Engine:

The Scirocco GTD is powered by a 1.6L VW TurboDiesel engine.

The base engine is a hydraulic lifter motor, VW code MF.  The block is from an 89 TD Jetta, the head is from a 91 TD Jetta, as is the injection pump.

The turbo is a KKK unit from a '97 Jetta TurboDiesel 1.9 IDI (engine code AAZ)  This turbocharger uses a small round inlet and 3 bolts fasten it to the exhaust manifold - very different from the four-bolt trapezoid used on earlier 1.9 and 1.6 engines, so the 1.9 exhaust manifold was required.  The Canadian-spec AAZ did not have exhaust gas recirculation (EGR) so there were no modifications necessary to fit the later manifold to the 1.6.  The intake ports on the 1.9 head and intake manifold are D shaped, and as such it would require heavy porting to match to the oval ports on the 1.6 head.  In order to use the 1.9 compressor elbow (from turbo to intake) the 1.9 turbo elbow was fitted to the 1.6 intake manifold.  In order to adapt the smaller diameter intake plumbing on the 1.9 Turbo to the 1.6 airbox,  I cut a 1.6 air inlet hose and a 1.9 air inlet hose and spliced them together.  I was able to force a short piece of thin-wall exhaust tubing inside the 1.9 air hose, then clamp the 1.6 air hose over top of this.

UPDATE May 2005 I replaced the original 1.6TD head with a 1.9 TD head (engine code AAZ.)  This head provides much better airflow than the 1.6TD head, due to its “D” shaped intake ports.  The 1.9 head and gasket (multi-layer steel) have additional cooling holes located between the cylinders that are not present in the 1.6 block, and the 1.9 cylinder diameter is slightly larger, resulting in a small increase in combustion chamber volume (I have not verified differences between the 1.6 and 1.9 combustion pre-chamber inserts.)  Other than these differences the swap was quite straightforward.

Instrumentation is provided by VDO oil pressure and temperature gauges located in a 3 gauge panel where the ashtray used to reside.  The oil temperature sender is on the oil filter flange, along with the high pressure sender switch for the stock oil pressure warning circuit.  A special adapter from the Audi 5000TD engine was used to allow these two senders to be plumbed into the turbo diesel oil filter flange, which only has one M10 port.  (p/n 035 103 717 and 035 103 715)  A VDO boost gauge (0-15 psi) is teed into the boost pressure line running from the intake elbow to the injection pump.  I used factory VW line from the fuel vapour recovery system to connect to the gauge in the cockpit.

Exhaust:

The original downpipe was manufactured from a 97 TD downpipe and an 84 TD downpipe, cut and welded together below the flex join.  The lower section was replaced by a 2.25" stainless mandrel elbow in the spring of 2003.

Unlike earlier turbos, there is no blockoff plate on the turbo housing for the wastegate exhaust on this unit.  This function is incorporated into the downpipe (part no 1H0 253 087 H)  Because of this, the downpipe and gasket are not interchangeable with earlier models - the bolt pattern is different (this can be seen in the photos above.)

The centre and over-axle pipes are stock Scirocco 8V.  The original muffler has been replaced with a 2.25" straight pipe with a turn-down.  This system was replaced with a 2.5" stainless centrepipe (from Techtonics Tuning) and a 2.5" single-in dual-out Magnaflow muffler.  The stainless flex union incorporated into the downpipe does a very good job of isolating the exhaust from engine vibration and rock, and the 2.5” Techtonics pipe is a perfect fit, with no rattles whatsoever.

Clutch and Transaxle:

The clutch unit is a Sachs reman from VW. The flywheel is a stock 200mm TD flywheel.

The close ratio 4K unit that came with the car has been replaced with a 7A gearbox (aka 4+E)  This transmission uses the same final drive as the 4K (3.94) but features a wider gear spacing with a tall fifth gear:  The car maintains its stock 90MM constant velocity joints. The 7A was available in 84 Rabbits and Jettas, and uses the newer style case housings that will accept 100mm CVs without modification.

7A transaxle - final drive = 67/17 (3.94)

Gear

ratio

~speed @ 3000rpm

2

35/18 (1.94)

43Km/h (27mph)

3

36/28 (1.29)

64Km/h (40mph)

4

30/33 (.91)

91Km/h (57mph)

5

37/52  (.71)

117Km/h (73mph)

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