To Boost or Not Boost | Castrol® USA

A long time ago if you were trying to figure out how to make your car go faster, you had a lot of reading to do. The process meant ordering hot-rodding magazines, cracking books by famous tuners, talking to gearheads at the local parts store and ordering snail-mail catalogs of go-faster bits. Gearheads today have Google and YouTube. With a long enough credit line, you can research and order enough simple mods to make your car accelerate faster in an afternoon. And, thanks to a robust global shipping network, you’ll have most of them next weekend.

Eventually, though, you’re going to want to see big horsepower gains, and that means thinking about forced induction. What do we mean by forced induction? Quite simply, forced induction is any means of filling a car’s intake with more air than it can suck in on its own. There are two main methods for achieving this goal: turbocharging and supercharging. In both cases, the engine spins an air compressor that forces more air into the engine. This added pressure is referred to as “boost.”

TURBOCHARGERS

Turbochargers work by creating boost using the engine’s exhaust gasses to spin a turbine that pushes air into the engine at huge volumes. Because exhaust and induction air can’t mix, turbos have a “hot” side — the exhaust side — and a “cold” side, which pushes fresh air.

SUPERCHARGERS

Superchargers work by creating boost using an engine-driven belt to spin a compressor. There are a few different kinds of superchargers with different benefits and drawbacks, but that’s a tale for another article. For now, just know that superchargers have the same basic function as turbos, but go about it in a different way.

THE DIFFERENCES

Because turbochargers use exhaust to create boost, the system is very efficient. It takes no engine horsepower to make boost. Because they are belt driven, superchargers create a certain amount of drag, which requires some horsepower to overcome. They also tend to make a bigger impact on fuel economy.

But because turbos need to be spun up by exhaust gas, there is a certain amount of lag between pressing the accelerator and boost pressure making power. Because superchargers spin up immediately, there is no lag between opening the gas and getting boost.

For those with a car that came from the factory with a turbo or supercharger, congratulations. Your path to more horsepower and quicker acceleration might be as simple as an ECU tuner and an appointment at the local dyno shop. If you really want to go crazy, opening your exhaust, chucking on a new downpipe, and a more aggressive tune will pay dividends.

NATURALLY ASPIRATED CAR

But if you have a naturally aspirated car — meaning a car with an engine that sucks fresh air directly into the intake — you’ve got some choices to make. Depending on the car, you can make power leaving the engine to breathe on its own. Modern naturally aspirated cars will also respond well to a dyno tune, a more open exhaust and a less restrictive intake. But those mods only give you modest gains. If you want to make double-digit horsepower increases, you need to start messing with the engine’s internals.

That gets expensive quickly and takes skills that are beyond the reach of your typical DIY gearhead. You need to have a pretty deft understanding of camshaft lift and duration, piston to valve clearance, compression ratios, and air-fuel ratios to get a naturally aspirated engine to make power.

And, at the end of the day, there really is no replacement for displacement in an NA engine. The bigger it is, the more air and fuel it can burn, the more power it can make. So, if you have a 1990 Mazda Miata with a tiny four cylinder, you’re just never going to make Chevrolet Camaro horsepower on the stock naturally aspirated setup. There are ways to increase displacement, but if you’re looking for more than modest gains, your best bet is forced induction.

The same applies for any small displacement four-cylinder engine; the law of diminishing returns kicks in pretty quickly, and the more modifications you make in the name of horsepower, the more street drivability and fuel economy will suffer.

STAY NATURALLY ASPIRATED

If you know your way around engine internals, you’re not concerned about street manners, and you want an engine that loves to rev, rewards momentum and feels sprightly and responsive, stay naturally aspirated. NA setups are lighter than forced induction, and are prized for their eager responsiveness, especially among canyon carvers and autocrossers. If your game is a simple, lightweight car with a rev-happy, fun-loving engine, stop reading here.

Without an engine swap or buying a car with a bigger engine, forced induction is really the best way to make your car go faster. Boost pressure from a forced induction setup is as good as increasing engine displacement. Stuffing more air into an engine means getting more fuel in, and that means more horsepower.

WHICH SETUP?

Deciding which setup to go with comes down to budget, drivability needs, desired power delivery, and ease of installation. Turbo kits can be had relatively cheaply online, and installation is comparatively straightforward. The operative words here are “relatively” and “comparatively.” Adding big horsepower is never fully straightforward, and doing the job properly will not be cheap.

But compared to a new car or a massively expensive and complicated engine swap, the $3,000 to $5,000 for a decent turbo kit is a bargain. Superchargers tend to be more expensive and heavier, but can be better for bigger engines and the same output benefit as turbocharging.

Deciding to go forced induction is a big deal, but for relatively cheap, accessible power, forced induction is a great way to make big power in short order.