Why do all the CSL like carbon boxes ditch the MAF ?

[Rombbb]

If you go for a box with a MAF or go for a box with no MAF, either way your relying on some small company to tune your car?

Be interested to see what you come up with

Idea is to keep the MAF in the exact same position and housing diameter so to avoid any tuning at all.

Very interesting and knowledgeable answer from Pokebridges from Severn Tuning on the Alpha N and sensitivity of MAF's in sister thread on zpost : https://www.zpost.com/forums/showthread.php?t=1786101

He is one of the few that tunes the z4m ECU instead of the easy Alpha N 'fix' (but still I prefer no tuning at all, not doing it for the HP's)

[mmm-five]

If you go for a box with a MAF or go for a box with no MAF, either way your relying on some small company to tune your car?

Be interested to see what you come up with

Idea is to keep the MAF in the exact same position and housing diameter so to avoid any tuning at all.

Very interesting and knowledgeable answer from Pokebridges from Severn Tuning on the Alpha N and sensitivity of MAF's in sister thread on zpost : https://www.zpost.com/forums/showthread.php?t=1786101

He is one of the few that tunes the z4m ECU instead of the easy Alpha N 'fix' (but still I prefer no tuning at all, not doing it for the HP's)

If you're doing it purely for the noise/looks, then won't you risk EML lights and running issues with different air pressure/volume coming in than the stock ECU fuel/air map is expecting?

So you may still need to 'tune' the ECU to get back your 'normal' performance.

[RedUn]

If you go for a box with a MAF or go for a box with no MAF, either way your relying on some small company to tune your car?

Be interested to see what you come up with

Idea is to keep the MAF in the exact same position and housing diameter so to avoid any tuning at all.

Very interesting and knowledgeable answer from Pokebridges from Severn Tuning on the Alpha N and sensitivity of MAF's in sister thread on zpost : https://www.zpost.com/forums/showthread.php?t=1786101

He is one of the few that tunes the z4m ECU instead of the easy Alpha N 'fix' (but still I prefer no tuning at all, not doing it for the HP's)

If you're doing it purely for the noise/looks, then won't you risk EML lights and running issues with different air pressure/volume coming in than the stock ECU fuel/air map is expecting?

So you may still need to 'tune' the ECU to get back your 'normal' performance.

I was thinking the exact same thing, unless the carbon box is the exact same size as the oem one and flows identically then it'll need a tune. Changing before the maf the maf can measure any differences but after it's not going to know is it?

Interesting response on zpost, what's the bypass valve diameter on a turbo car got to do with the intake on a naturally aspirated car? An airline can deliver 150psi but you wouldn't want to trade your mouth for one when going for a run would you?

Secondly MAFs are restrictive by design, have a look through one? Most High rpm high bhp per litre engines have no MAFs.

Fully get your view though, I'm the same I'd prefer to keep the mapping oem with the oem sensors etc hence running an eventuri whilst I work out what I'm doing airbox and cam wise

[Rombbb]

Idea is to keep the MAF in the exact same position and housing diameter so to avoid any tuning at all.

Very interesting and knowledgeable answer from Pokebridges from Severn Tuning on the Alpha N and sensitivity of MAF's in sister thread on zpost : https://www.zpost.com/forums/showthread.php?t=1786101

He is one of the few that tunes the z4m ECU instead of the easy Alpha N 'fix' (but still I prefer no tuning at all, not doing it for the HP's)

If you're doing it purely for the noise/looks, then won't you risk EML lights and running issues with different air pressure/volume coming in than the stock ECU fuel/air map is expecting?

So you may still need to 'tune' the ECU to get back your 'normal' performance.

I was thinking the exact same thing, unless the carbon box is the exact same size as the oem one and flows identically then it'll need a tune. Changing before the maf the maf can measure any differences but after it's not going to know is it?

Interesting response on zpost, what's the bypass valve diameter on a turbo car got to do with the intake on a naturally aspirated car? An airline can deliver 150psi but you wouldn't want to trade your mouth for one when going for a run would you?

Secondly MAFs are restrictive by design, have a look through one? Most High rpm high bhp per litre engines have no MAFs.

Fully get your view though, I'm the same I'd prefer to keep the mapping oem with the oem sensors etc hence running an eventuri whilst I work out what I'm doing airbox and cam wise

The idea was to keep it as similar as possible, but you're right, the shape and size of the box is itself a factor, which I conveniently disregarded a bit, so even with the same MAF housing size and position as stock there will be pressure difference between the boxes, influencing the mixture.

On the turbo analogy, I guess he meant that two 1 inch ports can allow for a lot of air / pressure, to emphasize that a 3,5 inch MAF housing isn't all that restrictive. But maybe it's apples and oranges. Another forum member heard from JC Racing that a factory tuned GT car got like 400bhp with stock intake, further indicating that it's pretty capable.

Personally (as relative) layman I'd say that the stock design also seems more optimal in that air comes in at the middle, allowing the first and last cilinders to draw an equal amount of air. With the CSL box the air comes in from the front which seems to disadvantage the cilinders at the back if most air gets to the first ones first. But that just me hypothesizing. BMW did put that design on their top model so it must be good for something. Also trust the OEM setup to be more watertight in a thunderstorm compared to a cone with a scoop directed to it. Water can act in unexpected ways.

Eventuri may be the best option after all. Am in contact with that German E-bay seller who does custom carbon. Depending on price may go for a box with as close as OEM dimensions as possible. Maybe combined with the Eventuri. Really dig that CSL intake sound

[pokeybritches]

Interesting response on zpost, what's the bypass valve diameter on a turbo car got to do with the intake on a naturally aspirated car? An airline can deliver 150psi but you wouldn't want to trade your mouth for one when going for a run would you?

Not sure what point you are making about an airline delivering 150 psi. I was providing a related example of how little the 3.5 inch housing restricts airflow- a 911 Turbo can move 700 horsepower worth of air with 1/6 the piping. This is mass flow, not just line pressure. By the way, I also use a 3.5” MAF housing to make the 700 horsepower, and the MAF sensor setup is draw through (non-pressurized side of the turbo compressor).

On the turbo analogy, I guess he meant that two 1 inch ports can allow for a lot of air / pressure, to emphasize that a 3,5 inch MAF housing isn't all that restrictive.

Correct.

Secondly MAFs are restrictive by design, have a look through one? Most High rpm high bhp per litre engines have no MAFs.

Any restriction through the MAF housing is minimal. I won’t say it’s non-existent, but it is so miniscule that differences in temperature and pressure will affect an alpha-n tune to a greater degree than the MAF will restrict horsepower. I have given multiple examples of how it is not a serious restriction, including cars that make 50 bhp more than the CSL using the stock airbox, Supersprint V1 stepped headers, Schrick cams, and a MAF-based tune. Z4Ms using MAF-based tunes can have a similar specific output to the 991.2 GT3 RS, even with 1000 less rpm to work with and an engine that’s 15 years older, built to a different price point, and still compromised for street use (other than no cats in the exhaust). Now let me ask a few of questions:
- How big are the S54’s intake runners in comparison to the MAF sensor housing?
- How many intake valves are open simultaneously, drawing air from the reservoir in the intake manifold?
- When air moves to fill a vacuum, such as the vacuum created when an intake valve opens and the piston moves down the cylinder, how fast do you think air moves to fill that void?

He is one of the few that tunes the z4m ECU instead of the easy Alpha N 'fix' (but still I prefer no tuning at all, not doing it for the HP's)

Tuning does provide other benefits besides increased horsepower, including mapping accelerator pedal sensitivity. You can have normal mode behave like sport mode, and turn sport mode into a sport plus mode. Or, you can go the opposite direction and make the throttle less touchy. SAP delete, rear O2 sensor delete, cat delete, etc. are all possibilities.

[RedUn]

Interesting response on zpost, what's the bypass valve diameter on a turbo car got to do with the intake on a naturally aspirated car? An airline can deliver 150psi but you wouldn't want to trade your mouth for one when going for a run would you?

Not sure what point you are making about an airline delivering 150 psi. I was providing a related example of how little the 3.5 inch housing restricts airflow- a 911 Turbo can move 700 horsepower worth of air with 1/6 the piping. This is mass flow, not just line pressure. By the way, I also use a 3.5” MAF housing to make the 700 horsepower, and the MAF sensor setup is draw through (non-pressurized side of the turbo compressor).

On the turbo analogy, I guess he meant that two 1 inch ports can allow for a lot of air / pressure, to emphasize that a 3,5 inch MAF housing isn't all that restrictive.

Correct.

Secondly MAFs are restrictive by design, have a look through one? Most High rpm high bhp per litre engines have no MAFs.

Any restriction through the MAF housing is minimal. I won’t say it’s non-existent, but it is so miniscule that differences in temperature and pressure will affect an alpha-n tune to a greater degree than the MAF will restrict horsepower. I have given multiple examples of how it is not a serious restriction, including cars that make 50 bhp more than the CSL using the stock airbox, Supersprint V1 stepped headers, Schrick cams, and a MAF-based tune. Z4Ms using MAF-based tunes can have a similar specific output to the 991.2 GT3 RS, even with 1000 less rpm to work with and an engine that’s 15 years older, built to a different price point, and still compromised for street use (other than no cats in the exhaust). Now let me ask a few of questions:
- How big are the S54’s intake runners in comparison to the MAF sensor housing?
- How many intake valves are open simultaneously, drawing air from the reservoir in the intake manifold?
- When air moves to fill a vacuum, such as the vacuum created when an intake valve opens and the piston moves down the cylinder, how fast do you think air moves to fill that void?

He is one of the few that tunes the z4m ECU instead of the easy Alpha N 'fix' (but still I prefer no tuning at all, not doing it for the HP's)

Tuning does provide other benefits besides increased horsepower, including mapping accelerator pedal sensitivity. You can have normal mode behave like sport mode, and turn sport mode into a sport plus mode. Or, you can go the opposite direction and make the throttle less touchy. SAP delete, rear O2 sensor delete, cat delete, etc. are all possibilities.

I was just making the suggestion that when you start involving pressure you can flow more but that doesn't mean it's not restrictive.

I wasn't saying the MAF is holding back the s54 either, I was just pointing out that by design, something like 30% of the surface area is plastic...hence a lot of high bhp/litre NA cars don't have them.

Sure you can tune with them, with cams, more compression etc etc you can still get good numbers it's just at some point (I'm not a mathematician) you'll need to open up the intake side more

[Beedub]

nothing wrong with a good speed density tune at all....

Used regularly in the High HP tuning world....