[s-cars] RS2 turbochargers

[Kaklikian, Gary]

The hot housing on the Porsche 944 Turbo S is a #8, so the turbo is a K26/8 vs the K26/6 on the standard 944 Turbo. From the factory, the Turbo S ECU/turbo allowed full boost (12psi) to redline, and the car produced 30hp more than the standard model.

There are all sorts of hybrids available, using either a K27 or Garrett cold side, and even K29's for the 2.8/3.0l engines. If you go to Rennlist (www.rennlist.com), and search the 944 turbo forum, there's much discussion and technical specs on the hybrids, some even sourced from that disreputable turbo builder in Golden.

My car originally had the K26/8, but the previous owner installed a K27/6 hybrid and a (proflow) MAF, exhaust,etc.  The boost threshold is around 3200rpm and, even with the tall 3.3:1 final drive, there is less lag than on S4's I've driven with K26's or Garrett's.  Still, I'd rather have the #8 hot housing. Also, the  stock (single-port) wastegates on these cars are pos and leak boost at even 5psi as they age; even the stock S4 wastegate/wgfv works much better.

I'm only running 14psi boost, since I'm not interested in replacing the head gasket again. Head gasket failures are common on the 944t at higher boost levels and there are even stories of heads lifting off the blocks at 18psi. Rod bearing failures are also common. Definitely not as bulletproof as the Audi 20vt.

Gary
'92 S4
'89 944 Turbo S


Date: Tue, 18 Jun 2002 10:08:05 -0600
From: "mlp" <mlped at qwest.net>
To: "Audi - Lists - AudiFans" <quattro at audifans.com>,
	urq at audifans.com
Cc: torsen at audifans.com, s-car-list at audifans.com,
	audi20v at rennlist.org, 200q20v at audifans.com
Subject: [s-cars] RS2 turbochargers


I don't have much grist for the mill to add to all this, & wouldn't but for
Dave's comments / point on the "Porsche" label on (I take it the intake
manifold) under the bonnet of his S2 (or is it a UrQ?) and Scott's respect
and admiration for the RS2 hot side, &/or Porsche &/or KKK's engineering
thereof and finally the benefits, real, imaginary or illusory, of additional
displacement I offer the following apocryphal information....

In the FWLIMBW category,

- I know the K24 exhaust exit port* is @ 45mm to 46mm in diameter;

- I believe an RS2's is @ 54mm or 55mm, depending on who is doing the
measuring, IIRC (some one needs to re-check this);

- A Porsche 944 Turbo "S"** hot side exit is slight more than 62mm, say
62.75!  This I know cause the 2.5" down pipe flange into the flare out to
the 3" down pipe system almost can't cover the turbo discharge port.

The 944S KKK hot side has been hookup to a Garrett TO4E 60 trim (at least I
think its an =CB" trim) cold side.  When (or if ever) the turbo gets hooked
up, it will have @ 2.5 liters (2.522 cc swept volume) of displacement behind
it to push the blades.

Lag?  Well, that's still a great unknown, but I welcome your speculation;
HP?  That's another big unknown.  Again, I'd welcome your thoughts.

mlp