Comparing Engines When Buying a New Car

Educational

Jul 22nd, 2021

Comparing Engines When Buying a New Car

Did you ever need to read tons of technical aspects before buying something important? If you’d bought a car before, you most likely did. 

Buying cars are almost like buying real estate, but the technical aspects involved are more continually evolving and more complicated. You’ll need to compare several cars and how each potential car performs against a set of criteria, which involves the heart of a car – the engine! 

And yes, you bet, it’s a big decision that involves due diligence and intelligent researching long before you pick the colour that you want for your new car.

Here, I am going to help you compare car engines. Let’s get to it.

How Exactly Do You Choose a Car Engine?

Will it be based on engine displacement, number of cylinders, and power output? Of course, those are parts of the criteria, but there are more factors to consider, and they require some technical knowledge and a lot more patience. 

Engine Size or Capacity or Displacement

Engine size, expressed in litres, is the total volume of an engine cylinder or cylinders. The bigger the engine size, the more air and fuel can be burned, producing more engine power. Conversely, smaller-sized engines burn less fuel, produce less power, and have lower fuel consumption rate.

Are 1-2 litre engines any good? 

With the seemingly unquenchable need for more power, manufactures had constantly increased their engine sizes. One example is the 8.1-litre Chevrolet Suburban, popularly known as the Workhorse. Fortunately, turbochargers got into the scene and gained popularity. Manufacturers deemed it more practical to put 1-litre engines, which now produce more power with less fuel, back under the bonnet.

What are turbochargers?

These are turbine-driven devices that force extra compressed air into the combustion chamber of a combustion engine to increase the power output without burning too much fuel.

Can a 1-litre turbocharged engine outrun a 3-litre traditional petrol engine?

Not quite. I will give you an example. A small 1.6-litre four-cylinder turbo engine used in the Peugeot 308 GTi 270 produces 201kW of power which is only 8kW lower than the much larger 3.6-litre Pentastar V6 engine used in the Jeep WranglerWhen it comes to engine size, bigger is not always better.

Engine Power and Torque

These are the basic specs that you will find in manufacturers’ brochures. Both metrics tell you how capable a car is, but more specifically, a car’s power (expressed in bhp or kW) gives you an idea about how much it can give you in terms of acceleration and top speed. On the other hand, torque (expressed in ft-lb or Nm) tells you of the engine’s initial acceleration and pulling force. 

SUVs, pickup trucks, and other vehicles expected to have higher load-bearing capacity should have higher torque. In layman’s language, torque measures how much work a vehicle is capable of, while power measures how fast it does that work in a given time.

Engine Layout

In your search, you must have come across the terms, straight engines, inline engines, V-engines, and boxer or flat engines. What’s the difference between these engine layouts and why do you need to bother with them? Let’s dig into this deeper.

Why don’t all engines use the same layout?

Well, engine layouts have something to do with the overall driving experience. 

  • For example, a flat engine offers a lower centre of gravity to the car, while an inline engine provides more space under the bonnet. 
  • A V-engine, on the other hand, offers both while accommodating more cylinders into the available space. 
  • The flat engine layout can now only be seen in Subaru models and Porsche 911. 

Most midrange passenger cars run on inline engines because of their lower complexity compared to V engines. However, V-engines had cemented their place on every high-end sport and luxury model that demands more power. You may read more about engine layout from our previous article.

Engine Design

Engine design is a broad word that covers, among many factors, the engine configuration, number of cylinders, stroke-to-bore (S/B) ratio, and valve overlap height. Here are some of the widely used engine cylinder configurations.

  • Two-cylinder engine – an example of this is the 2012 Fiat 500 manual that runs on a two-cylinder 0.9L turbo petrol engine. You can still find them under many low-powered cars.
  • Three-cylinder engine – this configuration turned out to be perfect for mini-vehicles. The Suzuki Mighty Boy, 2021 Volkswagen Polo 85TSI, and most city cars run on three-cylinder engines.
  • Four-cylinder engine – most cars are powered by 4-inline engines due to their compact size that allows accommodating other accessories under the hood.
  • V-6, V-8, V-12 engines - the V-shaped configuration plays a huge role in producing massive power from something small like an Alfa Romeo 156 GTA 3.7 V6. The cylinders are neither opposed nor inline and can offer double the number of cylinders that traditional inline engines can accommodate.

Fuel Type

In addition to this dilemma in choosing which car to buy, there exists an additional concern about choosing the right fuel variant. In Australia, most cars are available in both petrol and diesel variants, with options for cars that run on alternative fuels, such as biodiesel and ethanol.

The Great Diesel Vs Petrol Engine Debate 

Although there are now various fuel options available, there remains the undying debate over which is better – Diesel engine or Petrol engine. This comparison may soon wane with the uptick of EV sales, but not today. Yet.

If your choice is between diesel and petrol engine models, then you need to consider the following factors which these two fuel variants bring into the picture.

Cost

Are you shopping for a car within a particular price range? If price is an important consideration for you, then you should know that diesel variants of all vehicles are priced much higher than their petrol-guzzling counterparts. 

Gas Mileage

Power and fuel efficiency, oh, how we’d want both in our car. Unfortunately, this is one of those ‘best of both worlds’ kind of thing that you can’t have. 

Petrol cars give good initial power, while diesel cars provide higher performance in higher gears. Also, diesel cars offer higher fuel efficiency than petrol cars do. 

This means that if you drive short distances within the city, buying a petrol-engine car will make much more sense. If you plan on using your vehicle for travelling on weekends over longer distances, a diesel car can provide better output in terms of fuel efficiency and performance in higher gears.

Maintenance

Diesel engines were designed around the principle of compression ignition, and they require high compression ratios. On the other hand, petrol engines use spark ignition to generate power and require much lower compression ratios. 

Diesel engines running under high pressure will produce more vibrations and result in wear and tear of the engine components fast. This accounts for the shorter life expectancy of diesel engine parts and the need for more frequent maintenance services than a petrol variant. 

Resale Value

Resale value plays a significant role in car purchasing decisions of many buyers. Is it to you? Compared to petrol cars, diesel cars can fetch you a higher resale price, but engine fuel type is not the only factor affecting resale value.

What about Alternate Fuel Sources?

The trend today points toward electric vehicles, so if you’re interested in managing your fuel costs or reducing your carbon footprint, then you can simplify your selection more quickly. 

Other alternative fuel types are biodiesel, ethanol, liquefied petroleum gas, liquified natural gas, hydrogen cells, and compressed natural gas. Some of these alternative fuels may limit your choices to a few brands since automakers are still testing the waters for the more experimental fuel options. 

Hyundai and Toyota have plans for Hydrogen-fed cars, but we’re looking at two years away due to the country's lack of hydrogen refilling stations.

Conclusion

Buying a car is milestone for most car buyers, so you can’t afford to do anything careless. It’s a tough decision and many factors will distract you. Make no mistake, however, deciding the engine should come on top of your list. Do it, and everything will follow beautifully.

Frequently Asked Questions

1. What's the advantage of a bigger size engine over a smaller engine, and vice versa?

A bigger engine size gives you the advantage of having more power than a small-sized engine. On the other hand, a smaller engine offers good fuel economy at low power outputs.

2. Can’t we just choose an engine with a higher displacement?

This was the basic concept till turbochargers arrived. And it has changed a lot ever since the first production cars with turbo made their debut in 1962 through the Chevrolet Corvair Monza Spyder and Oldsmobile F-85 Jetfire. The Chevy Spyder had a 2.4L 6-cyl petrol, while the Oldsmobile Jetfire used a turbo-boosted edition of the 215-CID V8, generating 215 bhp @ 4600 rpm and 407Nm torque @ 3200 rpm.

3. Why should you choose a V6 over a four-cylinder inline engine, and vice versa?

A V6 offers more power and more stability without taking much space.

On the other hand, a 4-cyl inline engine is less complex and costs less much less than a V6 engine.


By Sooraj Sj