Ok so my friend was talking to a MINI service tech guy and he said that putting a new supercharger on a Cooper S would make the supercharger spin faster that it was designed for, and it would shatter the turbine. He even said hes seen that happen a lot. Is this true? My guess is that the ones he services for that problem have someting other than a 15% installed. i.e. a 17& or 19% or whatever. I only want to get a 15%, is there a worry of this happening?

 

Me-thinks the SA was trying to scare your friend into staying stock. If pulleys were making superchargers explode regularly, I'm sure NAM would be the first place to hear about it.

 

tThe JCW kit uses a 14ish% Pulley so obviously spinning the SC 1% faster isn't going to cause the shaft to shatter... and since when does steel "Shatter" . You would need to heat and shock cool the SC shaft many times to make it brittle enough to shatter. Sounds like more BS from someone that has absolutly no clue what they're talking about.

 

Thats what i figured. But as far as the JCW kit goes, it gets a new supercharger in addition to a 14.7%? pulley. But im not gonna be stopped from getting one.

 

That's true, but I wouldn't worry. Do you have any idea how many people on this board have a 15% pully. (I'd like to have dollar for every one). Me thinks Mr. Tech wanna be is full of poo.

 

No, the JCW kit is the EXACT same SC. On the early models, they swapped out the stock SC for one with ceramic coated vanes. As of 2005 every single MCS has the upgraded Gen 5 SC with the coated vanes. There's no doubt that spinning the SC 15% faster is going to reduce the life of the SC, It's not going to catastrophically fail at 12k miles though.

 

I did a quick search but didn't come up with it. I knew there was a thread that had the typical life of the s/c somewhere.

It was something like

Stock ~ 120,000 miles
JCW ~ 100,000 miles
15% ~ 90,000 miles
17% ~ 80,000 miles
19% ~ 70,000 miles

But don't quote me on those numbers

Anyone know which thread I am talking about?

 

The original JCW supercharger had a coating on the vanes that was not applied to the standard suerchargers, in addition to the smaller pulley. Beginning in late 04 the standard superchargers also received the coating. Except for the pulley size the JCW and standard superchargers are identical. Using a 19% pulley brings the supercharger closer to it's redline and may exceed it if the engine's redline is raised. More problematic however is possible cavitation in the engine cooling system (the water pump is driven by the supercharger) if the engine is run at high rpm for extended periods. That's why the 19% is not recommended for cars that are autocrossed or raced. In addition the 19% is more prone to throw or break belts due to it's smaller diameter and higher load. The 19% is more suited for cars that are mostly street driven, since it gives higher boost at lower rpm. From the posts I've read on here there don't seem to be any increased reliability issues with pullied superchargers but I would think they would wear faster since they run faster than standard. I've been reading about the pulleys for the last 5 years and I decided to go with 19% FWIW.

 

70,000 miles for a 19% pulley? Thats a little scary. I wonder how close that is to true. Seems like it would depend a ton on how you drove.

If swapping pulleys to a 15% saves me 20k miles it'd certainly be worth it!

 

I have just over 140,000 miles on my 03 and it is still running the original supercharger, and its had a 15% pulley for about the last 105,000 miles. I wouldn't worry about it!!.

Nik

 

Yeah i had read about the belt issue, but i didnt really know about the coating on 05+ superchargers. I have an 04 so i dont have the extra ceramic coating.

Good to know, thanks

 

Now thats more like what I want to hear!

I just bought my second used MINI, and it already has a 19% on. Although I'd prefere the 15% probably not worth the swap. Good to hear yours is having no issues though!

 

I did buy a new 05 supercharger and have it waiting in the garage, ready to go on when mine does decide to go.

Nik

 

115k miles on orginal supercharger, has had a pulley since 20k miles and still going strong

 

If what that tech said were true, then Deals Gap would have sounded like Baghdad this weekend...

 

In December '03 Helix installed a pulley hup with 15% outer. My car had about 35K miles at the time. In May of that year, I switched to a 19% outer section, which has been on the car ever since. Currently at 103K miles, same supercharger.

I change belts every 15-20K miles, but have never had one break nor have the belts I remove looked very bad.

I autocross frequently, and depending on the course I've never hesitated to run to the rev limiter or sit on it for a second or two. I'm using the GIAC flash, so the rev limiter kicks in at 7300rpm. The first event for this car was in October 2002. Since then, I've used it in about 150 events.

I wouldn't pick this combination for road course use, but it has served me well. It's not conclusive, but I can monitor both coolant temperature and oil temperature and I've never seen indications of water pump cavitation.

The issue is not the so much the pulley diameter as it is the dutycycle it is exposed to. The vast majority of my driving is below 3500rpm, typically more like 3000rpm. Even with the 19% pulley on my car, a more aggressive driver with a stock pulley who spends more time in traffic and reving up into the 4000+ range will probably wear out their supercharger (and the rest of the engine) well before I do.

Scott
90SM

 

Don't look now, Nik, but your SC is going to explode in 15,000 miles ago.

 

Aw hell, I knew that was going to happen.....

Nik