924Board.org

[ideola]

What we have here ladies and gentlemen is an Eaton M45-based supercharger from a Mercedes-Benz C230 application. On the left, with the stock manifold plumbing, and on the right without the manifold:


For comparison, here is the M62-based Cobalt / Ion supercharger:


What I'm trying to understand is the function of the dual inlet on the M45 Mercedes unit vs. the single inlet on the M62 Cobalt / Ion unit. Can anyone explain to me what the function of the dual inlets are on the merc unit, and the weird manifold that joins the one inlet to the outlet? Is this some sort of recirculation device? I don't get it. Please enlighten me. Thanks in advance!
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erstwhile owner of just about every 924 variant ever made

[ragenruin]

Since the mercedes is an on demand setup, I do believe it is part of the bypass.

The mercedes unit only comes on under significant load, the rest of the time it is off and just free wheeling. It is just like an AC setup in that regard either on or off.

I can't say exactly how it works, but obviously air still has to get to the engine when it is off and not pumping. I suspect you could find out more online or something.

I do know that what you are looking at is a newer generation. The older ones don't have all the extra stuff cast into them. Hope that helps. If I was going to use one, I would probably go for one without all the extra bits. Not unlike a M90 as seen on the thunderbird, when you remove all the extra intake junk you have a nice clean unit. But maybe the guys who have run them or installed them can tell you more.

[ragenruin]

http://cgi.ebay.com/ebaymotors/Parts-Accessories___Mercedes-Supercharger_W0QQitemZ290269048161QQddnZPartsQ20Q26Q20AccessoriesQQddiZ2811QQcmdZViewItem?hash=item290269048161&_trksid=p4506.c0.m245&_trkparms=72%3A543%7C65%3A12%7C39%3A1%7C240%3A1318

that is the style I have seen in the past

[ideola]

I believe that second unit is an M62.

The M90 is WWAAAAYYYY too big for what I'm contemplating. Which is a darn shame because they are cheap and plentiful.

The M45 is good. The M62 is probably ideal. I was just trying to understand why the Merc unit had dual inlets. Hmm. Food for thought. Hmmm.
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erstwhile owner of just about every 924 variant ever made

[leadfoot]

Just a guess...

Probably to help smooth out idle and vacuum during off throttle application.
The 2.3 ltr engine would suck alot of air and it might create to much engine braking when off throttle at higher RPMS.
I'm sure this would also help with keeping the lobes turning when the clutch is disengaged.
Not sure how Merc designed their clutch system. The MR2 used a combination bypass/boost solenoid and a timed delay so that the clutch wouldn't cycle on/off during slight lift off the throttle. I had problems with this in my setup as the torque created made the engine lurch, I don't think the gearbox/driveline liked it too much either. Adding extra fuel helped a little, but I ended up curing this by controlling the clutch purely by RPM and ditched TPS and Load triggering.

Stu.
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1981 ROW 924 Turbo -
carbon fiber GT mish mash
LS1 conversion in progress...

[ideola]

Stu, that makes sense. Last night I did some more research, and I think it may also have to do with boost at cruising. I didn't find info specifically on the Merc unit, but on the 2006- twin-charged VW Golf GT, there is a bypass that bleeds off boost during cruising situations to help with fuel economy. I suspect that that merc unit pictured above may have a similar function. In the case of the Golf setup, the bypass valve is electronically controlled to be closed during acceleration, and opened during cruising situations.
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erstwhile owner of just about every 924 variant ever made

[daveo]

the pipe that gose to the inlet is for a balance boost or recirculated air when the valve in this pipe is open, when the valve is closed the second inlet runs max boost (port without piping)
i have the pappers on this with the SC
Dave

[ideola]

Do you have all the extra stuff or just the main S/C unit itself?
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erstwhile owner of just about every 924 variant ever made

[daveo]

sorry
so if u block of the port that is for the recirculated air and have it on max boost, u would controle the boost with a blow/dump valve, just 2 pipes one in, one out
dave

[daveo]

dan on line at the same time
i just have the SC and the papers on it from merc
dave

[fezza575m]

So your bolting this to your car?

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Red 1977 Porsche 924 CGT...THE MORPH IS COMPLETE

[ideola]

[fezza575m]

haha nice!

Well be sure to make your own 'build' thread!

i am keen on going the supercharged route eventually on my 924
A couple of questions....
How much boost?
Will it need an intercooler?
What sort of power figures should you expect?
G
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Red 1977 Porsche 924 CGT...THE MORPH IS COMPLETE

[Splineless]

One of these went for $190 on Ebay last night. Was that you, Dan?


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Porsche 924 - 1978 Metallic copper over brown, changing to black. Custom black and brown leather seat covers.
Weissach-style wheels, 200 lb. coils, thicker roll bars, but bog stock engine. (It's on my list.)

[ideola]

Nope. Not yet anyway

I've been eyeballing the Cobalt / Ion M62-based units. They seem to be well suited to the 2.0L platform. But for my needs, I think the M45 would be even better.

I'm bargain hunting at the moment, since my application is for the post-UWB-project. Don't want to cannibalize those project funds too much, but if I find the right deal, I'll be all over it.
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erstwhile owner of just about every 924 variant ever made