Best Ideas for Boosting Horsepower without Boosting Fuel Consumption

Admit it, there are times when you'd like a little more. Like when you're joining the freeway and see a line of 18-wheelers bearing down. With more oomph under the hood you'd punch it and get out in front, but lacking supercar horsepower, you have to ease off the gas and tuck in behind.

One solution is to buy a quicker car, but if you don't want to change your ride there is another option: squeeze more horsepower from what you've got. Here are some of the best ideas around.

Replace the air filter

Stock filters restrict airflow into the engine. Running without a filter isn't an option because that risks serious engine damage, but you can buy filters that allow the engine to breathe more easily. This in turn increases the performance of your engine.

Fit a cold air induction system

This pulls in air from nearer the ground where it's more dense. To keep the air-fuel ratio where it needs to be, the engine management computer injects more gas on each stroke of the piston, increasing power. 

Go for forced induction

There are two approaches to forced induction--supercharging and turbocharging. A supercharger is driven by a belt from the crank, so it's always running, while a turbo is driven by the exhaust gases. In that sense the turbo is more efficient because it uses energy that would otherwise be blown out through the exhaust. Both are pricy installations and slightly out of range for the novice mechanic.

Install a performance exhaust

So far we've talked about ways to push more air in to the cylinders, but the exhaust side of the engine shouldn't be overlooked. A performance exhaust offers less back pressure. When it's easier to get the gases out of the cylinder, less power is wasted on sucking air in.

Modify valve opening and closing

Deep inside the engine is a camshaft. Driven from the crank, this controls when and how far the inlet and exhaust valves open. Performance cams have different profiles to the stock shaft, allowing improved breathing. As with turbocharging though, installation requires top-notch mechanical skills.

Modify spark timing

In older vehicles where ignition timing is set by the distributor, more power can be produced by increasing the “advance”. Modern engines have replaced the distributor with an Engine Control Unit (ECU) that measures speed, air temperature, and throttle position and determines when to send the spark. This is known as the engine “mapping”.

Some companies sell tools for modifying ECU mapping and replacement controllers optimized for performance.

The impact on fuel consumption

If you're going to extract maximum power all the time, expect to see your gas mileage go through the floor. But by making the engine more efficient, these mods will provide more oomph without too much of a hit on the consumption front. Drive carefully and you may even see better mileage.

And a final word of warning: Horsepower is addictive. After giving your ride an mph boost you'll be happy for a while. But then you'll find you want a little more.