Does Your Cold Air Intake Do Anything? Find out for Free.
May 31, 2025All cold air intake manufacturers claim their product increases power but do they? The good news is you can compare the performance of your cold air intake versus the stock intake without expensive tools and with some basic knowledge of how to work a spreadsheet.
Where to Start – Cold Air Intake Testing
We need data. Luckily modern cars give us all the data we need via the OBD port and the car manufacturers don’t charge us for it. Yet…
Method
To measure the difference an intake met we need to measure three things.
- Air mass entering the engine (MAF)
- Manifold absolute pressure (MAP)
- And finally RPM.
Tools
We can measure these three variables with a OBD II Bluetooth Dongle (vGate makes excellent products), an Android device and an OBD scanner app like Car Scanner.
Logging
Car Scanner will log the data from these three channels (MAF, MAP, RPM) against time and it allows us to export the data to a .csv file. Using Excel or similar spreadsheet program we can analyse the data to see how efficiently the engine is breathing before and after the cold air intake (CAI).
How
Ambient air temps and humidity should be the same or very similar for all datalogs.
We need to log data before we fit our performance intake and after.
To log data wait until the engine is up to normal temperature and do some pulls from low/mid RPM to high RPM and at full throttle. The more data we get the better. Three or four runs should be enough. Do this with the stock intake and then repeat the process with the performance intake.
The higher the MAP, the more we push the throttle, the more likely we are to see a difference. If the differences are large, we can repeat the process at lower throttle openings/less boost if we want to see at what point the CAI is starting to have an effect.
What we are looking for.
A performance intake is supposed to let the engine breath better and/or easier.
What we are looking for in the data is for a given RPM and MAP, a higher MAF (mass air flow) number with the performance intake. This indicates intake air is colder.
And for full throttle pulls, we want to see a higher peak MAP number. This will mean less vacuum in the intake manifold, which means more air in the intake manifold. The higher MAP number should also be accompanied by a higher MAF number. Ideally we want no vacuum in the intake manifold at peak power.
The Reality – Is CAI Testing Worth It?
All this sounds great in theory. It gives us a solid foundation from which to start testing the effectiveness of our CAI. However, the reality is we are probably not going to see much difference, if any, in the numbers. Factory intake systems are generally very good. The only time I’d expect to see a big difference in the MAF numbers is if the engine is producing a lot more power than factory (20% plus). If the engine is being asked to flow a lot more air than it was designed for, logically we are going to find restrictions.
And one last thing.
If the engine is making a lot more power than stock, it’s possible the we won’t see any improvement with a CAI even if the stock intake is a restriction. If we have a bigger restriction elsewhere, this is going to stop the cold air intake realising it’s potential. A restrictive exhaust and/or intercooler could be a bigger restriction than our intake for example.
