Chris Lockhart

What are your pulley sizes Darien? I'm looking to get into the 9-10 lbs range, but with the current setup it's only about 6 lbs.

I'm definitely concerned about over revving the s/c and alt.

hans14914

If you oversize the crank pulley like Keel and Murf do (constant diameter for all driven accessories) you do also need oversize power steering, and alternator pulleys. In the case of PS pulley, it also needs to be converted to a 4-rib or better belt.

There are several lower supercharger pulley rings available from manufacturers like Metco for the Ford applications. These come without hubs. Cheapest way to implement an oversize pulley is to order one of these rings and machine a custom hub that also includes the AC pulley. You can then next the factory crank pulley inside and keep all the original drives the same diameter and track.

Machining pulleys is not cheap, I really wanted to do it for mine, but was seeing minimum orders of 10 pieces at over $500 each for my design plus hardcoating lot fees.

Good luck with your project, but I recommend looking at making a custom hub for existing rings made in mass production.

Darien

Hi Chris,

I'll get some measurements of my 10lb and 12lb pulleys when I get home. Which SC are you running? I have the Autorotor 2.0L.

Chris Lockhart

Darien, I have the Jag/Eaton M112. Thanks!

Chris Lockhart

I re-measured my pulleys last night. Bottom is supposed to be 5" but technically it's 4.97". S/C pulley is 2.25".

What I was thinking, is to machine off the v grooves for the 6 rib S/C belt, machine a new larger diameter section, then press fit it onto the pulley. That way I can increase the lower diameter without effecting the accessory speed any more than it already is. I figure that it would be one of the best cost based solutions as well. I don't see how the S/C pulley could realistically get any smaller than the current 2.25"

Darien

Sorry for the delay...my 12lb pulley measures 2.25" and my 10lb pulley 2.5".

Chris Lockhart

Darien, I'm assuming that you're running the 5" crank pulley with those S/C pulleys? I'm kind of shocked because I've been using the 2.25' S/C pulley (came on the car) yet it was only approx. 6.5 pounds of boost. I guess I'll wait to make any mechanical changes until after having the S/C rebuilt/ported by Stegemeier (sp?) Performance. Thanks for measuring those. :-)

Darien

Hmm. I'm still using the crank pulley that came with the kit. Keep us posted on the SC rebuild. A lot folks have that SC.

Let me know if you would like to chat on specifics. PM

Imo000

First check that the diverter valve is not leaking when it's closed.

Chris Lockhart

Thanks Darien, will do.

Imo, thank for the tip. I'll check it out once it's all back together.

Imo000

A buddy of mine picked up an '03 AMG E55 when we I looked under the plastic engine cover, realized that the supercharger pulley had an electromagnetic clutch on it (looks like a beefed up version of the AC clutch). This car is stock and makes nearly 500hp so the electromagnet has to be pretty strong. Anyone tried adopting this for their roots/twin screw blower? It should remove wear and tear on the compressor and most of the parasitic loss of the blower.

As a reference, the below link has a picture.

http://mbworld.org/forums/c32-amg-c5...pulley-20.html

DKWalser

That's a very cool idea. By varying the amount of current, you could control the amount of slippage -- creating a variable speed compressor.

hans14914

Those superchargers were made by IHI and the same clutch drive is also used on the C32 AMG.

I havent seen anyone replicate this in the aftermarket. Wonder what the warranty rework is like on those drives?

davek9

Hello all Twin Screw R's to date I've only made it to page 80 of this thread trying to learn about the Twin Screw do's and don'ts and most importantly what work and mods Charles W. Pizzolato did.
I'll say this my hat is off to that man, nice job and some real extra efforts improving the kit and making mods available to others here. Also most impressed as always by this group of enthusiasts and the info shared, hopefully I too can contribute as I learn.

After running the car a few times, and taking it out on a Friday / Saturday night I'll say this Boost is addictive and received many a thumbs up after blasting off from a light
I've decide to keep the SC and move it to another car that already has a limited slip diff as I never see these SC units come up for sale and once set up they seem to be completely reliable.

Does any one know how many twin screw units are out there running around on 928's counting DR's?

Thanks,
Dave

BC

I have a 2006 E55. The clutch basically makes you feel a double bump coming from a stop. It also has an affect on things like shifting, etc.

Because of the rambunctiousness of the SC, AMG went to NA and then turbos. No one else has clutched AC assemblies in today's supercharged cars.

When a guy is serious about power in the E55 world, they dump A) The clutch, and B) The supercharger for a "better" one.

Also, the clutch wears out and adds additional strangeness to 1500-2800rpms.

I will be going to FSP on the E55 when I modify.

But the E55 has also made me want this type of SC on a 928.