In our last post regarding the comparison between a V6 and a 4-cylinder engine, we talked about cost of acquisition. Since a car with a V6 engine is touted have a larger engine (hence, more metal and moving parts are utilized) then it will be more expensive than the same model car with a smaller 4-cylinder mill.

But this does not necessarily mean that a car with a larger V6 engine is ultimately more powerful. Modern technology paved the way for modern metallurgy and higher engine tolerance rates. This means that through the utilization of improved engine metals and engineering techniques, a smaller 4-cylinder engine can even match or surpass the power output of a larger V6.

What You Need to Know When Choosing an Engine on a New Car

Have you ever heard of power-to-weight ratio and horsepower-per-liter? True, complex calculations such as the ones mentioned are best reserved for drag racers or highly-tuned automobiles. Why should a regular driver even bother about power-to-weight ratio and horsepower per liter?

The answer is engine efficiency and fuel economy. An engine that is under powered will not only work harder in order to properly propel the car but it will consume more fuel as well. An engine with a better power-to-weight ratio will not only be more exciting to drive but is touted to last longer too (since it need not rev higher and create additional engine stress for proper motivation).

How to Calculate Power-to-Weight Ratio

Take for instance the 2012 Hyundai Sonata SE 2.0T. This car is powered by a turbocharged 2.0-liter engine that develops 274 horsepower. The Sonata has a curb weight of 3,443 lb.

The power to weight ratio can be computed as follows: curb weight/engine horsepower

Using the data stated above, the power-to-weight ratio of the Sonata SE 2.0T is: 3,443/274 = 12.6

The ratio 1:12.6 means that the car utilizes 1 horsepower for every 12.6 lbs of weight.

Performing the same calculation on the 2012 Honda Accord EX-V6 with a 271hp 3.0-liter V6 engine, with a curb weight of 3558 lb, we come up with the following figure:

3,558/271 = 13.1

This means that the Accord has a power to weight ratio of 1:13.1, meaning that for every 1 horsepower, the engine will need to lug around 13.1 lbs. of weight.

The Hyundai Sonata wins in this regard since the smaller 4-cylinder engine only needs to propel 12.1 lbs. of vehicle weight for every 1 horsepower that it produces.

We will talk about horsepower per liter in the next post. Keep in mind that while this alone is not a guarantee of superior performance, it helps to know that new cars, even with a smaller 4-cylinder engine, are also capable of delivering inspired performance along with better fuel economy compared to those with a larger V6.