Hi guys.

I was thinking what size of pulley I should get.

Problems I've heard is that 19% pulley are giving so much heat to the air it compresses that actually you will get lower boost based on heat of the air and pressure, but 15% pulley will give more boost than stock but affordable heat so you end up with a bit more boost without heating the air to much.

Well, I live in Iceland, and tempratures we are getting are like -5°C / +5°C at winter time, and maby +2°C / +15°C at summertime.

That will give me colder air temprature than usual so maybe I will gain a bit more power on normal days, but on cold days I will gain a lot. And even when on track I will use Water spray 2 Intercooler so It will be even colder.

Good reason for taking 19% ??

 

I've read that 19% over heats if you drive it long on high RPMS such as on a track and autocrossing. So if your using it as a daily driver it should be fine, and it's a big plus with your temps. Once you get the 19% pulley, you can always add insurance with colder spark plugs, a cold air intake and etc. If you are hesitant about it, you can always go in the middle and get the 17%.

BTW I installed my 17% Pulley over the weekend along with my CAI. All I can say is wow. What a difference. The sound is exhilarating. When my mechanic test drove my car with me as a the passenger. I was practically laughing. When I drove it back to the shop, I was smiling. When I drove my friend, he was laughing. Then when he test drove it, he was giggling like a little girl. The whine is super loud, and at low RPMS the engine sounds mild and has a great whistling sound when you press and depress the gas pedal. But when you step on it, it sounds like "a thousand babies on fire screaming." Sunday morning, my girlfriend told me I woke her up in the middle of the night because I was shouting and making a weird noise that sounded a lot like the super charger whine. Had a good laugh about that one. THAT's how much of a difference the pulley and CAI made.

 

Wow, thanks for that great answer.



Think I'll take 19%, I have already got the car mapped from a guy from the MINI factory and have K&N Air filter (Cone).

 

Yep......only problem with the 19% is the life expectantacy of the SC and water pump at high RPM's. As long as you don't spend much time above 6000rpm you will notice a good deal of boost at lower rpms.

 

I have a 15%. I would have gone with the 17% BUT I live in south Texas where 100degree days are common. Go with the 17%

 

There hasn't been any proof that a 19% pulley effect the life expectancy of the super charger. It all depends on how your driving style is.

 

I track my MINI with a 19% and never have had s/c or belt issues tho my waterpump is starting to give at 50k

 

80000 MILES, 19%, daily driver, NO ISSUES. Pulley has been on since 20000 miles.

 

The buzz about 19% smaller pullies is that when you rev your engine up to redline, (especially in cars where aftermarket software flashes have raised the engine's factory redline), the supercharger is now spinning faster than its' recommended redline.

How many RPM's faster? I don't know if it is 2 or 2000, but it basically means that you're probably pressing your luck with the supercharger. Excess heat build-up, and potential shortening of its' lifespan is what is possible. The water pump is also therefore spinning faster than it is meant to, as well, leading to "cavitation". A fancy word that only engineers know. All I know, is that it sound like it's a vibrating, and A BAD THING.

But again, the real trouble presents itself if you make your car hit (and stay near) redline all the time, like on the track, I'd imagine.

That is why I'm surprised MINICORSA has never had any issues. May you keep your good luck, MINICORSA!

 

I went with the 17% pulley. After allot of reading that was the best choice of me. My Mini is a dally driver and I felt like the 19% would put to much strain on the supercharger, but I will defer to the people that have installed the 19% to tell you what they thank.
I can tell you I agree with MrCooperS about the 17% pulley. My wife refuses to ride with me now, and she has told me she can hear the car a block away.
Good luck

 

To some extent with the 17% pulley and to a much larger extent the 19% pulley you are exceeding the effective capacity of the blower and actually loosing boost as you approach redline. You will not run into this problem with a 15% pulley. That said, the 17 and 19% pullies will give you more boost (and power) up to that point of declining returns. I live between 4000 and 7800 rpm so I went with the 15% pulley. If you generally drive below 4000 rpm, you could safely go with the smaller pullies and get more horses at those lower Rs.

 

With my 17% I pull waaay past 4000 RPM waaaay too fast.

For a heads up, to fully utilize a 17% efficiently, one should always have colder spark plugs in mind as the next upgrade.

 

I fully trust Randy Webb who after significant effort determined that anything more than 15% is a waste. At those boosts the temperature rise starts eclipsing the than the pressure which actually reduces the charge. Why risk blowing the warranty for no gain?

 

IIRC, Randy had issues with breaking belts with the 19%. There may have been other rationale, but as a track rat he definitely preferred the 15% (and he's a guy who should know!)

 

Thanks a lot for all those replies.

I will go for 17%, and upgrade belt once a year.

I am thinking of making some cooling upgrades later on, but as I say, I will make my own intercooler water spray nozzle or nitro spray

 

Make sure you get a new belt along with that pulley. The pulley is smaller and will require a smaller belt. Also it's just cheap insurance.

 

And a tensioner stop!

 

Of corse I will take the smaller belt also.

Will just make my own tension stopper

 

I've had a 15% for about 70K km and loved it.

I then switched to a 19% because I don't take my car to a racetrack and drive "gently" on the street... I never go above 5-6000 RPM. I was looking for low-end torque and the 19% delivers it! I did some other mods to make sure it would be "safer" such as colder spark plugs and aftermarket intercooler. I have over 40K km on my 19% and everything is fine.

Just make sure you get a good belt to match the pulley's smaller diameter and you should be fine.

 

I noticed you did the same tranny upgrade as I did. Does your cruise control still work?

 

I'm in the process of a 15% reduction install. My mechanic says it's the safe bet w/ extra giddy-up.

 

Surely this can't be true, the 19% pulley is the devil!! (no pun intended)

Would you advise against tracking my car in South Florida with a 19% pulley? Stock intercooler, all I have are really cold plugs, an intake and the DT tensioner cable in case the belt snaps

 

19% FTW! Just get it tuned for it and add some injectors. Im at 224 WHP and 200 FLB with rmw cam and tune and my peak power is at 6400 rpms. AWSOME SON!

 

But, I was wondering, how high could you raise the rev limit on the stock head running a 15% pulley? Would the extra revs be better than the slightly higher torque from the 19% pulley??

 

The power and tq curves for either pulley will be about the same.......except that the 19% will have the power/tq start at a lower rpm but fade off at higher rpm's.

RMW safely raises the 15% pulley rev limit to I believe 7300 rpm with stock head.