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Supercharging a 944 - Why so hard?

Old 11-22-2017, 11:57 AM
  #31  
jderimig
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Details..Intercoooled? Pulley ratio? How much boost intent?
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Old 11-22-2017, 03:29 PM
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Does anyone know how hot the case of a M90 or M62 at the input flange would get under "moderate" boost? I am thinking of 3D printing intake interface of the ductwork.
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Old 11-22-2017, 03:44 PM
  #33  
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about as hot as the rest of the engine...likely cooler since it has all those strengthening ribs radiating heat off.
i have a pre-made intake "flange duct" for an 89-93 thunderbird M90 that i won't be using, it has a 2.5" pipe welded to it. ill sell it cheap, along with either/both of the "m90 outlet hats" pictured on the right side below.
it came from the godfather of all supercharged 944s, blown944's "lil mule" car if youve read about it.,

bottom middle...
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Old 11-23-2017, 05:04 PM
  #34  
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Dear Spencer..Have you considered using an Eaton blower off of a M-B C230? Looks like it could be adapted pretty easily with some ductwork/creative welding done. Looks small which would fit nicely in our 944 cars. Don't know about pressures/ pulley size, but might be a place to start..just thinking..
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Old 11-24-2017, 12:00 PM
  #35  
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Rich - no, too small for our engines, IMO. The Ford M90 that I've been basing my stuff around moves 2x as much air per RPM.

Also, they have tended to be more expensive than the Ford M90.
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Old 11-24-2017, 12:21 PM
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I am taking a hard look at the MB M62 for my potential project. From rough calculations it would need a 3" pulley to get the 6-7psi boost I am targeting. Probably would need to take the clutch of the M62 for that size pulley. However this level of boost is probably the limit on a 2,5L with the M62 as it will probably be hard to get drive with smaller pulleys. The m90 would be more "scalable" but I like the M62 because I am after more low-end torque. The M62 would be spinning faster for the same boost as an M90 and should have less leakage at the lower rpms.

So far my concept has evolved to:
1. M62 with ~3" pulley
2. No intercooler, but may try water/meth injection just for safety and detonation margin.
3. Standalone ECU (10% of MS Black Friday sale....hmmm) (Also noticed prices are higher since a few weeks back....hmmm)
4. AC delete. (Initially. If I like it then I can figure out a scheme to save the AC later)
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Old 11-24-2017, 11:38 PM
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The Jaguar Eaton M90 short snout would be my first choice.
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Old 11-25-2017, 04:32 AM
  #38  
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VEMS PnP systems were 15% off last week :P
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Old 11-25-2017, 10:07 AM
  #39  
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So what would be the performance gain for 1/2 bar of pressure? Seems like it would be better if it were upped a bit more say about 10 inches..The junkyard C230's have an intercooler, and with the water, methanol injection, seems like the boost could be as much as 1 bar of overpressure. You have to look at performance gains of the turbo boys here...might need to add another headgasket though or a thick cometic one to lower the overall C/R. I don't have any pressure data to confirm the Eaton blowers on the M-B cars and what they yield. Where could I find such data? Does Eaton publish a list of blower #s and their pressures at certain RPMs?
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Old 11-25-2017, 11:32 AM
  #40  
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Originally Posted by DarrenD View Post
The Jaguar Eaton M90 short snout would be my first choice.
yeah, i got one of those too, neat little package but i decided to continue with the brackets i had already to save another 5 years of development time, lol

Originally Posted by Raceboy View Post
VEMS PnP systems were 15% off last week :P
any kind of mail-in rebate for previous customers?

Originally Posted by Tiger03447 View Post
Does Eaton publish a list of blower #s and their pressures at certain RPMs?
Rich,
Eaton publishes a fair amount of info on the blowers but pressure doesn't depend on RPM.
Eaton blowers move a volume of air per revolution - the volume in cubic inches is the number after the "M" so my M90 supercharger is 90ci, some C230 use an M45, I think some use an M62.
GM 3.8 V6 came with either M62 or M90 depending on year, the Cobalt SS (the supercharger linked on the previous page of this thread) is an M62.

The blower itself doesn't make any pressure - but the spinning rotors forcing their displacement through every revolution and not allowing much "bleed back" is what creates pressure at the outlet side of the blower.
It's not quite linear due to thermal efficiency drop-off but in essence a 90ci SC at 1000rpm moves 90,000ci of air. At 5000 rpm it moves ~450,000ci of air, and so on.
The pressure only comes when the engine on the other side can't take in that much air on its own...but the blower is going to force that air in one way or another, the tradeoff is higher drive-power required by the SC, and HEAT.

Roots blowers are good for lower psi/lower rpm, you can run them harder but you really need to intercool, or run nitromethane.
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Old 11-25-2017, 12:23 PM
  #41  
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Originally Posted by Tiger03447 View Post
So what would be the performance gain for 1/2 bar of pressure? Seems like it would be better if it were upped a bit more say about 10 inches.
With 6-7psi I have estimated 40% more torque across the rpm range with a little fall off at the high end due to advancing parasitic losses. So its modest but that is my Stage 1 target because I want to keep my NA transmission, clutch and brakes. That is a conservative estimate and may get that with less boost because tuning and cam offset has reportedly gotten conservatively 10% more by itself.
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Old 11-25-2017, 05:10 PM
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Old 11-25-2017, 05:49 PM
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Bare in mind the cam offset will help you out (higher VE at lower rpm = more useable airflow and less boost pressure) but the tuning will not be additive as far as power. You will be taking out timing versus putting it in, due to heat induction and so on. Obviously power will be up but it's not 10% gain from tuning plus 40% from the SC.
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Old 11-25-2017, 07:16 PM
  #44  
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Michael, I agree. My point was that a 40% increase in torque would be conservative in that if I increase the VE of the engine then the SC boost pressure decreases at a given SC rpm. Less CS pressure = less heat = less parasitic losses = can be more aggressive on ignition timing. So it's not necessarily additive but it is synergistic.
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Old 11-25-2017, 10:36 PM
  #45  
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Well I just bought a C230 M62 off ebay. Seller claims it may be a refurbished unit. We shall see. $150 gambled....
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