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Thread: TWINcharged SC ???

  1. #1
    Join Date
    Aug 2012
    Posts
    26

    TWINcharged SC ???

    Hey, My name is Daniel. I've been a proud owner of my 92 for years now and btw im 17
    I have some big plans for my sc and I was wondering what you guys think. I'm planning on twin charging my sc in the future but I was wondering what you guys think, and some things I should think about.

    Current mods:
    10% overdrive pulley
    stage 2 cam
    matched port and polished heads
    cold air intake
    no cats/2.5 in. exhaust pipe/ flow master
    stage 2 clutch
    3200lb pressure plate
    t56 tranny (97 Selene mustang 6 speed)
    limited slip 2:1 differential
    100hp shot of nos (wet kit)

    what I was planning was mounting the turbo in the back like mid way theres room to mount next to the tranny and run a pipe off the air intake after the MAF sensor to the turbo , use the exhaust on the way back to the engine as the intercooler for the turbo. reroute the supercharger boost pipe to follow down over the air intake pipe. get an aftermarket intercooler, then a Y pipe to hook the turbo and the supercharger into the ic. put a butterfly valve or what ever its called before each pipe hooks into the Y pipe. then a blow off on the supercharger pipe for when the turbo out boost the supercharger and the door closes it can just blow off. I know I will probably have to rebuild the bottom end.

    My questions are:
    how much boost should I push (turbo)
    what kind of turbo?
    bottom end rebuild tips and upgrades?
    -pistons
    -arms
    -crank
    fuel system upgrades?

    anything else im not thinking of?

    thank you so much for your help and input, I wanna try to cover anything possible so I can start compiling a list of parts to buy. I can do the pipe work myself, and finally Ive researched other set-ups with the supercharger feeding into the intake side of the turbo but I can see that causing problems as it will pull more air than the sc can push. right?
    Last edited by DV_17; 06-02-2014 at 06:12 AM.

  2. #2
    Join Date
    May 2004
    Location
    Va. Beach,Va.
    Posts
    7,061
    Look up kenewagner, he's already done a remote twin turbo set-up. No one has done a compound boost set-up as you're describing.
    SCCOA Member #2406
    '94 SC AUTO - 2.3 Whipple
    '90 SC AUTO - Bone Stock
    http://www.sccoa.com/forums/garage_v..._vehicle&id=19

  3. #3
    Join Date
    Aug 2012
    Posts
    26
    I will do thanks

  4. #4
    Join Date
    Sep 2013
    Location
    New Oxford Pa
    Posts
    157

    Twin

    Might b cool.or check out how the kits work for cobra.a guy I work with his friend has a turbo supercharged cobra.he bought a kit designed just for the cobra.turbo only would prolly yeild way more power than twin charging.but it's a cool and dif idea to do.depends on what u wanna do with the car.power or wow factor I guess.and too much turbo could actually put that boost back into the blower and counter act it depending on the set up.i.e how the intake pipes are routed

  5. #5
    Join Date
    Apr 2002
    Location
    St. Charles, MO
    Posts
    21,033
    Quote Originally Posted by DV_17 View Post
    I will do thanks
    Search "compound boost" and you will find lots of discussion on the topic. About 10 years ago I looked at doing it to my 91 SC but went with a twin screw supercharger instead.

    David
    1991 SC AOD 4.2..2.3 Whipple..........10.910 @ 125.61
    2016 SRT Challenger Hellcat.............10.597 @ 135.78

    My Garage

  6. #6
    Join Date
    Jun 2002
    Location
    SCCoA Member#1257
    Posts
    3,330
    I've always wanted to do this to one of my birds. AFter several years of having a "thin" flock (from up to 7 at one point) I'm getting the itch again.

    My biggest problem was finding an electromagnetic clutch pulley to electrically disengage the supercharger at a given point. Some supercharged merc's have such a clutch pulley, but the sizes are all wrong.
    Current: 1993 SC 5.0L Auto Red, 1994 SC 5-speed Teal, 1995 SC 5-speed Chameleon Blue
    Old: 89 SC auto Twilight Blue, 89 SC stick Titanium, 90 35th stick, 92 Sport 5.0L stick, 94 SC stick Black, 1994 SC Auto Teal
    Also: 1992 Feature Mustang Convertible 5-speed Vibrant Red, 1991 BMW 850i 6-speed Red, 1994 BMW 850CSi 6-speed Red

    www.mamn12.com for your mid-atlantic mn12 needs!

  7. #7
    Join Date
    Jun 2009
    Posts
    56
    I always liked the idea but felt it more fitting for smaller displacement inline engines, supercharger giving it some tq and turbo still bringing in a solid top end. I personally don't feel it would benefit as much on a larger engine like ours that even N/A makes fair tq numbers, though the turbos would probably make up for a weak point of the top end. i'd personally try and run air out from the turbos through the MAF and back into the throttle body, you will greatly increase the flow capability of the TB and SC inlet by flowing pressurized air through it, I'd think with this setup you'd want a nice big flowing SC like an MPX and run it with a very mild OD and let the turbos make up the difference then just run a big FMIC. I suppose the air from the turbo may be still a little hot but it should be alot cooler if its remote mounted but you could run a small side mount off in the fender well with a fan so your not feeding the SC too hot of air.

    That's my .02 cents but i have no experience doing anything like this at all so i doubt its worth much...

  8. #8
    Join Date
    Apr 2002
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    St. Charles, MO
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    Quote Originally Posted by 91dak239 View Post
    I always liked the idea but felt it more fitting for smaller displacement inline engines, supercharger giving it some tq and turbo still bringing in a solid top end. I personally don't feel it would benefit as much on a larger engine like ours that even N/A makes fair tq numbers, though the turbos would probably make up for a weak point of the top end. i'd personally try and run air out from the turbos through the MAF and back into the throttle body, you will greatly increase the flow capability of the TB and SC inlet by flowing pressurized air through it, I'd think with this setup you'd want a nice big flowing SC like an MPX and run it with a very mild OD and let the turbos make up the difference then just run a big FMIC. I suppose the air from the turbo may be still a little hot but it should be alot cooler if its remote mounted but you could run a small side mount off in the fender well with a fan so your not feeding the SC too hot of air.

    That's my .02 cents but i have no experience doing anything like this at all so i doubt its worth much...
    That's actually very close to how I would do it. If you set the waste gate on the turbo to maintain 5 psi inlet pressure on the supercharger, you would be surprised how much air a stock late model supercharger and 75mm throttle body would move. I don't think there would be any need to pre-cool the air entering the supercharger because at only 5 psi it isn't going to be very hot. The supercharger won't work any harder moving the air either, and I don't think the increase in air temp exiting the supercharger would be any higher that over driving an MPX at 20%. Only thing different from stock would be the need for a blow through MAF and those are readily available.

    David
    1991 SC AOD 4.2..2.3 Whipple..........10.910 @ 125.61
    2016 SRT Challenger Hellcat.............10.597 @ 135.78

    My Garage

  9. #9
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    Apr 2002
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    Lakeville, MN
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    13,517
    In 2007 I was doing some research on the optimum setup. Obviously, disconnecting the supercharger with a clutch is not anywhere near an optimum setup. Doing such is simply a bad idea.

    Here is a quote from something I posted in this thread regarding calculating the size turbo you need (members area): http://www.sccoa.com/forums/showthre...=twin+charging
    Take a SC motor with a given CI of 232. For each turn of the crankshaft that gives us 116CI.
    A stock M90 has a displacement of 90ci per turn of the blower shaft.
    Ambient Air pressure is 14.7, but we'll pull out 1 for restriction of a filter.(seen used at www.turbobygarret.com)
    Set a target boost of 25psi (gauge boost)
    That is equivalent to a total Pressure of 38.7 (13.7+25)
    That gives us a total pressure ratio change of 2.8.
    Take the Square Root to assign this to each device in our twin charging system, giving us a Pressure Ratio Required per participant of 1.67. (assuming equal split)

    We can then calculate the total cubic inch increase per crankshaft revolution to get a 1.67 pressure increase, at 193.72.
    For our SC we would then need to overdrive the blower shaft per crankshaft revolution 2.15. This should be fine with a stock setup, which overdrives the blower, 2.77 revs per single crank rev.

    Now to spec our turbo, we need to first figure out total CFM needed for a particular RPM. So if we look at 5000 rpm, we take our needed CI of 193.72 times our RPM, and then divide it by 3456 giving us a needed 280CF per minute at 5000rpm.

    We can move that to an Air Mass rate (used in turbo sizing) by multiplying this value by the air density at sea level of .076lb/ft3 which gives us a mass flow rate of 21.30.

    So with a mass flow rate of 21.3, and a Pressure Ratio wanted of 1.67, I can go turbo shopping.
    This thread over at the Engine and Fuel engineering forum may be helpful as well
    http://www.eng-tips.com/viewthread.cfm?qid=174690

    I also created a spreadsheet then in google docs to help with the calculations when looking for a turbo.
    http://spreadsheets.google.com/ccc?k...s6qxHraQ&hl=en

  10. #10
    Join Date
    Aug 2012
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    26

    i did a little re design

    I did a little re design do you guys see any problems Name:  twincharge prototype.png
Views: 928
Size:  24.4 KB

  11. #11
    Join Date
    Dec 2009
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    699
    Your maf placement will not work very well. You need to place it in blow through configuration after the bov and before the tb (of course).
    03' mustang, scu 4.3 with a turbo. 7.0 @ 102mph

  12. #12
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    Aug 2012
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    26

    redesign 2

    after I did some research and read up on the links I now understand that superchargers work on a movement of air ratio. I.E. if the super charger runs a 1:2 ratio of air in vs. air out then if it sucks in air at 1psi it will leave the blower at 2psi. so after the turbo is introduced and is supplying the supercharger, lets say with 10lbs of boost than it will leave the blower at 20lbs. This is what I took form everything. boost ratios arn't added they are multiplied. here's a quick sketch of my new design. let me know what you think. Name:  twincharge prototype 2.png
Views: 633
Size:  18.2 KB

  13. #13
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    Your MAF needs to be just before the engine after the blow off
    ~Chris
    SCCoA Member #1826
    Bettie Riding jack stands
    SCARlit on drag duty now

  14. #14
    Join Date
    Dec 2010
    Location
    Palm Beach, Florida
    Posts
    373
    I haven't really read through the posts in this thread but saw your title and ffigured I would post up about my abandoned compound boost project. http://www.sccoa.com/forums/attachme...8&d=1378169854 thats how far I got before scrapping the supercharger and just going with the turbo only. I was hard headed in the past and didnt listen to the dozens of people telling me that it was an inefficient setup. I wasted a lot of money on the project but it was a fun project so at least there's that. I still want to see someone actually do a compound boost setup on a SC motor but doubt anyone ever will. Its simpler and cheaper to make more power with a turbo alone.

  15. #15
    Join Date
    Apr 2002
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    St. Charles, MO
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    This is how I would arrange it. Wastegate between supercharger outlet and IC is not needed, BOV needs to be after turbo outlet and prior to MAF, using a vacuum signal from somewhere after the Throttle Body. All the stock plumbing from the Throttle Body to the intake manifold would stay as it is, unless you wanted to add a FMIC. This also requires switching from a Draw through to a Blow through MAF.

    Name:  twincharge prototype 2.png
Views: 1331
Size:  35.2 KB


    David
    Last edited by David Neibert; 09-11-2014 at 08:13 PM.
    1991 SC AOD 4.2..2.3 Whipple..........10.910 @ 125.61
    2016 SRT Challenger Hellcat.............10.597 @ 135.78

    My Garage

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