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Old 07-28-2005, 10:42 PM   #1
reddevil
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Default Max boost a SC can produce? Any facts?

I bring this up cause I was talking to Kelly at Rallitek today and he asked why I don't just go turbo now that I have basically everthing now to do so. And my response was I just wanted to keep the SC and max it out.

My plan is to get the current setup pushing 12 psi. On the NA block with 9.5-1 compression, which is about max doable static compression. Which will be a screamer.

But.....

If I blow it up (oh, don't you worry, I will), I will install the turbo block with the lower compression. Its at this stage I need to go higher than 12 psi to even come close to the power the higher compression motor would/will have been making. Something like 16-20 psi.

So just like a turbo that maxes out it efficiancy, I will be maxing out my current M62. I will have to move up to a larger supercharger.

I just finished reading Modified Magazine, and the winner of a drift compatition was a Mustang with a 4.2 liter with a Whipple supercharger pushing 17psi! Can you imagine that supercharger on a 2.2-2.5 motor? I suspect you would be 25-30 psi, and not out of effeciency range.
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Old 07-29-2005, 01:04 AM   #2
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Well, the supercharger works differently than a turbo impeller. There are some superchargers that use a turbo impeller, but those are different. Basically, the Supercharger is going to flow more air as it spins faster. The turbo basically limits itself to one level of boost using the wastegate.

The supercharger is basically a turbo with no wastegate that makes 'umlimited' boost. So, what I'm saying is, there isn't an effeciency range for the supercharger. What will cap off the boost on the supercharger is the effective maximum speed you can spin it. If at maximum rotation speed, you're only making 12 psi of boost, then that's it, you can't get any more. If you're making 12 psi of boost and are only spinning the supercharger half it's maximum rpm, you'd be good for another 12 psi of boost or so (I think).

Maxing your M62 out on a 6,000 rpm engine... I think you're looking at 12 psi, but I'm not sure. An M90 which is deisgned for a 2.8l+ engine... I'd say, you may max that 'charger out at about 40-45 psi.

That supercharger, at 6,000 rpm on a 2.2 liter engine, would make about 55 psi. :P I think. Maybe a little less...

At least, this is how I understand things. ^_^
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Old 07-29-2005, 01:17 AM   #3
reddevil
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No, an m62 flow .75 liter per revolution. An m90 flows 1 liter per rev. So it would only go up 25% or so.
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Old 07-29-2005, 01:37 AM   #4
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Quote:
Originally Posted by reddevil
No, an m62 flow .75 liter per revolution. An m90 flows 1 liter per rev. So it would only go up 25% or so.
On the website, I thought it was at m62 at 1 liter per rev, and the M90 was at 1.5 liter per rev?

Oh well, how may RPM's is your supercharger spinning when your engine is at 6,000 rpm?
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Old 07-29-2005, 01:54 AM   #5
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I'm Wrong!!!!


m45 = .75
m62 = 1.0
m90 = 1.5
m112 = 1.84

memory failed
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Old 07-29-2005, 01:56 AM   #6
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I'm the one with so many hormone problems that my memory is as useful as a sieve that got shot with a 2 gauge shotgun.

I'd say you still have a ton of headroom with your M62. The M90 is actually a little bit of a stretch for the 2.5l, I think. Going to try it anyway.
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Old 07-29-2005, 02:10 AM   #7
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The current setup I have now actually allows huge boost. But the stock Legacy AWIC really saps the fueck out of the boost level, like 3-4 psi. I either need to get a true high flowing top mount IC, a nice front mount, or, most likely, modify my current AWIC and let it flow more. The problem is the intake to the AWIC is 1.75" TINY!!!!!!!

So, a few bucks paid to my whacko aluminium welder and I should be good to blow, I mean go.....
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Old 07-29-2005, 09:22 AM   #8
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Magnuson Motorsports has flow charts for the Eaton family of superchargers on their site.

M62: http://www.automotive.eaton.com/prod...argers/M62.asp
M90: http://www.automotive.eaton.com/prod...argers/M90.asp

You should be able to calculate out what each unit is capable of by using the max rpm, and your desired CFM, based uponpressure ratio and displacement.
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Old 07-29-2005, 01:13 PM   #9
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The biggest problem you are going to face with the eaton blowers will be the loss of efficiency as your boost goes up.

The big m90 could push 20psi plus at 12000RPM, but at that kind of pressure ratio its power requirements and temperature gains would be enormous (my figures are showing >100hp and >300f).

If you want to run boost levels over 10-12psi you should probably look into twin screw technology.

Disclaimer: I don't have my copy of supercharged! handy to check my calculations.
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Old 07-29-2005, 10:39 PM   #10
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12psi is the max you will get out of a m62 before the adiabiatic efficiency goes off the deep end on a 2.5L. At that level it will take about 30hp to turn the supercharger and you will not be able to turn it due to belt slip (I speak from experience) - you will need a wider belt or atleast a cogged one along with excellent pulley wrap. You can only put a certain hp through the factory belt before it begins to slip or in the worst case snap.

An M90 would be a much better fit for higher boost applications but to be honest you'd be better off looking at the 1.6L lysolm unit by whipple which can handle what your looking to do.
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Old 07-29-2005, 10:58 PM   #11
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Quote:
Originally Posted by Joncas
to be honest you'd be better off looking at the 1.6L lysolm unit by whipple which can handle what your looking to do.
Hello, My name is Marcus Anderson and I am the son of the former President of Nigeria. I would like you to send Reddevil a Whipple supercharger. I will pay you with a cashiers check. Cheers...

Marcus Anderson
Son of Ex-President Nigerian Arnold Anderson.

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Old 07-30-2005, 08:31 AM   #12
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reddevil: you can find many an inexpensive, large, bar and plate style front mount intercooler off ebay... yeah, they don't give pressure drop or any specific info like that, but you can find thin or thick ones for $100-$200
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