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Thread: variable geometry turbos (vgt), variable nozzle turbos (vnt)

  1. #1

    Default variable geometry turbos (vgt), variable nozzle turbos (vnt)

    there was an interesting question/discussion on socalevo. made me think of the days when i was learning about this and i dredged up some nice images.

    Quote Originally Posted by trinyDeX
    vgt turbos (any kind of variable geometry) is trying to do one thing by cheating. it's trying to get the best of both worlds by changing the shape/size of any particular parameter in the turbine. usually happens in the turbine because slapping a gigantic compressor wheel on a turbocharger isn't hard nor is it detrimental (this is up for debate since surge can sometimes develop but that may also be alleviated by the "proper" turbine)

    vgt turbos have been around. the ones used in oems are highly variable. if you have some intermediate stages you're asking for tons of trouble and complexity, so for an adaptation application you might be sol on the variablility.

    that in mind it's not hard to tune, it's about as complicated as a wastegate, simple actuation based on some sort of pressure parameter. it would be just as reliable as a wastegate and would probably operate off the same mechanisms, an arm reaching into the hot hell of turbine housing to turn/press/pull something.

    the big deal is that any vgt turbo has to be sized properly for the application. the other big problem is WHERE to make the variable geometry. you will probably never see them in the aftermarket although it's totally possible to adapt one.

    many many exist on the market but not typically for gasoline powered motors.

    i think the easiest style is the one i the honda rdx

    porsches is very complicated. there should be a picture somewhere that i posted up ages ago that shows the internals of the posche style. it's sophisticated and MAY yield good results but in the end a trap door style is much simpler.
    below is what volvo and porsche use, a typical vnt variable nozzle turbo
    I <3 Nisei Engineering

  2. #2

    Default Re: variable geometry turbos (vgt), variable nozzle turbos (vnt)

    then there's what honda uses. a trap door like system.
    I <3 Nisei Engineering

  3. #3

    Default Re: variable geometry turbos (vgt), variable nozzle turbos (vnt)

    Is that VTEC for teh turbo? :lol:
    05 Evo 8 - 333 whp / 318wtq - Tanabe DP, TP, Modified 3" noir cat back, GM boost solenoid, Walboro FP, RC 1000cc injectors, E-85

  4. #4

    Default Re: variable geometry turbos (vgt), variable nozzle turbos (vnt)

    actually... yeah hahaha.
    I <3 Nisei Engineering

  5. #5
    Join Date
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    Default Re: variable geometry turbos (vgt), variable nozzle turbos (vnt)

    Looks like just about every manufacturer is getting into turbos. There was a commerical for a Mazda or something SUV that was Turbocharged......:?

  6. #6

    Default Re: variable geometry turbos (vgt), variable nozzle turbos (vnt)

    i think it's weird that run of mill cars are getting turbos. more fuel = more money and more air means more fuel....

    i guess it's a way of putting small capacity motors into a car and making it put out more than small capacity motors usually do... but it's confusing. are we trying to save energy or not? you know? i guess a turbo cna make an engine more efficient but you have to properly size the engine first (small, tiny tiny) to save on gas.
    I <3 Nisei Engineering

  7. #7

    Default Re: variable geometry turbos (vgt), variable nozzle turbos (vnt)

    given that ethanol and its higher octane rating is coming (see bill signed into law yesterday) turbos make more sense now than in the past.

  8. #8
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    Default Re: variable geometry turbos (vgt), variable nozzle turbos (vnt)

    Europe has had this realization for quit sometime now. This was due to the effect gas prices had on them. The sudden realization this country is having is our "big boat" mentality isĀ* in jeopardy. Europe has had smaller size vehicles with small ddisplacement(1.8 liter and under) engines as the average people movers. Diesel are more popular too. Mass transit is used allot more and so are bicycles and mopeds. You know the mentality is foreign when bikes in bike lanes have the "Right of Way" over pedestrians. I had several close calls with mopeds on bike trails. The cops their even have portable DYNOS to test the moped to make sure they are under enforced limits.
    I guess moped modders have gone wild there.... :lol:


    Quote Originally Posted by trinydex
    i think it's weird that run of mill cars are getting turbos. more fuel = more money and more air means more fuel....

    i guess it's a way of putting small capacity motors into a car and making it put out more than small capacity motors usually do... but it's confusing. are we trying to save energy or not? you know? i guess a turbo cna make an engine more efficient but you have to properly size the engine first (small, tiny tiny) to save on gas.
    '06 IX WW RS

  9. #9

    Default Re: variable geometry turbos (vgt), variable nozzle turbos (vnt)

    Hah... VTEC for the turbo.... it really is.


    Throw it on the Evo!! Mivec Turbo with Mivec on the Turbo. JAJA

    I saw a picture and a thread somewhere saying that on the porsche, it makes mad higher EGT's.


    This is also new GTR technology too right? Thats gotta feel good having the response of a tiny ass VW size Turbo, but the grunt of an 18g or whatever.
    -Dick Pound

  10. #10

    Default Re: variable geometry turbos (vgt), variable nozzle turbos (vnt)

    wow, the honda style trap door style looks absolutely ghetto compared to the other style. But it also looks like it'll last longer in a gasoline engine.

    BTW, Aerocharger had made a 16g VNT turbo as a prototype about 10 years ago, and went on the Club DSM mailing list looking for someone to beta test it. I haven't heard from them since, except for one off's for various cars since.

    VNT's don't last long in gasoline engines due to the heat and materials available. Maybe if some exotic material comes down in price is where we'll see them more common for gasoline engines.
    05 Mitsubishi Lancer Evolution VIII MR - 3&quot; TBE with Cat. Stock boost control system. 260whp / 260 lb-ft torque<br />92 Plymouth Laser RS Turbo AWD

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