Well, we know he can build it...lol. My pulley looks fine, but you just never know. I had my stock pulley and my Code 3 pulley out today...and I have to say, that old Code 3 looks better than the other two...but looks don't mean much. Dependability does...

 

Khang Vo responded quickly to my e-mail. Apologized for my situation and said he will get me a replacement pulley ASAP. No hassle . . .

THAT'S GREAT CUSTOMER SERVICE!

Now I have to get my hood repaired and install a protective shield over the new pulley. Chris . . . Are you going to design and build a shield for us?

 

Funny you should ask.
after I saw your post the other day, that was the first thing that came to mind. I have the Karmen pulley on my latest SLK32 and I just recently had the hood repainted so I have zero interest in having a pulley damage my hood (and more). In NASCAR, we were required to run a scattershield on the clutch and safety loops on the driveshaft ... making a shield for the sc pulley seems like a good idea to me.

I'll let you know what I come up with,
Cheers,
Chris

 

I had an early used Karmen pulley for a couple weeks. I noticed when I would start the car up it would make noise for a few minutes and then quiet down. When datalogging I noticed it would stop making boost at a point on the graph and fall off. After a lot of head scratching I determined it was pulley slip causing the noise and boost issues. In my case, there wasn't enough friction between the pulley plate and clutch.

The heat buildup on the plate makes sense based on the clutch-to-plate slip I observed.

 

Funny you should bring that up . . . Some weeks before going to the track I was working to fix an issue with my car's acceleration cutting out near top RPM. I thought it was related to a starving for fuel problem and I THOUGHT I had remedied it when I turned up the fuel pressure.

When I got the car on the track the other day I noticed the same problem once. Then after the pulley grenaded and I got home and started thinking about everything, I wondered if maybe the pulley clutch was slipping at high RPMs thereby cutting off my boost. That, of course, would also cause friction heat and probably ultimately lead to the pulley failure. I think you've done some pretty good detective work there Anthony! Maybe the recommended gap is too large for that smaller pulley spinning at higher RPM. The faster you try to spin that supercharger the more load / torque it will take to spin it. At some point it will overwhelm the clutch. Probably need to install the pulley with less (minimal) gap like Doc discussed. How else would you able to increase the friction between the pulley plate and the clutch??

I remember that Khang had told me he had a friction coating that he could apply to the pulley (the grooved part of the pulley) to increase grip on the belt and help eliminate slippage of the belt. I wonder if that (or something like that) needs to be applied to the backing plate to improve the grip of the clutch??

So . . . we have new things to think about. What do you guys think??

 

I have the same problem with what feels like hitting the wall. I see the same data in my logs. Because I'm stacked, I attributed this to fuel starvation. But then added injector Duty Cycle to my logs and saw that this issue could happen at any time and never above 75% IDC. As if once it is engaged at higher RPM, it would stay engaged. And it would slip when I was not even pushing the car hard. Well... during my testing is when the pulley broke and I've been running my larger crank pulley with a EC 65mm pulley for the last 6 months. No problems.
A week ago installed the Karmen pulley again and this problem reappeared. Not as often since I removed one of the spacers and gapped it to 0.3mm. But this cutout of power still happens on occasion. Fuel should not be effected that much after switching from 65mm to 62mm, especially when just cruising at 70mph. All this leads me to agree with Anthony now. The pulley is coming off. I may even try the EC 61mm and see what that does.

 

At the risk of being told that I have not got a SC pulley other than the OEM one I will offer a possible cause for clutch plate slippage.
As the speed of the SC increases the forces to turn the SC increase in greater proportion than the speed increase. This results in the clutch plate slipping against the electromagnet.

Slipping causes friction and friction causes heat, none of which are helpful.

Certain materials have a greater attraction to a magnetic force, hopefully the clutch plate is made from such a material, to maximize the force available. Some materials get magnetized and stay slightly magnetized and will attract steel and iron, you do not want that either in a clutch plate as it will attract material peeled of the clutch plate and electromagnet causing more slipping if it sticks to the face.
A damaged electromagnet will probably cost more to replace than the pulley.

 

I was part of the initial group buy through Rudy. Just took mine off and inspected it. No sign of abnormality, no discolouration. Looks like new, fits very true and clutch spins freely. Been on the car for 3K miles and a few 1/4 m runs.

 

The other little piece of the puzzle we didn't discuss is that I am running just a few feet above sea level . . . more dense air here . . . more boost . . . requiring more torque to spin that supercharger at the highest RPM . . . overwhelms the clutch causing the clutch to slip . . . slipping clutch creates friction heat . . . bang . . . backing plate grenades! All the symptoms fit and I'm 99% sure that's exactly what happened.

 

... been busy out in the shop.

I finished the proto for the a scattershield. Going to install it tomorrow.

in the mean-time here are a couple of pics

Cheers,
Chris

 

Very nice.............cousin Chris to the rescue.

PS Sign me up plz.

 

Awesome Chris! Put me on the list! Thank you.

 

Holy Cow! Four days later, you have a product. That's impressive Chris. Please add me to the list.

 

Very Nice Chris!!

 

Lenin, are you running the 62mm pulley with a larger crank pulley?

 

Yes, 164mm crank and 62mm SC.

 

lenin are you double stacked.

 

No. This would be "double stacked"........

 

ok again I am a rookie. doesn't doublestacked mean you have a different pulley and crank. such as boostmonkey is running ASP 178mm and EC 65mm pulleys

 

No such thing as double-stacked. Stacked is larger crank pulley and smaller SC pulley.