Is cast iron or aluminum engine better?

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Is cast iron or aluminum engine better?

The cast iron engine is heavier than the aluminum engine. The cast iron engine is also more durable and can withstand higher temperatures.

The aluminum engine, on the other hand, is lighter and easier to maintain. The aluminum engine has a shorter lifespan than the cast iron engine, but it also requires less maintenance.

What are the advantages of aluminum engine

1. Cast aluminum advantage – good heat dissipation

As we all know, the main body of the car engine is composed of the top cylinder head, the middle cylinder block and the lower oil pan. Now most of the cylinder heads of the engine are made of aluminum. The reason is that the heat dissipation of aluminum itself is better than that of cast iron. As part of the combustion chamber, the intake, exhaust valves and valve guides are installed on the cylinder head.

During the operation of the engine, the components will generate high heat, and the intake and exhaust cams and valve guides are lubricated and cooled by the splash of oil splashed by the crankshaft rotation. On the one hand, the heat is high, and on the other hand, pressure lubrication cannot be used. As the processing technology matures, more and more engines use aluminum cylinder heads with better heat dissipation. Similarly, in addition to the aluminum cylinder head, the aluminum cylinder block is also favored because of its good heat dissipation and strong anti-knock performance! The engine itself has high heat and high heat dissipation requirements. If the thermal conductivity of the cylinder block itself is not good, it will easily lead to cylinder explosion or shorten the life. The application of aluminum cylinder block not only solves the basic heat dissipation problem, but also reduces abnormal combustion in the cylinder. The probability of occurrence, the same compression ratio, the aluminum cylinder block can also use lower grade gasoline than the cast iron cylinder block.

2. Advantages of cast aluminum engine – lightweight

Another obvious advantage of cast aluminum engines is light weight. Everyone knows that lightweight is a very important topic in the field of auto parts! Under the same displacement, the all-aluminum engine is about 20 kilograms lighter than the cast iron engine. According to research, the fuel consumption can be reduced by 6% to 8% for every 10% reduction in the car’s own weight, which is why some luxury brands focus on promoting The reason for the lightweight all-aluminum body and all-aluminum engine.

What are the advantages of aluminum engine

What are the advantages of cast iron engine?

1. Advantages of cast iron engines – higher strength, better ability to withstand high temperature and high pressure

However, cast iron engines actually have a natural advantage, that is, the unit strength it can withstand is significantly better than that of aluminum engines. In order to achieve the same strength as a cast iron engine, an aluminum engine needs to increase its volume, which is obviously an impossible thing to achieve in a car engine compartment with limited volume.

Due to the higher thermal load capacity of the cast iron engine block (resistance to high temperature and high pressure), it has a greater potential in terms of power liters and a greater potential for modification. A more classic example is the legendary red head 4G63 turbocharged engine of Mitsubishi EVO, which is made of cast iron, and the modified car owner can easily adjust the power to 500+, 600+ horsepower, and even the limit can be enhanced to a thousand horses. With a strong heart, 4G63 has also become an unforgettable love for car fans.

2. Advantages of cast iron engines – In addition to strong corrosion resistance and strength.

The second advantage of cast iron engines over aluminum engines is also in corrosion resistance. Since there are coolant holes in the engine block in addition to the oil holes, the temperature of the cylinder block is extremely high when the combustion work is performed, and the cooling requirements are naturally high. Aluminum reacts chemically, so the corrosion resistance of aluminum is not as good as that of cast iron, which is why some high-pressure turbo engines use cast iron cylinder blocks more.

3. Cast iron engine advantage – low cost

Finally, an obvious advantage of cast iron is its low cost, which is the core reason why many car companies favor cast iron engines. The core of cast iron is ductile graphite, which is an alloy composed of elements such as iron, carbon, and silicon. Nodular graphite effectively improves the mechanical properties of cast iron, and is easy to form and cheap.

Is cast iron or aluminum engine better?

Generally speaking, compared with cast aluminum engines, cast iron engines can be said to have their own advantages and disadvantages. Today, with the popularity of small-displacement turbocharged engines, the advantages of low-cost, corrosion-resistant, durable, and more stable cast iron engines are more reflected. However, it is also true that the aluminum engine is light in weight and has good thermal conductivity and heat dissipation performance, but its cost itself is slightly higher. Therefore, the current practice of most car companies is that the engine block is still made of cast iron, and the cylinder head is replaced with an aluminum alloy material with obvious advantages, such as Volkswagen’s Magotan and Golf models, which not only neutralizes the advantages and disadvantages of the two materials, There is also a balance between technology and cost.

Author: Mose Li

Author: Mose Li

Director of Project Engineering at 3Q Machining

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