10 Most Common Engine Upgrades And Their Benefits

Jun 02, 2023

These are the most common methods to squeeze out a bit more power from your car's engine.

Modifying cars is a reality for almost all — if not all — car owners, whether that be for cosmetic, acoustic, or for performance purposes. This is the reason why not even cars of the same model would be similar once their respective owners bring them out of the dealership.

Often times, though, people make modifications with peak performance of their engines in mind. Hence, people search for the budget-friendly but good aftermarket parts for their cars.

Below are 10 of the most common modifications car enthusiasts can do to their engines, ranging from the cheapest performance car parts, to the more expensive and complicated ones. Prices indicated, however, only reflect the actual cost of the parts, and not labor.

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Unlike most of the other parts in this list, spark plugs are regularly replaced after a certain time to ensure a good ignition of the air-fuel mixture in the combustion chamber. While some would go bad after just 30,000 miles, there are some spark plugs that would still be okay even after 50,000 miles.

Spark plugs may be simple, but they serve different purposes: some upgrade them with fuel efficiency in mind, while others use high-end spark plugs that are more suitable for tuning — one that can initiate combustion better.

The only possible drawback with this upgrade is if a plug was placed incorrectly; otherwise, it might be the simplest and cheapest modification to an engine.

Horsepower gain: Minimal, but would make car run efficient/ accelerate faster

Fuel injectors are responsible for squirting fuel to produce the air-fuel mixture, which is then ignited by the spark plugs. And like spark plugs, fuel injectors also need to be changed after a certain time — although in this case a little longer, around 50,000 to 80,000 miles.

Upgrading fuel injectors, however, will be necessary if there are serious modifications made to an engine — like if a car owner puts in a bigger and less restrictive intake system or a free-flow exhaust pipe. Changing injectors, and even the fuel pump, are called "supporting modifications", as they ensure that upgrades would be felt.

Usually, tuners go for larger injectors and those that put out more fuel. It is equally important however to know what size and what type of injector a car needs because putting in the wrong one might make the air-fuel mixture too rich.

Horsepower gain: Around 5hp to 10hp

Getting a high quality yet less restrictive air filter can make an engine more responsive for as cheap as $70 to $120. Mechanics discourage this practice though due to heat soak, or a condition where the intake sucks warm air to the engine — which is not ideal.

This is why a lot of tuners go with a cold air intake, as it ensures that air being fed into the engine is cold and condensed, making more horsepower.

Car enthusiasts however should ensure that an intake kit matches the specifications of their cars because getting more air without the correct fitment might lead to dust or particles entering the engine block, creating catastrophic problems. There is also the risk of losing power if the intake is too big.

Horsepower increase: It varies, but probably around 2hp to 30hp, depending on the car and intake quality.

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Many car owners upgrade to aluminum radiators because while copper ones have better heat transfer abilities, aluminum is just stronger and better at resisting corrosion and damage over time. A cooling system upgrade also has no direct effect on horsepower, but it allows a driver to put all the modifications without overheating or damaging the engine.

Aside from the radiator though, it might be necessary to upgrade other parts of the cooling system like the thermostat, cooling hoses, the water pump, as supporting modifications. Of course, picking a good coolant is also key.

Upgraded radiators tend to be pricey, though, especially those with multiple cores and those that offer better cooling benefits.

Mufflers are meant to reduce engine noises, but in the process, they also restrict the flow of exhaust gases coming from an engine. This leads tuners to have one of the most common and most perceivable upgrades installed: a new exhaust system.

There are different ways to upgrade a car's exhaust system, but most experts agree that a cat-back system, where all exhaust components located after the catalytic converter are replaced, would increase engine power the most.

A cat-back system offers higher power gains as restrictions to exhaust flow are removed, resulting in a lower back pressure for the vehicle. The drawback is higher noise levels and the possibility of a car no longer being street-legal.

Horsepower gain: Around 10hp to 20hp, depending on materials used.

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While most consider the clutch assembly as not a part of an engine, it is still important for those looking to produce more horses to upgrade it since the clutch connects the flywheel to the transmission, and ensures that power is transferred to the wheels.

A clutch does not have impact on horsepower, but the best kits transfer power at a minimal loss. Aside from that, the stock clutch kit can only handle a specific power band — any higher than that, it may lead to huge damage for the clutch or even the entire transmission.

It is important, however, to understand what kind of aftermarket clutch kit is needed by a car: does it need a heavy-duty clutch for hauling heavy items, or does it have to be lightweight and aggressive for tracking? Either way, drivability would be affected especially for manual transmissions, which means a long, hard contemplation will be needed.

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Stock or cast pistons are not bad, but it is best to upgrade a car's stock internals if an engine is pushed to its limits.

Almost all racing setups use a forged piston, as they can handle more power and stay in higher RPMs without degrading over time due to heat. This is also why some aftermarket companies sell forged internals like crankshafts, pistons, and connecting rods, because parts need to be durable to handle that extra horses, especially considering that only a sliver of oil prevents metal-to-metal contact.

Speaking of crankshafts and connecting rods, it is also good to upgrade these to produce more power safely. But for street applications, a lot of stock crankshafts can deal with a few additional horses.

Horsepower gain: None, but supports higher compression ratio brought by upgraded cams

Camshafts open the valves of an engine, allowing air to either pass through a cylinder, or the exhaust gases exit the engine. Stock camshafts are built to last for a long time, but original equipment manufacturer (OEM) parts may not be able to support a projected increase in horsepower.

Bigger and stronger camshafts would not only open valves more and longer, but they also allow car owners to stay at high RPMs without worrying too much about wear.

Upgrading camshafts requires a mechanical know-how, though, which means such upgrades may be better left to mechanics. A wrong camshaft setup may lead to issues in timing and rocker arm clearance, which can lead to poor engine performance.

Horsepower gain: 10hp to 20hp

How can you add around 100 more horsepower to your car? The quickest answer would be forced induction, or by slamming a turbo or a supercharger into an engine — and for an already-turbocharged car, putting a bigger turbine.

For normally aspirated cars, turbocharging them might mean a delay in throttle response at cruising speeds — also called turbo lag — but the increase in horsepower and torque once the turbo spools are so huge that some would live with it, and just improve their driving mechanics.

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One problem with turbocharging however is putting power that is more than a car can handle. A lot of videos have been uploaded to show what could go wrong if a car makes too much boost.

Turbochargers and supercharges are good, but only if an engine can actually support more power: this usually means putting all the above-mentioned modifications ahead of turbocharging.

Horsepower gain: 50hp to 150hp (or even more, depending on the setup)

The reason why upgrading cars is usually called tuning is because of this: a car's electronic control unit, which controls a lot of aspects in an engine like air-fuel ratio, timing, spark plug ignition, and other factors, are tuned by computer experts for optimal performance.

In short, the potential power gain from upgrades installed would not be reached if ECU tuning is not done properly. What remapping basically does is to control how much fuel is pumped in at certain power bands, and to select when the spark plug would trigger the combustion.

Remapping however only applies to modern cars, or those that utilize electronic fuel injection instead of carburetors. Also, remapping does not come cheap: tuners usually charge a hefty amount for use of the software, the dynamometer which measures horsepower and torque figures, and the expert's skills which have been honed over time.

Proceed with caution, though: remapping can void a car's warranty.

Horsepower gain: around 20hp to 50hp, but crucial for smooth ride and optimal performance

For the longest time, Gabriel Lalu has been covering Philippine politics and other news. However, he knew deep inside that he had an insatiable interest for cars, inspired by his expert mechanic father who also worshipped JDM items.Currently, he owns a Chinese kei van which he has been upgrading using JDM parts. He is still contemplating though whether the kei van should be built for off-roading or track days.