[s-cars] installing a hybrid turbo

Eric Phillips gcmschemist at gmail.com
Thu Aug 3 10:57:06 EDT 2006

 From: djdawson2 at aol.com<mailto:djdawson2 at aol.com>
> To: shr42 at msn.com<mailto:shr42 at msn.com>
> Cc: S-Car-List at audifans.com<mailto:S-Car-List at audifans.com>
> Sent: Wednesday, August 02, 2006 5:11 PM
> Subject: Re: [s-cars] installing a hybrid turbo
> A T3/T4 hybrid is a Garrett turbo that uses a T4 compressor housing mated
> to a T3 turbine housing and wheel.  What most of the Audi folks use is still
> a T3/T4 hybrid, but instead of the T3 turbine housing, a modified or
> aftermarket casting KKK turbine housing is used... so that we can bolt them
> to our OE exhaust manifolds.
> Garrett's complete current turbo offerings are listed here:
> http://www.turbobygarrett.com/turbobygarrett/catelog/Turbochargers/turbo_comparison_sheet.htm
> <
> http://www.turbobygarrett.com/turbobygarrett/catelog/Turbochargers/turbo_comparison_sheet.htm
> >
> These are all the "medium frame" sized turbos... both ball bearing and
> journal bearing turbos are offered.
> You won't find a T04E 50 trim on this list.  That is their "old"
> stuff.  However, they do still produce them, and you can still buy them, and
> it is a journal bearing turbo.
> Optimal match of KKK housing?  Well, it depends on who makes the KKK
> turbine housing, and how well it is matched to the Garrett turbine
> wheel.  Let's just say that the T3 housing was designed in conjunction with
> the T3 turbine wheel, the KKK was not.  For this reason alone, I think you
> can bank on them working better together.  Using the T3 housing also allows
> you to actually choose the A/R of your hot side, instead of having only one
> option.  Most folks running a stage 3 wheel with the aftermarket KKK housing
> do not like the boost threshold... too high.
> Summary:
> 1) If you are trying to get the best output and drivability from a Garrett
> turbo, it ought to be a complete Garrett turbo, not a KKK hybrid.
> 2) If you want the best reliability, use a journal bearing turbo.
> 3) The best results for a 2.2 Audi running high boost come from the older
> T04E 50 trim compressor.
> These are just my personal opinions.  But they do come from dozens of dyno
> runs using at least 10 different Garrett turbo configurations.
> Dave

Dave, thanks for the info.

I had thought about going this route when I imagined a bad turbo in my car.
But being able to bolt it up to the existing hardware would be a definite
plus.  I am assuming that the T3/T4 stage 2 .50 trim is NOT going to bolt
right up unless it's a KKK-hotside-housing hybrid.  Is this correct?

Besides higher flowing injectors, and a pump that will feed them, what other
hardware would be required?  (Assuming oil/water lines and MAF->turbo
hose hardware is necessary for the turbo install to begin with.)  I ask
because a rumor was circulated that an RS2 EM is required for anything
"more" than a K24, or there may be valve burning at #5.

And the final question is about driveability.  At what RPM does the boost
start, and when do you get into the "meat" of the turbo's range?

Thanks - the reading has been quite entertaining!


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