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Forced Induction What does turbine AR / Housing AR mean?

Discussion in 'Powertrain' started by 1337Rolla, Aug 6, 2005.

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    1337Rolla oh my

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    What does turbine AR / Housing AR mean?

    what do those numbers mean :superconf
    what's the difference between a .86 and a .64
    1337Rolla, Aug 6, 2005
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    JspeXAE102 Well-Known Member

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    A/R = Area/Radius ratio of the turbine wheel/blade, it is the ratio of the velocity of air/gas entering/exiting the turbine. Basically it is the size of slot there is where air/gas hits the fins. if this gap is larger, the A/R is larger. A .64 would spool faster than a .84 but the .64 would top out at a lower RPM.

    but remember a T28 is a T25exh /T3comp hybrid. I would estimate the .64 would be good to 8500RPM but you should check the compressor map against your engine.
    JspeXAE102, Aug 6, 2005
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    1337Rolla oh my

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    just talking to myself.. ignore if ya want

    ok, so our engines are 108CI
    using VAF = (CI/1728) x (RPM/2) x VE
    assuming VE is 100% so we don't run out of air.., and rpm max is 6500
    means we need atleast 203cfm from the pump

    ok, gotta double that since we're compressing that into the cylinders so,
    406cfm

    that puts us at 28 lbs/minute .. which is the top end of the GT28R sweet spot, good.

    PR1.5 puts us at about 7psi and right at the bottom of the best efficiency section 75%

    the .64AR turbine is limited to between 13-17 lb/min output
    the .86AR turbine is limited to between 17-22 lb/min output

    so, which is better, both handle the rpm range :superconf
    1337Rolla, Aug 6, 2005
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    Dr Tweak Mad Scientist

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    For a 1.8 you want the smaller of the two.
    Dr Tweak, Aug 7, 2005
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    JspeXAE102 Well-Known Member

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    oops I just noticed I've misread.. the "Housing: .86 ar or .64ar" is referring to the turbine NOT the compressor so just ignore everything I said. But it's about the same principal.

    edit.. tweek is right but this should give you more insight on turbine matching
    http://www.atpturbo.com/root/maps/gt28rsturbine.htm
    JspeXAE102, Aug 7, 2005
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