this.

both the 17% and the 15% have been proven reliable, its the 19% where some issue have ensued, and thats with the waterpump. plus it creates even more heat

you wont need a tune will you throw larger than 380cc injectors in, but it would be more helpful. and if your going to the track, youll want that rear sway bar, and prolly better brakes =)

 

If you plan on doing a lot of track time with this car I'd stick with the 15%. It's safer when running the car at redline. There isn't really a hp difference between the two pullys. It just moves your power band a little. I had a friend who tuned his car the same time as me. He had a JCW with CAI and exhaust. Put up the same numbers as me. Though I think my power came in a little bit earlier than his. But his tq curve was flatter in the higher rpm's than mine was. He had the stock JCW pulley on his

 

Yea the agenda is as follows:
15 OR 17% pulley depending on what i choose..
one ball mod
CAI
plug wires
colder plugs
Intercooler
rear sway bar
front/rear strut tower bars
polyurethane front control arm bushings (because my stock ones are on their way out)
coilovers
wilwood brakes

as for fuel, when things start getting a little more serious and i swap out the supercharger for a bigger one later on down the road i plan on running E85 so i can run a higher timing map without all the risk of detonation BUT with E85 ill have to get larger injectors/fuel pump/new fuel lines that can support the higher alcohol content but this is most likely summer 2015...

 

Just want to verify 1 more thing: the 380cc injectors are not required when upgrading to the 17% pulley right?

 

they are not neccesary, since you plan on running e85, youll need the 550's anyways and then youll need the tune, unless you can find them at a deal, the stocks should be fine, there is a AFR graph somewhere on this forum showing the 380cc and the 330cc injectors with both the 15% and 17%, youll be high up in the injector capacity, but not dangerously lean

 

Alrighty cool. Ill be going to e85 next year, since i just got the car i have to take care of the basics then do the more advanced stuff later on

So for now the plan is to go with the 17% pulley and leave the stock injectors in there

 

Are you planning on taking your car to the track a lot?

If it was me and I had an extra $1000 laying around....I would ditch the new intercooler idea and spend that money on 380cc injectors and a custom tune by Jan at RMW. You are going to see a much larger benefit from a custom tune than an aftermarket IC. Everyone seems to talk about expensive aftermarket IC's, but for the most part....you never really see any data backing them up.

And unless you are going to be taking the car to the track all the time, I wouldn't waste the money on a big brake kit either...but that's just me

And no...you don't need 380cc injectors for a 17% pulley.......I'm planning on running stock injectors with my 17% pulley.

 

If you plan to track the car I wouldn't run a 17% with stock injectors. I probably wouldn't buy a 17% even if you don't track your car. These cars have enough problems as it is, I just don't see the reason to be adding the additional heat and further leaning out the a/f ratio over the 15% when the difference in performance between the two is negligible. The s/c on these cars is pushed well enough beyond its efficiency even with a 15%, and with a 17% you're actually losing power at redline. IMO if you want to do it properly, bigger injectors and tune should be budgeted for with either size.

 

I was just reading through a thread and supposedly the gains between the 15 and 17% pullleys is <5hp BUT supposedly with the 17% you get more of a midrange performance increase, i hate to sound like a flip flop but it looks like ill just end up going with the 15% pulley because the power gain is negligible and puts me at higher risk to damage the sc.


I swear, a turbo is SO MUCH EASIER..

 

there is no higher damage, you just loose a bit at the topend if you stay there frequently. plenty of poeple have the same reliability with the 17% as the 15%, its the 19% where you start to damage, wether that is the 17% SC pulley and the 2% overdrive crank or just the 19%.

the 17% will have higher low end and mid range due to the SC spinning faster and creating more boost

 

My main concern is mid to top end range, i dont care much for low end power especially since the car is FWD...

 

exactly, where the 15% would more valueable, the 17% wont do damage, it just doesnt run efficiently in top range, itll just create more heat than more boost which will make less power

 

SaltySalt, thank you sir!!

 

you are welcome! glad to help

 

The 17% will also be spinning the water pump faster than the 15%. If you plan to track your MINI that is something to consider. You may have problems with cooling. As has been said high RPM with stock injectors can be a big problem. Running lean at high RPM will kill an engine.

 

The 17% at redline CAN cause cavuation (bubbles) around the waterpump impeller due to the viscosity of the coolant and the design of the pump....it is just not made to run that fast...
A track person at redline usually sees this as a spike in oil temp..the coolant cools the oil with the stock cooler, in part, with a coolant/oil loop....cut off the coolant....oil temps spikes...tge cast iron block CAN absorb the heat for short bursts ok...but the choice of a 15% if you track the car is imo a better choice....also less chance of shredding the belt (bigger surface area on the sc pulley).
I did get a 17%....no tune, stock injectors to start...was fine like many folks...meet my driving style as a daily....but ended up going much further.
Most important, enjoy the car!!

 

I was wondering actually the effect it would have had on the water pump but that was answered ^. I do plan on autox and sometimes taking it on a road course but the majority of the time it will be a weekend car.

 

What about the 16%? Middle ground, best of both worlds?

 

thats what im doing on my 104k mini

 

6600 rpm at the motor = 15,995 rpm at the SC with a 15% pulley

6600 rpm at the motor = 16,380 rpm at the SC with a 17% pulley

6400 rpm at the motor = 15,884 rpm at the SC with a 17% pulley

So....how much time to you spend above 6400 rpm? That's the only time a 17% SC pulley is going to spin the SC any faster than a 15% pulley at peak rpms.

When you are on the gas, and going through the gears...you are only at that RPM for a split second. I'd rather have more boost and torque out of my motor at all other RPMs and forget about the time the 17% pulley is harder on the SC because it's turning more rpm's above 6400rpms.

Most of the time when I'm out playing around, I'll shift around 6000 rpms anyway....

I guess what I'm saying is that people make a huge deal about 15% vs 17%....unless you are racing your car on the track and running it up at redline all the time, get the 17% pulley. When you start talking about a 16% vs 17%...you are just splitting hairs.