Why is it that everybody is going for the 15% pulley and not the 19%, well at least thats what i get from most of you guys, pardong me if this is a stupid question, i dont know to much about the mini cooper s engine.
so if you went with the 19% would you need to upgrade the injectorsetc? thanks guys.
im getting there slowly but surely.

 

it's in efficent cause it creates too much heat.....

 

Read the first question here:
http://store.webbmotorsports.com/ind...in_page=page_3

Jim

 

that makes alot of sence. thanks guys.

 

Like Tuls said, it creates more heat and is less efficent then if you were to run a 15% pulley. Also when you run a 19% pulley you will need to run bigger injectors to allow for more fuel to prevent from running to lean. Also with the bigger injectors, it is also suggested to run software tuning to get everything running smoothly. Another note is that if you plan on running the car on a track, autocross, or dragstrip, it is not recommended, i.e. builds up to much heat and more strain on the motor for those long durations! The key is to allow more air (boost) into the car, yet have the air as cool as possible! More heat is bad and you loose performance! Do a search for 19% pulley and you will get so much info on this topic!

Garrett

 

Malcon, there is info pro and con on the 19%, it is sort of like a religious question here on the forum. I think it depends on how you drive and what you want. Personally and again I say personally, I have the 19% with the JCW intake and injectors and I am very happy, great performance and NO problems. Good luck, choose your religion.

 

haha choose your religion. well ill have to do some more research. but yeah. thanks guys

 

Tuning is an art of compromise - for some the stock is OK, for a lot of people some nice tweaks are great, some others want the full tuning treatment and have the car as a spare and the disposable $$. It is a balance between what is possible and what you need.

In a lot fewer words: Horses for courses!

Good luck with your mods

 

The biggest issue is how do you use the car and how do you prefer to drive?

Heat / efficiency differences between the 15% and 19% pullies only really come into play at the very top of the rev range. Keep it below the last few hundred rpm and the 19% pully isn't spinning things any faster than the 15% is at redline.

I've used both on the same car with no other changes, and the 19% gives noticably greater torque in the engine speed ranges that most folks drive in on the street. For autocross, it isn't a concern with the possible exception of those with the redlines bumped up well above stock. The time spent at high rpm's is just seconds per run.

Running hard on a road course is a very different matter. In that fairly unique situation (unless you are seriously breaking the speed limit in the US or live in Germany) the engine typically spends far more time at very high revs. I personally wouldn't recommend a 19% pulley under those conditions unless long term durability isn't a big concern (dedicated race car) or some other measures are taken to deal with the heat.

For street use or autocross, if you are inclinded to put an aftermarket pulley on the car I would recommend the 19% if you retain a stock redline. With redline bumped up, JCW, 15% or 16% are probably better (more conservative) choices.

For me (lots of mild street miles combined with autocrosses a couple times a month Feb-Nov and no track time) the 19% is on to stay. The stock diameter and 15% pullies are now paperweights.

Scott
90SM

 

U guys that say it is inefficient how do you explain the people that have the 19% pulleys and are blowing by people with their overly conservative 15% pulleys. I guess you can call it what you want but 18+ lbs of boost versus just over 15 or something?? I wouldn't call it inefficient.

 

It maybe making more power, but if you run it long on track or autocross, it is going to create more heat and more heat means loss in power. when compared to running a 15% on a track or autocross, the 15% will perform more efficent and run better overal with those long periods.

Garrett

 

It's like on my Merkur (drove it this weekend) - it's a turbo car and the Garrett turbo used is of a specific size for drivability - spool up, etc. You can crank up the boost to a certain point (and cool the charge with an IC - none stock on the XR4Ti), but right after 20 psi or so, then the turbo is reaching the end of it's efficiency and is producing more heat than boost. One hot mod for the Merkur is to build a hybrid turbo with a same size exhaust side and different size compressor side turbine wheel. It moves the efficiency on that side upward so that you are producing boost and keeping the charge within your IC heat dissipation capacity. On MINIs the IC will eventually become a limiting factor in dissipating heat from the supercharger. You can address this through additional flow, a larger capacity IC or dry ice. Or move to Michigan!

In other words, with the 19% pulley you are moving to the upward limit on heat dissipation in steady state, high RPM uses. If you can't cool the air enough, your power gains will fall off. The 19% might be highly useful in other situations (autocross, normal street driving) but by it's nature it's stressing the rest of the system -- engine and IC cooling, oil cooling, wear on the SC blades and belt, etc, that much more.

 

You will get much more bang for your buck with a 19%, and it will be as safe as a 15% unless you spend lots of time at the RPM's redline

 

I could have not said it any better! Good post

Garrett

 

i more than likey will not be doing any auto X, and the redline will stay stock. but i do drive a little aggressive. hmm ill have to do more research, im kinda leaning to the 19% because i probably wouldnt be in the redline for more than what it takes when driving hard, no road tracks or autocross.

 

There is much info on this forum that talks about the 19%. Search and read! Best of luck!

Garrett

 

It seems like you are considering your options before you mod. Congratulations my friend - thinking is the first step in the successful mod!

(I think that 15% will be my choice, the car is just so quick stock!)

 

yeah for sure. thanks bud

 

I love my 19% so far (12000 miles) I hadn't had one problem with it. I drive my car very aggressive and haven’t experienced lag of any sort, belt slip or belt wear at all! I am not scared at all to run through the power band up to 7200 rpm in each gear(not so much 1st, no traction ). I had my belt off last weekend and it looked just as good as it did 12,000 miles ago. I love the down low torque and instant throttle response. Do understand though that with a 19% your warranty is pretty much void, but you may be able to fight it. I am looking forward to how my car is going to run this summer. Keep an open mind -- Johan

About the heat thing, this is my opinion. If you know that it's going to run hotter, take some steps to help cool! (Larger inter-cooler or perhaps h20 to air, larger injectors, cooler thermostat ect) Here is something that I don't understand yet either. There are people who say how inefficient the 19% is, but have to problem running a 15% and a 2% overdrive...

--anyway here is my latest dyno, with the 19%