Series I Modular Pulley System MPS

[aukc]

In a recent topic about my engine repairs - viewtopic.php?f=19&t=20946
Wes noticed my pulley setup, so I guess I'd better share. So I appologize for the poor quality pics and if this is lite on details, since I did this almost 5 years ago, so pics are with a lame camera, and I don't have any of my notes or receipts handy, but I could find the paperwork and tear it down and re-photograph the setup if there's any interest.

Also, please be aware, that I did this NOT for any performance benefits, if there is a minor performance benefit (and I think there is) I do not have any objective measurements to back it up. It may sound stupid, but the main reason I did this conversion is that I wanted to be able to put the thrashercharged decal on my window, and wear the thrashercharged tshirt.



Anyway, here's what I did:

remove belt, remove pulley retaining nut, remove pulley -

buy the modular pulley system from thrasher for the magnuson nose drive, the magnuson nose drive is a non-tappered keyed input shaft, same dimensions as the M62 input shaft, have a local machine shop make an aluminum spacer for correct pulley offset, the thrasher pulley is the smallest they offer for the MPS system 2.74 inches -


hub with spacer placed on it -

stock pulley and custom thrasher MPS side-by-side, offset looks good -

hub installed, retaining nut installed, spacer in place -

pulley bolted to hub -

belt installed -

[willwren]

One thing that concerned me about your pics is the amount of rust coming from the hub and the screws. You should kill it before it goes further. Replace the flat head cap screws with stainless.

From 2.8" to 2.74" is so close it could be a measurement error. If those are repeatable numbers, you're talking about 5hp or probably less at the most. All the way down to 2.5" is about 25hp for comparison, which is a 0.3" drop. Your drop is 0.060 (plug gap).

[aukc]

actually I was mistaken, that's what I get for trying to rely on my memory, the pulley is actaully rated as 2.76 according to the thrasher web site

http://www.thrashercharged.com/L67_htm/mod_pulley.asp

just in case I wasn't clear, I did not do this expecting any measurable performance improvement. Of course, if there was a smaller size available I would love to give it a try, but this is the smallest size thrasher offers for their MPS system

[00Beast]

So you put one thrasher part on there so you didn't look like a ricer with the sticker and the t-shirt?

Should go down to a 2.5 standard pulley and smoke them so they don't doubt your choice in parts.

[Wes]

Thats cool. thanks for sharin. I wasnt aware of a mps for series 1.

[willwren]

Thats cool. thanks for sharin. I wasnt aware of a mps for series 1.

There isn't. The size of the hub prevents the smaller pulley sizes needed by the Series 1.

[Wes]

So with that hub, you can't fit a smaller puller? I'm confused.

Bill, with a normal pulley, you had 2.2 w/o modding the snout right?

Whats the smallest you can go with that "mps" setup?

[95naSTA]

Great idea. It's lways nice to see someone look outside the intermediate community.

Other Series 2 MPSs go down to 2.55" and the m62 cobolt MPS goes down to 2.5". Maybe through a little inquiry, a smaller size could be had. They're not keyed but that wouldn't be that hard to do.

[myfirstbonnie]

So with that hub, you can't fit a smaller puller? I'm confused.

Bill, with a normal pulley, you had 2.2 w/o modding the snout right?

Whats the smallest you can go with that "mps" setup?

See the size of the hub, that will not allow the pulley to be any smaller. Willwren does not use a hub. The series I are keyed and therefore do not need a puller. Simply unscrew the nut and the pulley comes off, new one goes on and tighten.

Bill, do you have any pictures of your snout with and without the tiny button on it?

Picture for reference:

[J Wikoff]

The S1 pulley may be keyed, but it needs a puller too.

[willwren]

And I run a 2.0" as my smallest pulley, not a 2.2" (which I also have for daily driving).

Puller? No problem whatsoever. I do pulley swaps in 5 minutes with the puller.







2.2" on a Gen3:


2.0" using the custom idler I had to add to the path:






As you can see, anything smaller than probably a 2.5" is going to be about the same size as the Thrasher MPS hub. Not to mention the 2.2" or 2.0", but I doubt any Gen3 cars on this forum will ever again run that small. The cars are getting too old here to make it worth modding that far.

[aukc]

Just because I posted this topic to describe what I had done, does not mean that I was recommending this mod or suggesting that it is beneficial. I didn't make any recommendation to encourage anyone else to make this mod, and I didn't claim there were any benefits that would justify the effort involved.

By doing this mod, I end up with a pulley that is within a few hundreds of the stock pulley, there is no selection available of smaller size pulleys, even if there was smaller pulleys available (which there isn't), it would probably be more effort to do a pulley swap with this MPS than with a single piece pulley since with the M62 it is so easy to pull the old one off and slide the new one on, the MPS weighs more than a single piece alloy pulley (but maybe less than the stock steel one, didn't think to weigh them when I did the mod)

I just did it for the sake of doing it. I wanted the look of an MPS, and I wanted to put a decal on the car. It's an engine dress-up mod. I like the way it looks, I'm happy with it, been running it this way for 5 years, wouldn't want to change it. That's all there is to it.

I appreciate all the interest in this topic and I like to hear about what others have done, just want you to understand where I'm coming from

[myfirstbonnie]

We understand, but we were just clarifying for WES' question about why a smaller pulley can't be used with that hub on a series I.