Larger MAF on an S50 3.2

[Lee]

Im sure I have read somewhere that a MAF from a different BMW can be used with the MC, say a 540

can anyone confirm?

Thanks

[exdos]

Lee,

Are you trying to obtain a MAF which has a larger internal bore than on the MC in order to make the air intake as unrestrictive as possible? If my guess is correct, then would the MAF for a 850CSi be suitable? See:
http://www.realoem.com/bmw/showparts.do?model=EG91&mospid=47329&btnr=13_0355&hg=13&fg=15&hl=3

If you just put a different MAF in a MC would you need to have the ECU re-mapped to account for the different bore inside a larger MAF?


If you are going along the custom CF air box and Alpha-N route, is a MAF necessary?

[Lee]

Lee,

Are you trying to obtain a MAF which has a larger internal bore than on the MC in order to make the air intake as unrestrictive as possible? If my guess is correct, then would the MAF for a 850CSi be suitable? See:
http://www.realoem.com/bmw/showparts.do?model=EG91&mospid=47329&btnr=13_0355&hg=13&fg=15&hl=3

If you just put a different MAF in a MC would you need to have the ECU re-mapped to account for the different bore inside a larger MAF?


If you are going along the custom CF air box and Alpha-N route, is a MAF necessary?

Thanks, this could definitely be an option.

I am not going to go down the Alphan N route as I still want to retain the diveablility of the car in traffic etc

apparently after removing the MAF the stock ecu will revert to a standard map which is basically alpha N, this can be modified/mapped somewhat to the drivers requirements.

however this will result in lumpy erratic idling and make the car harder to drive in every day conditions.

I have heard that a larger BMW MAF can be used along with a re map.

so this would suit me for the carbon airbox, cam route :)

If I had an S54 I would definitely be sourcing a oem CSL airbox and getting it to work with the car,

can you imagine how extreme a M Coupe csl would be :?: :twisted:

[exdos]

Lee,

I've just been looking on the realoem website at the parts for the M3 CSL. There doesn't appear to be a MAF in the system, only an air temperature sensor.

Since the air intake at engine speeds below 3000rpm utilises a small(ish) air intake pipe and that the large butterfly flap opening the huge aperture into the CF airbox is only actuated at 3000rpm and above, then I have deduced (rightly or wrongly???) that the M3 must run some kind of 2-phase ECU map, where fuelling at engine speeds below 3000rpm are related to air entering via the smaller bore pipe and where the air temperature is used to calculate the volume based on air density values, and at speeds above 3000rpm the fuelling is related to throttle angle (alpha) and Engine rpm (N). Is this correct (Where's M3 Compact ? - he's sure to know :wink:)

Such a system would get around the problems of running a permanent Alpha-N system on a road car.

If you were to put a CSL air box onto a S54 MC I'd give some very careful thought about the locations of the air inlets before you proceed. You might be better fitting a Hamann front spoiler, which could be appropriately modified to ensure that you increase the ram-pressure at the front in line with the CFD illustration:
http://www.z3mcoupe.com/photopost/data//500/53front_splitter.jpg

This is a Hamann Front spoiler:
http://www.fantasycars.com/gallery/Cars/BMW/2000%20Hamann%20M%20Coupe/hamannmcoupe_2.jpg

[exdos]

Lee,

I don't know if you could use this part as a 3D "template" to get a CF airbox made up for your MC? It's cheap at the present price.
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=160004549568

It would give a CF fabricator the precise positions of the throttle's etc to work from.

[Lee]

Lee,

I don't know if you could use this part as a 3D "template" to get a CF airbox made up for your MC? It's cheap at the present price.
http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&item=160004549568

It would give a CF fabricator the precise positions of the throttle's etc to work from.

Thanks I will contact him!

he is a member of e36coupe.com!

[exdos]

Thanks I will contact him!

he is a member of e36coupe.com!

I see you've been following and participating on the thread at:
http://www.e36coupe.com/forum/viewtopic.php?t=75245&postdays=0&postorder=asc&highlight=airbox&start=0

Please read the third posting about the MC. I reassert that the MC's air intake system, particularly on the S54 MC, is nearly as good as you can get without spending a fortune to impove it.

[wfarrell]

The BMW M3 CSL does not feature a Mass Air Flow (MAF) sensor.

Optimum air-fuel combustion occurs at stoichiometric air/fuel ratio (AFR) conditions -- in the case of gasoline/petrol this is approx 14.3 to 1 MASS fraction (i.e. 14.3 grams of air for every gram of fuel).

So, for accurate AFR control the engine's ECU needs to calculate the mass of air entering the cylinder, then deliver the appropriate fuel mass to give the desired AFR (typically from 14.3 at part load, to 11:1 at full load)

The ECU will rely on a mixture of external sensor signals and internal software calculations to deliver the correct AFR.

In the CSL's case I understand that to get the minimum intake manifold pressure losses, BMW specified an ECU that required a Manifold Absolute Pressure & Temperature (T-MAP) and Throttle Position Sensor (TPS) signals. This allowed BMW to do away with the restrictive MAF sensor.

Using an ECU air strategy based upon the Ideal Gas Law (PV=MRT), the CSL ECU calculates air mass (M) based upon the following factors:
*Intake Pressure (P) [typically augmemted by a throttle-position based intake pressure model]
*Engine Speed (affects air density within the manifold - Mass/Vol)
*Air Temperature (affects air density within the manifold - T)
*R = gas constant

This is nothing new -- these MAP based systems were pioneered by both the French and Japanese manufacturers as lower cost alternatives to the costly MAF sensor systems -- in fact manifold pressure sensor-based systems are particulary accurate in full load (max power) conditions, whereas MAF sensors are susceptable to intake manfold resonance (particulary at low RPM).

Sorry if all of the above is a bit technical -- i was just trying to out-Exdos Exdos :wink:

- Will -

[Lee]

The BMW M3 CSL does not feature a Mass Air Flow (MAF) sensor.

Optimum air-fuel combustion occurs at stoichiometric air/fuel ratio (AFR) conditions -- in the case of gasoline/petrol this is approx 14.3 to 1 MASS fraction (i.e. 14.3 grams of air for every gram of fuel).

So, for accurate AFR control the engine's ECU needs to calculate the mass of air entering the cylinder, then deliver the appropriate fuel mass to give the desired AFR (typically from 14.3 at part load, to 11:1 at full load)

The ECU will rely on a mixture of external sensor signals and internal software calculations to deliver the correct AFR.

In the CSL's case I understand that to get the minimum intake manifold pressure losses, BMW specified an ECU that required a Manifold Absolute Pressure & Temperature (T-MAP) and Throttle Position Sensor (TPS) signals. This allowed BMW to do away with the restrictive MAF sensor.

Using an ECU air strategy based upon the Ideal Gas Law (PV=MRT), the CSL ECU calculates air mass (M) based upon the following factors:
*Intake Pressure (P) [typically augmemted by a throttle-position based intake pressure model]
*Engine Speed (affects air density within the manifold - Mass/Vol)
*Air Temperature (affects air density within the manifold - T)
*R = gas constant

This is nothing new -- these MAP based systems were pioneered by both the French and Japanese manufacturers as lower cost alternatives to the costly MAF sensor systems -- in fact manifold pressure sensor-based systems are particulary accurate in full load (max power) conditions, whereas MAF sensors are susceptable to intake manfold resonance (particulary at low RPM).

Sorry if all of the above is a bit technical -- i was just trying to out-Exdos Exdos :wink:

- Will -

Thanks Will, can never have too much info :!:

[exdos]

Sorry if all of the above is a bit technical -- i was just trying to out-Exdos Exdos :wink:

- Will -

:lol: :lol:

Will,

I'm always happy to learn from anyone who knows more than me. What I don't know I always try to speculate from first principles and it seems that my speculation isn't too far out. Thanks for your info.

[wfarrell]

...hey guys happy to chip in my two pence, then together we'll have a pound ! :D