Pulley Conundrum

J

Jeff S

Guest
Guys, Sal and I were studying the various compressor maps last night for Eaton M112 supercharger. Can someone tell me what the stock pulley sizes are for the blower drive pulley on the crank and then the pulley on the blower snout itself?

There are two things that I saw that concerned me - a) max blower speed for the M112 is 12,000 (blower) rpms and b) heat increases dramatically with increases in boost and then ramps up geometrically as the blower is spun past 8,000 (blower) rpms.

I don't know what the stock sizes are so I'm not sure what part of its efficiency range the supercharger is running in. So, I'd greatly appreciate that information.

Thanks!
Jeff S.
 
Hey Jeff,
I changed my pulley last night and it was a nightmare. I broke the ASP puller and had to take the front off the blower and have the pulley pressed off and on. Damn lot of trouble.
Anyway we messured the pulleys. Factory is 2.84" and the after market is 2.65".
I am planning on being at Thunder Racing about 11:00am Sat. unless something comes up. If you want I will call(please send no. as I lost the last one).
Alvin
 
I just went out and measured mine and to the outside edge of the pulley they are 3 1/4 inches and 7 7/8 inches. The belt is flat with the raised edge of the pulleys, so there's probably an 1/8 inch each side less.

Hey Hotdog. thought you were going to go with the Down's?? This is why I did not want to change the Supercharger pulley. Because SH-- happens!!

I sure wished that Eatton would have used a key system like Vortech does. SOOOOO much easier!
 
Hey All L2 Guys,

Regarding the Eaton S/C:
It is not widely know around here (for obvious reasons) that I am also a vintage Pontiac nut. Well, in some of my mags I have to deal with the late model corporate junk, too.

There is a company called RAT (Ram Air Technologies) that has an upgrade for the Eaton blowers on the Grand Prix. It is called the "Stout Snout." It is a replacement blower snout, stronger than stock, that gives one the ability to _quickly_ change pullies, like the Vortech, etc....

If any of you guys are interested, I will dig up the article and post some info and contact numbers.

Kevin Lewis
(Debating whether to sell the 68 Firebird 400??)
 
ACK! I've written this once already... D'OH! I hate it when my messages get eaten by the cyberspace gremlins.

Thanks, Jigawatt! I'm going to make some assumptions based on your information - mainly that the outer edge keeper ridges are the same on the blower pulley and on the crank pulley. Using a step-up ratio of 2.42 (diameter of crank/diameter of supercharger), at 5000 RPMs the supercharger is turning 12,100 RPMs. That means the M112 is redlined in the factory configuration!

If we use Alvin's blower diameters (where they were measured isn't really important, just so they were measured in the same place) then we get a further increase to 12,971 (let's call it 13,000 for the sake of round numbers) which is beyond Eaton's rated redline on the supercharger. Also, based on the graph below, it looks like blower discharge temps end up about 225 degrees F. I can't really make a judgement call on what this means for the intercooler, but at some point the temp increase will begin to overwhelm the intercooler and without some decrease in timing, it may lead to detonation.

deltaT.gif


Anyway, for what it's worth, I overspin my Vortech too... but I wanted you guys to be aware that you were getting into the red zone with blower. Proceed with caution.

Later!
Jeff S.
 
Damnit Jeff,
Now I'm scared and I thought JoLynn was the only thing that could do that, well maybe the thought of changing out another pulley on a ford in a Chev. speed shop.
As always thanks for your help.
Hey Jigawat,
I was going to do the Downs' but I thought I would go the easy way,"Ha!!!!!!!" Man why don't you move down closer so you can help keep the Hotdog running.
Thanks,
Alvin
 
Hotdog:

Linda's sister is in Thibodaux, but we've never gone to visit--inlaws--fat chance I'll make it there!! :) Plus, I don't speaka the southern language, ya'll understand-- ha ha ha :) Come on up here!! I've got an extra pair of snow boots for ya!! Even have a tractor to pull ya out of the ditch when you slide off the road. (driving in snow and ice can be real fun, especially that first time!!)

Don't worry about what Jeff says. It ain't runnin' good til it's in the red. :) ha ha!!

I always ran my Vortech wayyyy in the red. 250 degree intake temperature was just when she was starting to run good without an inner cooler! :) ha ha!!
 
Hey Jeff,

Your 225*F estimate isn't far off on outlet temps. From what I remember from the Roush dyno guys they have measured approximately 240-250*F at the outlet, and then around 140*F after the intercooler. And from what I was told the blower was at the top end of what Eaton would be happy with. Let me tell you, they worked a ton to eek out everything they could with that M112...there were a couple of different inlet designs floating around...and the "top inlet" was chosen because of its eficiency. Who in their right mind would have built an induction system THAT tall? 8)

...for what it's worth.

- Kevin
 
Hey Guys,
Has anyone talked about changing out the small radiator on the aftercooler. Man it is really a small unit and can't be doing as much good as a larger one. It looks like there is room to put one 2.5 times as large or larger.
I'm lossing coolant at rear of my blower somewhere around the intake. I have to take it to Baton Rouge and leave it. -- Hey Jeff, Can I stay with you until the truck is right?
Alvin

Hey Jigawat,
Can I go down to see your wifes sister and tell her you sent me. Man, your wife would love knowing we are talking about her sister on the internet.
 
Depends... do you do windows? ;-) When are you bringing it over?

Later!
Jeff S.
 
What about weight reduction? Is the downs unit really lighter than the stock?
 
Nathan:

The Down's is made from someone, "Bob" who makes it for anyone that want to sell it for him. Yes it's aluminum, that's what I was told anyway.

Alvin:

Sure you can stay with her as long as you like. I don't know what she has to say about it, but I don't mind :) ha ha ha!!!
 
Jeff,

Actually, the Eaton spins at 2.1 times the motor speed, so with a 5,000-5,250 rpm shift, the SC would be turning 10,500-11,000 rpms. Also, the stated limit for the supercharger is 14,000 rpms.

If the rotational speed of the SC is 11,000 rpms when the motor shifts, and assuming the diameters quoted in Hotdogs post are correct, the rotational speed with the new pulley would be 11,788 rpms. Still within either the 12K or 14K limits.
 
All the Eaton compressor maps have their curves ending at 12,000 RPMs, so if you could point me to the published source where the 14,000 number comes from, I'd appreciate it so I don't go 'round babbling bad info. Until then I have to assume that the Eaton maps end at 12K for a reason.

You're right about the change in numbers still being within the 12K redline if the 2.1 ratio is correct. I need someone to put a caliper on some pulleys.

Thanks!
Jeff S.
 
Both figures are from Eatons own website. They published the 2.1 ratio and the 14K limit. I'll be home @ 6:00 P.M. Eastern, and I'll post the links then.
 
Here's the link showing the rpm limit, look at #3, that's where they talk about it.

http://www.eaton.com/supercharger/whysuper.html

It looks like the link to the 2.1 SC rotations per crank rotation has been removed from their page. It appears they don't want us to know that. If you need confirmation that it was there, go to the Lightning section in the F150 homepage and do a search for Eaton. There are a few posts there that mention the 2.1 or mention rpms that you can determine the 2.1 by. I'm sure that, like me, the others saw the 2.1 number on Eaton's site.
 
Thanks!! I'm a little bit more edjukated.

Did Eaton list the 2.1 as the drive ratio on the Lightning?

Later!
Jeff S.
 
No they didn't make a distinction on applications, they just said 2.1 times the engine speed.

Eaton made it seem that they use the same pulley diameter on all applications, but who knows if that's true or not. Maybe in the case of the Jag they had to tone it down due to the higher rev limit. The Jag makes peak HP at 6150 rpms.
 
Hotdog if your leaking coolant check the right side of the engine above the aft coil. My coil just shorted out from coolant leaking on it from the hoses just above the #4 coil. Sal was saying that this is a problem on other trucks with the same hose setup. My coil was soaked with coolant. I've been smelling coolant for some time now but couldn't find the leak and the fluid levels were not getting low. It must have been a real small leak. I plan on doing the upper supercharger pulley how hard was it going back on? Did you try heating the new one to expand it? Scott
 
Hey Scott,
God I love the way people help each other on this web sight. Thanks, I'll check it out.

My pulley may have been one in a million, but after 6 hrs.,we got it. Most of our time was spent with the pulley puller. We heated, beat with a brass hammer, waited giving the pulley time to work free and finally broke the pulley puller. You will find that the puller will bend and distroy the pulley before it breaking. And parts fly when it does break.
Once we pulled the front of the blower off things went really easy. The press worked very well and it is not a big job. We just would not give up on the puller.
I also found that we had to grind quite a lot off the front of the blower nose to get the pulley to fit correctly. This took some time but I did not want to have an alinement problem with the belts.
My gear change went just as badly. I may give up working on this truck --- that was a lie and we all know it.
Alvin
 
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