August 2, 2011

Engines - Volkswagen W8

You know of the W12 in the Bentley and big Audis, and the W16 in the Bugatti Veyron but what about their smaller cousin on the Passat W8? According to some, "the most expensive engine ever put on a Volkswagen passenger car". A block with staggered cylinders connected to a flat-plane crankshaft, all of it shoehorned into an engine bay that was never meant to receive it.

The four piece aluminum manifold is a beautiful thing in this age and age where most are made of plastic. It is really the only thing you can appreciate from the top side. Getting to the spark plugs is easy. Replacing the Oxygen sensors and working on auxiliaries - "a challenge" to say the least. Still, it really elevates the Passat platform to a whole other level (when everything is working well).


The one sitting in my car is still humming after 150,000 miles.

The piston arrangement and twin balance shafts are clearly visible in this diagram (Source)

Unusual cylinder arrangement makes for a short block of relatively square footprint.

The timing chain system and adjustable camshaft system. A duplex to the relay and simplex to the camshafts. I am still wondering how long those plastic guides will last. (Source)
Five bolts and the plenum chambers are off...

With the plenum chambers removed, the coil packs are easily accesible.
With the four-piece intake manifold removed, fuel rails and that ridiculously expensive thermostat are clearly visible (Source).
The electronic thermostat.

Water Pump (Part no. 07D121008A)

Cylinder head (bank 1) showing valves, coolant, and oil passages (Source).
Exhaust Manifolds
Variable valve timing actuators and it's under-engineered screens, the Achilles heel of the W8
(notice the missing screen on the left oil port).
Engine block (bank 1) showing pistons coolant and oil passages (Source).

Very tight tolerances going on on that crankshaft! (More photos of engine internals at the W8 forum)

A good view of the lower crankcase displaying the oil pump (Source).

Front view showing the inner and outer banks of pistons, long intake runners, the location of the twin balance shafts, and the shallow but very wide crankcase. Hard to believe that it holds up to 9.0 quarts of oil in there!
The short crankshaft is very apparent in this side view. A significant amount of space is dedicated to both the oil pump drive chain and timing chain system.


Advertised power curves show a pretty flat peak between 2750 and 5000 RPM. An area where this car pulls like a train at higher freeway speeds. (Source for all diagrams: VW Self Study Program 248 - The W Engine Concept).


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