Can the MAF handle boost?

[SeekB00st]

As stated, we are relocating the MAF and wanted to know if we can place it on charge piping? Can the MAF handle 17-22 psi?

[destrolock]

I may be wrong but I don't think the MAF can read compressed air.

[2001A4QUATTRO]

Some can, I dont believe ours can. I would think that the plastic would not hold pressure?

[turbo_bootin]

Yeah velocity is related to pressure... the readings will be off. If you could adjust the voltages accordingly you could do it... not sure how you'd calibrate it though.

[SeekB00st]

We'll im going to test it out.

Anyone selling a MAF let me know. I might blow this one.

[dcampana]

i think i have 2 sitting in my room. (for AWM) good luck with this/

[vaporhat]

So you are relocating the MAF after the turbo? = not a good idea. hopefully you are doing something else..

[Dynamite]

If you have a spare one floating around then give it a go and see what happens.
What I will say though is that the way our mafs work is as the intake air flows through the maf housing it flows over an element, the element is made of something unfortunately I cant remember what, which changes its resistance with temperature readily. when the air flows through the maf housing it cools the element in the same way wind chill cools you down when its windy but not that cold, this changes the resistance across the element which is read as a voltage change by the ecu. the ecu then uses this information to calculate how the velocity and hence the volume of air that is going through the maf and consequently into the engine. by moving the maf to the other side of the turbo then it will change the pressure of the air going through the maf, the ecu will not know how to deal with this (or that it is happening), and it will assume that the maf is still on the intake side of the turbo. as velocity is depended (not linearly) on both pressure and density which change as boost pressure changes, when the ecu dose its calculations to estimate the volume of air going into the engine the calculations will result in the ecu thinking that a different mass of air is going into the engine that what actually is the other issue is that the air from the turbo is heated when it is compressed so the temperature will be much higher than the out side air temp. I dont know if the ecu takes air temp into account, but if it dose then it will be a different temp from what is going through the maf after the turbo.
What i cant tell you, because I dont know what assumptions the ecu makes or the calculations it uses is how big the errors will be. I would however suggest that when you have a go and see if it will work you should keep a very close eye on the air fuel ratio and also put the maf after the intercooler.

[Thi]

any updates?

[SeekB00st]

Lets update this:

MAF has been relocated on the charge piping right behind the throttle body.
I run an apexi NEO and an AEM Tru Boost. We just need a simple reading off the maf so that we can get a tune. From there is it tunned with a wideband & egt - about to be injecting meth to keep temps down.

I'll update this thread with pictures and information - maybe even some logs.

Right now it is running perfectly fine. However, we are only allowing the turbo to control the wastegate (Much like being in limp mode). Essential is limp mode as boost levels will be the same. The N75 valve was removed along with almost all vacuum lines except those necessary to maintain idle. The boost controller is having no influence as it is not connected.

[flandog]

what is the purpose for doing this MAF relocate?

[MLFHNTR]

what is the purpose for doing this MAF relocate?

ditto?

[SeekB00st]

ditto?

Also, there are a lot of components that were removed. This allows me to directly consult the problem.
There is so much bullshit involved within VAGCOM's 1.8t design that perpetuating the problem can become a lengthened dilemma.

[SeekB00st]

what is the purpose for doing this MAF relocate?

When it comes to repercussions a lot is incurred; this is also relevant to the pros, as there honestly, there is not much.
When it comes to tuning however, there is a lot involved in doing this and a blow through design utilizing the math directly prior to the throttle body.
Most people purchase tunes from companies, I have not and never will purchase a tune. Where is the fun in that?

We are tuning with a K series turbo right now - financial factors have not allowed for the Gt30 to go in. Not to mention that we are having way to much fun with our egt sensor ( I spray meth to keep the temps down).

[dowsett6]

just an easier time at making an intake setup, and to be able to run a bov easier

[Scotty@Advanced]

The volume of air entering the turbo is greater than the volume of air exiting the turbo. However the mass of the air into the turbo is the same as the mass of the air exiting the turbo, which mean that the turbo is ingesting more air (flow) than it's outputting, thus more mass per given time (flow) at the inlet than at the outlet, however the air at the outlet is denser and at a higher temperature.

Since air mass entering turbo = air mass exiting turbo the MAF will be measuring the SAME Air density if it is mounted in the inlet or outlet of the turbo... HOWEVER a temperature adjustment needs to be done because the air exiting the turbo is hotter due to the inefficiencies of the turbocharger, so you need to put it in a cool spot.

To test this install a MAF on both inlet and outlet and measure the voltages, they will be very close to each other.

The reason it is a bad idea to put it in the discharge side of the turbo is that the turbo spews microscopic drops of oil into the intake stream and these will collect on the MAF sensor making it read incorrectly, so it will have to be cleaned or replaced frequently.

More things to consider:

Supply side MAFS don't see large temperatures, so by putting it in the discharge side you may be operating it past it's design limitations.
The plastic tube may burst.
The seals on the MAF insert may not hold up to positive pressure.

However the largest problem with mounting the MAF after the turbo is the small fog oil that leaks past the turbo, overtime this will coat the MAF resistor and give false readings. The older thin wire MAF's burned most of this oil/dirt crap off at shutdown, however the newer thin film MAF sensor don't have that capability so they will periodically need to be cleaned or replaced.

[SeekB00st]

The volume of air entering the turbo is greater than the volume of air exiting the turbo. However the mass of the air into the turbo is the same as the mass of the air exiting the turbo, which mean that the turbo is ingesting more air (flow) than it's outputting, thus more mass per given time (flow) at the inlet than at the outlet, however the air at the outlet is denser and at a higher temperature.

Since air mass entering turbo = air mass exiting turbo the MAF will be measuring the SAME Air density if it is mounted in the inlet or outlet of the turbo... HOWEVER a temperature adjustment needs to be done because the air exiting the turbo is hotter due to the inefficiencies of the turbocharger, so you need to put it in a cool spot.

To test this install a MAF on both inlet and outlet and measure the voltages, they will be very close to each other.

The reason it is a bad idea to put it in the discharge side of the turbo is that the turbo spews microscopic drops of oil into the intake stream and these will collect on the MAF sensor making it read incorrectly, so it will have to be cleaned or replaced frequently.

More things to consider:

Supply side MAFS don't see large temperatures, so by putting it in the discharge side you may be operating it past it's design limitations.
The plastic tube may burst.
The seals on the MAF insert may not hold up to positive pressure.

















However the largest problem with mounting the MAF after the turbo is the small fog oil that leaks past the turbo, overtime this will coat the MAF resistor and give false readings. The older thin wire MAF's burned most of this oil/dirt crap off at shutdown, however the newer thin film MAF sensor don't have that capability so they will periodically need to be cleaned or replaced.

Well put.
The oil that you refer to is going to be my main problem.
However, the MAF is only temporarily there. Soon enough, we will not need the MAF as it will be fully tunned.
The hardware/software that I am utilizing fools the ECU anyways, telling it exactly what the readings are.

Soon enough there will be no necessity for the MAF once the tune is written.

Pictures will be up shortly.

[ZacharyWS]

Bosch Maf's deff dont like boost. that being said. I boost test my car from the air filter (not turbo inlet) and i have put 23PSI through a Maf housing with no problems..... the issue shouldnt be with the housing cracking. but will be with getting the sensor to read correctly.

[ZacharyWS]

iirc, it calculates airflow through temp and speed? which results in airmass in g/sec. putting it under boost pre intercooler would be disasterous. but even post boost may put the temp out of spec and the MAF readings would be off.

Dont quote me on any of this, its all theory.