Mitsubishi Karman Vortex Air Flow Meters: How they really work

[Guest]

To be honest, with pod filters it can be a bit hit and miss, though mostly miss. Most don't work, though occasionally there is someone who doesn't have any issues whatsoever.

I think a large contributing factor is the pod adaptor, with the correct one you probably get a much better air flow. After looking at a few I get the feeling that most just don't have a wide enough opening which interferes with the air flow into the MAF.

It would be interesting to see what % of airflow frequency difference over standard there is with different pods AND different pod adaptors.

I think my pod could be better due to it being enclosed. Hopefully I can get some testing done this weekend. Definately keen to see if there is any performance gains and dodgey AFR's ...
Glad this thread popped up, some interesting reading here ...

 

[SiliconAngel]

Glad this thread popped up, some interesting reading here ...

Agreed. Thanks Kenneth! :bigsmile:

Interestingly I learnt quite a lot about our intake system from your original post, but I didn't know it was written by you until tonight! Naughty Carsten

 

[Guest]

...........I didn't know it was written by you until tonight! Naughty Carsten

Ban him!! Ban Him!!

For what it's work I have a HKS Super Power flow thingy - Simply because the Pro-Shop IIda Throttle body pipe doesn't fit with the standard airbox in place. Not noticed a power difference but my MPG is hideous, even my VR-4 standards!

 

[Guest]

The wrong filter type will cause horrendous fuel economy. Swap it out for teh correct style filter and expect a fuel economy improvement

 

[Guest]

The wrong filter type will cause horrendous fuel economy. Swap it out for teh correct style filter and expect a fuel economy improvement

Ideed. However, as mentioned above I can't do that right now. I knew it would screw the MAF up when I fitted it, but beggars can't be choosers - Anyway, once I get a Map ECU it'll go in the bin along with the MAF and the rest of the Turbo inlet piping!

 

[Guest]

bump

what is the diameter of the afm on a vr4

 

[jaygore]

hey guys i get pretty terrible economy and this week i drove really easy and made sure i didnt hit boost and im only going to make about 320 i recon out of this tank...

should i get rid of the ARC airbox and go back to the standard air filter and snorkel?

 

[godzilla]

should i get rid of the ARC airbox and go back to the standard air filter and snorkel?

100% Yes.

 

[jaygore]

ok so i bought the car like this and i have the evo bonnet with a direct air feed from the bonnet... still need to get rid of it?

 

[Kenneth]

With an ARC airbox you should be ok with the MAF frequency counts.

Unless you have the standard airbox lying around to try, it would probably be better to try replacing other things such as the Oxygen sensor.

The MAF is only one sensor which, if not working correctly, can cause horribly fuel economy.

 

[jaygore]

yea i have the o2 sensor sitting there hahaha just too lazy to do it lol, but i sreally should as im spending way too much on petrol at the moment, if this isnt it then i will have to source the stock snorkle and air filter

 

[Guest]

Dave, surely isolating (through the use of piping and a cold air box) the air being drawn in through the filter is beneficial as it will be colder? Just sticking a pod filter on before the MAF sensor means the air you're sucking in will be quite hot to start with, right?

Not to drag up a dead post but cold air will not affect a boosted vehicle whether it be supercharged or turbocharged. As the air is sucked into the compressor the air is compressed(lol go figure) thus increasing the temperature. Thats why companies don't generally sell cold air kits for turbo vehicles as it doesn't matter. Now after the air has been compressed is a good time to cool it as each 10 degree drop in temperature increase 1hp. (dunno KW)
Thats why a bigger intercooler will net better numbers. Although too much of a good thing is bad as well. A massive front mount on a stock turbo will generally net lost compression of the air as it will expand and the molecules will be seperated. resulting in less dense air. meaning less oxygen to burn with the same amount of fuel.
just my 2 pennies...

 

[frozen]

John id like to disagree - as soon as my engine bay warms up and hotter air is being sucked in, you can feel a very big difference in power... also at night i can light up all 4 quite easily, during the day its just a chirp.. pulls ALOT harder at night. If the air is already more dense and cooler, the turbo compressing it will still warm it up, but not as much as if the air was already hot..

 

[Gary31]

Was going to type a large technical post but feel lazy.

the cooler the air going into a compressor the more efficient the compression process.
that is the temperature difference between outlet and inlet will be smaller with lower inlet temperatures.

This is the simplest way i can explain this without getting one of my old thermodynamics books out, as its been a while since i used any thermodynamics.

 

[Guest]

Just passing along what I was taught obviously it was wrong. Just curious though wouldn't the inlet vice the outlet temperatures be more drastic with lower inlet temperatures. I went and read a bit more and the denser the air just makes it easier to compress but it will still heat up the charge the same just quicker.
Kinda makes me sad I was taught that because I had this idea to make a "box" where my maf attaches to my intake filter. It would be more of a piece of sheet metal welded to keep the engine air out.

------------------------------------------------- ^about here and have a hole that the maf sensor would go through.

 

[SiliconAngel]

Sorry John, your assumption ignores some pretty fundamental laws of physics, specifically (as Gary said) thermodynamics. Basically if you have something at a given temperature and you attempt to cool it down with a specific method, and then you increase the thing's temperature by say 2°C and then use the same method to cool it down, the resultant temperature will be exactly 2°C higher than the first time. If you wish to cool it down further you need to change your cooling method.

This means if ambient (basically air) temperatures increase from 10°C on a cool night to 40°C on a hot summer's day, the temperature of the intake charge ending up in your cylinders will be 30°C hotter, which means less dense, thus less oxygen, thus less power. This is the major downfall of turbo cars; their performance is hugely dependant on ambient conditions, so while a car might blitz the NA opposition on a cool day at sea level, on a hot day the same car against the same competitors may be smoked by the NA cars which will suffer a relatively minor performance difference.

There are some really great books out there (and even some online) explaining turbo theory and how to get the most out of a turbo application, including correct intercooler selection (bigger is definitely not necessarily better), ducting and airflow etc. It would behove you (and indeed anyone interested in combustion engine performance) to spend a bit of time reading what real experts have to say, not just mechanics, performance shop parts suppliers and heresay on internet chat forums

 

[frozen]

NA cars still get a pretty big difference from hot to cold, but yeah ive definately noticed the VR4 has a much bigger difference (my previous car, first car, was a NA lancer lol)