Performance modifications, what really does work and what does not work? From one conflicting statement to the other, you as a newbie are indeed getting confused at different parts you’ve been hearing here and there. Performance modifications need not be complicated. Let us first define what basic performance modifications are, these are the basic bolt-on parts you install to increase performance. Contrary to popular belief, these will not make your car radically fast nor add a huge amount of horsepower. They will give you some gains but don’t expect too much.
Basic engine performance modifications consist of intake system, exhaust systems, exhaust manifold (headers). Being basic, these are relatively easy to install and should not be hard to find as well.
Since the engine combusts a mixture of air and fuel, better airflow means increased performance. Air filters are made with different kinds of materials, each with their own filtration properties. Examples of materials used for filters are paper, cotton gauze, foam, and steel mesh. Paper is normally used for original equipment applications as these are economical to produce and deliver adequate filtration for normal road use. For performance applications, paper has been tested to be restrictive and robs the engine of its hidden potential. Hence the introduction of performance air filters. There are two kinds of performance filters, the drop-in and the open-type. And with the development of performance kits derived from racing application, cold-air intake systems were evolved.
A drop-in filter is a direct replacement filter which you simply install inside the original air intake box. These have less restrictive materials which allow more air to flow through. The advantage of this type of filter is, you get to keep your original air intake box which was designed to resonate air intake noise.
An open-type filter was designed to replace the air intake box, thereby directing more flow to the engine. Like the performance drop-in filter, the open-type uses less restrictive materials to allow better airflow. An adapter is required to install this type of filter, but is usually provided. The advantage is unrestricted flow as air is directly fed into the air filter. The downside of the open-type filter is that it produces more noise because of the absence of the intake box.
Intake System Types
A short-ram intake uses a short tube (aluminum, stainless, or plastic) to connect the intake manifold to the filter. This usually runs until before the headlight. The advantage of this is because the intake tube is relatively short thus air is sucked in fast towards the intake manifold, downside is it can also suck in the hot air inside the engine bay due to location of the filter. This is an all-weather setup.
Cold air intake system
A cold air intake system employs an open-type filter. Unlike the basic open-type filter, specially designed piping is used to direct airflow to the engine. The filter is usually located away from the engine compartment to reduce air temperature. Some use special heat retardant materials for the pipes to improve performance. Since it is about increasing airflow, and cold air gives better performance, true performance enthusiasts go for this type of setup. The setup unfortunately is restricted to dry weather due to the risks of the engine sucking in water.
Ram-air intake system
The Ram-air intake system employs an open-type setup meaning there is no filter being used. Unlike the cold air setup, this setup gets its air directly from a hole straight to the throttle body. No filter means no restriction and the air is forced into the intake system as the car speeds up as if it were being rammed-in, hence the name. Usually the headlight is replaced with a specially designed funnel to direct the air to the intake pipe; some use the front grill, while some use the bumper. Setup styles may vary but the principle is the same. This setup is to be used only for competition purposes and not for street use especially when the headlight is replaced with a ram air system as it is illegal to run only with one working headlight. It is also unsafe for the engine to run on a ram air setup on a daily basis due to the absence of a filter as foreign objects might go inside the engine and damage it.
An exhaust system is the set of tubes and chambers that remove exhaust gases from the engine, reduce noise of exhaust pulses, and direct poisonous gases away from the passenger compartment. It is basically composed of pipes, a primary silencer and a muffler. Without an exhaust system, the engine would make a very unpleasant sound, as well as increase the risk of poisonous exhaust gases entering the passenger compartment. It is also illegal to drive a vehicle without an exhaust. Original equipment exhaust systems were designed to produce less noise and meet emissions requirements; they are usually designed restrictively thereby robbing the engine of potential power. Aftermarket exhaust system designs vary on application, two in particular, street legal and racing. The main objective of a street performance exhaust system is to free up the backpressure while still maintaining a tolerable sound pressure level to meet legal noise and emission regulations. A racing exhaust system is designed for maximum performance without having to consider legal regulations on noise and emissions.
Exhaust System Types
Street Performance System
As more air is fed through the engine by means of an intake system upgrade, that air has to go out faster for the engine to produce more power. A modern street performance system basically has four things to do: remove the exhaust gases from the engine as efficiently as possible, reduce the noise of the exhaust pulses to acceptable levels, reduce harmful emissions in the gases, and direct the poisonous gases away from the passenger compartment. These are also commonly referred to as cat-back systems as they bolt-on to the catalytic converter. Street systems come in two muffler configurations, they are either chambered or free flow. There are two kinds of street systems, the chambered and free-flow, referring to the muffler design. Normally, free-flow design mufflers will give a slightly bigger gain than chambered mufflers with the expense of reduced comfort levels due to increased noise. These systems are designed to meet strict legal regulations on emissions and noise levels.
Racing exhaust systems have only one goal, increase performance. Modern racing exhaust system utilize different metals like stainless steel, and titanium to produce the most power at the lightest possible weight and offer increased durability. Most racing systems utilize straight pipe designs because of the consideration of the racecar not having a gas tank underneath to block the way of the exhaust pipe and risk a fire. As noise is not a factor in racing, these systems utilize free-flow muffler designs for lighter weight and increased flow rates. Emissions requirements are also not applicable in racing that is why these systems connect directly to the exhaust manifold. These systems are strictly for use on the race track as they are not guaranteed to meet emissions and noise regulations.
These are exhaust systems which combine both Street Performance and Racing System designs. They are primarily street systems with free-flow design racing mufflers which are equipped with silencers for street use. These silencers can be removed for use on the race track or engine tuning for the engine to realize higher potential.
The exhaust manifold or exhaust header as it is commonly referred to is the primary outlet of engine exhaust gases. It is a very critical performance upgrade as a wrong manifold design will have detrimental effects on engine performance. For inline 4-cylinder engines, there are two configurations which are 4 into 1 and 4-2-1. For inline 6-cylinder engines, 6-2-1, 6-3-1. While there are different metals used to make exhaust manifolds like mild steel, stainless steel, titanium and Inconel, mild steel and stainless steel is commonly used in aftermarket systems. Titanium is usually used in custom manifolds, they are very much expensive compared to mild and stainless steel. Inconel uses high strength austenitic nickel-chromium-iron alloys that have exceptional anti-corrosion and heat-resistance properties. Inconel has been used by Formula One and Champ Car exhaust systems for years and is even more expensive.
A good exhaust manifold has to be mandrel bent. Custom made crush bent manifolds won’t do much, and will in most cases decrease engine performance and increase fuel consumption abruptly. For most street car applications, recommended material for headers are ceramic coated or aluminized mild steel to stainless steel. Ceramic coating and wrapping stainless steel headers helps maintain high exhaust velocity and increase scavenging. Another advantage is to protect the car and the driver from fatiguing high temperatures caused by radiated heat from the manifold.
The above modifications are just basic modifications to improve the flow of air in and out of your engine. After installing these modifications, expect your throttle response to improve as well as overall engine performance. Fuel consumption will still depend on how you drive the car. Never expect to consume less fuel with these modifications as they were never designed to conserve fuel. As you increase air, you also need to increase fuel to make more power. As for how much power you gain, it is best to leave it to a dynamometer to tell you that. Have a before and after dyno test to find out how much power you gained from your modifications rather than guess with your butt.