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Twin charging make sense

Discussion in '4 Stroke Turbos/Supercharger' started by kinger, Mar 16, 2011.


  1. kinger

    kinger VIP Member VIP Member

    Messages:
    6,096
    Location:
    Clear Lake, IA
    Snow is gone so brainstorming begins on sled for next year. Got to thinking about adding a turbo to my sled with the SC.

    Basically lower compression to 8.25:1 with pistons and shim, flip the pulleys on my stage 1 to run 5-6psi, then get a stage 2 turbo system running around 16-17psi total. This would allow me to still run 91 according to the boost calc and pick up 60hp for a even 300 on 91 gas.

    At light loads going down the trail I would only see the SC boost so 5-6 psi vs my current 10-11 psi so hopefully my MPG would be a little better off the gas going down the trail at 60-70mph on those long straight railroad beds.

    Starting from scratch it makes no sense and stupid expensive but since I already have all that and turbo kits used are getting cheaper and cheaper maybe it makes sense?

    I couldn't just run a turbo and NO SC because it would be a laggy SOB with that low of compression.

    Perhaps that is too low of CR to even think of running? Fuel is my limiting factor, 91 is all I got and not interested in race fuel barrels all over the garage.

    Can this system work with stock injectors and my MPI controller? I already have the 255 pump and there is mixed reactions to the injectors and how much HP they will support but most say 280-300 is the limit.

    The only thing I cant think of is how the Sc and the TC air outlets get into the same intercooler, will the Sc be pressurizing the TC at low loads and creating a restriction?

    anyway on to summer bench racing! LOL
     
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  3. thamax

    thamax Pro

    Messages:
    173
    Location:
    2 falls, ID
    that sucks we still have several months of riding out west still. i know there is a twin turbo nytro and he claims to build boost like a supercharger i think having to systems could work well u can find that out make sure u have a backup sled cause not having a boosted sled to ride is no fun at all
     
  4. kinger

    kinger VIP Member VIP Member

    Messages:
    6,096
    Location:
    Clear Lake, IA
    Yeah it sounds silly but it would be unique and hopefully not a unique headache LOL
     
  5. headache

    headache Newbie

    Messages:
    11
    Location:
    Norway
    I am running 7.6:1 on my twinscrew and the trottle respons is way above anyhing else I been riding. Don't worry about the comp...
     
  6. kinger

    kinger VIP Member VIP Member

    Messages:
    6,096
    Location:
    Clear Lake, IA
    thanks headache.

    Doing some more research I cannot simply plumb the turbo outlet into the intercooler AND the SC outlet as it would only just pressurize each other and build no boost or cause the engine to stall.

    I either A have to have a diverter valve that shuts the Supercharger off (blow off all the air its making) when the turbo comes on and vice versa.

    Or B sequentially plumb the output of the sc into the inlet of the Turbo and the outlet of the turbo into the intercooler. Problem there is you get compound boost and compound efficiencies meaning 7 psi from Sc and 7 psi from turbo will give you almost 20 psi to intake and if the Sc is 60% effificent and the turbo is 70% efficient the compounded outlet charge temp could become way to high to cool back down before entering the engine. (hundreds of degrees too high over ambient temp)

    I will look at some bypass valves to do what I want and how to position them before I give up.
     
  7. yooper1

    yooper1 Expert

    Messages:
    361
    Location:
    Houghton, Michigan
    I had a system made on my last Dodge diesel, your on track with the way you would plum it into the s/c. It would be hard to explane but the reason for twins is to keep each Turbo in the correct efficiency curve. So if I remeber right it is psi of turbo + s/c (i want ot say) 14.7 = total boost in that application. I used to run 70 psi on my truck.

    I think the heat would be okay, I would want to know both manifold pressure for intake and exhaust.

    Detroit Diesel used to have a set up like that. S/C to turbo, it was cool.

    I'll try to find some information and pm/email you it. Plus I know a ton of people that have ton something similer.
     

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  8. RED

    RED Lifetime Member Lifetime VIP Member VIP Member

    Messages:
    1,058
    Location:
    alberta
    The 2 stroke detriot was setup with the turbo sitting on top of the blower. Not sure if there is enough room in a sled for all the plumbing. Your super would have to feed the turbo, then turbo feed the engine. Not saying it cant be done, but it will be alot of work. Wish more people out west would look to the supercharger. Except for mpi yrs ago was such a flakee run business, then seem to have there stuff together now. They did some odd business things yrs ago. Good luck with your build.
     
  9. yooper1

    yooper1 Expert

    Messages:
    361
    Location:
    Houghton, Michigan
    The turbo can sit anywhere, it has piping.

    If you Google "twincharging" you can read about this. There is a lot of down side to this.

    If it were me?
    I would try a Variable geometry turbocharger. You get that right and the world is your Oyster. Maybe off an old 1989 Shelby CSX-VNT utilised a turbo from Garrett, called the VNT-25 because it used the same compressor and shaft as the more common Garrett T-25. This type of turbine is called a Variable Nozzle Turbine (VNT). Turbocharger manufacturer Aerocharger uses the term 'Variable Area Turbine Nozzle' (VATN) to describe this type of turbine nozzle.

    However a rear turbo mount system you could plum into the S/C and could most likly be simple.
     
  10. dirk_03

    dirk_03 Expert

    Messages:
    492
    Location:
    Lake Crystal, MN
    Kinger, you should just trade sleds with me. My turbo have very good response, also gets good gas mileage.
     
  11. nate007

    nate007 Moderator Staff Member Moderator Lifetime VIP Member VIP Member

    Messages:
    2,789
    Location:
    Iowa City, Iowa
    Country:
    USA
    Snowmobile:
    1. '06 Apex -twin screw
    2. '04 Redline Revolt 800
    3. '09 Nytro XTX - twin screw
    Just by stacking two methods of producing boost doesn't necessarilly mean you get the sum of the two. There are other flow, pressure, restriction, and physical limitations to consider.
    You would reduce the mechanical load on the supercharger by feeding it with a turbo, but you may actually block the turbo from making full boost if the s/c isn't spinning fast enough to consume it, or you'd be wasting boost, either way depending on how you have things designed.
    One way I've seen a few times on race or specialty vehicles is for a low boost turbo to feed a s/c. The turbo would aid the s/c in making much more boost since it's not relying on atmospheric pressure to draw air in. It would still increase boost substantially, but in theory reduce the mechanical drag of being engine driven, while making incredible throttle response.
    IMO, if you want to do something unique and test your engineering skills, that's a killer idea to definitely be different and experiment with different setups, but if you're looking for a specific goal, I would choose a single power adder and start with a clean slate and tailor one to your needs.
     
  12. t_thall

    t_thall Extreme

    Messages:
    77
    Location:
    saskatchewan, canada
    This is doable but you wouldn't want an off the shelf turbo kit. You would want to size the turbo for what your engine acts like with the blower (Say on 6psi your engine moves as much air as a 1500cc engine), then you would size the turbo to meet your power goals on that engine and plumb your turbo into the supercharger inlet. You would get the turbo wastegate signal after the supercharger so you can always control total boost. You would be able to get away with a larger turbo and larger a/r turbine to keep the intake temps very low with the super helping to spool the turbo...
     
  13. kinger

    kinger VIP Member VIP Member

    Messages:
    6,096
    Location:
    Clear Lake, IA
    Its been 7 years still want to try this, I happen to have a apex with a SC and a mid mount impulse turbo sitting next to each other in the garage with no buyers....Hmmm

    My thought was for packaging I can only plumb the turbo into the SC inlet just like the mustang terminator guys who feed their factory eaton with a turbo. It makes the SC work less hard improving mpg and you get the compound effect. It would have to be 5 psi each blower to make ~12psi at motor and safe for 91 on current compression. Now that I have a winder maybe I will be more apt to play with the apex. I miss the 20mph grunt and snap of the SC but LOVE the top end WHOOOOSH of the turbo pushing the sled to over 140mph (with skis dangling I might add when you move fuel under seat). I wonder if compounding them will be give me the benefits of both or just land somewhere in between. I even have a Motec I could play with if that doesn't sell.

    I need a bigger garage so I can get the sleds in and not kick the summer toy out!
     
  14. Yamadog

    Yamadog Lifetime Member Lifetime VIP Member VIP Member

    Messages:
    5,340
    Location:
    Minneapolis
    Almost sounds like a turduckin!
     
  15. kinger

    kinger VIP Member VIP Member

    Messages:
    6,096
    Location:
    Clear Lake, IA
    Even you want twin charge Yamadog just admit it :)
     
  16. Yamadog

    Yamadog Lifetime Member Lifetime VIP Member VIP Member

    Messages:
    5,340
    Location:
    Minneapolis

    Oh Kinger you know it!!! I was just looking at the drag sled the other day and saying to myself what's next? I mean I got 4 runs in on it last year at the Weenie roast after the Epic 3 year build - I NEED MORE POWER :o|

    Not Turduckin - "Turchargenos" - Webster Says Turbo, Super Charger with NOS :die Nothing says 1/4 mile on fire better than that! :nos
     

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