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  1. #1
    Kit
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    Rear mount turbo systems

    I was wondering what the negatives where in such a setup?

    Can the outlet for the turbo be turned around on something like a HX35 or 50?

    RWD V8 Hilux Mk2

  2. #2
    - Fezcock -
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    Reckon phil should do this with his V10 M3

    this runs two gtk-35 turbos (turbonetics) At a guess similar to a Holset HX35?

    First Widebody Twin-Turbo Lexus IS-F - TuneMyToyota.com
    Last edited by - Fezcock -; 06-08-2011 at 21:17.

  3. #3
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    By rear mount I would imagine you mean a turbo mounted in the rear if the car, doesn't sound like that's what you are asking though :s

  4. #4
    Kit
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    Quote Originally Posted by MrLuke View Post
    By rear mount I would imagine you mean a turbo mounted in the rear if the car, doesn't sound like that's what you are asking though :s
    That's exactly what I was talking about, the same as the pic posted by Fezz except with a single turbo?
    RWD V8 Hilux Mk2

  5. #5
    spl dori master
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    Tuuuuuuuuuuuuuurrrrrrrrrrrrrrrrrrrrrrrrrrrrbbbbbbb bbbbbbbbbbboooooooooooo lag

    The turbine should be as close to the combustion chamber as possible. the greater the volume of gas in the manifold the more the time delay in spooling up. Same goes for the compressor outlet to intercooler.

    Also the time delay in getting pressurised oil to the bearing housng on the turbo could wreck the bearings. I can't see how the oil return works either
    Last edited by 4_Stroke; 06-08-2011 at 21:32.

  6. #6
    Kit
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    Quote Originally Posted by 4_Stroke View Post
    Tuuuuuuuuuuuuuurrrrrrrrrrrrrrrrrrrrrrrrrrrrbbbbbbb bbbbbbbbbbboooooooooooo lag

    The turbine should be as close to the combustion chamber as possible. the greater the volume of gas in the manifold the more the time delay in spooling up. Same goes for the compressor outlet to intercooler.
    I've yet to see any evidence of this that proves there's a real-world effect, lots of people said the same about having gigantic intercoolers.

    The flow off a HX35 on a 1UZ sized engine I expect to have minimal lag.
    RWD V8 Hilux Mk2

  7. #7
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    Quote Originally Posted by 4_Stroke View Post
    Tuuuuuuuuuuuuuurrrrrrrrrrrrrrrrrrrrrrrrrrrrbbbbbbb bbbbbbbbbbboooooooooooo lag

    The turbine should be as close to the combustion chamber as possible. the greater the volume of gas in the manifold the more the time delay in spooling up. Same goes for the compressor outlet to intercooler.

    Also the time delay in getting pressurised oil to the bearing housng on the turbo could wreck the bearings.
    Not always NO. Plenty of info around for good rear mounted turbo systems.

    E46 325 here:- ControlSA

  8. #8
    spl dori master
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    Ok.... Just going by my experience at Holset. turbo spooling is helped by exhaust "pulsing" the further away from the manifold the smaller the pulse. As the exhaust cools it loses energy which reduces turbine efficiency.
    Last edited by 4_Stroke; 06-08-2011 at 21:41.

  9. #9
    Kit
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    In which case you've got to size the turbo correctly, i'm sure there would be a lower inlet charge temperature which would offset the losses in efficiency.

    Do you have any figures on how lower exhaust temps and pulse actually effect efficiency?

    If you work at holset, could you tell me if it's possible to take appart a HX35 and rotate the charge outlet so it's pointing in the same direction as the exhaust inlet?
    RWD V8 Hilux Mk2

  10. #10
    spl dori master
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    Quote Originally Posted by Kit View Post
    In which case you've got to size the turbo correctly, i'm sure there would be a lower inlet charge temperature which would offset the losses in efficiency.

    Do you have any figures on how lower exhaust temps and pulse actually effect efficiency?

    If you work at holset, could you tell me if it's possible to take appart a HX35 and rotate the charge outlet so it's pointing in the same direction as the exhaust inlet?
    Exhaust temperatures at the turbine inlet should be between 750 and 950 degrees (they can go up to 1000). If you slacken the clamp screws on the compressor housing you can rotate it round, same goes for the turbine housing. If you dismantle the internals remember the compressor nut is a left handed thread.

  11. #11
    Kit
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    Yeah but what is the actual %/hp effect if the exhaust temperature is say 200 degrees and what about pulse, what's the %/hp effect of having it and not having it. Can you quantify these facts?


    Cheers for the info on the housing, i've never dismantled a big turbo before (just a little one of a 206 HDi ) so that'll be interesting.
    RWD V8 Hilux Mk2

  12. #12
    spl dori master
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    Quote Originally Posted by Kit View Post
    Yeah but what is the actual %/hp effect if the exhaust temperature is say 200 degrees and what about pulse, what's the %/hp effect of having it and not having it. Can you quantify these facts?


    Cheers for the info on the housing, i've never dismantled a big turbo before (just a little one of a 206 HDi ) so that'll be interesting.
    The energy recoverd by the turbo and converted to compressor power can be related to temperature drop in the turbine. Typicaly a a 850 degree inlet temperature will result in a 450 degree outlet temperature (400 drop). So the higher the inlet temperature the greater the efficiency. Race cars use nickel alloy exhaust manifolds to run higher temperatures. Not sure what happens when you get so low.

    For those that are intereted the pulse effect is why some turbine housings have a splitter blade. They are for 6 cylinder engines where the exhaust manifold is split into 2 halfs the. 3 cylinders feed into each side of the splitter getting the greatest effect from exhaust pulsing.

  13. #13
    Kit
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    How does the % temperature drop increase efficiency?

    I still don't understand from your answer how exhaust pulse helps efficiency?

    Am I being stupid here
    RWD V8 Hilux Mk2

  14. #14
    touge runner
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    run anti-lag with this turbo system would work sweet

  15. #15
    spl dori master
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    Quote Originally Posted by Kit View Post
    How does the % temperature drop increase efficiency?

    I still don't understand from your answer how exhaust pulse helps efficiency?

    Am I being stupid here
    The relationship between temperature an efficiency is complex. The temperature drop relates to the energy recovered at constant inlet temp. Turbine efficiency drops off significantly as the turbine inlet temp drops.

    The official description (not mine!)"The turbine
    expansion ratio rises slightly with decreasing inlet temperature yielding necessary
    isentropic turbine enthalpies for constant compressor power.
    The turbine inlet temperature influences the local Mach number which affects the
    flow characteristics in the turbine. When the inlet temperature decreases the speed
    of sound follows yielding increasing Mach number in the turbine. This results in rising
    flow losses which influence the turbine efficiency"... simples!



    Pulsing is seperate. as the exhaust gas pulses hit the turbine they help it spool up faster.

    I would like to know how the oil return issue is solved. I am assuming it may have a scavange pump or some kind of dry sump system. The turbo has a considerable oil flow.

    When it comes to oiling the turbo I was always told the maximum delay in getting oil to the turbo was around 8 seconds after fire-up. After that the turbo bearings will have scuffed.

    Here is some good general tech on turbos.
    http://www.turbobygarrett.com/turbob...o_tech102.html

    I have been doing some digging and it does look like there are several sysems out there. BUT a lot of the tech crap is being put out by the vendors (especialy the US ones) who have a vested interest and are looking to create the next fad. They also seem to be running very low boost which means you can get away with more. Its hard to get impartial advice from experts. For me its the WORST place to put a turbo for all the reasons I have said (and goes against the recommendations of the turbo manufacturers) but its up to you. Let me know how you get on.
    Last edited by 4_Stroke; 07-08-2011 at 09:53.

  16. #16
    Kit
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    Ahhhhhhhhhhhhhhhhhh I get it, sound moves faster through a hotter substance which helps drive the turbine

    I'm not sure how pulsing helps but i'm sure you're right!

    Actually i'm not thinking of mounting my system right at the arse end of the motor like is commonly seen, I want to keep it as close the engine now after your advice as possible.

    Do you have any recommendations on scavenge pumps available in the uk?
    Last edited by Kit; 07-08-2011 at 14:37.
    RWD V8 Hilux Mk2

  17. #17
    Miseryguts

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    Done right, its 100% fine and as good as up front.
    Done like 99% are, inc STS setups, and it works, but its a bit average compared to the same thing up front.

    If you planning on spooling a 35 and deffo a 50, I hope you got a fairly big engine to do so or a well thought out setup.

    There are setups running 7sec 1/4s and no less response than they had up front, but needs to be done right.

    Zero point asking on here, even the obvious tech info is 5th hand BS on here these days, never mind something thats almost never done in the UK.

    Personally, unless you have a mega good reason to do it, I wouldnt bother, esp as you only just grasping how turbos work etc going by above.

  18. #18
    Kit
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    The engine is 1UZ in my mk2 i'm planning on running the radiator in the rear and replacing it with the largest intercooler I can fit.

    Where's best for me to learn more about doing this type of system right?
    RWD V8 Hilux Mk2

  19. #19
    Miseryguts

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    1UZ with a rear mounted 35 will spool it even with the shittest setup in the world. 50 would not be thta easy even up front.

    Wouldnt bother with a rear mount rad as a rear mount 35 wouldnt need that big an intercooler on a 1UZ anyhow so can keep it simple and both up front.

    Stock or basic log/short manifolds merging into single 2.5in pipe to rear, 4in turbo back stubby pipe, heat wrap it all, quickspool valve if you feeling flashy, but prob no need, zero lag, done.

    Order a scavenge pump from the USA, normal diff oil pumps etc dont cope well.

  20. #20
    Kit
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    I'll probably still do the rear mount rad as it's something i've always wanted to do, is a 35 the best sized turbo for a stock 1UZ, this guy is running a HX55 on one: 10 Second 1UZ-FE - HomemadeTurbo - DIY Turbo Forum ?

    Are these the guys I need to grab the pump off: Turbo Oil Scavenge Pump - 12V (DC)
    RWD V8 Hilux Mk2

 
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