JCW Pulley is actually a 13.43% Reduction

[Itzamazn]

I read some information that Randy had contributed to one of the threads and it got me to thinking. I trust Randy's knowledge without question.
I don't know if it makes any difference to anyone or not, but I found it both interesting and bothersome at the same time.
You see I have had this little comfort zone established in my mind that if my dealer gives me grief over installing the ALTA 15% Reduction Pulley, ALTA Intake, and Scorpion Exhaust on my car, I was going to say "How can you give me grief if JCW is using a 15% Reduction Pulley and the same basic s/c and similar Exhaust?"
After reading Randy's information that the "standard" 15% Pulley is 2.17 inches and the "JCW Pulley" is 2.21 inches.
I saw my argument go up in smoke!
Check my math on this, but here goes.A 15% Reduction pulley is actually 85% of the original size. So, reduced size(15%)= 2.17.
If I divide 2.17 by 85 I get 1% = .0255294, so 100%=2.55294 for the actual stock pulley.
To check this I mutiply 1%(.0255294) by 85 = 2.169999 or 2.17 rounded off, which is the "standard" 15% pulley size
Now if I take the JCW pulley at 2.21 inches and divide by .0255294 =86.56686. So that means that the JCW Pulley is 13.43314%, "not 15%" as I previously thought.
In summary: "Standard" 15% is really 85% of the size of Stock Pulley
"JCW" 13.43% is really 86.57% of the size of Stock Pulley
I suspect the mysterious coating used on the Eaton 45 s/c for JCW is used , as many have already said, to increase the tolerances thus lifting the Boost Percentage which then compares to what we get with the "standard" 15% Pulley.
All this said, the JCW Modifications Kit seems now, at least to me, to be very conservative as far as Redline Numbers and Rev. Limits are concerned. And unfortunately, "blows" my prepared argument right out the window.
I also believe that the ECU, Exhaust system, and Head work improves JCW's end result performance to some thing very similar to the Mods that Randy and others are doing with 15% pulleys, ECU remapping, Intakes, and Exhausts.
This new understanding of what the JCW Kit really is has in no way caused me to reconsider the Mods that I am doing, I will; however, have to find me another "comback" when the day my dealer does my first 10,000 mile service comes. Anybody got some good lines I could use?
Thanks for listening, Itzamazn

[Liam"S"]

max the std pulley is in imperial but a metric equiv is 66.6 mm BTW its the top of the Vee

Liam

[TonyB]

That might be hard to get in this thread as many JCW guys might not be reading this... Maybe I'm wrong. I like the approach though!

I organized a pulley party here in NorCal and at that time Randy noticed oil on the underside of my engine, prior to the install. It made me sick when he said that I should go to my dealer asap... as I'm getting a warranty-voiding mod installed at that very moment But, I knew, and several folks standing around my MCS (witnesses ), that the reduced pulley was not obviously the cause...

I let my dealership know via a phone the next day, with a follow-up email, with photo attached to show the oil drip points. I also made clear point blank about the pulley, and how & when this was discovered. An appointment was set-up, and they verified that it was the valve cover gasket. The part got ordered, and installed the following week...

I've put my MCS up on the ramps a few times since, and no oil! Previously, wipping her clean would expose a drop or so the next day...

I realize that not all dealerships are the same, but I would be upfront about it. If my mods cause issues, I take full responsibility and I wouldn't want otherwise. And, if its the other way around, I will hold them to task...

I'm still a little upset about the crack in my windhshield that will not be covered b/c of a chip mark. Yes, I'm aware of the many threads...

Oh well, best of luck, and hope someone can get Max that JCW pulley figure...

[TonyB]

I stand corrected... Liam comes to the rescue!

[NEMINI]

QUOTE=TonyB]
I'm still a little upset about the crack in my windhshield that will not be covered b/c of a chip mark. Yes, I'm aware of the many threads...
QUOTE]

Thats what 0 deductible glass coverage on your insurance policy is for ... mine costs me a grand total of 6 dollars a year extra and does NOT raise my premiums if I need new glass (have had 6 windsheilds and a side window replaced in the last 14 years)

[TonyB]

You are right. I guess I'm just a little perturbed that this should be an insurance claim... Off topic, but I appreciate the input. Sorry guys!

[jlm]

from itzamazin: " I trust Randy's knowledge without question.
...
I don't know if it makes any difference to anyone or not, but I found it both interesting and bothersome at the same time.
...
After reading Randy's information that the "standard" 15% Pulley is 2.17 inches and the "JCW Pulley" is 2.21 inches."


for the record:

the stock pulley I measured at 2.586" diameter (65.6mm)

(from Liam: "max the std pulley is in imperial but a metric equiv is 66.6 mm BTW its the top of the Vee".. the measure must have suffered a Lorentz transformation travelling at internet speeds.)



the 15% P&D pulley measures 2.200" dia, exactly 15% reduction.



OD is measured from vee tip to vee tip in the area where the belt rides.

I have not measured any other pulleys, but If the JCW pulley measures 2.210", that is a 14.6% reduction.

[Liam"S"]

Quote: Originally Posted by jlm

from itzamazin: " I trust Randy's knowledge without question.
...
I don't know if it makes any difference to anyone or not, but I found it both interesting and bothersome at the same time.
...
After reading Randy's information that the "standard" 15% Pulley is 2.17 inches and the "JCW Pulley" is 2.21 inches."


for the record:

the stock pulley I measured at 2.586" diameter (65.6mm)

(from Liam: "max the std pulley is in imperial but a metric equiv is 66.6 mm BTW its the top of the Vee".. the measure must have suffered a Lorentz transformation travelling at internet speeds.)



the 15% P&D pulley measures 2.200" dia, exactly 15% reduction.



OD is measured from vee tip to vee tip in the area where the belt rides.

I have not measured any other pulleys, but If the JCW pulley measures 2.210", that is a 14.6% reduction.

ahh I shall have to get my mic out then I was just refering from a proudction drawing and the wrap circumference is 130.3 mm so I'll work out what wrap we are gonna get with 15% smaller pulley. ahhh hang on just a thought. prehaps us brits couldn't handle the power from a 1mm smaller pulley like the yanks can hahahahahahahaha

[Itzamazn]

Liam"S",
Actually that makes me feel a little better, since we are closer to the specs that the JCW Team adopted I feel there less chance of problems down the road.
Thanks for the correction. Regards, Itzamazn

[Liam"S"]

I stand corrected, John is correct. It appears that the drawing took the measurment from the belt guide and not the top of the vee. so the actuall size is 65.6mm hehehehehehehe.
Never trust a drawing hey

[bigbaddaboom]

not that you guys are being anal or anything...

[Grings]

does this even matter? The JC works it a totally different supercharger isn't it?

So comparing the pulley size is not a good indicator is it?

(runs and hides in case he gets flamed)

[QQQ]

Quote: Originally Posted by Grings

does this even matter? The JC works it a totally different supercharger isn't it?

So comparing the pulley size is not a good indicator is it?

(runs and hides in case he gets flamed)

Same supercharger (Eaton M45), just a different coating on the rotors

[bigbaddaboom]

Quote: Originally Posted by Max

and then we'll try and work it out and have a discussion about the math...

Is that with your grade 1 O'level....

[Airedale]

FYI.
Measured the stock pulley OD at 2.585 and the JCW pulley OD at 2.285. Therefore, the JCW pulley is 11.6% reduction, ((2.585 - 2.285) / 2.585 * 100).
Airedale