FREE Air-Intake Mod: Full Details on Page 6 of this thread

[exdos]

I've noticed that S54"s running hot cams (from race teams) take oput the MAF and run on some sort of Alpha N (somletimes with a piggy back ECU). >Is that a necessity?

For the MAF to work properly with the ECU, the housing in which it sits must be of a known and calibrated size. The Z4M's MAF is Part No: 13 62 7 839 014, and this MAF is used with several different BMW models and must be housed in an 87mm diameter aperture. Therefore, if you want to remove any restriction into the intake, such as by using a wider inlet into a CF airbox (i.e. CSL style), with the mouth greater than 87mm, you've got to find a way around this, and Alpha-n is one way of doing this. A different MAF which sits in a larger aperture could be used, but the ECU maps have all be compiled using the Part 13 62 7 839 014, so it's probably easier to go Alpha-n. In the case of a race car, they're only really bothered about WOT so they won't have to worry about all the other fuelling conditions required by a road car.

[Shooter]

Finally got around trying the mod this week-end !!!
Along with the carbonification of my front bumper splitter, i used some of the carbon wrap to seal the hole in the air box.



Easy job. And it has only advantages : i can easily puncture the carbon wrap from the top if there ever is a water accumulation in the box, and since it's carbon, it means my car is now lighter* !


*: everyone knows that adding carbon fiber, even if it a vinyl wrap, removes weight...

[srhutch]

Of course it reduces weight, cf will weigh less than the hole that was there

[sam1832]

Should of wrapped the whole box more weight to be saved lol

Sent from my GT-I9300 using Tapatalk 2

[Shooter]

Should of wrapped the whole box more weight to be saved lol

It has been the question all day long : when is more carbon too much carbon ?

[mmm-five]

Strange, I thought I'd posted my results previously, but came to add some more after I've added an RPI scoop and couldn't see anything.

Anyway, here's the results I got (using DashCMD, iPhone 4s, ODB bluetooth dongle). Intake temp on all 3 tests (about 9 runs in total) was between 16ºC and 18ºC (there are more runs, but these were the closest temps to maintain a bit of consistency and the standard box at 26ºC showed a max of 29.04lbs/min anyway).

Standard - 30.92lbs/min


Exdos mod - 31.54lbs/min


Exdos mod & RPI scoop - 31.86lbs/min


The last one has 2 runs on the same log (as I forgot to turn the logger off) but gave exactly the same result!

Just got to wait until winter now to see how much difference 10-20ºC temp reduction makes

[exdos]

Tony,

Thanks for posting that.

Below is a a recording I did on 14th July 2013 of an acceleration in 2nd gear with all my air-intake and exhaust mods. As you can see I recorded 36.42lbs/min at the redline. I have recorded 36.81lbs/min in 3rd gear.




If you now fit a pair of gutted OEM silencers then you will see another increase in airflow, which translates into an increase in Volumetric Efficiency and torque (power). If you can get a pair of OEM silencers to me then I will do this for you.

[mmm-five]

All mine were done in 3rd gear (60-100mph runs), and all had the Rogue Diablos fitted.

Maybe your ramcharger mod and the MAF screen will add a bit more, and I'd love to do them if I can get another 4.6lbs/min!

Even my OE max is about 1lb/min less than your's, so there's something different somewhere.

[exdos]

All mine were done in 3rd gear (60-100mph runs), and all had the Rogue Diablos fitted.

Maybe your ramcharger mod and the MAF screen will add a bit more, and I'd love to do them if I can get another 4.6lbs/min!

Even my OE max is about 1lb/min less than your's, so there's something different somewhere.

If you'd like to do some comparative datalogging to see the differences then you are welcome to come here and we can spend some time changing bits and pieces.

I'm about 95% sure that I'm going to produce a Ramcharger because it certainly provably works.

[mmm-five]

If you'd like to do some comparative datalogging to see the differences then you are welcome to come here and we can spend some time changing bits and pieces.

I'm about 95% sure that I'm going to produce a Ramcharger because it certainly provably works.

I've still got to take you up on your offer of a ride on the B16/PSS10.

[monaco_blue]

Thread resurrection time...

I have read this thread with interest. A question if I may: Air flow rate is a function of air density which is influenced by the barometric pressure - were the runs done on the same day in fairly quick succession to rule out any influence from different weather?

And a couple of comments: The OBD port has loads of data available but the latency is quite high because of the low data rate so its only pseudo real time and drawing firm conclusions is a little difficult.

Your analogy about the leak in the air box being akin to trying to fill a bath without the plug in place is not really accurate. Most any bath will drain faster than it will fill because of the relative size difference between the drain pipework and the (smaller) fill pipes. The airbox at speed is just the opposite - the amount of air coming in is far greater than the amount of air leaking out of the drain hole.

I have a datalogger that I used when I was messing around with looking at intercooler efficiency on a 911 turbo - it samples at 10hz. Will have a look and see if I can figure out how to attach a pressure sensor to the intake system to see if there's a pressure difference at speed with and without the airbox hole plugged.

[exdos]

Thread resurrection time...

I have read this thread with interest. A question if I may: Air flow rate is a function of air density which is influenced by the barometric pressure - were the runs done on the same day in fairly quick succession to rule out any influence from different weather?

I used a DashDyno Datalogger see: http://www.auterraweb.com/dashdynoseries.html, which requires the details of the prevailing conditions of Altitude, Barometric pressure, Temperature and Humidity in the settings as well as specific details relating to the vehicle. Therefore any of the results produced for Dyno runs are "standardised" and thus comparable. All my runs are done in the same place and I never run in windy conditions. I run in opposite directions on the same stretch to check for disparity.

And a couple of comments: The OBD port has loads of data available but the latency is quite high because of the low data rate so its only pseudo real time and drawing firm conclusions is a little difficult.

If you can find a better way of datalogging a car in "real world" driving conditions with affordable equipment then please let me know how to do it. Whatever the shortcomings that may apply to all ECU datalogging methods via the OBDII socket, it gives far more accurate information that the butt dyno, and I would also argue a static dyno too. It's always possible to datalog 1 PID at a time, where, in the case of the Z4MC, you will obtain around 9 samples per second, so that you can see if the same sample trends are reflected when datalogging multiple PIDS.

Your analogy about the leak in the air box being akin to trying to fill a bath without the plug in place is not really accurate. Most any bath will drain faster than it will fill because of the relative size difference between the drain pipework and the (smaller) fill pipes. The airbox at speed is just the opposite - the amount of air coming in is far greater than the amount of air leaking out of the drain hole.

An analogy is a way of using a generally understood comparable to describe something unfamiliar in order to help convey understanding of the new topic. I think you are being a real pedant by claiming the analogy doesn't work because you are creating an argument about the comparative flow rates in the analogy! Hilarious!

I have a datalogger that I used when I was messing around with looking at intercooler efficiency on a 911 turbo - it samples at 10hz. Will have a look and see if I can figure out how to attach a pressure sensor to the intake system to see if there's a pressure difference at speed with and without the airbox hole plugged.

So you think 10Hz is accurate enough?

[StevenH72]

I have read this thread with interest. A question if I may: Air flow rate is a function of air density which is influenced by the barometric pressure - were the runs done on the same day in fairly quick succession to rule out any influence from different weather?

I've only just seen this thread, not sure how I missed it previously.

If the Air Flow Rate is a function of density, do IATs need to be taken into consideration when considering the changes between plugging and not plugging?

Some of the examples, whilst showing higher flow rates, also show IATs as being lower....surely you'd need to standardise the IATs to create comparable data?

[exdos]

If the Air Flow Rate is a function of density, do IATs need to be taken into consideration when considering the changes between plugging and not plugging?

Some of the examples, whilst showing higher flow rates, also show IATs as being lower....surely you'd need to standardise the IATs to create comparable data?

As I stated in the earlier posting above, the DashDyno in Dyno Mode calculates a "standardised" result. This means that you can do a dyno run on a coast road of the Arctic in the middle of winter in high pressure conditions and low humidity, when air density is greatest and directly compare the result with a dyno run done in Mexico City on a steaming hot day and the results will be directly comparable, because the DashDyno does the maths which incorporates air density into the results. I believe the maths also allows for differing aerodynamic drag in different air density conditions.

If you datalog IAT you will soon see that it is never a fixed figure when the ambient temperature remains the same and it is constantly changing so it is impossible to say that when ambient temperature is at, say, 20degs C, the IAT will be at a fixed temperature of, say 28degs C. The IAT will rise when the car stops and will fall when you accelerate and it will even rise during gear changes! However, you can compare IATs with different air-intake configurations and see how close to ambient that you can get the IAT during acceleration. So far, I've found it impossible to get the IAT of the Z4MC closer than 5degs C above ambient temperature with modifications.

For my own purposes, I like to use Volumetric Efficiency as one of the best ways of monitoring performance differences from modifying air-intakes and exhausts and to do this I datalog the following three parameters: 1. Airflow through the MAF, 2. Engine RPM, 3. IAT. I then use the datalog files in .csv format in Excel, in a spreadsheet that I've composed which produces VE figures, line by line. Since the calculation of VE requires IAT, the differences in IAT at any data sample point is "neutralised" in the calculation of VE, thus performance under different conditions can be directly compared this way. I additionally record the vehicle speed with the other 3 parameters, so that I can see the how speed has a dynamic effect on VE because this demonstrates the Ram Effect. Using my methods datalogging shows me whether any modification, helps to lower the IATs and/or increase airflow through the Ram Effect, both of which will increase the VE and give a performance gain.

I am totally objective with modifying and I trust the ECU to give me sufficiently accurate data to show me whether something works or doesn't. I don't pursue lost causes no matter how much time and effort I've invested. I once spent ages partially gutting the cats for a Z3MC and the data logger proved that they were detrimental to performance so they instantly got ditched, even though my butt-dyno couldn't tell any difference.

[EdButler]

I get wet dreams over threads like this... OK not quite but i do like them a lot Shame i don't have an M to tinker with

Must agree with Monaco_Blue though. Its been a while since i learned this back when i did my flying exams, but you can easily get a up to 3% difference from air pressure changes. You'll also lose about 1 millibar (0.1%) per 30' above mean sea level in an NA car. Then there's the 3.5% or so you gain with a 10C seasonal temperature drop (between 10C => 0C for example)

So a car at 0C and 0ft AMSL and 1020mb pressure could have ~8% more power than a car at 10C, 600ft AMSL and 995mb. That an estimation - not using a calculator!

Therefore comparing from car to car, or even road to road can be a bit variable. If Tony did his runs on the same peice of Tarmac on the same day however, awesome result!