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If I am looking at a cold intake system that costs over a couple of hundred euro, there are some things I want to hear from the manufacturer and some things I don’t.

Cold Air Intake Systems – The Fundamentals Required for Power

There are two ways to increase engine power with a cold air intake

Reducing the vacuum at the turbo inlet on turbocharged engines and reducing the vacuum in the inlet manifold at full throttle on normally aspirated engines


Lowering intake air temperatures

Either one of these will increase engine power and both together is better than one or the other

These are only two things matter.

Intake temperatures

Pressure/vacuum inside the intake system at the turbo inlet/throttle body

Mandrel bumps, smooth piping, big bore pipes etc etc etc, only work if they address these two things.

The only way an engine can make more power with a cold air intake system is if the intake air is cooler and/or there is less vacuum before the turbo/in the inlet manifold.

Cold Air Intakes – The Marketing

A lot of BS is talked about cold air intakes and to be honest I don’t recall any manufacturer actually addressing the fundamentals of power production in their marketing

When I start to hear these terms, my bs meter starts twitching:

-Ram air

-Mandrel bending

-Filter orientation

-Restrictive factory intake

-Tight bends

-Ribs in pipework


These terms are completely irrelevant until we have analysed the standard intake system and identified if, it has any problems ie is there vacuum at the turbo inlet at any any load/rpm? and/or are the intake temps higher than ambient temps at any point? And if so by how much.

I want to hear the intake manufacturer telling what the problems are with a specific car first. And then what it has done to fix it.

The fact is, no cold air intake manufacturer I know off does this.

If the stock intake system has one of these problems, only then, do we need to start looking at the factory intake system for improvements.

If we only have an intake temperature problem with the factory intake system, “tight bends” & “90 degree turns” are not causing any problems whatsoever.

What is extremely thin on the ground are cold air intake manufacturers stating “we designed our system for this car to address X & Y problem in the stock intake system and our system now records A & B figures whereas before the figures were C & D“.

I don’t think I have ever seen a cold air intake manufacturer state where exactly their system is better than the stock system

For example they could say “with the stock intake system we measured a 2 PSI vacuum at the turbo inlet at X RPM, at X load, at X inlet temp and at X ambient temp, with our cold air intake the vacuum was reduced to 0.2 PSI of vacuum in the same conditions”

They could say this, some might say they even SHOULD say this but again,

I do not recall ever seeing these figures.

Could it be that the standard intake systems on most cars are extremely good and cannot be improved upon, at least when cars are running stock power levels, so the time and money to do this kind of measurement makes no sense?

Cold Air Intakes – Why So Popular & Why So Many Companies?

A cold air intake is quite easy to make, it has no moving parts and no electronics. It is simply pipe work with an air filter at the end.

This makes it easy to “design” which means there is a low barrier of entry to new manufacturers.

Cold air intakes are also easy to install which makes it appealing to consumers because it is a “power adder” they can install themselves without having to resort to a garage and its labour costs.

It is much more appealing to fit a 300 Euro cold air intake which you can fit yourself compared to fitting a 300 euro lightweight flywheel which requires a lot of skilled labour hours and means the vehicle will be off the road for a day

So low barrier to entry for manufacturers, popular part amongst consumers because of promised power “gains” and it is something an average consumer can install themselves without taking the car of the road.

A recipe for a big industry.

Cold Air Intakes – For Cosmetic Purposes

There are manufacturers making intake systems that cost  hundreds if not thousands of Euros.

While I don’t have any issue with the price, I do have a problem when these manufacturers say that their products cost this much for performance reasons.

The best 200 Euro cold air intake will have power gains indistinguishable from a 1000 Euro or 200 Euro cold air intake.

I would much prefer it if these manufacturers were honest and said “our intakes cost 2000 Euro because they look absolutely amazing”

Absolutely nothing wrong with dressing up the engine bay, but there is no need for a manufacturer to justify their product to me based upon highly questionable performance gains over cold air intakes costing 80% less.

The difference between the ultra expensive intake systems and the normal priced intake systems is their cosmetic appearance only.

Cold Air Intakes – Do They Work?

The newer the car the less likely a cold air intake will make any difference. Power gains will usually be tiny and not noticeable

If you are running more power than stock, if you are using a remap for example, then we are getting into an area where a cold air intake might be beneficial but the same vacuum tests need to be carried out before we start spending money for no reason.

Specifically is there a vacuum at the turbo compressor inlet? (Temperatures at the turbo inlet will be not be effected by increased power)

Cold Air Intakes – Side Benefits


The most obvious benefit to a cold air intake is the sound. The intake sound of the engine and turbo will normally be louder and if the factory diverter valve is dumping air into the cold air intake, these sounds will also be louder

Throttle Response

For reasons I can’t explain, on some cars the throttle response will be faster, I suppose it could be to do with the time it takes to mobilise the air that is sitting in the intake system pipework??

Some cars will benefit, others won’t.

Cold Air Intakes – Things To Look For

Cold air intake manufacturers are probably not going to be able to supply you with the crucial data I highlight in this article ie vacuum and temp figures, before and after. So without them, what else can we look for?

Bell Mouth

A bellmouth on the air filter of the intake can make a huge difference to the amount of air flow a filter can cope with.

AEM bellmouth test on a flow bench

Whether this will make any more power is up for debate ie does you intake need to supply any more air? Again, back to the vacuum figures.

Just because an cold air intake can flow 50% more air (a favourite “spec” of cold air intake marketing departments) does not mean it makes more power.

If the stock intake system is fine, greater air flow capability will do absolutely nothing to engine power because the engine doesn’t need any extra airflow of the standard intake system.

Air Filter

The most important factor of all. A good air filter is a must. Cheap air filters will let in dust which will slowly sand your engine from the inside.

If at all possible, choose an OEM paper type filter if you want your engine to last tens of thousands of miles. Failing that, use a high quality air filter, preferably one with may layers of filtration media. ITG for example. A filter you can see daylight through is probably not the best.

On a race car tens of thousands of miles of engine life is not a priority ie filtration is not a high priority, air flow is.

If you are happy to treat your engine like a race engine ie an engine which you might need to rebuild every twenty or thirty thousand miles, a race filter is perfect.

For me, I’ll take the handicap of a couple of hp to have an engine that lasts a couple of hundred thousand KMs+

Air Filter – Again

Some “performance” air filters have a plastic or metal mesh on the outside of the filter.

This is bad.

This cage will heat up and warm the air as it enters the intake system. Even a relatively small change in air temperature can make a big difference to acceleration and power.

But if a cold air intake manufacturer was measuring the intake temps, they would know this was a bad idea……..

Cold Air Intakes – What Difference Does Temperature Actually Make?

So your intake air temperature is 10C more than ambient, so what? That is nothing right?


Here is a video of a test I did.

Long story short, an 8.3 Celcius (14.94F) drop in temperature makes the car accelerate 0.3 seconds/7% faster from 115km/h to 140km/h (4.3 seconds vs 4.0 second). 

This is a massive difference. 

The difference is so big that I would say any manufacturer that is quoting acceleration times or power increases needs to state the ambient air temperatures alongside these performance figures.

Cold Air Intake – Modern Cars

The chances of there being a big restriction in the intake system is small.

But temperatures?

This is an area where there could be room for improvement. Most intake piping is black and the routing tends to be long giving heat, plenty of time to get into the intake air.

And yet the big marketing terms Cold Air Intake manufacturers focus on are restrictions with intake temps coming a distant second despite the fact their products are called cold air intakes.


There is a lot marketing nonsense out there in relation to cold air intakes

Very few if any manufacturers measure/quote the performance of the standard intake system (vacuum at turbo inlet, intake temps vs ambient temp) to determine if a car actually needs a better intake.

Are cold air intakes worth the money?

Depends on the car and what you expect to achieve

Do you need to spends hundreds or thousands on an intake system?

For power? Probably not.

For looks? Absolutely.

For sound? Absolutely.

A case in point

Find performance parts on ebay

This page was last modified Mar 26, 2020 @ 5:04 pm

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