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Whether you prefer an iron or aluminum engine block, both have some advantages and disadvantages worth considering.
When it comes to engine blocks, the debate between which material is the toughest, most durable, and most convenient seems endless. Some folks argue that aluminum engine blocks lead to better car performance. Others say that iron supports high power better than aluminum build.
Until a few decades ago, iron was the ultimate engine block material. A large percentage of cars produced from the mid-'90s pack an aluminum engine block under the hood. Aluminum alloy metals continue to gain popularity in the market. Aluminum blocks have already made their way into popular cars.
These include the Ferrari F12 Berlinetta and Audi R8, among many others. And chances are, your car has an aluminum block, or at the very least, aluminum internal components. A good engine starts from a good engine block.
Both engine types have some pros and cons worth considering. Whether you want to perform a swap and are researching sick engines to buy or just want to learn more about engines in general, you'll want to know the difference between iron and aluminum blocks.
Updated August 2022: We have updated this article with more information on iron and aluminum engine blocks. We also give you an idea of why despite their age and outdated nature, iron blocks are still in use.
We’ll discuss the advantages and drawbacks of iron and aluminum block engines, focusing on their strength, weight, power, cost, reparability, and durability.
Iron blocks have been around since the birth of the engine. Up to this very day, the iron block material is a standard choice for engine manufacturers.
Iron blocks are cheaper than aluminum blocks. On average, a pound of aluminum costs $1 while a pound of iron only costs 25 cents. That said, it’s easy to accept that the use of iron will reduce production costs, making it more appealing. The reason why iron is the standard material is due to its durability. An iron engine block is stronger and more durable than an aluminum block.
It can also withstand higher pressures than its aluminum counterpart. Another advantage you’ll find with an iron engine block is power. Due to its massive strength, the iron block can handle more power and boost than an aluminum one. These days, aluminum blocks are capable of handling as much power as the latter. But, an aluminum block tends to suffer more than an iron block, especially at lower thresholds.
One major disadvantage that comes with iron engine blocks is that they are susceptible to rusting. Since the iron block makes more power, it likely undergoes a lot of pressure. So, rusting is a major factor and something inevitable since you’re dealing with metal. Also, iron blocks are heavier than aluminum blocks.
This extra weight can affect the car’s performance and fuel economy. When it comes to repairing, it’s much harder to repair an iron block than an aluminum one. Indeed, the iron block costs less. But when components of the iron engine block need repairing, it can cost you as much as a new block. It's easier to replace an iron block than it is to repair it.
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Aluminum engine blocks are very popular alternatives to the longest-staying iron blocks.
Most folks go for aluminum engine blocks because they are easier to repair than iron blocks. As we stated earlier, repairing an iron block is a challenge that’s not worth the effort. But, aluminum engine blocks are simpler to fix. A solid aluminum block is the one in the Chevy Camaro ZL1. Aluminum engine blocks are lighter than their iron counterparts. Aluminum weighs half as much as iron.
Weight reduction has been a milestone for automakers for ages. This is common in the sports segment. So, the aluminum engine blocks make a desirable option. Less engine weight gives you better gas mileage. It also makes the car lighter, leading to greater acceleration and speed. Aluminum blocks handle heat better than iron blocks. As such, an aluminum engine block is less likely to experience overheating. This improves the engine’s life.
Aluminum engine blocks are more prone to warping, especially when under pressure. This is because they aren’t as rigid as iron cast blocks. Also, aluminum blocks are costly, which makes them expensive to produce. On the consumer’s end, it elevates the car’s price. One more important aspect to consider is that aluminum blocks produce less power.
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The best engine block is cast iron. Today, the Ford Coyote for drag racers is a solid option. Its more durable, cheap, and higher power rating than the aluminum engine block. The major downfalls are the rust, the added weight, and the reparability, or lack thereof. This doesn’t make the aluminum counterparts any less desirable.
They are lighter, easier to repair, and less susceptible to overheating. But aluminum engine blocks are less strong, more prone to warping, and pricier. Under the right conditions, an aluminum block can produce as much power as an Iron block. Engine makers are working to make the aluminum engine more rigid. But for now, iron cast blocks are your safest bet.
Most automakers have shifted to making aluminum engine blocks because of the weight advantage and easier casting methods on offer. That being said, iron blocks are not completely out of usage because the GM LS Series and Ford's Modular engines still use cast iron blocks. And most of the diesel motors still come with an iron heart. While BMW has completely moved out of the practice, they still use cast iron liners in certain engines.
Wilfred Nkhwazi is a screenwriter, actor, and sports car enthusiast from Blantyre, Malawi. He has written 2 feature films and a thriller trilogy. Wilfred is pursuing an Electric Car Technology program and spends a lot of his time writing for hotcars.com, penning down fast whips, celebrity collections, and everything else in-between. When he isn't writing, he loves to take long drives around the city, make music, and drink hot chocolate.