924Board.org

[Shurick]

It is the scheme, used in Lancia Delta S4. We can use screw blower for low end and turbocharger for top end performance. The only question is can it be made in a simple workshop?
Such kind of setup offers flat torque curve through the all RPM. And it gives the opportunity to use a huge turbo for some massive hp output.
Some thoughts:
Intake plumbing can share the same IC and further way for both blowers. Two solenoid-controlled throttle bodies and Y-pipe can be used to switch intercooler intake. Supercharger with electromagnetic clutch can be controlled with the ECU by RPM.

Any ideas?
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WBR, Shurick
'79 931 -- intercooled K26-3060-6.10 turbo @ 1.2 bar, EFI+EDIS, 951S brakes, stripped interior, 951 look.
'86 924S -- R.I.P.
https://www.instagram.com/ru_pacecar/

[morghen]

i've been thinking about this for a while now...i think it can be done.
but i think one would at least need one of those E-WUR things to control the mixture troughout the RPM range if not a compete EFI system...tho EFI would require more time and money...i'd stay with DITC and CIS + E-WUR.
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Supercharger and EFI kits
https://www.the924.com

[Shurick]

I think EFI is must have for such setup, while CIS can't feed reliable more than 220-240 hp.
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WBR, Shurick
'79 931 -- intercooled K26-3060-6.10 turbo @ 1.2 bar, EFI+EDIS, 951S brakes, stripped interior, 951 look.
'86 924S -- R.I.P.
https://www.instagram.com/ru_pacecar/

[ideola]

Here is what I'm planning for the post-UWB project:

• Ram air hood scoop on LHS of car feeding SC inlet
  
• IHI Lysholm-style SC mounted on the A/C mounting ear
  
• SC outlet feeding stock 951 FMIC
  
• FMIC outlet feeding a one way valve connected to Tee connector
  
• One side of the tee will draw fresh
  
• The other side of the Tee will go directly to turbocharger inlet
  
• Turbocharger outlet to TMIC inlet
  
• TMIC outlet to throttle body / intake

The positive displacement SC will provide 6-8 psi of boost from idle. The one way valve will be closed to the fresh air side of the tee while under 8 psi. As soon as the SC spools up the turbo and it starts drawing air above 8 psi, the one way valve will close due to pressure differential, and the turbo will draw all the air it needs from the fresh air inlet. An electro-magnetic clutch on the SC will disengage based on MAP such that the SC will free-spool when the one-way valve is closed. Boost from the SC will be controlled by an integral blow-off valve. Boost on the turbo will be controlled using the stock wastegate and a conventional boost controller.

The TMIC will be one of three options: CGT replica based on air-to-air RX7 core; battery tray air-to-air core; or liquid-to-air (several mounting alternatives). This arrangement provides dual intercooling and the most direct path with fewest bends. This system is essentially identical to how it's setup on the twin-charged 2006 VW Golf GT.

For superchargers, I evaluated two different Eaton M62s, one from the Mercedes E-Class, and the other used on the Cobalts and Saturn Redline Ions; I also looked very closely at the G-Lader used on the VW Corrados; and of course, I settled on the IHI Lysholm-style. The G-Lader was interesting, but was too worrisome in terms of reliability and too expensive to rebuild. I liked it for it's small packaging and possibility of mounting on the stock 931 alternator mount, but ruled it out because there were too many downsides. Until I found the Millenia SC, I was very very close to purchasing one of the Cobalt/Ion units, as they are ideally oriented for the above arrangement.

If you're interested in looking over the materials I've collected while researching this, I just uploaded a bunch of it to this album:
http://picasaweb.google.com/streetlegalporsche/Superchargers#

Here are some of the most interesting pieces from that collection:




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erstwhile owner of just about every 924 variant ever made

[Shurick]

So, according to the pictures....
VW uses to blow through the turbo with SC while turbo isn't producing enough boost. And than it bypassed with butterfly valve. When we have spooled up the turbo we can disengage SC and open that valve. Yes! It's the answer!=)
Dan, why do you want to use two IC units? It's waste of space and excess weight.
I plan to use SC14 or SC16 Toyota supercharger and KKK K27 turbo. SC bypass valve can be made from throttle body, controlled by the wastegate actuator, feed powered from intake plenum through the solenoid valve.
Actuator can be used from any low pressure turbocharger with internal WG. Solenoid control by PWM signal based on the RPM.
It looks simple...
_________________
WBR, Shurick
'79 931 -- intercooled K26-3060-6.10 turbo @ 1.2 bar, EFI+EDIS, 951S brakes, stripped interior, 951 look.
'86 924S -- R.I.P.
https://www.instagram.com/ru_pacecar/

[Rocco R16V]

I too think two intercoolers just adds expense and complexity. in the system propsed only one power adder is heating the air at a time. if you go W/A get a huge radiator, big as will fit, and a decent sized resivoir.

I think A/A intercooler and water/meth inj, if you need more, is the way to go on these twin-charged motors.
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"Government exists to protect us from each other. Where government has gone beyond its limits is in deciding to protect us from ourselves. "
Ronald Reagan

[924OZY]

I am sure it will work,
I have a couple of magazines around here where it has been done on other cars. Just with a single front mount.

Doesn't the toyota blower already have some bypass valve that opens when it gets turned off?

if so could that be used, blow through, with the Turbo feeding it?

I would like to try this to spool my Garrett GT42,
Poor things been sitting around waiting for ages.

What size Turbo are you hoping to spool up with it?
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924 N/A snailshell, superpro linkage bushes, 2.5"exhaust

4.0L ef Fairmont, 3000rpm stall, shift-kit, J3 chip, 3" exhaust, self tuned using tunerpro, soon to be boosted,
expecting 350Kw at wheels at 10psi.

[ideola]

The idea behind a dual intercooled setup is that the S/C will definitely put a lot of heat into the charge, being able to remove it before the compressor inlet may be a good thing. The ideal config would be a CGT-style TMIC, as that setup really adds very minimal complexity. Bear in mind, this is so far just a theoretical exercise for me, although I've acquired almost all of the major parts to do it. If you only went with a single intercooler, my opinion is that a fairly massive liquid-to-air setup, post turbo with huge front mount rad as Rocco suggested, would be the best option given the space constraint and plumbing-routing options on the 931. My thinking on the dual setup is that given the location of the SC and Turbo on the setup I described, you're going to have a fairly significant run of piping from the SC to the Turbo anyway, why not add a FMIC in that path. Very direct, minimal bends, take advantage of the space that's there to remove as much heat from the charge as possible.

As for the turbo, I would probably up the AR on the turbine since the SC will be providing low end boost, such that the turbo came on a little higher in the revs, maybe 3500 RPM, leaving plenty of headroom to take build boost all the way to redline, then size the compressor for massive CFM, capable of pushing 25psi of boost with ease. I think the S1 turbine wheel would be about perfect, and then the K27 964 compressor setup I've got on my hybrid turbo, or perhaps something even a bit larger.
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erstwhile owner of just about every 924 variant ever made