Developing a MAF sensor housing for custom air intakes

[Rival Autosport]

You should have made the diameter of the tube where the MAF housing falls into larger, this will work, but it will be too restrictive for any real HP gains to make it's way to the throttle body no?

The Mirage untuned already has issues with excessive airflow to a degree. Increasing air velocity is the best way to do things before making the intake plenum larger. Tuning will be required for larger plenums.

[chris_top_her]

The Mirage untuned already has issues with excessive airflow to a degree. Increasing air velocity is the best way to do things before making the intake plenum larger. Tuning will be required for larger plenums.

This.. engine has to be tuned to flow more air to make more HP/TQ. Simply increasing the volume of (uncompressed) air does not. An easy measure of this is g/s read with a ob2 unit/app

[Rival Autosport]

This.. engine has to be tuned to flow more air to make more HP/TQ. Simply increasing the volume of (uncompressed) air does not. An easy measure of this is g/s read with a ob2 unit/app

This is basically what I said. Hence why the air box was removed in favour of straight through piping with the same inner diametre. Increasing the air velocity while retaining the same volume. I used OBDII datalogging to monitor the effects of the intake and compare to the factory air box datalog.

[Messy Mitsu]

Isn't the ECU self learning? Therefore if you make more air than the ECU should adjust the fuel map to balance it? Well it may throw codes, but this is how it should work.

[91cavgt]

You should have made the diameter of the tube where the MAF housing falls into larger, this will work, but it will be too restrictive for any real HP gains to make it's way to the throttle body no?

If you were to do this without a tune the engine would run EXTREMELY poorly. The diameter of the tube effects the air flow speed through the tube. This in turn has a direct effect on what the MAF sensor reads. If you increase the diameter of the tube, the air flow at a given rpm will decrease. This will give a false reading by the MAF sensor which will then throw your air/fuel ratios off and make the car run REALLY bad. Keep this in mind too. A 2" diameter intake pipe can support a decent amount of horsepower. But without a tune, the motor would not be able to out flow a 2" diameter pipe. So unless you are wanting to increase the compression, add a radical cam, increase the engine RPM limit, and add a BUNCH of other mods, a pipe larger than 2" is a waste as you will not gain anything.

This is a 1.2L motor we are dealing with here. At it's rev limit of 6500 rpm, it flows approximately the same amount of air that a 2.4L motor does at only 3250 rpm.

[91cavgt]

Not to mention that if you went with a larger MAF sensor body, and tuned the car, if you did not replace the throttle body with a larger one then you will get absolutely ZERO performance gains. Think of the entire intake system on a car as a straw. If the bottle neck is say the intake valves then replacing the throttle body of the MAF sensor with a larger one will have no performance gains. If the bottle neck is the throttle body then replacing the MAF sensor or going with a more radical cam will do you no good.


With a stock 74 hp, a 2" MAF sensor housing is not going to be a bottleneck.

[Daox]

91cavgt and the others are right. We can't go messing with the diameter of the MAF housing. It is designed for its size. If we alter the diameter, we alter how the engine is tuned and we don't want to go there. If we want to alter a tune, we want to do it electronically.

Also, as stated a 2" diameter intake pipe is really not even close to a restriction for a 1.2L engine intake. The pressure loss on a 12" long by 2" diameter at 110 CFM (roughly what the 1.2L flows at 6500 rpm) is only 0.04 psi. Atmospheric pressure is 14.7 psi. So, you loose 0.04 of that 14.7 psi pushing air into your engine. This equates to a .2% loss in power. And, that is only at 6500 rpm and wide open throttle. At anything less than that, the losses are even less.

The real benefit of an aftermarket intake is extending that 2" pipe as far as we can. This will help increase torque across the power band, but it'll probably be most visible in the low and mid range.

Thanks to you guys who PMed me with interest in testing. I'm thinking about how I want to move forward with things and what would be required to do the testing.

[Kiwi]

We need to figure out the piping and mounts. Most CAI piping connections and filters range from 2 1/2" thru 3"

Here is speedlabs design without a Maf housing

Or go super charger

[btavish]

K&n makes a bunch of different 2"id cone style filters, and you could get the couplers, pipes ect from siliconeintakes.com. Then fab a bracket from the intake to the threaded bolt hole in the valve cover. You can even make a plastic air duct to route grill area air to the filter. Atleast thats my plan anyway.

[Daox]

I've been doing some reading up on air filters, and at this point I prefer AEM Dryflow filters. They've been tested to have excellent filtering, they are easily washable and reusable. They also don't need to be oiled, so you don't have to worry about gunking up your MAF sensor.

K&N has gotten bad press in the past few years saying they have poorer filtering than the OEM filters, and over oiling them can cause MAF sensor issues.