What's a NASP (naturally aspirated) engine & how to tune it?

Car tuning tips:NASP engines and tuning options."

When deciding on a power train which should you go for? Both have merits. The answer really depends on driver style and preference but I will admit to being a little biased towards turbos. Here is my take on NASP Engines.

When it comes to petrol engines, there are two types available: naturally aspirated or forced induction (Turbocharged or Supercharged).

Individuals may favour one over the other and may articulate a compelling and impassioned argument for why one is preferable.

Rather than engage in this age-old and unresolved debate, we will simply give tuning recommendations for each engine type separately. This article is intended for lovers of NASP engines and will discuss tweaking possibilities.

"NASP Engines (Naturally Aspirated)"

These engines suck in the air they need filling the vacuum created as the piston moves down the cylinder. Large naturally aspirated engines and high compression engines produce a lot of power. The power delivery is instantaneous and the torque curve will gradually build as the engine revs increases.

How NASP engines work

As the piston descends the cylinder, it generates a vacuum, which draws air into the engine. The bigger the cylinder, the more air is pushed and the more power is generated.

A NASP engine rewards the driver with a smooth power delivery and torque accessible from low to high rpm.

The benefits are the steady stream of power and lazy delivery across the rev range. There are plenty of tuning options open to you but you are best to focus on CAMS and getting the head flowed and ported. While you are working on the head a 3 angle valve job does wonders for engine intake and will at the same time improve the economy of the engine (in most cases).

When it comes to NASP engines, there is a practical limit of roughly 100bhp per litre, however developments in technology are enabling vehicle manufacturers to surpass this.

NASP induction improvements

The primary goal of tuning a NASP engine is to increase airflow into the cylinder; this is accomplished by eliminating limitations to airflow in the head and extending the engine's suction duration. The camshaft controls duration, therefore a quick road cam will keep the valves open for a longer period of time.

Within the head, you should concentrate on polishing and porting to allow more air into the cylinder; a three-angle valve job significantly increases air flow into the engine and actually improves economy and power.

Many automobiles' air intakes are restricted, therefore widening them and installing a bigger MAF sensor is often the solution. Fitting twin wider throat carburetors to a carbureted engine will also boost power, provided the fuel and air ratios are suitable.

An induction kit with a suitable cold air feed or preferably a sports panel air filter and full stainless steel sports exhaust with a sports catalyst will also help to free up the power particularly at higher rev ranges.

NASP throttle body upgrades

Adding Throttle Bodies Has Benefits

Your car's performance may be greatly improved with the installation or alteration of a throttle body. Adding a throttle body has a number of significant advantages, including:


The most obvious advantage of installing a throttle body is an increase in your engine's power output. More air intake is often believed to be the cause of the 5-15 hp boost in power. The effective mixing of air and fuel is really what's responsible for this. It is possible to direct this peak power precisely where it is needed if you know what you're doing.

Tuning tips and articles Engine tuning Transmission tuning Care care Intake & exhaust mods Improve handling Forums

Throttle Response That Is Good:

When you step on the gas, you'll see an immediate reaction. It's because the intake manifold is filled with more air. It enhances the car's responsiveness and dynamism.

Effortless Acceleration:

Fast acceleration is also the result of a car with high power and a strong throttle response. There is no longer a lack of airflow preventing your automobile from performing to its full potential, and improved fuel atomization is the result.

In order to save money on gas,

Fuel savings may be substantial if the AF ratio is adjusted correctly. In addition, a leaner engine uses less gasoline, resulting in better gas economy for you.

Before Adding a Throttle Body, Here Are Some Things to Consider

Because of the advantages listed above, adding a throttle body is strongly recommended. Consider the following considerations before making a final decision.

  • Type of Engine: Consider the sort of engine you have. Throttle bodies are not required for certain engines, such as those with direct injection or diesels.
  • The compatibility of the device with the application: Make sure your vehicles' throttle bodies and engines are compatible. Throttle bodies may not be an option in certain vintage vehicles. As a result, instead of gaining more, you wind up losing more.
  • Your Specifications: Make your objectives very clear. Make a list of your car's power, acceleration, and torque needs. It will assist you in making an informed decision on the throttle body.

Capacity of the Engine Housing:

Analyze how large is big enough if you're trying to increase the size of your throttle body. Is there enough room in your engine block to accommodate a bigger throttle body? Throttle body protrusion necessitates cutting huge vents in the engine compartment, so keep this in mind while installing your new system.

Restrictions on Flow

Think about the engine's capacity to move air and exhaust; if any of these is hindered, you won't get the most out of your power improvements. Your engine power won't go up if you don't have a large enough exhaust system since you'll need to expel more gas if you've increased air intake.

NASP engine mods

Balancing, blueprinting and a lighter flywheel will free up a fair bit of power allowing you to exploit a higher RPM redline limit. Increasing the compression ratio is also a good way of extracting more power from a NASP engine.

Balancing and blueprinting let you to operate at greater rpm limitations, therefore broadening your power spectrum. Honda is a master at developing engines with a high rpm range and lots of power.

Additionally, increasing the compression ratio of the engine allows for more power to be generated but requires the use of high octane gasoline. This normally entails using higher compression pistons, but it might also include a rebore and stroker kit.

NASP remapping

After you have finished on your internal modifications you should get the engine remapped, typically the timing will be slightly advanced allowing for more power and greater efficiency. An ECU remap will also control the fuelling allowing you to fine tune the engine under WOT full load and partial load conditions.

Timing advancement may also be useful, although caution must be used to prevent pre-ignition. Remaps are beneficial for modern ECU-controlled fuel injection engines because they allow you to fine-tune the fuel delivery and ignition characteristics over a broad variety of load circumstances.

Fuelling may also be uprated for bigger power gains but it is generally harder to tune a NASP engine than a Turbo one as it requires a lot of internal engine work.

NASP Fuelling Upgrades

When you boost the engine's power, you'll also need to increase the fuelling to keep up with the increased air flow. Most typical systems can handle a 20% increase in power, but anything more than that will cause the engine to run lean, necessitating the use of injectors and upgraded fuel pumps.

Check out TorqueCars new YouTube channel, and see their awesome new content...


Please use our forums if you wish to ask a tuning question, and please note we do not sell parts or services, we are just an online magazine.

Help us improve, leave a suggestion or tip

Your Constructive comments on this article