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Old 08-09-2012, 09:18 PM   #1
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Default How to make this nose pulley smaller?

I have a cone type nose pulley on my 1.6 M45 and am trying to upgrade it. I also have a machine shop that will make a pulley from scratch at a reasonable price, just trying to get the design down before I draw it up and pull the trigger.

From my own measurements, it doesn't look like you can make the pulley much smaller and still clear the nose of the charger without decreasing the wall thickness of the pulley. If you just decrease the thickness, what is the minimum recommended before it's too thin?

Also, I have been to the link below but looking for more detailed info.

http://www.lightweightmiata.com/jrsc/sc/

(Asked this on M.net but wanted to get other opinions too)
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Old 08-09-2012, 09:19 PM   #2
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For reference here are a few pictures of the nose of my supercharger with the nose pulley removed. The pulley sits back on top of the nose.







From my measurements, the clearance from the ID of the pulley to the OD of the nose was ~ 2.5mm. I don't know if it's safe to go much closer than that. Only other alternative would be to thin the walls of the pulley. That would make it weaker but I have no idea how weak is too weak to work.

The Tony pulley must have been made on the same principle. Maybe he closed the gap by another 0.5-1mm and thinned the wall by another 2mm. That would give you the difference from 72.5mm for a stock 1.6 pulley to the 67.5mm Tony pulley.
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Old 08-11-2012, 10:06 PM   #3
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None of the machinists out there have any tips?

My thoughts would be to make the new pulley the same as the current but decrease the clearance to the nose a bit and make the pulley wall thinner. Will stick with steel since the wall is getting smaller.
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Old 08-11-2012, 11:43 PM   #4
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Get us some more pics of the supercharger.

I'm assuming the pulley looked like this?



If so, that is the old style "sebring supercharger" setup that pre-dates the Jackson Racing M45 kits. It's essentially the same. Call TDR on Monday and ask them for whatever pulley that you want.
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Old 08-12-2012, 12:20 AM   #5
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Sorry, it is the older Sebring supercharger but it has the cone style nose pulley as shown in your picture. The TDR pulley's will not work for my supercharger. Their pulley's work with the next generation of Jackson Racing M45 kits which had a different pulley.

Only aftermarket nose pulley I am aware of is the Tony pulley but they aren't made anymore. Would be great to know how those were made. My other option is custom, which is what I'm trying to design.
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Old 08-12-2012, 12:29 AM   #6
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Looks like you already machined the snout of the blower to fit a smaller pulley so that option is out. Bigger crank pulley would be the only option IMO. Even if you could fit smaller I bet you'd start to have belt slip issues. Also remember that blowers have a redline just like engines not sure how fast you're spinning yours. I used to over spin my m62 quite a bit but it was only for the last 500 rpms till redline. Honestly you're not going to get much power out of that tiny mp45 no matter which way you stack it. I would try to upgrade to an MP62 or a TVS1320. If you want to get away from eatons a lysolm 1.3 wouldnt be bad either.
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Old 08-12-2012, 01:49 AM   #7
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I haven't machined a nose pulley yet, just figuring out how best to go about doing so. I am running the stock 72.5mm nose pulley that came with the kit. Already have a 150mm crank overlay on the car. Makes about 8psi at redline as is. Currently have no significant belt slip.

My understanding is that for every 2.5mm I reduce in the nose pulley size, I would gain 1 psi of boost. These are rough numbers but I am using them as a rule of thumb.

As far as max RPM of the blower, I have already ran this past Gary @ TDR. Since my motor is intercooled, he thinks that a 65/150 mm combo is doable and should put me around 10-11psi at redline. Don't think I can get down that small due to the snout of my old-design blower but I think picking up a couple psi would be worth the effort. Especially because the cost isn't that high to make one and see what happens

I also have a few machine shop connections in my professional life so I may give them a call for advise on how to figure out the construction needed.
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Old 08-12-2012, 01:51 AM   #8
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No I mean the actual snout of the blower has already been machined smaller for extra pulley clearance.
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Old 08-14-2012, 01:13 PM   #9
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Quote:
Originally Posted by Leafy View Post
No I mean the actual snout of the blower has already been machined smaller for extra pulley clearance.
The nose of my blower looks to be the same as the other image posted. I have not machined it smaller and I that is the way it comes from Sebring/Jackson. Not a bad idea to machine it smaller but I think it would be difficult to do on a lathe for a machine shop. How do they spin in??

I need to get my pulley off the car and take some more detailed measurements. maybe even model it to really get a visual of what I'm dealing with.

Does the nose pulley get subjected to high lateral loads under boost? High stress area?
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Old 08-14-2012, 01:17 PM   #10
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Throw baby blower in a lake. Buy slightly less baby blower kit. You're wasting your time trying to pulley the micro blower.
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Old 08-14-2012, 01:25 PM   #11
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Old 08-14-2012, 01:26 PM   #12
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I could make that for about 6 bucks.
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Old 08-15-2012, 12:33 PM   #13
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Quote:
Originally Posted by vehicular View Post
Throw baby blower in a lake. Buy slightly less baby blower kit. You're wasting your time trying to pulley the micro blower.
I like my setup just fine, thank you. Always looked to tweak things, not an overhaul.
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