If you've ever tried to join a conversation on an enthusiasts' forum about modifying your car for better performance, it may have seemed to you that everyone was speaking a foreign, abbreviation-based language.
What's the difference between NA and FI? I/H/E? What's that? Should you just add more NOS? If so, do I pour it straight into my FMIC? Some of you may already know the answers to these questions, but many are probably staring blankly at these seemingly random groupings of letters.
In this week's edition of the ABCs of Car Tech, I'm going to try to explain the most basic of this tuner terminology so that you can sound less like a noob when discussing possible performance upgrades.
OEM: Original equipment manufacturer
OEM parts are the stock parts that are supplied by the manufacturer of any vehicle. They're often the most reliable parts to use when replacing a component, but where's the fun in that?
NA: Naturally aspirated
The vast majority of vehicles on the road are powered by naturally aspirated engines. These engines do not use any sort of forced-induction system (see below) and rely only on the vacuum created by the engine's retreating pistons to draw air into the cylinders for combustion. Naturally aspirated engines are cheaper to manufacture, simpler to maintain, and typically more reliable than forced-induction engines. This setup is also known as "going all motor" in some circles.
SRI: Short-ram intake
The SRI is, for many car-loving kids, the first (and easiest) modification to a fuel-injected vehicle. OEM intakes make horsepower sacrifices in the name of noise reduction, fuel economy, and, above all, keeping manufacturing costs down. An SRI replaces the restrictive air box and plastic tubing with a freer-flowing intake pipe (often made of metal) and a high-flow air filter. The result is often more power and a more noticeable (read, louder) engine note.
CAI: Cold-air intake
A cold-air intake is an elongated intake pipe that positions the vehicle's air filter somewhere outside of the engine bay where cooler and denser air can be drawn into the engine's cylinders, which often results in more top-end power than a comparable SRI. However, there are trade-offs. CAIs usually sacrifice a bit of low-end torque for the top-end gains and can sometimes place the air filter in a position where it is more susceptible to water and dust.
I/H/E: Intake, header, and exhaust
The triumvirate of air intake, exhaust header (or headers, with V-configuration engines), and exhaust system is a bit of a blueprint for driveway tuners who want to add a bit of power to their ride with little more than basic hand tools. These three mods improve performance by helping the engine to inhale and exhale more efficiently and have the nice side effect of increased (and, some may argue, improved) engine sound.
CAT, CB: Catalytic converter and catback exhaust
The catalytic converter (or cat) is an exhaust system component that uses heat and catalyzing elements to convert harmful emissions (such as carbon monoxide, hydrocarbons, and nitrogen oxides) into less harmful ones (carbon dioxide, nitrogen, and water) by way of a chemical reaction. It is illegal to remove the catalytic converter in most municipalities, so a catback exhaust is an upgraded exhaust system that only replaces components downstream of the cat.
FI: Forced induction
The simplest way to get more power out of an engine is to get more air and fuel into each cylinder. Forced induction is the act of mechanically cramming air into the cylinder--usually via a turbocharger or supercharger system. This process is known more colloquially as "boosting" or "blowing." The pros and cons of the different types of FI systems when compared with each other and with NA engines are varied and subtle. We'll dig into the specifics of how each system works in later articles.
FMIC, TMIC: Front-mount or top-mount intercooler
The compression of intake air during forced induction creates heat, and, as I mentioned earlier, heat is bad for power. What an intercooler does is passively cool the intake air, allowing it to regain a bit of its density before being shoved into one of the combustion chambers and exploded. Top-mount intercoolers, such as those on the Subaru WRX or Mazdaspeed3, are mounted atop the engine, while front-mount models are mounted down in the front bumper. Again, there are pros and cons to both that we will discuss in a later article.
SS: Short shifter (kit)
A short-shifter kit essentially reduces the throw of the H-patten shifter of a vehicle equipped with a manual transmission. This means the shift knob travels a shorter distance when pulling, for example, from first to second gear or pushing from second to third. A shorter distance means a faster shift, theoretically. There are other factors that affect your shift time (such as flywheel weight and clutch heaviness), but the SS is often the first and easiest mod for most cars. (Note: a short shifter doesn't necessarily shorten the length of the shift lever. We'll discuss in a later article why that's a good thing.)
BBK: Big brake kit
Adding power and building speed quickly is all good, as long as you don't forget it's equally important to be able to shave off that speed just as quickly. A big brake kit is exactly what it sounds like and replaces your brake rotors and the calipers that grip them with larger (and often lighter) components. Larger calipers have a larger surface area, generating more friction for faster stops; larger rotors dissipate heat better for less braking fade; and lighter components have less rotational inertia and unsprung weight.
LSD: Limited-slip differential
The standard open differential used on most cars allows the wheels at each end of an axle to spin at different speeds. This is great because it allows the vehicle to turn. However, the open differential's design sends power down the path of least resistance (or in this case, the wheel with the least grip). So when one of the wheels on the drive axle slips, it gets all of the available torque, causing wheel spin. A limited-slip differential solves this problem with either a clutch or specific gearing to send power to the wheel that actually has grip, translating into better power delivery while cornering and more grip in slippery conditions.
FSB/RSB: Front/rear sway bar
Perhaps the more accurate nomenclature for these U-shaped suspension components is "antisway" bars because what they do is attempt to cancel the effects of body roll or sway when the vehicle is cornering. Fitting a stiffer, larger-diameter antisway bar to the front or rear axle of a vehicle will help to keep the car flatter in a turn, increasing grip up to a point. Go too stiff and you can cause the vehicle to lift an inside wheel during hard cornering, resulting in potentially worse handling than before. Again, we'll no doubt get into the specifics of how FSB and RSB kits work in a future edition of the ABCs of Car Tech.
STB: Strut tower bar (or brace)
A strut tower brace is literally a bar that connects the top ends of the left and right suspension towers of a vehicle. This inexpensive mod is often one of the first upgrades that young tuners can make to their vehicles, but it's also one of the least understood. One common misconception is that an STB works by making your suspension stiffer, but it doesn't. This brace actually makes the chassis of the vehicle more resistant to flexing under load, which allows the suspension to perform more precisely. The best STBs include a third mounting point that connects to the vehicle's firewall for maximum stiffness. Steer clear of universal STBs with hinges near their mounting points, as building flex points into the bar defeats the purpose of running the brace in the first place.
CF: Carbon fiber
A magical material that simultaneously makes any car faster and more expensive. Seriously, when discussing cars, we're more specifically discussing carbon fiber-reinforced polymer (CFRP), a composite material that is both very lightweight and extremely rigid. Although race applications and supercars use the material extensively for everything from chassis to suspension components, aftermarket applications are more often for body work. A well-made CF hood or trunk lid can save valuable pounds over an otherwise identical metal part. When a car loses weight, it gains improvements to handling, acceleration, and braking. Beware, however, of cheaply made carbon fiber components, which can be heavier (and in some cases, weaker) than the OEM part.
NOS, N20: Nitrous oxide
NOS technically stands for Nitrous Oxide Systems, which is a manufacturer of components used to enable nitrous-oxide gas injection for gasoline engines. However, much in the same way that some people call all photocopiers Xeroxes, many uninformed or lazy tuners refer to all implementations of nitrous-oxide injection and even the gas itself as NOS.
Nitrous oxide (or simply "nitrous" for short) is sometimes used as a low-strength anesthetic by dentists and doctors. However, this oxygen-rich gas can be injected into the intake of a car to boost horsepower for a short burst. As I mentioned earlier, more oxygen flowing into the combustion chamber means that more fuel can be injected, which, in turn, means more power can be generated per combustion cycle. In small doses, nitrous-oxide injection is mostly harmless, but larger "shots" of the gas will require that the fuel system and engine components be upgraded to keep the ratio of oxygen and gasoline within the acceptable range and to cope with the more powerful explosions.
That's it for this week's installation of the ABCs of Car Tech, but there's plenty more tuner terminology to define and explain. We'll delve deeper into many of terms discussed in this article in subsequent posts. Next week, however, we'll be changing gears and clarifying the alphabet soup surrounding passenger-car safety tech.