If you were to whip up a performance car cocktail, what ingredients would you need? Almost every major automaker has dabbled with this recipe to certain concentrations, and each of them take the principles I’ll lay out in this article to whip up some intoxicating products.
You may not actually consider tires to be part of the recipe during an automaker’s vehicle development process, but in fact tires are specifically chosen or in some cases co-developed with a tire brand during the car’s formative stages. The better the rubber you’ve fitted to your performance car, the better your vehicle will be at transferring power to a road surface and maintaining traction. At the basic level, rubber compound, tread pattern, and tire width significantly play into vehicle grip.
Wider tires means a greater friction patch, but width without a high performance (summer) tread pattern won’t do much for a car’s grip. As for the rubber compound (which is a mixture of rubber and filler), high performance tires use a softer compound for better grip, though at the cost of durability, and in the case of summer tires, all-weather traction.
[pullquote]At the end of the day, it’s a question of what you can live without in the name of performance.[/pullquote]Though it may not be obvious, tire technology has come a long way over the past several decades. The greatest strides have towards precision engineering of each tire, better rubber compounds, and data-aggregating tools built right into each tire. For example, Pirelli has been testing “digital tires” on Ferrari’s FXX K supercar to collect data about coefficient of friction, footprint, and pavement grade which is then communicated to the car’s ECU and traction control systems to optimize power delivery based on grip. Obviously this is next-level technology, but it demonstrates that tire manufacturers aren’t just rehashing the same old concepts when it comes to performance rubber. And, when an automaker approaches a tire manufacturer to specially-design a sports car’s shoes, it’s a multi-million dollar process.
The right tires can turn a mid-level performance car into a supercar’s nightmare by enhancing the vehicle’s grip in corners, traction under hard braking, and power delivery.
Equally as important as a good set of tires is a performance car’s stopping power. What good is a high-powered performance car if it’s not able to stop before the first corner on a track? There are several ways to piece together a high performance braking setup, with some elements costing far more than others.
[pullquote align=”right”]More complicated are the ways performance disc brakes scrub speed quicker.[/pullquote]At this stage of the game, most new cars on the road use front-wheel or four-wheel disc brakes, and that’s especially true for performance models. Disc brakes are fairly straightforward: a caliper clamps down on a rotating disc to create friction and bring the disc to a halt. More complicated are the ways performance disc brakes scrub speed quicker.
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One of the ways brakes perform better is by creating slots within rotors to allow hot gases, water and other debris to move off of the face of the rotor. While these types of brake rotors wear faster than solid or cross-drilled ones, they perform far better during high performance driving stints.
Another hardware update comes from larger calipers and multiple pistons. By increasing the size of a friction contact patch (with a larger caliper), and by adding pistons for greater, more even pressure, a car can decelerate much more quickly. Further, using a high-friction, more durable brake pad can cheaply and easily improve braking performance. Higher performance pads use additives such a copper or coke powder (a compound designed to dissipate heat and increase friction) improve durability.
Then there’s the brake fluid and lines. Performance brake fluid doesn’t absorb moisture as easily as lower-spec fluids, so they maintain lubrication levels. As for brake lines, standard rubber ones can swell, decreasing brake fluid pressure. Braided steel lines are not only more durable, they keep even, consistent fluid pressure for optimal stopping power. Finally, improvements can be made with the disc compound. While most brake packages use steel rotors, some ultra high performance setups use ceramic or carbon ceramic rotors that resist heat better than lesser compounds.
While some automakers will immediately jump to power to solve performance deficits, all know that the real issue at hand is a strong power-to-weight ratio. If your vehicle foundation is already as light as possible, then obviously you’ll need to turn to engine enhancements, but in many cases, using lighter construction materials or cutting out superfluous convenience features can rapidly improve a car’s power-to-weight ratio and therefore make it faster all-around.
Weight reduction can start out pretty easy, but quickly becomes a more complex issue of “what’s essential, and what’s not?”. Removing heavy sound systems, infotainment displays, 18-way power adjustable, heated and cooled, massaging seats and the like can shirk a ton of weight. Beyond that, automakers need to get creative, because safety regulations mandate some hefty airbag and structural reinforcement setups that can’t be unloaded.
Some tactics commonly used, depending on how aggressive the performance car’s intentions, include: removing the rear seats (usually in exchange for a roll bar), replacing door handles for straps, swapping in thin, light sport seats for heavier leather ones, replacing leather and metal trim for Alcantara microfiber, and in some cases, removing “luxuries” like cruise control. There are always more extreme measures to save grams, not pounds, but that’s mostly reserved for racing-spec models.
The alternate method to cutting out weight is replacing core vehicle construction materials with lighter components. One common practice on high-end performance cars is to swap steel chassis materials with carbon fiber ones. Not only is carbon fiber extremely strong, but it’s ultra light as well.
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Down the chain, many automakers have replaced steel with aluminum (for example, Ford’s new F-150 saved 700 pounds by applying aluminum body panels instead of steel ones). Automakers have also become creative in terms of bonding metals and creating new composites with the benefits of lightness and strength. At the end of the day, it’s a question of what you can live without in the name of performance. A lighter car will not only be faster in a straight line, it will be easier to manage in the corners, and there won’t be as much force to “act on” with your brakes.
Aren’t we onto power yet? Not quite. Another essential ingredient for a delightful performance cocktail is your suspension tuning. There are some incredibly advanced systems out there these days, but I’ll keep it to the basics. The springs, shock absorbers, and linkages connecting wheels to the vehicle body comprise the suspension. Tuning the setup to be softer or tighter affects the vehicle ride and handling characteristics, but there’s more to it than that. The goal is to keep tires in contact with the road as much as possible, and while a softer suspension setup might lend itself to that purpose, it would also increase body roll or vehicle dive and lessen handling potential.
Spring rates are a big part of how a vehicle handles. In performance designations, higher spring rates mean a vehicle will handle rapid changes in weight transfer better than lower spring rates. On a track, that means vertical and horizontal compression at speed is held better in check.
A common difference between a normal vehicle and a performance vehicle is ride height. Sure, some “stance” vehicles which have no business being on a race track are lowered, but the point of a lowered suspension is to drop the center of gravity, and therefore mitigate weight transfer. Just lowering a car isn’t enough to make a significant difference in handling, but it’s one element. Another critical piece to a high performance suspension setup is damping.
Damping relates to a shock absorber’s resistance or compliance to vehicle travel and suspension movement. Without good damping, a vehicle will settle its sprung weight (weight that’s resting upon the suspension) quickly after movement. Modern suspension systems control fluid in shock absorbers to change damping rates. At the highest end of performance damping are systems like MagneRide, which use magnetically controlled dampers to make micro-adjustments within fractions of a second based on how a vehicle’s ECU communicates performance needs.
Another element of suspension tuning is lateral rigidity. By using thicker sway bars (which connect driver and passenger side suspension components) at the front and rear of a car, a car will handle better by reducing body roll. Pretty much all mid or high-end performance vehicles use independent suspensions, as opposed to solid or “live” axle setups. While solid axles are more durable, an independent suspension leads to greater handling potential by letting each wheel rise or lower without impacting the opposing wheel on an axle, creating more traction in corners. Differentials play into handling performance as well by controlling power delivery based on which wheel or wheels have the greatest traction at a given moment, but I won’t go too in depth with that now.
Engine: power, forced induction, cooling
Now that you’ve laid the groundwork, it’s time to pour in the power. There are numerous ways to increase engine output, which could comprise its own article, but I’ll focus on a few popular methods. Forced induction is one of the most common ways to quickly boost engine performance. Superchargers and Turbochargers approach injecting air into an engine in different ways and with unique results.
A turbocharger spins a turbine wheel via exhaust gases that’s connected to a compressor wheel. The resulting pressure is regulated by electronic controllers and a release valve and then funneled back into an engine.
“Turbo lag” occurs because it takes time to spool the turbine, meaning a delay in acceleration. In non-performance cars, turbochargers are used because they create power efficiently (without using a ton of fuel). In high performance cars, multiple turbochargers are often used to reduce turbine lag, where one turbocharger operates at lower rpm’s while the other takes over in the upper part of the rev range.
Some automakers choose to use superchargers instead, because they have virtually zero lag time between throttle and boost pressure. This is because a supercharger is constantly spinning to match the engine speed. Why would anyone use turbochargers when a supercharger doesn’t have a delay? One drawback to a supercharger is the fact that it requires engine torque to operate, and therefore robs some power from the engine, and is also not as fuel-frugal.
Presently, automakers either use superchargers on high-horsepower vehicles like the Dodge Challenger SRT Hellcat, or in combination with a turbocharger to create a more efficient setup, like on Volvo’s new 2.0-liter turbocharged and supercharged four-cylinder. There are a few types of supercharger systems. A Roots-style supercharger uses paddles on two rotating drums to push air into the intake. The benefit to this system is that the compressor can produce the same pressure at any engine speed.
Another style of supercharger is the screw-type system, which produces cooler air that a roots supercharger. Finally, there’s the centrifugal style supercharger, which looks like a turbocharger to most people. This system has better thermal efficiency than a roots supercharger, is more compact, and pairs better with an intercooler. Automakers most commonly use twin-screw or “twin-scroll” superchargers which enable instant boost pressure.
With greater power comes greater…heat, and that’s why performance cars commonly have upgraded cooling systems when compared to a standard vehicle. The best method for cooling when using a forced induction system is through an intercooler, which takes the hot air released from a turbocharger or supercharger and cools it (most commonly with liquid) before applying it to the engine. Another method of cooling the engine is through water injection. Water and methanol are mixed and sprayed into the compressed air to not just add power but to cool the system so more air can be funneled in.
Two other common ways to add power are to install a high-flow exhaust system, which lets exhaust gases escape easier and therefore limits back-pressure or an air intake system, which lets cooler air funnel into the engine in greater quantities.
Beyond these methods, automakers employ performance cam shafts, which increase the duration and timing of valve openings during the engine stroke or add upgraded headers, which more efficiently allow exhaust gases to escape (likely to a higher-flow exhaust system). The list of other possible enhancements to an engine or exhaust system is long, but just as important as any power-adding system is proper tuning of the ECU (engine control unit). Whenever something is modified under the hood, tuning the ECU for optimal performance is essential to getting actual output gains.
Transmission: auto or manual, shifting times
Once you’ve leveled up under the hood, it’s time to get that power to the ground. There are several categories of transmissions these days, and while enthusiasts (myself included) will defend the manual transmission to our dying breaths, the fact is that semi-automatic and full automatic transmissions within high performance vehicles shift faster and, in some cases, more intelligently that man ever will with a manual.
The manual transmission holds a place of high regard because it requires great skill to shift efficiently, matching engine speeds during downshifts and modulating steering inputs and braking during track driving. If an automaker does offer its performance vehicle with a manual, most will use a six or seven-speed setup where the final gear is an overdrive (for fuel efficiency). Undeniably, standard transmissions offer the greatest driver engagement, but if you want a faster car, you’ll need something else.
Basic automatic transmissions have been around single the 1920s, but at this stage, they offer eight gears (or more) and can move between those gears incredibly quick. In mid-level performance vehicles, automatics usually come with manual controls, letting the driver toggle between gears via steering-wheel-mounted paddles or via the gear selector. Worth mentioning is the growing popularity of CVT (Continuously Variable Transmissions). While these are almost never used on high performance vehicles, they are more efficient than automatics because they create a virtually limitless range of gear ratios via adjustable pulleys.
The non-manual transmission of choice for performance vehicles is a dual-clutch (DCT) gearbox. Pioneered in race cars, these transmissions combine the control of a manual with the efficiency of an automatic and the precision of a computer. Two clutches are used to change gears by pre-loading half the available gears on one clutch and the other half on the other clutch. This reduces shift times dramatically, whether the driver is shifting via paddles or whether the computer is controlling shifts in fully automatic guise.
Another benefit of this system is that the computer can analyze driver behavior to optimize gear changes based on how it estimates the vehicle will be driven (to the redline or just to an early shift point). Not only is a dual-clutch the fastest automated transmission (shifting in fractions of a second), it’s also the smoothest.
Aerodynamics are critically important in racing, where downforce at high speeds keeps a vehicle planted to the road instead of sailing through the air. As road cars near and sometimes surpass race car performance levels, automakers have needed to incorporate aerodynamic principles in production models.
There are two general types of aerodynamics: static and active. Static aerodynamics are either non-adjustable fixtures like a side skirt or hood, or require manual adjustment like some rear spoilers or front splitters. Active aerodynamics uses sensors to adjust the pitch and deployment of aero elements based on available grip or vehicle speeds. Not only do aerodynamics create much-needed downforce at speed, they help reduce the coefficient of drag on a car to let it slice through the air easier. It’s all about controlling airflow through and around a car.
Both underbody and top-of-body aerodynamics play into how efficiently a performance car moves through the air. Flattened underbodies help channel air quickly beneath the vehicle, as opposed to open sections which gain resistance to airflow as speeds rise. In terms of overall vehicle design, smooth curves and channels (like behind wheels and along a car’s hood) help manage airflow. For a vehicle to be fast straight from the factory, it will have undergone hours of wind tunnel testing to assure its design is as streamlined as possible.
Low-drag designs minimize air resistance, but downforce components keep all four wheels on the ground. That’s where front splitters, rear spoilers, and winglets come in. These “add-ons” manage vehicle lift at speeds (not like 100 mph, more like 200 mph). For this reason, though they look cool, most cars that aren’t engineered with aero elements from the factory don’t need them (sorry, tuner cars).
There are nearly limitless modification options to increase performance, which is why the aftermarket industry is so successful, but these core ingredients are employed by every automaker that develops a performance model. With the fear that this would turn into a novel, I did not mention elements like limited-slip differentials, traction control systems, torque vectoring, steering responsiveness, chassis stiffening methods, and more, but those are impact the driving experience to a certain degree.
Every cocktail has its own flavor profile. Some automakers and enthusiasts like to live dangerously with high-horsepower, oversteer-prone muscle cars, and others develop ultra light roadsters that feel at home on a technical road, but struggle on the straights. There are thousands of recipes to choose from; it’s all a matter of taste.