SPARKY WRX

Hi,

I have a hks induction kit with the mushroom filter, its looking a bit tatty so I thought I would replace it with a larger cone type filter.

Would it be possible to measure the air flow for both filters by reading the signal voltage from the MAF sensor, I was thinking about hooking up a volt meter to the MAF.

Would I be able to see if there was a difference if air flow between the two types of filter from the voltage readings.

Do the voltage readings go up or down in accordance with the amount of air flow.

Has anyone tried to compare filters in this way.

john banks

You'd need datalogging with RPM and boost for it to make any sense.

Very approximately the airflow is proportional to the square of the voltage minus an offset with a lot of airflow meters.

SPARKY WRX

Im not particulary interested in what the air flow is, I just want to figure out which has the better air flow.

Is it not just a case of the higher the voltage reading, the higher the air flow.

Cheers

john banks

Definitely not. Airflow patterns varies between filters/pipes and alters the calibration.

SPARKY WRX

Ok thanks John, What could I expect to see If I had extra airflow

would I see a bit more boost? leaner fueling etc

My HKS looks a bit small and restrictive compared to some I have seen.

I did notice a rise in boost since fitting my HKS

john banks

If the sensor was reading artificially low because of the airflow pattern it would be leaner. If the airflow pattern was the same between two filters then you would not expect a significant difference in AFR unless the map had a steep gradient in that area.

In short you cannot compare filters in the manner you suggest, because the act of changing the filter changes the calibration of the meter.

SPARKY WRX

Ok thanks

While we are on the subject of MAF, I read a thread a while ago about replacing the MAF sensor which is a cheaper alternative than replacing the whole unit which is rarther expensive for my 94 wrx

I carnt remember or find the thread it was on, I have had rich fueling since I had the car over a year now and carnt seam to get to the bottom of it, I have already changed my lambda with no change. The next thing was the MAF but I wasnt going to pay all that money for something on the off chance that it might be busted.

Do you know where I could get the sensor part from, I think it was about 78 quid or something

Cheers

mark

marks

Would It be possible to take air pressure readings from before and after the filters using a home made device to see which gives the best flow.

Just an idea.

john banks

Yes put two water manometers in the car