R50/53 Pulley 15% or 17%?
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2nd Gear
Joined: Nov 2007
Posts: 80
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I think is clear. like afinley said, if you don't go over 6500-6600rpm you won't hurt the SC with the 17% pulley.
we can even say that is better for the SC if you have the 15-17-19 pulley and drive between 2000-4500rpm than if you have the stock pulley and go to 6900rpm. that will generate more heat and more revs on the SC.
we can even say that is better for the SC if you have the 15-17-19 pulley and drive between 2000-4500rpm than if you have the stock pulley and go to 6900rpm. that will generate more heat and more revs on the SC.
Last edited by luchini; Mar 1, 2008 at 04:44 PM.
6th Gear
Joined: Jun 2006
Posts: 4,166
Likes: 401
lemme toss a few data points into this discussion, and thanks for all the interesting reading thus far!
1. i'm running a jcw setup, which has the limiter at 6,850 i believe
2. i have 94,000 miles and no detectable problems - the car was just cleared by both Turner Motorsport and Mini Peabody for the '08 season - subjectively it feels as healthy as ever
3. the car has run about 48 autocross events, four seasons at 10-12 events a year
4. i datalog the autocross runs
5. with the '04 tall 2nd gear only a fast (read > 60mph) course puts the car over 6,000 rpms
6. we do run about 5 fast courses a year, and I have hit the rev limiter once or twice, and at that venue routinely run > 6,000 in the fast sections
7. all of that having been said, I would estimate that the car has spent between one and two minutes in the 6,500 rpm vicinity in it's entire life!
8. that's 5 fast races, with two fast section/race, with an average of 3 seconds at peak speed in each section --> 30 seconds a year!
9. except during competition, I very rarely change up any higher that 5,000 rpm, and never approach 6,000 - there is just no call for it on the street
This is the argument I use to ward off the evil ju-ju of supercharger failure (or indeed any major drivetrain failure) and keep my hope alive that I can run the car well over 100,000 miles reliably.
We'll see.
How much time do you folks spend > 6,000 rpm in a day? a week? Am I the only wuss out here that stays away from the redline on the street?
But to finally bloody get to the point of the thread, I guess I'm saying that the way the car is driven would to me be a critical factor in determining what a safe pulley selection would be.
1. i'm running a jcw setup, which has the limiter at 6,850 i believe
2. i have 94,000 miles and no detectable problems - the car was just cleared by both Turner Motorsport and Mini Peabody for the '08 season - subjectively it feels as healthy as ever
3. the car has run about 48 autocross events, four seasons at 10-12 events a year
4. i datalog the autocross runs
5. with the '04 tall 2nd gear only a fast (read > 60mph) course puts the car over 6,000 rpms
6. we do run about 5 fast courses a year, and I have hit the rev limiter once or twice, and at that venue routinely run > 6,000 in the fast sections
7. all of that having been said, I would estimate that the car has spent between one and two minutes in the 6,500 rpm vicinity in it's entire life!
8. that's 5 fast races, with two fast section/race, with an average of 3 seconds at peak speed in each section --> 30 seconds a year!
9. except during competition, I very rarely change up any higher that 5,000 rpm, and never approach 6,000 - there is just no call for it on the street
This is the argument I use to ward off the evil ju-ju of supercharger failure (or indeed any major drivetrain failure) and keep my hope alive that I can run the car well over 100,000 miles reliably.
We'll see.
How much time do you folks spend > 6,000 rpm in a day? a week? Am I the only wuss out here that stays away from the redline on the street?
But to finally bloody get to the point of the thread, I guess I'm saying that the way the car is driven would to me be a critical factor in determining what a safe pulley selection would be.
lemme toss a few data points into this discussion, and thanks for all the interesting reading thus far!
1. i'm running a jcw setup, which has the limiter at 6,850 i believe
2. i have 94,000 miles and no detectable problems - the car was just cleared by both Turner Motorsport and Mini Peabody for the '08 season - subjectively it feels as healthy as ever
3. the car has run about 48 autocross events, four seasons at 10-12 events a year
4. i datalog the autocross runs
5. with the '04 tall 2nd gear only a fast (read > 60mph) course puts the car over 6,000 rpms
6. we do run about 5 fast courses a year, and I have hit the rev limiter once or twice, and at that venue routinely run > 6,000 in the fast sections
7. all of that having been said, I would estimate that the car has spent between one and two minutes in the 6,500 rpm vicinity in it's entire life!
8. that's 5 fast races, with two fast section/race, with an average of 3 seconds at peak speed in each section --> 30 seconds a year!
9. except during competition, I very rarely change up any higher that 5,000 rpm, and never approach 6,000 - there is just no call for it on the street
This is the argument I use to ward off the evil ju-ju of supercharger failure (or indeed any major drivetrain failure) and keep my hope alive that I can run the car well over 100,000 miles reliably.
We'll see.
How much time do you folks spend > 6,000 rpm in a day? a week? Am I the only wuss out here that stays away from the redline on the street?
But to finally bloody get to the point of the thread, I guess I'm saying that the way the car is driven would to me be a critical factor in determining what a safe pulley selection would be.
1. i'm running a jcw setup, which has the limiter at 6,850 i believe
2. i have 94,000 miles and no detectable problems - the car was just cleared by both Turner Motorsport and Mini Peabody for the '08 season - subjectively it feels as healthy as ever
3. the car has run about 48 autocross events, four seasons at 10-12 events a year
4. i datalog the autocross runs
5. with the '04 tall 2nd gear only a fast (read > 60mph) course puts the car over 6,000 rpms
6. we do run about 5 fast courses a year, and I have hit the rev limiter once or twice, and at that venue routinely run > 6,000 in the fast sections
7. all of that having been said, I would estimate that the car has spent between one and two minutes in the 6,500 rpm vicinity in it's entire life!
8. that's 5 fast races, with two fast section/race, with an average of 3 seconds at peak speed in each section --> 30 seconds a year!
9. except during competition, I very rarely change up any higher that 5,000 rpm, and never approach 6,000 - there is just no call for it on the street
This is the argument I use to ward off the evil ju-ju of supercharger failure (or indeed any major drivetrain failure) and keep my hope alive that I can run the car well over 100,000 miles reliably.
We'll see.
How much time do you folks spend > 6,000 rpm in a day? a week? Am I the only wuss out here that stays away from the redline on the street?
But to finally bloody get to the point of the thread, I guess I'm saying that the way the car is driven would to me be a critical factor in determining what a safe pulley selection would be.
like.. 4-5 times a month... if that
Thread Starter
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2nd Gear
Joined: Nov 2007
Posts: 80
Likes: 0
lemme toss a few data points into this discussion, and thanks for all the interesting reading thus far!
1. i'm running a jcw setup, which has the limiter at 6,850 i believe
2. i have 94,000 miles and no detectable problems - the car was just cleared by both Turner Motorsport and Mini Peabody for the '08 season - subjectively it feels as healthy as ever
3. the car has run about 48 autocross events, four seasons at 10-12 events a year
4. i datalog the autocross runs
5. with the '04 tall 2nd gear only a fast (read > 60mph) course puts the car over 6,000 rpms
6. we do run about 5 fast courses a year, and I have hit the rev limiter once or twice, and at that venue routinely run > 6,000 in the fast sections
7. all of that having been said, I would estimate that the car has spent between one and two minutes in the 6,500 rpm vicinity in it's entire life!
8. that's 5 fast races, with two fast section/race, with an average of 3 seconds at peak speed in each section --> 30 seconds a year!
9. except during competition, I very rarely change up any higher that 5,000 rpm, and never approach 6,000 - there is just no call for it on the street
This is the argument I use to ward off the evil ju-ju of supercharger failure (or indeed any major drivetrain failure) and keep my hope alive that I can run the car well over 100,000 miles reliably.
We'll see.
How much time do you folks spend > 6,000 rpm in a day? a week? Am I the only wuss out here that stays away from the redline on the street?
But to finally bloody get to the point of the thread, I guess I'm saying that the way the car is driven would to me be a critical factor in determining what a safe pulley selection would be.
1. i'm running a jcw setup, which has the limiter at 6,850 i believe
2. i have 94,000 miles and no detectable problems - the car was just cleared by both Turner Motorsport and Mini Peabody for the '08 season - subjectively it feels as healthy as ever
3. the car has run about 48 autocross events, four seasons at 10-12 events a year
4. i datalog the autocross runs
5. with the '04 tall 2nd gear only a fast (read > 60mph) course puts the car over 6,000 rpms
6. we do run about 5 fast courses a year, and I have hit the rev limiter once or twice, and at that venue routinely run > 6,000 in the fast sections
7. all of that having been said, I would estimate that the car has spent between one and two minutes in the 6,500 rpm vicinity in it's entire life!
8. that's 5 fast races, with two fast section/race, with an average of 3 seconds at peak speed in each section --> 30 seconds a year!
9. except during competition, I very rarely change up any higher that 5,000 rpm, and never approach 6,000 - there is just no call for it on the street
This is the argument I use to ward off the evil ju-ju of supercharger failure (or indeed any major drivetrain failure) and keep my hope alive that I can run the car well over 100,000 miles reliably.
We'll see.
How much time do you folks spend > 6,000 rpm in a day? a week? Am I the only wuss out here that stays away from the redline on the street?
But to finally bloody get to the point of the thread, I guess I'm saying that the way the car is driven would to me be a critical factor in determining what a safe pulley selection would be.
1st Gear
Joined: Jan 2008
Posts: 30
Likes: 0
From: Philly area.
I for one have intake, exhaust, suspension, tire and wheel mods with a 15% pulley. I use the car daily but would like to hit the track again do a few auto crosses this year.
Changing the intake and exhaust made a little difference in performance.
BUT Getting rid of the stock run-flats and wheels, replacing them with Tean Dynamic wheels and Falken AZENIS RT-615 tires...AND adding the 15% pulley were two of the most instantly noticeable mods, no doubt about it.
We have MINI Coopers, they are great, but they are MINIs, keeping them alive and well is a good thing...remember that nearly everything in our machines is somehow connected/related/effected by something else.
More power means more stress on nearly everything...what about the alternator, SC, engine mounts/brackets, valves, CV joints, oil, etc...
Jeez, just thinking about what I've done makes me want to apologize to the car...oh it's a car
, but it seems to be having more fun than ever !!!
Changing the intake and exhaust made a little difference in performance.
BUT Getting rid of the stock run-flats and wheels, replacing them with Tean Dynamic wheels and Falken AZENIS RT-615 tires...AND adding the 15% pulley were two of the most instantly noticeable mods, no doubt about it.
We have MINI Coopers, they are great, but they are MINIs, keeping them alive and well is a good thing...remember that nearly everything in our machines is somehow connected/related/effected by something else.
More power means more stress on nearly everything...what about the alternator, SC, engine mounts/brackets, valves, CV joints, oil, etc...
Jeez, just thinking about what I've done makes me want to apologize to the car...oh it's a car
, but it seems to be having more fun than ever !!!
I don't remember the numbers (they are in some long-forgotten threads), but I remember reading that a 15% reduction pulley does NOT mean 15% increase in SC RPM -- the number is slightly higher . . . maybe around 17% additional load on the SC? (I'll have to dig that thread up, unless someone happens to know the numbers).
I just mention this 'cause, technically, just using 15% to calculate the redline limits is not exactly accurate.
I just mention this 'cause, technically, just using 15% to calculate the redline limits is not exactly accurate.
6th Gear
Joined: Jan 2007
Posts: 3,362
Likes: 1
From: Winston-Salem, NC
15% if you are going to run the car a lot at high RPMs such as track or canyon carving. 17%-19% for more low end go such as drag racing, stop light runs and such. Not sustained high RPM runs. The way I understand it is that the smaller pullies build more heat quicker and reduce the thermal efficiency to a point that the gain in air flow is lost on longer runs. Just my 2 cents.
2nd Gear
Joined: Feb 2008
Posts: 86
Likes: 0
From: Raleigh, NC
Well, I spent a chunk of my morning looking more into this. I am waiting to hear back from Eaton on what the maximum shaft speed is on our chargers, and what the limiting factor is.
There is a thermal effeciency range, and there is a maximum shaft speed, and they aren't the same thing. They do have maps on their site, and I do think that the higher reduction pulleys do start to walk off the maps.
What concerns me is shaft speed. The gears are not oiled or cooled, so exceeding the SP is not a good idea. The idea that overspeeding something "for awhile" is ok, is silly. if your car had a 14000rpm redline, would you think you could overdo it every now and then if you didnt do it all the time? Now, think of the same scenario, only with no oil in your car.
because of the helix gears, my guess is that that maximum shaft speed is because of balance and stiffness issues. the thought of the supercharger worm gears polishing each other into my motor isnt a good thing for me.
but before I make up my mind, Ill wait to hear back from the people who know, and I'll keep you posted.
There is a thermal effeciency range, and there is a maximum shaft speed, and they aren't the same thing. They do have maps on their site, and I do think that the higher reduction pulleys do start to walk off the maps.
What concerns me is shaft speed. The gears are not oiled or cooled, so exceeding the SP is not a good idea. The idea that overspeeding something "for awhile" is ok, is silly. if your car had a 14000rpm redline, would you think you could overdo it every now and then if you didnt do it all the time? Now, think of the same scenario, only with no oil in your car.
because of the helix gears, my guess is that that maximum shaft speed is because of balance and stiffness issues. the thought of the supercharger worm gears polishing each other into my motor isnt a good thing for me.
but before I make up my mind, Ill wait to hear back from the people who know, and I'll keep you posted.
but I remember reading that a 15% reduction pulley does NOT mean 15% increase in SC RPM -- the number is slightly higher . . . maybe around 17% additional load on the SC? (I'll have to dig that thread up, unless someone happens to know the numbers).
https://www.northamericanmotoring.co...ight=reduction
see posts like # 7:
If you consider belt effect, (15% pulley = 17.65% SC overdrive)
(17% pulley = 20.48% SC overdrive)
(17% pulley = 20.48% SC overdrive)
Last edited by eager2own; Mar 3, 2008 at 12:31 PM.
5th Gear
Joined: Feb 2007
Posts: 658
Likes: 0
From: Denver, Colorado
The MINI's roots style S/C with the stock pulley creates a 7-8PSI boost level. With a 15% reduction pulley it raises the boost level from 8PSI to about 11PSI. With just that small increase of boost you will have about 15-20HP gain. From all the research i've done the 15% reduction is the most productive. Although the 17% and 19% create a higher boost level the air is a lot hotter and is some what counter productive. (When you compress air witch is what the S/C does it warms up). also a 17% or 19% increases your risk of over spooling your S/C. If you have any questions please call me. 720-878-5485
Last edited by tommy_zito; Apr 3, 2008 at 07:38 PM.
6th Gear
Joined: Aug 2005
Posts: 3,902
Likes: 2
From: SoCaL (Agoura Hills)
The MINI's roots style S/C with the stock pulley creates a 7-8PSI boost level. With a 15% reduction pulley it raises the boost level from 8PSI to about 11PSI. With just that small increase of boost you will have about 15-20HP gain. From all the research i've done the 15% reduction is the most productive. Although the 17% and 19% create a higher boost level the air is a lot hotter and is some what counter productive. (When you compress air witch is what the S/C does it warms up). also a 17% or 19% increases your risk of over spooling your S/C. If you have any questions please call me. 720-878-5485
.
5th Gear
Joined: Feb 2007
Posts: 658
Likes: 0
From: Denver, Colorado
i was on the phone with MINI today and the JCW pulley is somthing like 14.3%. thats straight from the service advisor...but you never know!
2nd Gear
Joined: Feb 2008
Posts: 86
Likes: 0
From: Raleigh, NC
the 16krpm number, to me at least, is bulletproof. the 10% number, alot of speculation.
the one piece of info i did not get from Eaton was what the factor for the max shaft speed is. if it starts shucking teflon, there isnt a way around that. if it has balance issues, i dont know either.
a thought though, is that the JCW also comes with a different charger. once i know why the limit on the SC is what it is, we may be able to see that the JCW charger has somehow improved on that.
6th Gear
Joined: Aug 2005
Posts: 3,902
Likes: 2
From: SoCaL (Agoura Hills)
thought about that too, plus the higher redline.
the 16krpm number, to me at least, is bulletproof. the 10% number, alot of speculation.
the one piece of info i did not get from Eaton was what the factor for the max shaft speed is. if it starts shucking teflon, there isnt a way around that. if it has balance issues, i dont know either.
a thought though, is that the JCW also comes with a different charger. once i know why the limit on the SC is what it is, we may be able to see that the JCW charger has somehow improved on that.
the 16krpm number, to me at least, is bulletproof. the 10% number, alot of speculation.
the one piece of info i did not get from Eaton was what the factor for the max shaft speed is. if it starts shucking teflon, there isnt a way around that. if it has balance issues, i dont know either.
a thought though, is that the JCW also comes with a different charger. once i know why the limit on the SC is what it is, we may be able to see that the JCW charger has somehow improved on that.
.
2nd Gear
Joined: Feb 2008
Posts: 86
Likes: 0
From: Raleigh, NC
well, just FYI: i quoted the email in another thread. i asked for the maximum shaft speed of a 3rd gen m45. the answer was 16k.
after some more reading tonite, i have my doubts that we have 3rd gen chargers (which is something i got off mini2) seeing that Eaton only has info for 5th gen on their site.
and after more reading while im writing this:
16k isnt even on the map, and it ends at 40% eff @ 15500
i guess my answer from Eaton only left me with more questions. They were really fast getting back with me today. I've got a class to teach in the morning, but i will email them again right after that, and hope for an answer before the weekend.
after some more reading tonite, i have my doubts that we have 3rd gen chargers (which is something i got off mini2) seeing that Eaton only has info for 5th gen on their site.
and after more reading while im writing this:
16k isnt even on the map, and it ends at 40% eff @ 15500
i guess my answer from Eaton only left me with more questions. They were really fast getting back with me today. I've got a class to teach in the morning, but i will email them again right after that, and hope for an answer before the weekend.
Let's not lose sight of the fact that there are a few different questions in play here:
1) At what RPM are you likely to damage or significantly shorten the useful life of your SC, if you reach that RPM for even a single brief period?
2) What's the "duty cycle" of the SC near this limit... what percentage of the time could you run at 99% of that limit (or 95%, or 90%) with similar consequences?
3) What's the *real* difference in longevity of the SC when run at or beyond these limits using, say, a 15% pulley, vs. the stock or JCW pulleys? Does the SC or the gearbox die 10% earlier? 20%? 50%? the day that you hit the high RPM? (I don't think that last one is what happens.) While question 1 above might be relatively easy to answer (with proper testing) and question 2 is "answerable" (though more complex), this question is pretty hairy, because of the infinite variability of real-world driving conditions and styles... As we've witnessed, LOTS of people have put a good number of miles on 15% pullied cars - while there are some SC failures out there (some of them on stock pulleys), I haven't seen any data that correlates real world failures to pulleys installed and miles driven... nor have I seen enough anecdotal evidence to guesstimate a trend... I'm not suggesting that we're not putting more stress on our SCs... only that, in the grand scheme of things, it may not matter, regardless of what the specs say (and believe me, I'm into specs). Otherwise I think we'd see SC's grenading all over the place, with all the pullied cars being driven at track days...
4) While efficiency and air heating are important, they're related to an entirely different question IMHO... what's the typical RPM performance profile for a particular driver, given their driving style? i.e. if I'm going for mid-range torque on the street, I may be willing to sacrifice optimal top-end performance which would be important to a different person on the track.
1) At what RPM are you likely to damage or significantly shorten the useful life of your SC, if you reach that RPM for even a single brief period?
2) What's the "duty cycle" of the SC near this limit... what percentage of the time could you run at 99% of that limit (or 95%, or 90%) with similar consequences?
3) What's the *real* difference in longevity of the SC when run at or beyond these limits using, say, a 15% pulley, vs. the stock or JCW pulleys? Does the SC or the gearbox die 10% earlier? 20%? 50%? the day that you hit the high RPM? (I don't think that last one is what happens.) While question 1 above might be relatively easy to answer (with proper testing) and question 2 is "answerable" (though more complex), this question is pretty hairy, because of the infinite variability of real-world driving conditions and styles... As we've witnessed, LOTS of people have put a good number of miles on 15% pullied cars - while there are some SC failures out there (some of them on stock pulleys), I haven't seen any data that correlates real world failures to pulleys installed and miles driven... nor have I seen enough anecdotal evidence to guesstimate a trend... I'm not suggesting that we're not putting more stress on our SCs... only that, in the grand scheme of things, it may not matter, regardless of what the specs say (and believe me, I'm into specs). Otherwise I think we'd see SC's grenading all over the place, with all the pullied cars being driven at track days...
4) While efficiency and air heating are important, they're related to an entirely different question IMHO... what's the typical RPM performance profile for a particular driver, given their driving style? i.e. if I'm going for mid-range torque on the street, I may be willing to sacrifice optimal top-end performance which would be important to a different person on the track.
5th Gear
Joined: Nov 2007
Posts: 723
Likes: 0
From: Jeddah, Saudi Arabia
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6th Gear
Joined: Jun 2006
Posts: 4,166
Likes: 401
can anyone point me at such a thread? i'm tempted to title a new thread and see if any reports of such failures turn up...
If you use google and do this search:
supercharger failure site:www.northamericanmotoring.com
you can find some things to read.
supercharger failure site:www.northamericanmotoring.com
you can find some things to read.