1. Join the Community!

    DSMtuners is a massive archive of DSM information - but more importantly, it's a COMMUNITY! Join in and participate with other DSMers, and invite all of your DSM friends to make this place their home. Chat with others, create a build thread, post questions and answers. Get involved! Logging in will also remove many of the advertisements, along with this notice. ;)

Compound Turbo Thread

Posted by RWD4G63, Oct 31, 2012

Please Support Kiggly Racing
Please Support Feal Suspension
  1. RWD4G63

    RWD4G63 Proven Member

    245
    10
    Joined Dec 7, 2011
    Mattawan, Michigan
    This is the thread to post and discuss all of your compound turbo setups.

    If you're posting your setup, please give details like piping size, A/R sizes, and obviously which turbos you're using.


    I'm using a twin-scroll HX30 and HX40 in mine. The HX30 has a 12cm2 TST3 housing and the HX40 has a knife edged TST3 21cm2 housing. Still in the build process.

    A550C080-7E3C-439E-910F-50B32AB2CFB7-13949-000013BECE443168.jpg

    The beginning:

    a4e89d46.jpg
     
  2. AK Maniak

    AK Maniak Proven Member

    1,131
    12
    Joined Jul 9, 2009
    Butte, Montana
    Madre De Dios! This looks like it has the ingredients to be an epic build. Can't wait to see more as you progress.
     
    AK Maniak

    528  0

    1999 Mitsubishi Eclipse GSX
    · 2G DSM
    Loading...
  3. Sp1kE

    Sp1kE Proven Member

    333
    11
    Joined Dec 24, 2005
    stratford, ON, Canada
    Cool, I was waiting for this.
    Here is my setup:

    DSCN0812.jpg
    DSCN0811.jpg
    DSCN0808.jpg
    DSCN0806.jpg
    DSCN0791.jpg
    DSCN0895.jpg
    DSCN0901.jpg

    I have only ran it up the road to about 20psi... But I had problems with engine management and am in the process of switching to an EVO 8 ECU

    Turbo's are 16g and Hy35(Will probably need to go bigger) with a water to air intercooler
    Engine is a built 2.4L bottom end and a budget head, hks 272 profile regrinds and evo behives.
    Car is meant for street driving and maybe the track once a month.
    I hope to be using it this summer.
     
  4. RWD4G63

    RWD4G63 Proven Member

    245
    10
    Joined Dec 7, 2011
    Mattawan, Michigan
    Interesting setup. I like the more "open" design of it. What do you have each wastegate set at? How does it feel?

    You're definitely going to run into backpressure issues if you run at higher boost with those small housings. If you do plan on upping the boost, I'd switch to an HX35 with a larger housing.
     
  5. Blurred Talon

    Blurred Talon Proven Member

    1,634
    38
    Joined Jan 2, 2004
    Paradise, NL, Canada
    I'm keeping my eyes open for an HX55 to do a Evo 3 16G HX55 combo.
     

    Street Build 1K  0

    1996 Eagle Talon TSi AWD
    manual · 2G DSM
    Loading...
  6. Sp1kE

    Sp1kE Proven Member

    333
    11
    Joined Dec 24, 2005
    stratford, ON, Canada
    I didn't get any good test runs with it because on my EMS being screwy, but it felt pretty smooth. For the 20psi run I think the 16g was at 12 and the holset did the rest.

    I was just going to run the setup until I ran into issues, then start changing stuff around. Kind of a work in progress..

    Thanks for the input... Any idea when you think I will get backpressure issues?
    What will be some early signs?
     
  7. 95GSXracer

    95GSXracer DSM Wiseman

    1,363
    97
    Joined Jul 25, 2002
    LaRue, Ohio
    I think everyone has seen my setup already. I'll update later when I get the new setup done. T3 50 trim on bottom, S475 on top. It went a best of 8.80 at 156 with boost in the mid 40s. Back pressure was 1:1 up to 8000 rpm, then it slowly crept up with rpm to about 3 psi over boost. This was due to the S475 comp wheel maxing out at such a low PR.

    Compoundturbobackpressure.jpg


    The next version will have the same 96mm turbine and 1.32 T6 housing, but will step up in comp wheel size to something that moves more air at ~2:1, and a bigger small turbo.
     

    Drag Race Build 2K  5

    1992 Eagle Talon TSi
    7.961 @ 171.10 · 1G DSM
    Loading...
  8. caged

    caged Proven Member

    100
    0
    Joined Jan 2, 2009
    Brisbane, Australia
    Evo 4 twin scroll Tdo5 16gHR and HX40 pro billet 7 blade.
    IMG_20120604_214308.jpg IMG_20120224_122555.jpg

    <iframe width="420" height="315" src="http://www.youtube.com/embed/i-J0taYLxeQ" frameborder="0" allowfullscreen></iframe>
     
  9. RWD4G63

    RWD4G63 Proven Member

    245
    10
    Joined Dec 7, 2011
    Mattawan, Michigan
    Nice! Talk about a sleeper. How does it feel? Have any more shots of the pipe work from another angle? I thought about using a 16G with my HX40, but I liked the HX30 for mine because of the higher flowing turbine/turbine housing.

    For sure man, I'm not an expert by any means, and I'm all for the experimentation.

    When I think about backpressure from the big turbo, I think like the 4G and small turbo are just a bigger engine. So let's say you make 300whp at 4500rpm (just a reference), what engine usually makes 300whp at 4500rpm? Probably something like a 3.5 liter V6. Would you want to run a HY35 and it's 9cm2 housing on a 3.5 liter? Probably not. This to me is the "easy" way. Yes, you can throw in a lot of math and actually figure it out scientifically, but for most people I think this makes sense, and gives a good rough idea of what size turbo and turbine housings to use.
     
  10. 95GSXracer

    95GSXracer DSM Wiseman

    1,363
    97
    Joined Jul 25, 2002
    LaRue, Ohio
    Engine displacement times small turbo PR is roughly what the big turbo will feel like it is attached to. Also, turbine drive pressure of the big turbo will be multiplied by the turbine expansion ratio of the small turbine, so you naturally want both as low as possible. If you run a restrictive exhaust it gets even worse. Exhaust back pressure x big turbine expansion ratio x small turbine expansion ratio will equal total turbine drive pressure at the exhaust manifold. It adds up fast!
     

    Drag Race Build 2K  5

    1992 Eagle Talon TSi
    7.961 @ 171.10 · 1G DSM
    Loading...
    camocorvette likes this.
  11. imagine-02

    imagine-02 Proven Member

    155
    1
    Joined Apr 19, 2008
    Chippewa Falls, Wisconsin
    I'm still in the planning stages of my compound setup.
    I have an hx30 with a single scroll 6cm housing (non wastegated) and an hx40 that currently has a big twin scroll housing on it (T4 18cm^2 IIRR). I've been thinking about using a BEP .70AR housing on the HX40 instead.
    For wastegates I plan on using two externals around 44mm (one for each turbo).

    Engine it will be used on is 2.0L with forged rods, forged pistons, forged crank, BC valve springs, and 272 cams.
    Goal is roughly 600hp.


    Thoughts on this setup?
     
    Last edited: Nov 1, 2012

    351  0

    1995 Eagle Talon TSi AWD
    manual · 2G DSM
    Loading...
  12. Sp1kE

    Sp1kE Proven Member

    333
    11
    Joined Dec 24, 2005
    stratford, ON, Canada
    Thats great info.
    Is there such thing as an exhaust pressure sensor that I should maybe look at getting?
     
  13. Tyeler18

    Tyeler18 Proven Member

    2,065
    76
    Joined Dec 16, 2008
    Casa Grande, Arizona
    Just a question on typical setups I'm seeing, why use the big turbo as your inlet turbo (the one sucking in atmospheric air) and feeding into the small turbo? Why not have the small turbo feeding into the big turbo instead? Saw the question asked in pauls compound thread, but how does the small turbo (ie pauls 16g) utilize the 35+ psi being pumped through it by the larger turbo, when it can't by itself handle that kind of pressure. Shaft speed is obviously a big issue, so is the smaller one just a carrier and doesnt actually see shaft speeds that would result from it trying to turn the say 35+ psi it would try and turn on its own?
     

    Drag Race Build 642  1

    1991 Eagle Talon TSi AWD
    awd · automatic · 1G DSM

    Road Race Build 667  0

    1990 Eagle Talon TSi AWD
    manual · 1G DSM

    Autocross Build 894  0

    1998 Mitsubishi Eclipse GSX
    manual · 2G DSM

    Road Race Build 1K  0

    1991 Mitsubishi Galant VR-4
    manual · Galant VR-4
    Loading...
  14. Kapok6

    Kapok6 Proven Member

    1,229
    254
    Joined Aug 10, 2004
    Fort Worth, Texas
    I have wondered this as well. Wouldn't the smaller compressor housing choke the air being pumped by the bigger turbo?
     
    Kapok6

    Street Build 2K  0

    1991 Mitsubishi Eclipse GSX
    11.3 @ 130.75 · 1G DSM
    Loading...
  15. imagine-02

    imagine-02 Proven Member

    155
    1
    Joined Apr 19, 2008
    Chippewa Falls, Wisconsin

    351  0

    1995 Eagle Talon TSi AWD
    manual · 2G DSM
    Loading...
  16. dacowgod

    dacowgod Freelancer

    390
    80
    Joined Feb 3, 2006
    Morgantown, West Virginia
    Through some trading I ended up w/ Pauls old setup and put a little twist on it...right now its configured with an EVO 3 16g and a PTE 6262 setup but I have 5 small turbos(14b,14g,small16g, EVO3 16g, and 20g) and 3 big turbos (HX35 in .58 AR T4, HX40 in .96 AR T4, and PTE 6262 in .68 AR T4) to try out Its going on my 97 GSX... 10.5:1 compression 2.0 E85 Auto build w/ Curt brown 2g head, Curt brown ported EVO 3 intake mani, w/ s200 cams and a pile of other goodies... I've got a Precision Converter stalled at 4000 and a stocker to try out as well..and a big ass Trans cooler as I want to do my very best at keeping this a street car :)

    My goal is to have near instant spool and run a 9.99 while retaining air conditioning... Initial plans were to fire it up and run it down the track this month.. but seems Hurricane Sandy in all likelyhood ruined that plan...oh well it will be up and running by Spring regardless.
     

    2K  0

    1997 Mitsubishi Eclipse GSX
    10.920 @ 133.900 · 2G DSM
    Loading...
  17. LandSpeed-DSM

    LandSpeed-DSM Proven Member

    1,991
    65
    Joined Dec 5, 2011
    Chicago, Illinois
    I'm always amazed that this question comes up in every discussion on compressors in series.

    You ever see how manufacturers don't list boost pressure on compressor flow maps?

    They list PR on the vertical axis, then volume or mass flow on the horizontal axis.. and what you should notice is that shaft speed curves laid across the efficiency islands correlate with PR.

    The turbo is just going to multiply whatever its fed by whatever PR is dictated by the shaft speed

    So at sea-level, a turbo running at xxxxxx shaft rpm generated a PR of 2 is going to take the volume introduced at the inlet at ~14.7PSIa pressure and spit it out at 29.4PSIa, which would show is 14.7PSIg on your boost gauge.

    If you took that turbo, at that same shaft speed (PR2.0) and took it to 10,000' above sea-level where the air is roughly going to be 10PSIa, it would spit out 20PSIa, but what your boost gauge would read boost depends on what type of gauge you have

    Now depending on your turbo, if you go up in altitude far enough you may not be able to turn the boost up far enough to provide sea-level mass flow.

    This is referred to as the 'Critical Altitude' and a T25 for example would probably be in this position at only 6000-7000' above sea level.

    What the primary turbo in a compound setup (neglecting charge heating entirely for the sake of discussion) is doing is akin to taking that smaller secondary turbo and going many thousand feet below sea level by increase the charge at the inlet.

    It's the part of the reason forward facing turbos can move more than their charted massflow at the big end of a high speed pull.. you are creating positive pressure at the inlet
     

    2K  0

    1992 Mitsubishi Eclipse GST
    · 1G DSM
    Loading...
  18. 95GSXracer

    95GSXracer DSM Wiseman

    1,363
    97
    Joined Jul 25, 2002
    LaRue, Ohio
    Any typical sensor with the right range will work for back pressure. I have used spare 5 bars (not enough range) and also have some 0-150psig sensors as well. Just hook them up to a spare channel on the ECU and log it.

    Regarding the question about the order of the turbos, it has to work this way. The small turbo can't move enough air to keep up with the big turbo, but it can keep up with the big turbo feeding it. The first turbo to see charge air doesn't have the help of another turbo pushing air into it, so that has to be the big one. The small turbo still moves the same volume of air it always does, it's just moving much denser air, so more air mass. Compressor maps are often shown in with mass air flow on the X axis (how I usually prefer it), but it's really just volume flow converted to mass flow using some standard for inlet conditions. We're just messing with the inlet conditions by putting another turbo in front of it. Volume flow at a given PR doesn't change, so neither does shaft speed. Total airflow divided by big turbo PR in addition to small turbo PR will put you in the ballpark on the small turbo's compressor map if you want to play around with it.

    The old example I always use is that people generally know what happens to a turbo at high elevations, this is like putting the small turbo 10,000 feet below sea level. Volume flow is the same in either case, and you wouldn't expec the turbo to blow up or anything. To use some convenient numbers, if a small turbo moves 500 cfm, which turns out to be 50 lbs/min at sea level, it will move 100 lbs/min if we double it's inlet pressure to 30 psia, or 15 psig, with the big turbo. Volume flow remains unchanged, density doubles, and so does mass flow. Hopefully that helps.
     

    Drag Race Build 2K  5

    1992 Eagle Talon TSi
    7.961 @ 171.10 · 1G DSM
    Loading...
  19. RWD4G63

    RWD4G63 Proven Member

    245
    10
    Joined Dec 7, 2011
    Mattawan, Michigan
    You're definitely not going to want to run the BEP housing on the HX40. It is much to small for a compound setup. Sounds pretty similar to my setup overall, except I have a 2.3.
     
  20. imagine-02

    imagine-02 Proven Member

    155
    1
    Joined Apr 19, 2008
    Chippewa Falls, Wisconsin
    Isn't the .70AR housing enough to max out an HX40? Maybe I'm remembering wrong.

    Is there a bigger single scroll housing available that will work on an HX40?
    I don't really want to use a twin scroll housing if it's not going to be used in twin scroll form.

    Where did you get a 12cm^2 housing for your HX30? I've never seen one with that big of a housing.
     

    351  0

    1995 Eagle Talon TSi AWD
    manual · 2G DSM
    Loading...
  21. caged

    caged Proven Member

    100
    0
    Joined Jan 2, 2009
    Brisbane, Australia
    Dont forget the small turbo makes the same effect as a bigger capacity motor feeding the large turbo so you will need a much bigger rear housing than normally on a 2L. My T3 18cm on my hx40 almost feels to small. I wouldnt want anything smaller at all.
     
  22. RWD4G63

    RWD4G63 Proven Member

    245
    10
    Joined Dec 7, 2011
    Mattawan, Michigan
    What caged said, and they are a pretty rare wastegated housing. It's not as big has the HX35 12cm2 housing, but a lot larger than what normally comes on a turbo this size, and should still spool awesome with the twin-scroll. Have you checked to see if you have the 40 or 44mm inducer on your compressor wheel?

    5C2B3BFF-ED28-4762-A050-C36BF69F9FC8-2794-0000019CB8F583DC.jpg

    I haven't been able to find a large enough single scroll housing for the HX40, so I'm getting a 21cm2 housing from a WH1C machined to fit and knife edging the divider.
     
  23. imagine-02

    imagine-02 Proven Member

    155
    1
    Joined Apr 19, 2008
    Chippewa Falls, Wisconsin
    Ohh that makes sense. Maybe I'll just try the housing that's already on it until I find a big single scroll. There's gotta be something out there, even if machining is needed.

    I'm not sure if my hx30 is 40 or 44mm. I'm thinking it might be 40mm. I don't have my turbos at home so I can't check.
    What's the flow difference between the two?
     

    351  0

    1995 Eagle Talon TSi AWD
    manual · 2G DSM
    Loading...
  24. bastarddsm

    bastarddsm Proven Member

    4,430
    999
    Joined Aug 26, 2003
    Mendota, Illinois

    To simplyfy it down, a turbo chokes on inlet volume not mass. So the 16g can intake like 600cfm, it doesn't care if its at 14.7psia or 100psia, It can only move 600cfm. So if a 16g chokes at about 44lbs/min when the intake pressure is at atmosphere (14.7psia), its moving about 600cfm, now you increase the inlet pressure to 30psia (twice the pressue of atomsphere ~2 times the density) It should be capable of flowing 88lbs/min.


    Why don't you just have a single garret housing machined for it?
     

    Showcar Build 5K  1

    1991 Eagle Talon N/T
    9.805 @ 144.00 · 1G DSM
    Loading...
  25. imagine-02

    imagine-02 Proven Member

    155
    1
    Joined Apr 19, 2008
    Chippewa Falls, Wisconsin
    I've been thinking about using a Garrett housing too since I've seen them on hx40's before. Just haven't look into it very much yet.
    What would be the ideal AR size for a goal of roughly 600hp?
     

    351  0

    1995 Eagle Talon TSi AWD
    manual · 2G DSM
    Loading...

Share This Page

Support Vendors who Support the DSM Community
Archer Fabrication ECM Tuning ExtremePSI Feal Suspension Fuel Injector Clinic Jacks Transmissions JNZ Tuning Kiggly Racing Morrison Fabrications OHM Racing RockAuto SouthBay Fuel Injectors STM Tuned Track Decals Track Sculptures VR Speed Factory WheelWell.com