Mechanical tuning vs forced induction

There are plenty of car enthusiasts that like to modify their vehicles. As I had mentioned in the Zaniest car mods post, a car is an extension of themselves, in the same way that a painter’s art is an expression of the artist. Exterior modifications express the owner’s vision of themselves and the car, though sometimes those displays are best kept to themselves. I prefer to keep the exterior of the car as stock as possible and mod the thing that matters most, the engine. I would like to buy a stock car and turn it into a sleeper; something that you wouldn’t expect to blow past a super car.

There are always at least two sides to any argument. In the case of getting more power from your engine, while there is the mechanical way, the turbocharged way, or the supercharged way, it all boils down to making the engine breath better. In the same way that breathing deeply or more rapidly can help when you go for a run, an engine that breathes better, performs better. Not just in terms of power output, but fuel efficiency too.  The modifications listed below are more affordable and take less time to perform. Keep in mind that engine mods may result in a void warranty.

Mechanical tuning

I am a huge fan of normally aspirated engines. A powerful free-revving engine that has a linear progression of power delivery just makes my day, which is why I am an advocate of mechanical tuning. Rather than using forced induction to force more air into the engine, I would prefer to keep the engine’s natural aspiration but change the way it breathes by upgrading the intake system, the exhaust system, and the ECU.

A cold air intake kit is an aftermarket system that brings cool air into the internal combustion engine. Normally, a car regulates the temperature of air as it enters the engine, providing warm air when the engine is cold, and cold air when the engine is warm. Cold air intake kits, however, can lead to higher performance and engine efficiency, based on the idea that colder air is denser than warm air, which means that it contains more necessary oxygen for a more dynamic combustion. A cold air intake should be mounted some distance away from the rest of the engine so that the air taken in remains cold.

cold air intake mounted on the Ford Mustang's V6 engine
The conical cold air intake mounted on the Ford Mustang’s V6 engine. (Image source: Wikipedia Commons)

Adding new headers and a better-flowing exhaust system allows waste gases to exit with greater ease. A modern car’s muffler and catalytic converter exists to reduce noise and harmful emissions, but they also increase a car’s back pressure and impede the car’s ability to get waste gases out of the engine, thereby wasting power. Installing a new exhaust manifold that provides both smooth and equal-length pipe sections to exit gas from each of the engine’s cylinders, along with installing an exhaust system (not just a big muffler and tailpipes) that minimizes bends and increases pipe size, can have marked effects on your car’s performance.

Porsche 924
This old Porsche 924 has had an entirely new exhaust system put in to help the car sound better and deliver more power and be more efficient. (Image source: Author’s own)

The ECU (electronic control unit) does the job of making sure everything in the engine runs smoothly. It uses actuators and sensors to adjust air-fuel ratio, ignition timing and idle speed to keep the engine’s performance hiccup-free. When it comes to fuel-injected or direct-inject engines, the ECU adjusts the air-fuel mixture as necessary. Reprogramming the ECU (or “chipping”) alters the mapping parameters to increase performance and, in some cases, enhance fuel economy.

Installing new spark plugs made from platinum or iridium will also help deliver better combustion which could aid performance and efficiency.

Mazda MX-5 Super 200
While BBR makes all sorts of modifications for various types of MX-5s including turbochargers, the one that interests me the most is its Super 200 kit. (Image source: evo.co.uk)

These modifications will allow for more performance while ensuring the engine’s characteristics do not change though the gains in performance are not as big as with forced induction. Check out BBR’s ND MX-5 conversion to see how they have mechanically tuned the new MX-5.

Turbocharging

While people claim that turbochraging is one of the most affordable and easiest tuning methods, this is far from true. As I mentioned above, the increasing the amount of air going into your engine will deliver better performance (technically called increasing the volumetric efficiency). The turbo uses the exhaust gases coming out of the engine to spin a turbine that sucks in more air into the intake system. When there is a sufficient amount of exhaust gases making the turbine spin, the turbocharger provides a sudden boost of power and torque, giving the car a very characteristic rush of sudden rush. boosted engines do offer much more performance but compromises the original character of the engine.

turbo
The characteristic trait of a turbocharged engine, told through memes. (Image source: Various)

However, if you increase the amount of air/fuel in the cylinders, then the compression in the cylinder will also increase, which could lead to trouble. In order to keep the final running compression the same, the initial compression (without boost) has to be dropped to compensate. Otherwise, a phenomenon called pre-ignition or engine knock could occur. This is where the fuel ignites under pressure before the spark happens which can cause a piston to move in the opposite direction if it has not reached the top dead centre and will have disastrous consequences for the engine. Besides changing the compression ratio (by boring or stroking out the cylinders), all the mods for a normally aspirated engine will be useful for turbocharging as well, specifically the ECU remapping.

Supercharging

A supercharger pressurizes air intake to above the normal atmospheric level so that more air can go into the engine, thus combining it with more fuel to produce more power. Powered mechanically via a belt or chain from the crankshaft, a supercharger spins much faster than the engine itself in order to force air into the combustion chamber. This makes space for more fuel, which creates for a larger combustion. Power delivery is usually quite linear like naturally aspirated engines, but some energy is lost as the engine itself is used to run the supercharger. Attaching one to the engine of a normal sized car will immediately make it behave like a much larger, more powerful vehicle. Like the turbocharger, you would have to take care to avoid similar issues.

1968 AMC AMX
That is own massive supercharger on this 1968 AMC AMX. (Image source: Wikipedia Commons)

However, engines are always made with certain tolerances. A richer mixture of fuel and air in the cylinders could lead to detrimental effects on the engine like knocking, stalling, and even blowing the engine apart. One reason why tuning older Japanese cars is such a big part of car culture is that they were launched with over-engineered motors that could produce more power without changing the internals of the engine to make it more robust.

So which is better? It’s a personal preference. If you want great performance gains on paper and don’t mind changing the character of your engine, go for forced induction. The price-to-power ratio is better when compared to mechanical tuning. As I said right at the beginning, my preference is for the latter.

Note:

Always remember that engine tuning cannot be done in isolation. The tyres, suspension, brakes and gearbox may also need to be upgraded in order to better handle the extra power that your car now makes. Depending on the type of car and how much power it makes, a spoiler may also be necessary.

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One thought on “Mechanical tuning vs forced induction

  1. As an owner of a non charged large capacity (2.8l) and a turbo 1.4l I have to say each has its place. They are both very similar in terms of 0-60 times and top speed although they couldn’t be different in character. Sometimes the swooshy straight 6 is perfect but often I just love feeling the turbo kick in!

    Liked by 1 person

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