[Diy_efi] Turbine inlet & outlet pressures, housing A/Rs

[Grant Beaty]

Oh Greg,

Just saw some old posts of yours in the archives,
http://www.diy-efi.org/diy_efi/archive/1999-January/msg00237.html

> >I think the REAL unexplored gain is in (more efficient) pressure recovery
> >from the Mach .75 velocity in the gas spiral at the turbine outlet,
though.
> >The circumferential component of the flow in that gas is distinctly
greater
> >than the axial component.

Hugh McInnes states that increasing pipe diameter right after the turbine
outlet will convert axial flow into turbulent flow. But in your post you
don't seem to consider that as an option, instead opting for a banjo
discharge. Is there any reason for that? Have you tried larger pipes without
success? Any idea how much larger the pipe needs to be than the turbine
inducer?

Forgive my lack of understanding of your post, but are you suggesting that
exhaust gas velocity post-turbine could be more than doubled by
straightening the flow? Wouldn't that imply pressures < ambient? Or would
total velocity out the turbine decrease, and more would go out the
wastegate? Either is good, I guess.

Thanks for any help,
Grant Beaty

----- Original Message -----
From: "Greg Hermann" <bearbvd at mindspring.com>
To: <diy_efi at diy-efi.org>
Sent: Monday, January 06, 2003 10:56 PM
Subject: Re: [Diy_efi] Turbine inlet & outlet pressures, housing A/Rs


> At 7:21 AM 1/6/03, Grant Beaty wrote:
> >Does anyone know how turbine outlet pressure effect the inlet pressures
(TIP
> >& TOP)? Does it work off of a pressure ratio like the compressor, or is
it
> >linear, and increasing TOP by 1 psi results in a 1 psi increase in TIP?
>
> Absolute pressure ratio, all the way.
> >
> >How about exhaust housing a/rs. Will a larger a/r always produce a lower
> >TIP,
>
> Sure should.
>
> Higher EGT at the turbine inlet should require a bit lower pressure ratio
> across the turbine to get the same shaft power (boost level at a given
> engine rpm) out of the compressor.
>
> Greg
> >
> >Thanks for any help,
> >Grant Beaty
>
>
>
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