The Audi 4.2 V8 engine is a high-performance engine produced by the German automaker Audi. First introduced in the early 1990s, this engine quickly gained a reputation for its exceptional power, efficiency, and durability.
Over the years, Audi has continued to refine and improve the 4.2 V8, making it one of the most sought-after engines in the automotive industry. Here’s a brief insight into this engine, what it has to offer, and what some of its main problems are.
Big Power From the Aluminum Heart
The Audi 4.2 V8 engine was first introduced in 1991 and quickly made a name for itself as a powerful and high-performance engine. The first generation of the engine was used in the Audi V8, producing up to 276 horsepower and 295 lb-ft of torque. This was a significant improvement over the previous engine used in the V8, which only produced 250 horsepower and 246 lb-ft of torque.
What made the Audi 4.2 V8 engine special at the time was its innovative design. The engine was designed with an aluminum block and heads, which made it lightweight and efficient. The engine also featured a five-valve-per-cylinder design, which allowed for better air and fuel flow and increased power output.
In addition to these design features, the Audi 4.2 V8 engine introduced several engineering innovations that set it apart from other engines of its time. One of the most notable of these was the use of a dual overhead camshaft (DOHC) design. While a common thing today, it was cutting-edge technology back when this engine first appeared. The use of two cams per head allowed for more precise control over the engine’s valve timing, resulting in increased power and better fuel efficiency. The initial version of the engine featured 40 valves, as mentioned above. However, Audi has switched between a 32-valve and 40-valve setup several times during the evolution of this block.
Another innovation introduced with the Audi 4.2 V8 engine was the use of an electronically controlled variable intake manifold. This allowed for greater control over the amount of air entering the engine, which resulted in improved power output and throttle response. Variable intake was complemented by a direct ignition system, which eliminated the need for a distributor and allowed for more precise control over the engine’s ignition timing.
The Audi 4.2 V8 engine also introduced a number of advanced materials and manufacturing processes. For example, the engine’s cylinder walls were coated with a layer of iron using a process known as plasma spraying. This resulted in increased durability and reduced wear over time. The engine featured a forged crankshaft and connecting rods, which made it stronger and more resistant to the stresses of high-performance driving.
Over the years, Audi continued to refine and improve the 4.2 V8 engine. The second generation of the engine, introduced in 1997, featured a direct fuel injection system that improved fuel efficiency and reduced emissions. The third generation, introduced in 2007, featured an updated direct injection system, improved timing chain components, and other upgrades that further improved the engine’s performance and reliability.
Audi 4.2 V8 Applications
In addition to the popular Audi models mentioned earlier, the Audi 4.2 V8 engine has been used in several other vehicles over the years. These include the Audi S6, Audi S8, and Audi RS6. The Audi S6 featured a 4.2 V8 engine that produced 340 horsepower and 310 lb-ft of torque, while the Audi S8 produced 360 horsepower and 317 lb-ft of torque. The Audi RS6, which was only sold in Europe, featured a 4.2 V8 engine that produced a whopping 450 horsepower and 415 lb-ft of torque.
The Audi 4.2 V8 engine has also been used in several racing applications. In 2000, Audi introduced the R8 race car, which featured a modified version of the 4.2 V8 engine. The engine produced 610 horsepower and was capable of propelling the R8 to speeds of up to 205 mph.
Here’s a list of some of the cars that use this engine:
- Audi S4 (B6/B7): 340 horsepower and 302 lb-ft of torque
- Audi S5 (B8/B8.5): 354 horsepower and 325 lb-ft of torque
- Audi RS4 (B7): 420 horsepower and 317 lb-ft of torque
- Audi RS5 (B8/B8.5): 450 horsepower and 317 lb-ft of torque
- Audi A8 (D3/D4): 350 horsepower and 325 lb-ft of torque
Audi 4.2 V8 Generations
The first generation of the Audi 4.2 V8 engine was produced from 1991-1994 and was used in the Audi V8. This engine featured an aluminum block and heads, as well as a five-valve-per-cylinder design. The second generation was produced from 1997-2005 and was used in several Audi models, including the A6, A8, and S4. This engine featured a direct fuel injection system and produced up to 335 horsepower and 310 lb-ft of torque.
The third generation of the Audi 4.2 V8 engine was introduced in 2007 and was used in the Audi S5, RS4, and RS5. This engine featured an updated direct fuel injection system and produced up to 450 horsepower and 317 lb-ft of torque. In addition, the third-generation engine featured several upgrades to the timing chain and valve train components, which improved durability and reduced the risk of catastrophic engine failure.
Audi 4.2 V8 Most Common Problems
One of the most common issues with the Audi 4.2 V8 engine is excessive oil consumption. Many owners have reported that their engines consume large amounts of oil between oil changes, which can lead to engine damage and failure. This issue is often caused by worn piston rings, which allow oil to leak into the combustion chamber.
Timing Chain Guide
A common problem with the Audi 4.2 V8 40V engine is timing chain guide failure. These were originally made of plastic and were known to break with some frequency. Audi rectified this issue in the 32V versions that feature a different timing chain guide design.
Timing Chain Tensioner
The original NA version of the 4.2 V8 used a timing belt, yet the cams still used a chain to keep everything in time. The tensioners on these chains are known to fail prematurely, potentially causing damage to the engine. The issue is made even more complex by the fact that one head features the chain in the back, near the firewall while the other has the cams chained up in the front.
Oil Filter Housing Coolant Leak
The same NA older 4.2 V8 suffers from a coolant leak that occurs in the oil filter housing. These engines use coolant to cool down the oil. However, the way the coolant is transferred to the oil cooler makes this entire system prone to coolant leaks. Namely, there is a small plastic pipe in there that is known to crack over time. If the crack is severe enough, you’ll get coolant leaking into the oil filter housing. While a small problem on its own, accessing and replacing this component is often a difficult job. We’ve done a guide on this issue that goes more in depth on how to fix this little pipe.
Variable Intake Issues
With the older 4.2 V8 that uses port injection, the variable intake manifold issues come in the form of broken actuator arms. These are made of plastic and are known to fail prematurely. Fortunately, they are relatively easy to replace.
On the more modern FSI iteration of this engine, you’ll find variable intake flaps, also made of plastic, that also love to fail prematurely. This fix is somewhat more complex as you need to take the entire intake apart.
Valve Cover Gasket Leak
Valve cover gasket leaks are another common problem with the Audi 4.2 V8 engine. These leaks can occur due to worn or damaged gaskets and can result in oil leaking onto hot engine components. If this happens, it can lead to a fire hazard and other engine problems.
Carbon Buildup
The introduction of the FSI system in the later versions of the 4.2 V8 brought on the same issue that ended up affecting just about every early direct injection engine out there — carbon buildup. With port injection systems, the fuel mixture enters the cylinder from the intake. In doing so, the fuel washes the valves with every intake cycle.
With direct injection, the fuel is introduced directly into the combustion chamber through a hole that bypasses the valves completely, hence the name. Now, with nothing there to clean the valves, you get a constant buildup of carbon. Over time, this can affect engine performance to varying degrees.
Get Quality Parts for Your Audi 4.2 V8 at eEuroparts.com
Your average Audi 4.2 V8 engine is a powerful yet somewhat delicate machine. It can be loads of fun if you treat it right and stay on top of the issues we’ve mentioned above. Speaking of which, solving these problems doesn’t have to be expensive. Check our catalog and find quality parts for your 4.2 V8 that are made by some of the best brands in the industry. We stock anything from genuine Audi and OEM parts to quality aftermarket options.
Are the bellhousing bolt patterns the same on all generations of the 4.2 engine ?