Home Technical Talk A Brief History of Porsche’s V6 Engines (1991-2002: The Early Age)

A Brief History of Porsche’s V6 Engines (1991-2002: The Early Age)



Porsche usually produces flat-4 (H4) and flat-6 (H6) engines, because most of its sports cars are rear-engine layout.

The Porsche Cayman is using rear-engine layout

However with introduction of the Cayenne SUV and later on, the Panamera sedan, there is a need for new engines other than the H4/H6 types. Major reason is: for a rear-wheel-drive layout SUV or sedan, it is impossible to place a flat-4 and flat-6 engines in the front engine compartment, without significantly affecting the vehicle’s front/rear weight distribution.

2003 Porsche Cayenne

For example: if a flat-4 or flat-6 engine is placed too close to the firewall, the horizontal cylinder banks will block the steering shaft passage. Hence the typical solution is to move the engine all the way in front of the front axle, obviously the weight distribution will be greatly compromised.

Side cutaway of the Toyota 86: the horizontal cylinder banks will block the steering shaft passage. For this specific model, the solution is moving the engine almost all the way in front of the front axle.
2016 Mazda MX-5 Miata side cutaway: since it is using an inline-4 engine, there is no packaging limitation like the above Toyota 86. Therefore Mazda engineers can place the engine behind the front axle, make it close to an optimized FMR layout.

With that being said, inline or V-shaped engines are the way to go. Porsche engineers picked the later choice. This article series is a brief review on history of the Porsche V6 petrol engines. I will present you some interesting analysis, and explain why Volkswagen/Porsche make those decisions.

Cayenne is using the VR6 engine

1991-2002: The Early Ages – VW VR6 v.s Audi V6

Back in the 1980s when the historically famous “Audi 5000 Unintended Acceleration Allegations” started to unfold, Volkswagen group was facing a huge setback in the US market. For example, Audi sold 74,061 cars in US in 1985, but the sales drop to the bottom of 12,283 units in 1991 and the sales did not recover for 3 whole years. The rapidlly worsen market condition even prompted VW to consider the option of withdrawing from the US market back in 1993.

1984 Audi 5000 advertisement

During that period, senior management of Volkswagen made a strategic decision to let the VW/Audi brands move upmarket.

1992 Audi 100 lease deals. In fact, $449 per month to drive an Audi 100 cannot be considered as a good lease deal, even in today’s money.

One action from this plan is to develop a series of 6-cylinder engines, to be placed into various VW/Audi vehicles. For your reference: at that time, almost all VW/Audi cars have either 4 or 5-cylindern engines.

In case you are unaware of Volkswagen’s distinctive corporate structure and culture: the German automaker, who is employing close to 600,000 employees (nearly 3 times the size of Ford), is strongly decentralized and extremely vertically integrated. This means overlap and duplication is a common norm in Volkswagen’s operations. How Volkswagen develop those 6-cylinder engines is a typical example of such corporate culture.

1993 B3 Passat. Its front axle is too close to the firewall, no enough space for a V6 engine.

For Volkswagen brand, the target models to receive 6-cylinder engine are Passat and Golf. They belong to the transverse front engine layout, most popular trims are with 4-cylinder engines. Therefore, the car body design is optimized for the I4 engine application, which means very tight engine compartment, especially very limited room between the front axle and firewall. This makes it impossible to fit a typical V6 engine. The relatively narrow body also renders difficulty in putting an inline-6 engine.

VR6 engine installed in a Mk3 Golf

So Volkswagen engineers came out with a workaround: the VR6 design – it can be viewed as a narrow angle V6, with interlaced cylinders. The angle is so narrow that all cylinders share a single cylinder head. The VR6 is narrower than the I6, and shorter than the V6, so it can fit into the Passat/Golf perfectly.

Volkswagen VR6 Engine

The VR6 comes with an initial displacement of 2.8L (starting 1991, used on the B3 Passat and Mk3 Golf), and later expanded to 2.9L. At first there are two valves per cylinder, later on it changed to 4 valves. During this period (1990 – 2000), these VR6 engines output around 150 – 200 hp, which is similar to other mainstream 6-cylinder engines in the market at that time.

Cylinder block of the VR6 engine
1992 Volkswagen Golf VR6

Next let’s take a look at the Audi side. They need 6-cylinder engines to install on the Audi 80/100. At that moment the special corporate culture in VW showed its effect: Audi decided not using the VR6 developed by VW itself, instead they designed its own 90-degree V6.

Audi 100 is one of the brand’s earliest models to receive the V6 engine. Although it is based on the FWD layout, the V6 is installed longitudinally.

There are multiple reasons led to this decision, one major factor is: Audi models mount engine in the longitude direction, therefore are not subject to the space limitation like the VW Passat and Golf; and also, Audi did not want to accept the comprise of using the VR6. So finally, Audi decided to develop its own 90-degree V6.

The reason why Audi selected bank angle to be 90-degree instead of the more common 60-degree, is because it is derived from the brand’s 90-dgree V8 family. This also becomes a tradition since then.

1991 Audi 100

During this period, the Audi V6 has several versions, displacement  varies from 2.4L, 2.6L and 2.8L. Each cylinder has 2 valves, or 4 valves and even 5 valves. Their output is similar to the VR6 counterpart, ranges from 150 to 200 hp.

Regardless whether it is VR6 (VW) or V6 (Audi), all those engines use multi-port fuel injection, and they do not use direct injection until 2006. Just looking at its peak output, during 1990s the VW VR6/Audi V6 engines are inline with other mainstream competitors.

The 1st-gen Porsche Cayenne came into production in 2002, and it picked the VW VR6 as its powerplant. This marks the end of the first era of VW group’s 6-cylinder engine venture.

(to be continued)




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