Today, aluminum is one of the most commonly used metals in many industries, including automotive and aircraft, and is often utilized because it’s lightweight. In fact, in 1903, the Wright brothers used an aluminum engine block in the Wright Flyer for this specific reason. At this time, iron was the most widely used component for engine blocks—aluminum was rarely used.
However, in the 1960s, strict environmental regulations to curb carbon emissions and fuel consumption tipped the scale in favor of aluminum. Because it’s lighter than iron, engines made with aluminum burn less fuel and have lower carbon emissions. Now, aluminum engines, particularly custom-made aluminum cylinder heads, are dominating the market.
In this article, we discuss the benefits of using custom-made aluminum cylinder heads and the advantages of aluminum as a primary material for other parts used in automobiles.
Benefits of Custom-Made Aluminum Cylinder Heads
Aluminum alloys are best suited for highly stressed engine cylinder heads due to their low density and excellent thermal conductivity in the critical temperature range of 482-572°F (50–300°C). This combination allows aluminum cylinder heads to release heat generated from combustion more quickly than iron counterparts.
Aluminum can also be beneficial when used in the valve bridge and water jacket components of a cylinder head. A valve bridge permits a single rocker to actuate multiple valves, while water jackets are water-filled casings that surround devices in the engine that require cooling. The valve bridge experiences an extreme temperature of more than 572°F (300°C) during full-load operation and tends to contract when the engine cools down, leading to low cycle fatigue (LCF). Meanwhile, the water jacket side of the head is exposed to high cycle fatigue (HCF) when it goes through millions of combustion cycles. As a result, the head develops cracks around the water jacket. This crack can lead to a complete part failure.
Aluminum tends to address both these issues with ease. Its high-temperature strength offers excellent LCF resistance, and it shows excellent creep strength performance to cracks in the valve bridge area. However, the HCF resistance of aluminum solely relies on the microstructure, porosity, and surface quality of the aluminum used.
Aluminum has a good thermal conductivity of 118 BTU/(hr·ft⋅°F) compared to 17 BTU/(hr·ft⋅°F) for steel, which is why cylinder heads made of aluminum contribute to long engine life. The cylinder heads absorb heat from the motor and the oil during combustion cycles and help your engine cool down with an efficient radiator in action.
Some of the most popular turbo diesel passenger car engines with aluminum used as head and block material include the following:
- BMW 2.0 turbo diesel
- Honda 2.2 i-CDTi
- Volkswagen 2.5 TDI
- Mazda 1.5 Skyactiv diesel
- Dodge 426 Hemi
The new 426 Hemi V-8 aluminum engine delivers 590 horsepower and is 100 pounds lighter than the 392 cast-iron models.
In this regard, cylinder heads made out of A356, 319, and A357 aluminum alloys achieve higher creep resistance and reduced mechanical fatigue due to the addition of dispersoid formers. These alloys receive a T4, T5, T6, or T7 heat treatment to achieve higher tensile strength.
However, 6061 aluminum is even stronger, with a tensile strength of at least 42,000 psi (290 MPa). It is only used for the highest level engine blocks used in extreme motorsports.
Aluminum for Other Automotive Applications
Aluminum isn’t just used in custom-made cylinder heads—it also has benefits for other automotive applications, such as in crash management, squirrel cage rotors, and electrical appliances, as described below.
Apart from custom-made aluminum cylinder heads, the automobile industry considers aluminum alloys for high yield strength applications and crash management. High-Pressure Vacuum Die Casting (HPVDC) aluminum alloys offer the casting design flexibility to produce thin, lightweight structures with fewer assembly steps.
Common structural applications of aluminum include in:
- Shock towers.
- Bumper plates.
- Space frames.
- Vibration dampers.
- Engine cradles.
- Toque boxes.
These structures rank high on crashworthiness performance parameters while exhibiting excellent corrosion resistance without any secondary coating.
Squirrel Cage Rotors
Due to their high electrical conductivity and creep resistance, aluminum alloys are preferred to design squirrel cage rotors in squirrel cage induction motors. However, it is often a challenge to strike a balance between conductivity and castability with aluminum alloys. The purity of aluminum is directly proportional to its electrical conductivity and indirectly proportional to its castability.
Working with a local metal supplier with metallurgical know-how to source aluminum alloys with tight composition control can help guarantee maximum castability and high electrical conductivity at each level, allowing you to create cast aluminum rotors that weigh 30% less yet offer approximately 60% of the conductivity of an equivalent copper.
The 6000 series aluminum alloys, best known for their high conductivity and creep resistance, are used for manufacturing conductor cables. While these cables are often produced using copper, aluminum is a better option because of its reduced weight-to-performance ratio. It’s even possible to draw wires down to a 0.2mm diameter with some specific alloy formulations.
Purchase New and Recycled Aluminum from a Reliable Metal Supplier
Located in the San Francisco Bay Area, Industrial Metal Service has more than two decades of experience supplying and recycling metals. We have a wide inventory of new and recycled aluminum and other metals, including titanium, steel, and copper. We offer Mill Test Reports (MTRs) for the metals we sell that are sourced straight from U.S. mills, and for our metal remnants, we verify their quality and composition using Thermo Fisher Scientific XRF analyzers.