Differences Between Modern and Older Car Engines

Have you ever wondered what the difference is between old and new car combustion engines? As it turns out, quite a lot.

Despite the basic concept remaining relatively unchanged, modern cars have undergone a series of improvements over time. Here we'll focus on 4 of the most interesting examples.

What are the differences between old cars and new cars?

The basic principles of the very first cars are still used today. One of the main differences is that modern cars have developed as the result of pressure to improve the power of engines and, ultimately, their fuel efficiency.

This has been driven, in part, by market pressure from consumers, as well as larger market forces like the price of oil over time, and governmental tax policies and other regulatory pressures.

But, before we get into the nitty-gritty, it might be useful to explore how an internal combustion engine functions. 

An internal combustion engine, in essence, takes a fuel source, like gasoline, mixes it with air, compresses it, and ignites it. This causes a series of small explosions (hence the term internal combustion engine) that, in turn, drive a set of pistons up and down.

These pistons are attached to a crankshaft that translates the reciprocating linear motion of the pistons into rotational movement by turning the crankshaft. Then, the crankshaft transfers this motion through the transmission, which transmits the power to the wheels of the car.

Interestingly, the conversion of reciprocating force into rotational force is nothing new. A very early steam engine was devised by Hero of Alexandria in the 1st-Century AD (pictured below).

This device used steam to turn a small metal sphere attached to an axle by venting the steam out of a pair of angled nozzles—or exhausts—on opposing sides of the sphere. While Hero never developed it beyond this, it was an interesting early application of steam technology.

Some other basic concepts found in car engines, like the crankshaft, are very old concepts too. Some evidence suggests that some of the first examples may have originated during the Han Dynasty, China.

Modern cars are more efficient than older cars

Burning fuel like gasoline isn't particularly efficient. Of all the potential chemical energy in it, only around 12-30% is converted into power that actually moves the car. The rest is lost to idling, other parasitic losses, heat, and friction.

To help combat this, modern engines have come a long way to squeeze out as much energy as possible from the fuel. Direct-injection technology, for example, does not pre-mix the fuel and air before reaching the cylinder, like older engines.

Rather, fuel is directly injected into the cylinders, which provides up to a 12% improvement in fuel efficiency.

Another interesting improvement in car engines is the development of turbochargers. These devices use exhaust gas to power a turbine that pushes extra air (meaning more oxygen) into the cylinders to increase efficiency by up to 25% (though improvements are usually far more modest). 

However, there are occasions where turbochargers can be worse than conventional aspirated engines. 

Variable valve timing and cylinder deactivation further improve efficiency by only allowing the engine to use as much fuel as it actually needs.

Newer car engines are more powerful

While some might believe so, it turns out, on average, the modern engines are not only more efficient on a like for like basis, but are also relatively more powerful. 

For instance, A 1983 Chevrolet Malibu had a 3.8-liter V-6 engine that could spew out 110 horsepower. By comparison, the 2005 version had a 2.2-liter inline four-cylinder generating 144 horsepower. 

Modern car engines are much smaller than those of older cars

This drive, no pun intended, for better efficiency in engines has also shrunk their size over time. This is not a coincidence. Car manufacturers have learned that you don't need to make something bigger to make it more powerful. All you need to do is make the object work smarter.

The same technologies that have made engines more efficient have had the side effect of making them smaller. The Ford F-series trucks are a great example. The F-150 had two versions in 2011; a 3.5-liter V-6 engine that generates 365 horsepower, and a 5.0-liter V-8 that generates 360 horsepower.

However, it should be noted that the same series also had a  6.2-liter V-8 that generated 411 horsepower. But, relatively speaking, the smaller V-6 is comparable in power to both V-8's even though it is considerably smaller. 

It is also interesting to note that modern cars, on the whole, are often thought to be heavier than their older counterparts. However, given that they are also larger and are carrying more safety equipment, the average weight for most models has actually not increased by much. What has changed is an increase in fuel efficiency, safety, emissions, and convenience features. 

Modern engines are more reliable

Modern engines are also the result of a gradual replacement of the mechanical parts with electronic ones. This is because electrical parts tend to be less prone to wear and tear than mechanical ones, on average. 

Parts like pumps have increasingly become replaced with electronically controlled ones rather than their mechanical ancestors. This helped reduce the need for part replacements over the lifetime of a car engine. 

More electronic-rich modern engines also require less frequent tune-ups when compared to older engines. 

Other key engine components, like carburetors, have also been given an electronic-makeover. 

Carburetors have been replaced with throttle bodies and electronic fuel injection systems. Other parts, like distributors and caps, have been replaced with independent ignition coils controlled by the ECU.

Also, sensors more or less monitor everything. However, this push for more sophistication may have made newer cars less secure. 

On a basic level, modern and old car engines work via the same principles, yet it is clear that modern engines have undergone a lot of change over time.

The main drive has been the race for efficiency over power. A nice set of side effects have resulted in modern engines becoming relatively more powerful and generally smaller.

This is thanks to, in part, the replacement of older mechanical analog parts with electronic counterparts.

All in all, modern car engines are more efficient, smaller, relatively more powerful, smarter, and less prone to wear and tear. On the other hand, repairs and servicing now require more skill and consume more time.

But is the price of increased complexity for improved efficiency a price worth paying? We'll let you decide.