Announcement

Collapse
No announcement yet.

Compound turbo setup with Holsets

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Compound turbo setup with Holsets

    Curious to hear your thoughts on this setup.

    Engine
    M50B28
    Shooting for 700hp

    Small Turbo (basically an HY35)
    CHRA: from 7 blade HX35
    Comp Housing: from 7 blade HX35
    Comp Wheel: from 7 blade HX35/HY35 (54/78)
    Turbine Wheel: from HE351/HY35 (58/65)
    Turbine Housing: T3 .63 AR
    External Wastegate: 44mm

    Large Turbo (basically an HX40 w/ HX50/52 size wheels)
    CHRA: from regular HX40
    Comp Housing: machined HX40
    Comp Wheel: aftermarket billet 7 blade (67/89)
    Turbine Wheel: from H1E (67/76)
    Turbine Housing: T3 1.06 AR
    External Wastegate: 44mm
    Last edited by imagine-02; 01-16-2017, 07:19 PM.
    :crazy:

    #2
    Sounds like a packaging nightmare
    2.7i Stroker Turbo Build Thread

    90 325i | 95 Miata

    Comment


      #3
      why not just a twin scroll gtx3582r with a twin scroll manifold?
      www.cp-e.com

      1989 Zinno 325i m52 turbo coupe
      2015 Ford Fiesta ST, Daily Driver.

      Comment


        #4
        What are you hoping to achieve? You say 700hp, but if you just want the number on the dyno chart why do you need two turbos?

        Presumably if you are looking at compound turbos you are trying to get as much boost early on as well as your 700hp figure. Guesstimates here, but lets say a good turbo for ~700hp may come onto required boost at say 4000rpm, so you are looking to fill 1000-4000rpm with boost from your smaller turbo. Is your turbo you have suggested small enough to do that? And what happens when that big turbo comes in? are you going to have a bypass or blow the big turbo through the small turbo? What kind of boost control are you going to use? i know you mention wastegates on both, but im not sure that will be enough. if you look at the FD-rx7 compound setup its got actuators and electronics to keep the smooth power delivery. Nothing worse than a huge hole in the change over region, or a huge power spike. I understand that even with the fancy electronics the FD does have a bit of a power hole.

        To design compound turbos correctly is going to be complicated, lots of staring at compressor maps and doing calculations at key points in the rev range, and your whole design is going to revolve around your boost goals. 10psi at 2000rpm? 15psi? and your boost goals are going to be determined by your required airflow at your desired power output read off the compressor map. And then you have the added complication of the interaction of the air flow of the two turbos. Microsoft excel is going to be your friend.

        I would think you could achieve your goals with a correctly sized modern single turbo and good supporting hardware to go with it, this will be half as complicated as your compound setup and probably less than half the cost. But hey, i too am always up for a challenge, so perhaps the compounds might be worth it with alot of work.

        Comment


          #5
          Davie is right, you really need to look at compressor maps. Two holset turbos do not equal faster spooling time. The exhaust and waste-gate exhaust get massively complicated for two turbos regardless on an e30 chassis.

          Comment


            #6
            As you guessed, the point is to build boost at low RPMs. The low RPM boost is wanted for tight and technical courses I race and drift on without having to shift. The high hp is wanted for larger and more open courses. Gotta keep up with the turbo V8s!

            Sadly I can't refer to compressor maps very much because both turbos will have modified wheels and housings.
            I'll be starting off with just the modified HX35 and decide from there if it spools soon enough to be used as the small turbo.

            My brother has built a couple compound setups on Cummins trucks, so I have a pretty good understanding of how the plumbing works. I'll be mimicking existing designs so the tubes don't end up winding around all over.
            :crazy:

            Comment

            Working...
            X