Induction kits & what they do.

"An introduction to induction kits"

As induction kits are probably one of the most popular modifications for car tuning projects we thought we should add a introductory article to explain what they are, what they do and the theory behind them.

What is an induction kit?

An induction kit is quite simply an air filter. Most cars have air filters mounted in an air box. These filters are generally constructed of paper which filters out the particles from the air and prevents these from getting into the engine.

The airboxes are designed to reduce the noise of the engine and have various vanes and angles cut to maximize this noise reduction.

Because the air is not flowing freely through the filter there is potentially a loss of power due to the turbulence caused by all that sound deadening.

To make up for this loss of power the air filter surface area is a lot larger than the intake tubes so manufactures have effectively closed the gap between, noise reduction and performance.

Induction kits

When it comes to car tuning noise reduction is generally the last thing on peoples mind.

Swapping out the restrictive air box with an open filter helps to improve the flow of air into the engine and fully releases the induction roar, a noise associated with tuners cars the world over.

The induction kit is quite simply an open air filter shaped like a cone, dome or tube.

Downsides/pros and cons of induction kits.

So it would appear that induction kits are a win/win situation. However there are some downsides.

As the filter is sited in the warm engine bay it will suck in warm air which carries less oxygen.

Thankfully after a mile or so the air temperature in the engine bay is much reduced and closer to ambient temperatures. Fitting a cold air feed pipe taking air from outside the engine bay will help to counter this problem.

Engines with induction kits fitted typically see the power gains quite high up the RPM range.

However low end power can be compromised. In small engines the effect of an induction kit is often a noticeable loss of low end power.

This is fine if you want to use the top end of the RPM range all the time, like you would in a race environment, but on the street this is just not viable. Fuel usage would be much higher and you will be causing a noise nuisance to your neighbors.

Induction kits flow better than paper elements partly because they do less filtering. Induction kits are still efficient filters but they are never going to be as effective as an OEM paper filter.

Do induction kits always add power?
NO - typically power gains are toward the top end of the RPM range and some engines will show a power loss, especially low down.

Do induction kits add fuel economy?
By sucking in warm engine bay air the engine will use less fuel, so round town you might notice a slight improvement in MPG but the induction roar promotes a heavier driving style which negates this.

Engines can be a little more efficient with induction kits so pull in more air.

This generally means you get more power from your fuel but if you adjusted your driving style, to use less throttle and settled for your previous power figures, you can get improved mpg with induction kits.

Are all induction kits the same?
No, quality varies considerably. We recommend filters that are using a cotton gauze filtration medium.

Some kits come with high flow air boxes and air intakes designed specifically for a car and these will usually out perform basic filter only kits.

Are induction kits hard to fit?
Induction kits are very simple to fit. You may need to cut a pipe or two but most kits can be fitted in 4 minutes with just a screwdriver.

Why are induction kits so popular?

They sound great, so there is a massive placebo effect of perceived power increase, and they are one of the cheapest most easy to fit mods around.

Sadly though most setups in average cars see little to no power gain by fitting one.

That said if you are modifying your car an induction kit can have a useful place in your parts list

I fitted an induction kit and I have flat spots?
Wait for a while. Modern engines may need to adjust to the new air flow characteristics. They will auto trim the fuelling based on lambda readings.

If after a tank of fuel you still get flat spots then you should check your fuel delivery. Running lean can be a problem and some have noted that fitting a sports exhaust will further improve things.

What is the main benefit of an induction kit?
If you are looking for more power then there are lots of better things to spend your money on.

If you want the induction roar noise then the induction kits are good value.

What do we think of universal induction kits?

Not a lot if i'm honest. Anything universal is little more than "a very generic, we couldn't be bothered to optimise anything" box shifting exercise.

Intake involves flow, and bore sizes, filter shape and positioning are all important and generic universal kits rarely work well in anything.

If you would like to discuss induction kits for your car please join us in our modified car forum.

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Leave a Reply to Jesse

Your Constructive comments on this article

7 Responses to “What is an induction kit and what does it do.”

  1. Eric says:

    My intake system causes my powertrain light to come on? Do I need to take it in to be tuned? Also I gave it a minute to run and get used to the new intake and the damn light still comes on after a few miles…

    • Doug says:

      I would take the air induction kit back .Simply put in a K&N you will not only notice performance but when you get on it it is plenty loud heads will roll it sounds good and no check engine light .Just do not over oil it when you clean it you have to spray it with oil.It is transmission fluid red and all .Good luck mine runs sweet with 164,000 miles.

  2. Jesse says:

    Hello i recently put a open air cone filter on my volvo s60 and i want to know if i will damage the car?

  3. shadowalkr says:

    I have a 99 toyota corolla and i’m considering getting an ram air intake kit but i’m wondering is irt going to cause a conflict with the mass flow sensor

  4. Tudor says:

    Why does an intake that lets your engine breathe more cause power loss at low rpm? I mean, it lets more air in, so why would it lose power?

    • TorqueCars says:

      It’s to do with air speed. A narrow pipe causes air to flow more quickly, when the intake pipe is wide, you admittedly have the ability to flow more air, but at low RPM the air is moving more slowly than it would in a narrower pipe, so you get less air into the cylinders. There is an ideal pipe width for a volume of air, and this also depends on the airs pressure and temperature. This is why you lose power low down in some cars under certain conditions with induction kits.

  5. Brian Lowery says:

    I put in an induction air filter (carbon fiber canester with hose set-up) after I installed a stainless 2.25 inch catback exhaust (oval muffler) system. The car (98 honda civic lx 1.6) hesitates when not under full throttle and at idle randomly misfires. If I go full throttle it will go to redline without shifting (yes it is an automatic) until I back-off the throttle to let it shift.
    My question is that it seems to be fuel starved and will the factory system adjust for this in short time…or… am I messing this up somewhere else..thanks

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