...and please keep it coming!

It looks like we have quite a few people who throwing caution into the wind are living happily with the 19%.

The reason i opened this thread is that in miata-land (where i came from) the *rules* changed as people pushed the boundaries further and further. 5 years ago, few people would have thought that the miata would handle the huge turbo's & SC's that people are strapping on today. I am sure that there will be a learning curve and comfort level here as well.

It's starting to really look like the 19% just isn't the devil-spawn that it was originally thought to be. I really like the idea of all the low speed torque. I will not track my MINI (tried it in the miata, wasn't for me) and my autocross events are few and far between. It will be a street car, and torque on the street is where the fun is.

I do like the idea of a 15/4% or 17/2% combo, of course, it's more money! But, you do get the benefits of the lightweight crank pulley (without the hassle of doing a lightweight flywheel) If i were to go that route, I think the 17/2% is what i would look at, keep the accessories only a *little* over-driven.

As for the redline & the SC rev limit, i am seeing a lot of different numbers on that. My own driving style is not one to really beat on the limiter day-in, day-out. With the miata i typically shift in the 4500-6000 range, in the meat of the power band. So, i don't think that is as much of an issue for me.

Also, if randy is now offering his warrantee on 15/2% combos, they have to be fairly safe, no? So, that gets around the belt issues, but does kind of state "Hey, the SC is ok with the 17% speed bump".

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For those of you who haven't yet, can you add a few things to make this thread complete:

•*Do you have pulley alone, or supporting mods (specifically injectors and software)

•*if you went from pulley alone to the injectors & software, how was that change?

•*What specific belt are you having the best luck with?

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Thank you all for your input, even the JCW Flag waving...knew we would get someone!

-jac

 

Fishbulb carefully read the post by k-huevo, he has it right. There is alot of rehashed bull by alot of people that dont have a logical leg to stand on. I do love the controversy that this issue raises. it is wonderful to hear individuals support their choice with misplaced logic and lack of common sense.

It is a shame that this passion for discussion does not result in positive suggestions to assist you in the enjoyment of whatever choice you make.

Read it all, digest it all, and make your decision. Remember that there can not be a wrong decision, they are all right depending on your set and weight of parameters.

 

I think I'll keep my 19% and the stock crank pulley. Even if I pay $20 for a new belt every year, that's cheaper than buying a crank pulley. :smile:

Any mod you do has the potential of doing long term damage, but IMHO, the 19% is great for what it is.

 

is the 19% reduction pully really closer to a 20 % or is it 19.4% or smaller, just curious with all this discussion.. and is the 15% a 15.0% or something else,,, I understand the JCW is really more of a 14% pully based on rounding...

 

Here's an interesting little snippet from the Bosch Automotive Handbook about pulleys. For a standard 6-rib DIN 7687, the effective diameter is the diameter of the pulley peaks plus 3.2 mm (0.126" for you sliderule types ). This of course applies to both the drive and the driven pulleys.

So, stock:

(5.460+0.126)/(2.58+0.126)=
5.586/2.706 = 2.06

This matches up nicely with the MINI tech documents, which state that the supercharger turns 2.06 times engine speed.

Not taking into account belt slippage, these are what the relative increase in supercharger speeds should be based on measurements done by myself and others:

stock: 0% (duh!)
jcw: 15.8%
p&d "15%": 16.8%
p&d "17%": 19.4%
p&d "19%": 23.2%

 

I find that my 19% works just fine and has for about 20K ....no...NO...issues and i drive pretty hard. It seems that the people who use it are in favor and those who criticize have never had it on their car. I do know of people with 15% who have lost belts

 

Hmm...that is a going point there as well. between my miata & subaru, i don't even do 10K a year. One yearly belt change, everyone is happy!

I still need to get up to your neck of the woods and have that displayed for me!

thanks for the input!

-jac

 

I had another question concerning this very issue, as I plan on a pulley once the Mini is in my hands.
What effect if any does the climate you live in act on the overdriven SC?
Such as living in Florida where its hot and humid most of the year. Does the SC being over driven get even hotter in these hot climates? Causing even more of an issue?

 

The 19% pulley in hot weather has pros and cons. On the one hand, when you wind out toward redline, the supercharger is making an awful lot of heat and performance suffers as a result, especially in hot weather. On the other hand, performance suffers anyway in hot weather, and it's nice having that extra boost at lower rpm to alleviate some of that bog feeling you get while leaving a stoplight or tollbooth at part throttle in hot weather. I personally wouldn't worry too much about damage from the 19% compared to the 15% or even compared to stock. There has to be millions of combined miles with aftermarket pulleys (plenty of them with 19%) on this board and reports of engine failures of any kind are rare, let alone ones directly attributable to the pulley.

 

i can not find any reason not to run a 4% crank pulley verses a stock diameter aluminum crank pulley, if you run your engine at 3000 rpm or 6000 rpm everything is running faster at 6000, right? so if redline is at 6900 and then raised to 7200 via ecu, are the accessories running faster? i think so. how about someone do some calcs and figure boost using 19% and a 4% crank pulley. it seems the twin charge setups are ok at 21 psi without to many issues. i bring this up as i have put together a combo using the following components:
cai
15% sc pulley
4% crank pulley
ported head with oversized valves
cam
380 injectors
ic diverter
obx header
magna flow exhaust
mth software
i think this will result in 200whp easily, not bad for $4000.00 the car will get the head and crank pulley in nov, still driving and having a ball.

 

trying for 21psi with the sc is to experience diminishing returns due to rapid heat build-up by a Roots blower spinning that fast. the addition of the turbo gets around this and in fact, you can run an oversize sc pulley to draw less engine hp and shift even more of the load to the cooler turbo

 

Quite a few folks in Hawaii have 19% pulleys w/o issue. For those that run autocross and track --routine belt replacement seems to prevent issues. I have had 19% for over 2 yrs and do monthly track days (short 20 minute runs) & autocross w/o any problems. I've replaced belt twice since original 0535 belt installed by Helix & now replace my belt every 6-8 months if i've tracked the car a lot.

We've seen belts break on cars with 16% pulley & crankpulley's.

 

i agree with that, i am curious what 19% sc and 4% crank pulley will produce in boost, i do not think it will hit 20 psi. is this a realistic combo? my intentions are 15% and 4%. if this is not enough i will consider twin charge with oversize sc pulley as you mention.

 

It won't do 20 psi? Come watch my boost gauge sometime.

 

Personally, i am planning on doing the 17%/2% crank pulleys. I may consider the 15%/2% also. I like the idea of the lightened crank and 19% overdrive is fine in my book!!!

 

Why not just compromise and do a 17%? it should be 'safer' than a nineteen but still produce more boost that a 15%. thats my plan anyways... with a 15% sc pulley and a 2% crank pulley the cost is double plus your putting extra wear on the other componets in the belt system, altanator, etc. :impatient

 

not all people want to compromise, the vendors sell them, buy it
Howcome I have never seen anyone come on here complaining about all these "potential problems" actually happening to their cars. Cuz the stuff doesn't happen??
oh but it must happen u proved it on paper...19 just creates heat blah blah blah...I OBJECT

 

I have a 19% pulley on my 05' cooper-s for over a year now, and still no problems. I had heard all of the stories and myth's about the 19's, so to be safe I had the dealer put it on, so if anything happened I knew who would take care of it. I push my car pretty hard, and love the torque that I get from my 19. I also run a water to air intercooler, and keeps it running very cool. I wouldn't change my 19 for a 17,15,14,13, or stock.

 

Anybody in Texas weather running 19% now that used to run a 15%? Impressions?

 

A half dozen folks have 19 pulleys in Hawaii with no issues, except need to change belts more often especially when doing track day activities. Temp isn't quite Texas but its always between 80 and 90.

 

Hahah, that's nowhere near Texas weather.

1) It's humid
2) 80 is a cool. Think high 90s to 100s.

There's a reason why Houston is one of the fattest cities in the US. Nobody goes outside because there isn't any air conditioning outside.

 

Guys like Randy who track their cars religiously almost never drive south of 5K while most of us on the street shift in between 4-5K. The SC does not get near redline at this rpm and is still working just fine just moving its power down the rpm line.... The M45 SC is the limiting factor on our engines... it is really only meant to be used on engines from 180 - 200 hp max.... the heat that is built up at high rpm THEORETICALLY is destructive to making power.... I can not prove this because my car keeps making power and pulls very strong to red line (go for a ride w me at the Dragon) I have shed a belt 75 mi from home and had to sit with my date for a truck...which sucked.....
for me I am very happy with my 19%.... I have the belt checked regularly and all is good..... do you really drive your car all day over 5K?

 

Eric has been recommending 19% for the larger blower on the JCW. This moves the boost to 17 lbs, avoids the out-of-parameter error and keeps the blower torque requirements within the capability of the belt. I believe he is recommending a lesser pulley for the MCS.

 

JCW has the same charger as the 05 and 06 cooper S, which is the same as an 02-04 Cooper S's SC, just with teflon coating on the rotors.... the JCW just has a 14.3% pulley instead of our oversized hockey puck of a pulley

 

Good point. I may just have to go that direction now. I'm just worried the hot and humid texas heat will make the situation worse in combination with the 19%. But the other point is if the jump in power from 15% to 19% is really worth it since I would have to sink in another $100 for parts and an even large amount for installation labor for a marginal amount of power.

Now, the question is, should I go 19%/2% or just 17%/2%?

Did you have a wrong sized belt?