Cleaning the Conforti Air Intake System

I’m a big fan of the Conforti Air Intake System, since installation the unit has not given me any trouble and has offered great performance (plus it sounds good). But the time had come to clean the filter. Thankfully cleaning this air intake is nowhere near as involved as cleaning the dinan air intake.

I simply unscrewed the bracket around the filter and then gave the filter a light tug. Once removed, I beat the dust off the filter with my hand then used water to flush it clean. I let it sit awhile to dry, then sprayed some more of that dust catching spray that came with the Conforti kit on the filter and reinstalled it. Later I was informed that soap and water is the recommended cleaning method.

While the filter was drying I looked at the area under the filer, there was a lot of sand and debris in there so I used a shop vac to clean up the area. Once everything was back together I went for a drive to see how much more power I could feel…. couldn’t tell a bit of difference, oh well cleaner is better anyway.

Dinan ///M Air Intake

The ///M engine can benefit from additional air (mass) intake, however the Dinan design (specifically for the M roadster and M coupe) concerns me. Look at the picture below, the air filter is exposed in the lower air intake (front bumper). While this may provide additional performance I really question the long term effects. The K&N filter is rather durable, but what happens when it gets wet. I’ve heard a report of a check engine light coming on after a car wash. I also look at the amount of rock chips this section of my bumper has picked up and wonder how long a paper filter could last against this kind of impact abuse.

For these reasons I would not recommend the Dinan intake unless it was only for Autocrossing or Track use, even under those circumstances I question if the Dinan design has any advantage over the ECIS or Jim C design.

Update: I have been informed “Dinan is now shipping (for free) filter covers, a la K&N condoms, which are supposed to solve these issues”. I think this shows great customer service and reminds everyone why Dinan is such a popular company to do business with.

Conforti/Shark Air Intake System

Pros: Factory appearance,improved performance,great sound
Cons: Slightly tricky installation
Cost: $449 plus shipping from Eurosport High Performance

Shark Intake

Publishing product reviews on the MZ3.Net is beginning to take on a life of its own! After I posted a complimentary article on Jim Conforti’s OBDII Performance Reprogram I received an e-mail from Josh MacMurray, head man at Eurosport High Performance in Salt Lake City. Eurosport is one of Conforti’s two national distributors, and Josh invited me to review Jim’s new Shark Air Intake System. I don’t need much prompting to try out the latest wrinkle on my M Roadster, and since I had already reviewed the ECIS Evolution Air Intake System I was anxious to see if the Shark Intake lives up to the great comments which have been appearing on the BMW bulletin boards. Eurosport arranged to ship me the appropriate system for my M Roadster, and the system arrived several days later carefully packed in styrofoam pellets with individual components of the system sealed in foil or plastic envelopes. Very neat!

The intake system consists of a molded plastic shield, an intake pipe with O-ring and clamps, an ITG Maxogen foam intake filter with a spray can of retention oil, plus all of the clamps, seals and fasteners required to complete the installation. The included instruction sheet is a model of clarity and features photos of critical steps in the removal of the stock air box and the installation of the Shark system. My first installation attempt ended almost before it began when I got too muscular with one of the intake pipe clamps and broke it off of the pipe. I e-mailed Eurosport and they responded immediately, overnighting a replacement intake pipe assembly. Comforting to know they’re ready to help out even the most ham handed! Josh MacMurray tells me that they have experienced about a three percent breakage rate for this part, a rate which they consider much too high, and have redesigned the clamp attachment point. The redesigned intake pipe should be available by the time this article is posted.

Given the new pipe, I completed the installation. Casual mechanics should have no problem with this 30-45 minute procedure as long as they pay attention to step 10 of the instructions which says in part; “Install the shield. Sounds simple, but it will require a little patience and wiggle technique.” Indeed!! If I hadn’t been forewarned, I might well have thought they sent me the wrong shield. But by applying “a little patience and wiggle technique” the shield did slip into place as promised. Once in place, the shield is fastened to existing mounting points, no drilling or fabrication required. I got a little nervous when the install was complete and I discovered that I had a few small parts left over, but a quick review of the instructions revealed that Conforti includes parts necessary for all versions of the six cylinder Z3, which vary in detail model to model.

Jim C has obviously gone to a lot of trouble to design a system which maintains a factory appearance under the hood. The black plastic intake pipe attaches to the mass air sensor with factory-like spring clamps and the black shield, with its seal, looks very much like the electronics bay next to the firewall on the right side of the engine compartment. The hose clamp which secures the ITG filter to the intake pipe appears to be identical to the BMW clamp which secures the rubber air duct to the back of the mass air sensor, and the ITG filter itself has a really businesslike look with black foam filter and aluminum trumpet. Very attractive! Not to enter into any ITG vs. K&N controversies, but a non-automotive friend of mine thought my own K&N looked like a pink lampshade. I’ve been reading posts on the BMW bulletin boards from lots of K&N owners who are switching to ITG just to improve under hood cosmetics. Additionally, the ITG is claimed to provide superior filtration ability, especially of harmful particles in the 10 to 20 micron range, and exceptional dust load up tolerance; the ability to absorb large amounts of dust without reducing air flow capacity

Road test time! On a brisk run on local farm roads my butt dyno senses a definite performance improvement, particularly at higher RPMs, accompanied by a subtle shriek approaching redline. Though I don’t have access to a dyno, several dyno runs on late model M3s equipped with the Shark Intake have appeared on the net. Eurosport provides a dyno sheet in Adobe Acrobat format, but to save time here’s the Eurosport Dyno Run as a .jpg file. Boston Performance Group, Inc. has also posted a comprehensive E36 Intake Shootout on their web site, including dyno runs, and both sources validate my butt dyno impressions (Editors Note: Web link removed, web page was no longer valid). If you’re buying the Shark Intake, seriously consider getting Jim C’s OBDII Performance Reprogram at the same time. The Conforti reprogram is great value and is optimized for use with the Shark Intake. The combination is my candidate for leading bang-for-the-buck performance enhancement for your Z3.

The FOGG/FONG’ed 2.8 Cold Air Intake

Pros: Increased performance, low cost, keeps stock air filter
Cons: Do not screw up cutting the plastic cover for the headlamp
Cost: $30 and 2 to 3 hours of your time

First I want to thank Shawn Fogg for the original idea to supply cold air to the intake, WITHOUT spending up to $500, and labor. His instruction and basic concept to modify the air intake helped me to modify the 2.8’s airbox & intake delivery system.

* Tools needed: 10-mm open/boxed end wrench.

* Metal File

* 8-mm ¼-inch socket wrench.

* 6″ long ¼-inch socket extension.

* Flat head screw driver-med.

* Philip head screw driver-med.

* Dremel & cutting wheel OR a keyhole saw.

* Magic marker.

* Hot glue gun with heavy-duty glue sticks.

* Hair dryer

* Things to Buy: Go to the nearest Home Depot or the like and in the ventilation section get an aluminum 5″ to 4″ duct adapter. This is a tubular piece to allow a 5″ hose to plug into a 4″ hose.

* Buy a 4-inch aluminum flexible duct tube. This will be the new air supply tube.

* Buy a 5-inch stainless steel hose clamp.

* Hot glue gun and heavy-duty glue sticks, if you do not have any.

** NOTE THAT ANY DIRECTIONS I MENTION IS IN BODY POSITION **

PLEASE READ THESE INSTRUCTIONS. You will notice that the pictures show the completed product and not before modification.

1. Basic design of the 2.8 (00) airbox and air supply route: The stock unit’s air supply comes from the driver side of the radiator. It funnels through a 3.5 X 4.5-inch triangular opening.

2. That opening then feeds into a semi-enclosed space that surrounds the rear of the headlamp assembly and wire harness.

3. From there, the air funnels once more through a 3-inch tube that goes into the airbox.

4. The air passes through the filter then into another funnel (3-inches diameter) that leads to the air-mass sensor.

1. Making the Intake: First thing you need to do is to make the 4″ inlet out of the adapter you bought at Home Depot.

2. To do this on the expansion funnel (between the 4″ and 5″ tubes) you need to drill out the two rivets. This lets you separate the adapter into 3 pieces, the 4″ tube, the expansion funnel and the 5″ tube.

3. We only need the 4″ tube with the ‘rib’ on the side that was connected to the expansion funnel which opened up to the 5″ piece.

4. Using the hack saw, take the 4×36″ diameter tube and cut it down to 6 to 8-inches. Make sure that the tube IS NOT EXPANDED when you are measuring and cutting. This will become your inlet into the airbox.

5. Now dry fit the adapter and tube together. It will be a very tight fit. You might need to cut a 2″ slice, either on the tube or adapter, to make the tube slide onto the adapter correctly.

6. Once you are satisfied with the fit, take apart the tube and adapter and place it aside for later

1. Removing the 2.8 (00) airbox from the engine compartment: Remove the stock paper filter and holder from the airbox.

2. Use the flat head screwdriver to unfasten the (2) snap clips that holds the rubber hose & air mass sensor. Slide off the hose from the airbox. When removing the unit, there will be a rubber O-ring between the airbox & runner hose. Its purpose is to maintain a good seal between the plastic & rubber.

Tech Tip: When reinstalling the O-ring, install the O-ring, then wet your CLEAN finger and run it along the inside diameter of the O-ring. This will allow you to slide the rubber hose together with the plastic airbox when you are ready to reassemble the components.

3. Snap off the overfill hose from the radiator. It is located on top to the passenger side of the airbox.

4. To unbolt the airbox, you only need to unbolt (1) 10-mm nut, located on the driver side, plus the rubber hose to the engine. You do not need to undo the nut all the way.

5. Now this will take some fannagling, the small overfill hose to the radiator will be in the way during the removal of the airbox. To remove the airbox, you will need to pull & stretch the tubing around the airbox, as you are pulling the air box out of the engine compartment. The easiest way I was able to remove the air box is by stretching the tubing towards the passenger side of the airbox.

6. Once the airbox is out, you will want to clean out all the little bugs, dust and rocks the filter has trapped. It is also a good time to replace the filter – – mine had almost 18,000 miles.

1. Removing & modifying the air restrictions within the airbox for the 2.8 (00) When looking inside the airbox, you will see a plastic funnel that is attached to the driver side of the airbox. The funnel can be unattached by unscrewing the Phillips head screw on the outside wall of the airbox. The funnel can be pulled straight out of the airbox.

2. Now is time to put on your SAFETY GLASSES. You will be cutting the funnel in half. Starting at the widest portion of the funnel, (the side that empties into the airbox).

* Take the hacksaw and saw from the widest portion of the funnel towards the inlet of the funnel.

Tech Tip: There is a line that you can see that is called a parting line. The term is used for injection molded components. You can use the parting line as a guide.

* Now stop short of cutting into the ribbed area.

* Take the hacksaw and start cutting on the side that DOES NOT have the screw boss that attaches the funnel to the airbox. (You need to be able to remount this in the airbox).

* Use a file to smooth the edges. Then use a damp cloth to clean the surface. Once that is done, you may reinstall the modified funnel. Do not forget to use the screw to hold it back in place.

1. Removing the 2.8 (00) headlamp and fog lamp assemblies First, we will remove the fog lights (the easier of the two).

2. Using a medium sized flat head screw driver, remove the plastic cover that is towards the passenger side of the fog lamp.

3. You will see (2) 8-mm hex head bolts that hold the lamp in place. Remove them.

4. To remove the lamp assembly, just pivot the lamp from the passenger side edge and pull towards you (front of the car).

5. To remove the wiring, it is located behind the lamp. There are (2) pressure clips on either side of the wire harness. You might need to employ someone with small hands (your wife, girlfriend, your young son or me… LOL) to be able to reach behind the lamp and squeeze the clips together.

6. Once the wire harness has been released, remove the fog lamp and place in a safe spot.

7. Second is the headlamp assembly.

8. Located behind the lamp and in front of the airbox location. You will see a plastic housing that has the wiring for the headlamp going into through rubber grommets.

9. Those grommets are on plastic doors, that are removable from the plastic housing.

10. You will need to reach inside the housing to twist and remove the individual light bulbs from the headlamp.

Tech Tip: Do not touch the surfaces of the bulbs with your fingers (the oils from the skin will help DECREASE the life of the bulb).

11. Now is the fun part of unscrewing the headlamp from the car.

12. There are (4) 8-mm hex head bolts. You will need to use the 6-inch extension arm with the 8-mm socket.

Tech Tip: Use a magnet to magnetize your sockets. This will help you REMOVE and not loose the screws down within the car body.

* (2) are easy to see – they are located on top portion of the headlamp.

* (1) is on the passenger side, accessible through a steel hole.

* (1) is on the driver side accessible through a steel hole.

13. Once all the screw bolts are free, remove the headlamp and place in a safe location.

1. New Air Supply Tube You will notice once you have removed the headlamp, you will notice on the bottom portion of the plastic headlamp housing, there is a 2 ½-inch hole that appears to be plugged. How ever, you will be able to remove that plug by pressing in the (3) plastic clips towards the center of the hole. It will just fall down towards the fog lamp.

2. Now you get to cut things up. You will now follow the instructions of Shawn Fogg (with the necessary modifications to make it work for the 2.8 (MY00) Z3.

* When I cut my new air supply hole, I did not remove the plastic cover from the car. I believe that it is possible to remove it, but it would be a problem to remove and reinstall. BMW used a something similar to a drywall expander nail system. It is easy to remove the nail, but not too easy to remove the expander part that is in the wall. To remove either part, you would need to use flat head screw driver and needle nose pliers. You would have a greater chance of scratching the paint, during the removal of the units. That is why I left the plastic cover in.

* Now comes the fun part, you need to cut a 4″ hole where the stock hole is. Put the 4″ side of the inlet over the hole and draw a new circle on it with the marker. Do not center the new hole over the old one. You want the new hole to be as far to the passenger side of the box as you can make it. There is limited real estate to enlarge the hole. In addition, the surface of the area is not flat.

Tech Tip: INITIALLY CUT THE HOLE SMALL AND WORK YOUR WAY TO THE CORRECT SIZE. YOU ONLY GET TO CUT THE PLASTIC ONCE!

* If you have kept the plastic cover installed, I HIGHLY SUGGEST covering any exposed areas that hot plastic bits might fly to.

* Now PUT ON YOUR EYE PROTECTION!!!!! – Using whatever method you decided on, cut out that 4″ circle. This is the most time consuming part of the project. If you use a Dremel, you will experience hot, nearly liquid plastic flying around, so be careful!

* When I cut my hole, I had to make sure I had some land area to allow the new air supply funnel to be mounted on a semi-flat surface. This way it would be easy to apply the hot glue.

3. After you cut the hole, test fit the inlet into it. The inlet should fit through the hole but stop at the ‘rib’ on the inlet. For the test, it is easier if you just put the 4″ side through the top of the plastic cover. If you cannot get it to fit use the Dremel’s grinding wheel or a file to smooth and enlarge the hole. The fit needs to be tight as possible, WITHOUT distorting the inlet.

4. After you are satisfied with the fit, you may dry fit the aluminum tubing. This way you can determine if you need to resize the length of the tube.

5. Now is the time to clean the inside of the box.

6. Scrub out the inside of the air box with a brillo pad or something similar to remove all the plastic bits that got thrown around when you cut the hole.

7. Also, use a damp cloth to wipe down & remove any particles remaining.

8. After you get it all cleaned out, dry it.

9. Now put the inlet into the airbox for real.

10. Attach the aluminum tubing to the 4-inch adapter. Keep the aluminum tube UNSTRECHED and UNBENT. Do not attach the hose clamp at this time.

11. You will install the assembly from the TOP of the plastic cover (over the fog lamp). The side with the rib goes inside of the box with the 4″ tube & aluminum tube will be pointing down towards the fog lamp. The rib will keep the inlet from pulling through the box if you cut the hole properly.

12. Now slide the hose clamp from the bottom of the aluminum tube and tighten. Make sure to have it snug up against the bottom of the plastic cover. Do not overtighten the hose clamp as you could deform the inlet.

13. Now the top of the plastic cover, you will be applying hot glue between the rib and the floor of the plastic cover.

14. A slight air leak here isn’t critical, as it’s still before the air filter, but do the best you can. Do NOT use silicone glue as it could cause problems with your O2 sensors.

15. Let the glue cure for a hour, good time for a beer break – – if you are of legal age =:o

16. After the glue has cured, you will now need to stretch and bend the aluminum tube down and towards the front of the fog lamp assembly.

17. You will notice that my aluminum tube is bent slightly towards the plastic cover for the fog lamp. I am leaving that cover off to have a semi-ram-air effect to the air box. However, as Shawn said in his discoveries, he did not notice any difference when he place a scoop below the fog lamp. In addition, there was enough air movement going around the complete fog lamp to allow plenty of cold air to enter the tube.

18. The use of aluminum helps keep the tube in position and is easy to relocate, if you are not satisfied of its current placement.

19. You will need to use the fog lamp to determine good placement.

20. Once you are satisfied, reinstall everything like before.

21. One thing that I did before I drove my car with the modifications, was to disconnect the power from the battery for at least 24 hours. During the workweek is the best time.

22. Please note that I have NO modified computer chip. Therefore, I expect better results with persons who have the modified chip

* After thoughts: I did notice an increase of torque using my butt-seat-sensor. I sold my old G-tech unit, so I cannot verify any decrease of 0-60 times.

* The sound is deeper than stock.

* I still have the stock exhaust. I am looking at a Supersprint unit.

* I do not have a modified computer chip. I am debating between a Land Shark or a Dinan chip.

* Some people might be thinking why not just, run the new air supply from the fog lamp area to the air box directly. After talking with Shawn about Hydro-lock, I felt that connecting the tube all the way might up the possibility of it actually happening. Having the tube not connected will almost eliminate that chance.

ECIS – Evolution Air Intake System

Pros: Measurable performance improvement and great sound
Cons: I can’t think of any
Cost: $225 plus shipping from East Coast Intake Systems

I monitor the M3 bulletin boards regularly for news and opinions on performance modifications which might apply to my M Roadster, and there I saw quite a bit of favorable comment on the ECIS cold air intake system. ECIS stands for East Coast Intake Systems, and their product is called the Evolution Air Intake System. Common unshielded open air intakes seek to increase air flow by providing a larger air filter, but often produce less power than the factory air box because of the twin problems of turbulent fan wash and underhood heat. ECIS insures that the larger filter receives only cool, non-turbulent air by constructing a shield which completely isolates the filter from the engine compartment, receiving air from the same source as the factory filter box. They offer both their complete Evolution Air Intake System; consisting of their custom heat shield, mandrel bent inlet tube, 6″ K&N cone filter, brackets, silicone connection hose, clamps and detailed instructions for $225; or the heat shield alone for $70. The heat shield can be used with a number of aftermarket open filter systems available from BMP Design, Bavarian Autosport, and Turner Motorsport, as well as other aftermarket suppliers.

At the time I first read about ECIS they offered only systems for the M3, but I e-mailed them and quickly received a return message from Sean Cain at ECIS informing me that the M Roadster system was in the design stage and due out soon. Then, 45 days later, I got another message from Kenny Bernatsky of ECIS to let me know that the M Roadster system was now complete, with details available on the ECIS web page. Their web page provides just about all the info you need; photos, dyno runs, testimonials, an FAQ, and ordering information. The web page does not support on-line product ordering, but they have a handy order form which you can fill out and print, then mail with your check. I sent my order in that day and several days later received an e-mail from Kenny citing a delivery date and Airborne Express tracking number. My shipment arrived as promised, neatly packed. My relations with ECIS couldn’t have been better. Sean and Kenny answer inquiries promptly and keep in touch, qualities often absent with other web merchants. As I was writing this, I got a Christmas card from them. How’s that for customer service?

When I unpacked my carton from ECIS, I found the ECIS custom shield, the K&N filter, still packed in its original box, the various bits and pieces to attach the filter to the air flow meter, and a colorfully illustrated set of installation instructions. I was impressed to find that the silicone connection hose was in place on the inlet tube, held on by the loosely tightened hose clamps. No possibility that this amateur mechanic won’t know where the parts fit. More impressive still, a bolt which is required to attach the inlet tube support to a bracket on the inner fender of the car was carefully taped to the end of the support. For sure, this bolt isn’t going to be thrown out in the trash! The shield itself is a really neat piece. Constructed from lightweight, slightly flexible material which I believe is sheet fiberglass. The fiberglass was obviously cut from a single sheet, then folded and riveted into its final shape. The outside is finished with insulation which matches the car’s underhood finish, and the inside is sprayed with undercoating. The top edge of the shield is weather stripped to seal against the underside of the closed hood, fully enclosing the filter. Three holes are provided in the shield at the points where the shield mates to the air flow meter, the air inlet flange, and the car’s rubber air box support grommet. No holes need be drilled in the car in order to install the ECIS system. I had expected to provide a step-by-step installation guide, but ECIS’s instruction sheet is so well presented, and the installation so easy that I’m going to dive right into my driving impressions and performance testing.

On my first drive, my admittedly inexperienced butt dyno couldn’t detect any obvious performance improvement, but the engine seems to run smoother and, though not loud, the intake makes a low, pleasant moan which sure makes the car sound more powerful. My wife—she of the exquisitely sensitive hearing—approved of the new sound. More driving convinced me that, though not dramatic, the car did accelerate more forcefully, especially as it approached redline. I decided then to go back and perform before and after objective tests to validate the performance improvement my butt told me I had achieved.

The almost trivial installation procedure made returning the stock air box to the car a matter of, perhaps, ten minutes. Not wanting to torture the clutch, skin the rear tires, or invite the unwanted attention of the sheriff, standing start tests wouldn’t do. I decided to perform acceleration tests in second gear, timing from 1000 rpm to 6500 rpm. This test had the advantage of testing almost the entire rpm range, without having to exceed the speed limit. I drove the car hard for about 100 miles to insure that the ECU had readapted to the stock air box, then took the car out to a straight, flat section of country road nearby. I let the car settle at 1000 rpm in second, then started my watch as I floorboarded the accelerator, stopping my watch as the tach reached 6500 rpm. I timed eight runs, four in each direction, discarded the fastest and slowest times, then averaged the remaining six times. My average time for this series of tests was 5.71 seconds. I then reinstalled the ECIS intake, another ten minute job, and again drove the car hard for 100 miles to readapt the ECU. Another trip to the country road, using the same timing techniques as before, yielded an average time of 5.55 seconds, an improvement of .16 seconds.

So is the ECIS Evolution Air Intake System a worthwhile performance modification? For my money, the sound alone is worth the price of admission. Dealing with Sean and Kenny made the purchase really pleasant and I’m particularly impressed with the clarity of the instructions they provide. The system itself is well designed, with high quality construction. That it provably provides a small but measurable performance improvement is icing on a very large cake.

1.9 ROAR “RAM-AIR” Intake

Pros: Improve sound and performance, carbon fiber components and shield to hinder recirculating hot air intake
Cons: Vague installation instructions, intake system enclosed in engine compartment
Cost: $348

Despite the discontinued sales of the 1.9 Z3 in the US, there are many 1.9 owners who want added performance and most of all who still love their cars. With this in mind, there has been a slow start of third party manufacturers that offer upgrades and modification(s) to these loved but not forgotten Z3s.

Presently, there are a few manufacturers who offer an ‘air-intake’ solution to the 1.9 Z3. According to a previous article on the MZ3.NET, the K&N filter charger has some inconsistent performance results. THe K&N filter charger successfully addressed the restrictions in the stock intake allowing more volume of air to enter the engine. However the flaw with the K&N filer charger system was that the source of intake air was the (hot) air trapped under the hood of the Z3. While the intake was allowing more air volume to enter the 1.9 engine, the actual air mass varied greatly depending on the air temperature under the hood. Because of this flaw it was actually possible to loose engine power. (In case you haven’t caught on, cold air has more mass than hot air). Because of this, many Z3’ers (especially those living in hotter climates) avoid in installing such a design in their vehicles.

Since I received the DINAN UPGRADE for my 7/97 build 1.9, there has been no answer as of yet for the release of the DINAN COLD AIR INTAKE SYSTEM for the 1.9 since its debut for the 6 cylinder Z3s. Because of this I wanted to see if there are any third party companies that offer such a system for the 1.9 besides the K&N filter charger. I came across a company called “ROAR” (www.roarfilter.com) that offers such a system for most BMWs including the 1.9 Z3. Though fairly new to the name I decided to call and investigate what this company offers and stands for: I called the company and left a voice mail message with them explaining my interest in their air-intake system for my 1.9 Z3. Two days later I received a call back and spoke to a very nice and enthusiastic sales manager of Roar named Scott. He was very friendly and excited to explain to me how their air-intake system functioned and how it was designed. He welcomed the challenge of putting the ROAR air-intake system against any other system designed for the BMW Z3.

The ROAR intake system is similar to the K&N filter charger system in that it addresses the air flow restriction of stock BMW airbox. Where the ROAR system differs is that it also addresses the problem of air intake temperature, by providing a carbon fiber shield that helps reduce the engine’s intake of hot air from inside the engine compartment. The construction of the Roar air intake system is mostly comprised of carbon fiber due to its low relative heat absorbence.

Review: After installing the Roar “Ram-Air” Intake System to the DINAN equipped 1997 1.9 we put it up against a 1998 1.9 which only consisted of an exhaust upgrade (Supersprint). Both Z3s being tested are manual and had no passengers in the vehicle. The test consisted of both 1.9s cruising head-to-head at 50mph in 5th gear. Once each front nose were equal we then cued each other to accelerate without downshifting. Both of the 1.9s remained head-to-head up until we hit 60 mph (3600 rpm) and the 1997 DINAN equipped with Roar system pulled out ahead of the 1998 Supersprint exhaust 1.9 by almost half a car length. This concluded that the ROAR system with the DINAN upgrade improves performance at higher RPM.

Other test(s) included 0-60mph runs recorded before and after the installation of the ROAR system. With a passenger operating the stopwatch, four runs were record before the installation and four runs after the installation. The results showed that after installing the ROAR system with the DINAN upgrade, the 0-60mph timing was reduced almost 3/8 of a second.

Note: testing in this manner resulted in extra weight due to the timekeeper sitting in the passenger seat. It should also be noted that potential human error is possible, due to the time it takes a human hand to start and stop the stopwatch.

Stock 1.9Roar Intake Installed

6 month update

With the Roar Ram Air System installed and after few thousand miles later, I have concluded that I am quite happy with my investment. The performance gain is a plus as well as the sound. The sound will be noticed when the engine is at load as opposed to a constant, maybe annoying, low resonance sound.

The journey of the Roar installation

After leaving several messages with Scott at Roar and no return calls, I received the package on the very day that was discussed during the sales transaction. With the help of Carter Lee (CTG) and Fred Byrom (Teachum) we immediately looked at the contents within the package and read the instructions. Let me first tell you that the instructions were vague and offered no pictures of installation. This is not a plug-n-play upgrade for those who are not ‘handy’.

Fortunately, with the help of Carter and Fred, the three of us made the installation procedures a lot easier. The first step is to remove the stock air box: unlatch four(4) clips which removes the cover and after doing so the box itself is only held down by two(2) 10mm bolts. For more detailed instructions on the removal of the stock BMW airbox, please see this article on MZ3.Net.

Tools Needed:

* 10mm socket and wrench

* 10mm bolt

* 2.5 in drill bit and drill

After complete removal of the stock air box:

* The next step is to mount the mounting bracket (a) to one of the existing posts where that previously held the stock air box. You can use either the same bolt that held the stock airbox in place or use another one.

* Take one of the filter(s) provided and spray oil on the outer shell. The oil is located in the white aero-spray can that is provided. Do not spray the inside of the filter. After spraying the filter, place it within the funnel system and tuck the filter underneath the carbon fiber nose to hold it in place.

* Get ready to drill a 2.5in. hole into the air-intake system (b) for the temperature sensor location. There should be a rubber boot for allowing the temp sensor to be inserted. The boot acts as a tunnel/bridge connection from the air-intake system to the temperature sensor.

* After mounting part (a) you then will need to install two (2) rubber washers (provided) to size match the filter system (b) prior to installing it. After this, you can insert the filter system onto the the Z3’s hose intake located where (b) is on the picture. Once installed (remember it is going to be a tight fit so you can use water to moisten the rubber washer for easier slip) you want the mounting bracket (a) to have its clamp to hold the very end (located where the Roar filter system and the Z3 intake meets) of the filter system.

* Once the clamp is successfully holding the system (do not tighten at this time) take (c) vacuum/valve cover and insert it to the air pressure vacuum hose located where (c) is on the picture. Position the vacuum/valve cover opening tilted opposite from engine (there will be a filter opening and you want it position towards the driver’s side opposite from engine). After the above steps are installed, tighten the clamps just enough so its stays in place (do not overtighten).

* Next step is to locate the temp sensor. After completing the drill, making sure it will be snug, plug the temp sensor into the rubber boot on the air-intake system that was placed.

Taking out the stock box Stock box removed Roar Bracket

Discuss this article and other Performance upgrades in the

///MZ3.Net discussion forum.

1.9 “Fogged” Airbox Modification

Pros: Increased Performance, Proven Results, Retains Stock Airfilter
Cons: The stock airbox is expensive to replace, so don’t mess up
Cost: Roughly $20, and 3 to 4 hours of your time

In the year and a half since I first posted the DIY instructions to modify the M44 Z3s airbox I’ve found that I get the same sorts of questions. I figured a document that tied all the info together would help me and those also interested in the modification. This primarily deals with the Fogged Airbox mod for the M44 but also talks about how the fuel injection system on the Z3s works as well as alternate intake products that are available and my thoughts on them. The instructions are slightly updated from my original plans to make assembly easier and to add an optional safety step.

Engine and Fuel Injection:

The fuel injection in the Z3s is a mass air fuel metering system. What this means is your car directly measures the weight of the air being draw into your engine and injects an appropriate weight of fuel (in the ratio of 14.7 parts air to each part of fuel) which it then ignites through your ignition system. Under cruising conditions and light acceleration your cars computer (DME) uses feedback from the oxygen (O2) sensors to fine tune the mixture.

The DME measures the weight of the air using a sensor called the Hot Film Meter. (HFM) The HFM is basically a film through which a current is passed to heat it. If you were to look at the inside of your HFM you will see that the film is very small and it actually only samples a small fraction of the air that passes through the meter. By measuring the temperature change of the film (and knowing the intake air temperature) the DME is able to calculate the mass (weight) of air that is flowing over the film. It can then calculate the total mass of air flowing through the HFM. This works if the airflow through the meter is smooth and evenly distributed, in other words laminar flow. The DME then uses this to determine how much fuel needs to be injected to keep the AFR at 14.7/1, also called Lambda=1. An AFR of 14.7/1 results in the most complete combustion of your fuel which gives you the least emissions. If an engine is running rich OR lean (more or less fuel to air) the engines emissions will increase. At full throttle the DME runs the engine richer for more power.

Now a key point… if you increase the airflow into your engine, the DME will measure it using the HFM (assuming smooth airflow) and will increase the fuel injected to compensate. The DME must do this or your engine would run leaner which would increase emissions. If you increase the amount of air, to keep the ratio between air and fuel at 14.7/1, the DME must add more fuel. If you increase airflow and burn more fuel you have increased your power output.

Problem:

As delivered from BMW the M44 engine in the Z3s really is not as rev happy as say the engine in a Miata. Above 5000 rpm the power feels like it has reached a plateau and there isn’t much more to be gained by revving the engine higher. The reason for this is because up high your engine’s ability to breathe is being restricted. I wanted to see if I could correct this and verify an improvement.

After looking into the intake systems that were on the market or known to be ‘in the works,’ I determined that there was nothing out there that I would put on my car. The following are a few of the setups I found and some of my reasons for rejecting them:

Drop in K&N filter ($40): in my opinion, K&N filters do not filter as well as your stock paper filter. I will not put one on my car. Your filter is the first and only line of defense against letting dirt into your engine. The K&N is made from an oiled cotton gauze, if the oil dries out the ‘filter’ basically stops all filtering. I have heard it said that when a K&N filter gets wet the water can ‘wash’ the previously filtered dirt right through it and into your engine. The person who told me this raced motorcycles and said that when he switched from K&Ns back to paper filters his engines lasted much longer between rebuilds. Lastly, Greg Hudson had performed dyno tests comparing a new stock paper filter against a new drop in K&N filter… the result was a LOSS of power with the K&N. That demonstrates that the paper filter isn’t what is limiting airflow as the paper filter has a huge amount of surface area for the size of our engine. Swapping filters does nothing to address the real source of restriction in your intake.

K&N Filtercharger cone filter ($149): Has a lot of problems. It has the same filtering concerns as the drop in filter and the rest of the setup adds a few more problems. The cone filter can suck in hot radiator air which will hurt performance. This is because cooler air is denser air (heavier), the more air weight you can get into your engine the more fuel will be injected and the more power you will get out of your engine. The circular shield that some sell might help a little but it will also increase restriction as it blocks the filter somewhat. It still doesn’t get all that great of a source of cold air either. As with most other cone setups the tube that connects the filter to the HFM changes diameter at the cone filter and at the HFM. Those ‘adapters’ are not a good idea. When they increase or decrease in size it will cause turbulence and restrictions in the airflow. For the HFM to meter the air weight properly it needs a smooth flow of air through it. The connecting tube changes size right at the start of the HFM, this could cause turbulence which would result in improper metering by the HFM. If the HFM isn’t able to properly measure the airflow into the engine the DME is going to be injecting the wrong amount of fuel. This will keep the engine from running optimally and won’t be making the power it should. Additionally, the filter is right in front of the HFM and the airflow doesn’t have much space to ‘settle down’ so it will still be turbulent from passing through the filter itself when it hits the HFM. There will be more on this later.

Art of ROAR cone filter (~$200): Mostly the same problems as the K&N setup above.

ECIS (~$200, when available): Uses a K&N cone filter so it has all the same filtering concerns and most of the other problems except it has a shield behind/besides the filter to block off the filter from the rest of the engine compartment to help with the heat problems.

Dinan Cold air intake ($299): uses a K&N cone filter so it has all the same filtering concerns. It positions the filter behind your foglight to avoid the hot engine air problem but exposes it to more water. Has the same type of ‘adapters’ and the problems they can cause that all the above cone filter setups share.

What I was looking for was a setup that kept the paper filter (they filter well.. even when wet) that had a smooth airflow to the HFM for proper metering, and had a good source of cold air but that allowed the engine to breathe better.

Factory airbox setup:

On the stock M44 airbox the air intake is in a snorkel between the passenger side headlight and the edge of the radiator. The snorkel has a fairly narrow opening which may limit airflow somewhat plus it isn’t in a direct path of air, the hood support blocks it somewhat. From the snorkel the air flows through a 2 5/8″s insulated hose over the top of the radiator then down the other side where it connects to a plastic funnel on the airbox itself. Each turn causes restrictions.That funnel has a 1 3/4″ opening into the airbox itself and is ,IMO, the biggest source of restriction in the intake.

After the air is inside the airbox it has a good amount of area to expand to evenly pass through the filter then changes over to the HFM as BMW designed for proper air metering.

The solution… aka the ‘Fogged Airbox’:

It increases the air intake hose into the airbox to a 4″ diameter hose. That is about a 700% increase in surface area for air to flow through easier. The setup grabs its air from behind the foglight for a good source of cold air. It keeps the paper filter for maximum engine safety and the flow to the HFM is exactly as BMW designed it. In my opinion, it addresses the real problems with the factory airbox and doesn’t create any additional problems like the other setups do. It costs around $20 and takes about 3-4 hours or so to build and install.

Testing, Does it work?:

Instead of using formulas and/or a flow bench I tested the best way possible, the actual DME measured airflow into my engine. This is the ideal way to test because if your intake/engine has a bigger restriction elsewhere the formula/flow bench methods will give you misleading numbers that won’t be realized in the real world.

As was mentioned above the DME in the Z3s has a hot film sensor to calculate the actual mass (weight) of the air flowing across it based on the temperature of the film. The cooler the film is the more air mass that has passed over it. If the airflow is smooth through the HFM it will be metered properly. From this and a few other sensors the DME can calculate the mass of the air being taken into the engine. In other words, your DME knows exactly what the airflow is… all I need to do is have the DME tell me that information on before/after runs and compare the two.

Getting that data is actually very easy, provided you have the proper tools. OBDTOOL plugs into the OBDII port on your car and can grab data directly from the DME. For this test I need to grab airflow (expressed as pounds per minute) and engine RPM and log that, in real time, to a file.

Grabbing the data is easy. You set OBDTOOL to log the data to a file, drive at about 1000rpm in second or third, then just floor it till redline. When you are logging two data points (airflow + RPM) OBDTOOL is able to receive 2-3 updates per second. To get more data points (for more accurate airflow curves) I made multiple runs and merged the data points together. The higher the gear you are in the more data points you receive as well.

For the first set of data I made 3 runs with my car in its normal modified state. That includes the Fogged airbox , a +3mm big bore throttle body and a Remus exhaust. My car is a ’96 without traction control so it doesn’t have the secondary throttle body in the air stream.

Since I’m interested in just the effect of the airbox mod that is all I changed for the second set of runs.

There is one slight problem though… I can’t get my airbox back to exactly stock as I modified my personal airbox. The factory stock setup has that 1 3/4″ diameter inlet into the airbox which is the largest source of the restriction in the intake system. So I made a 4″ diameter plate (size of the Fogged’ airbox inlet) that has a 1 3/4″ hole in the center to simulate having the stock inlet in the airbox. This plate fits right in front of the rodent screen on my inlet and is held in place by it with tape around the outside edges to seal better. Because the airflow on the incoming side of the restrictor plate is still less restrictive (because it is still attached to the 4″ hose of my setup vs. a 2 5/8″ hose and the stock snorkel ) the airflow numbers recorded are probably higher then if the airbox was fully a stock setup. Still, the test will give a fairly accurate result of the real world results of opening up that stock 1 3/4″ inlet to 4″s.

Looking at the graph (click on the picture to the right for a larger view), at low RPMs the Fogged’ box seams to flow a bit better than stock. In the midrange the flow is basically stock, then at 4000 rpm or so the difference begins to grow and above 4800 it grows very quickly. The difference is about an 8.5% increase of air flow at 6400 RPM. That means your engine is burning about 8.5% more fuel there too… which also means you are producing about 8.5% more power! In fact because you are getting more air in the cylinders at higher RPM (increased volumetric efficiency) you will have a higher effective compression ratio and you will extract slightly more power from the air and fuel you were already burning before the mod in addition to the extra power for the extra air and fuel.

Now my thoughts as to why the ‘Fogged’ midrange flow is nearly stock. Simply because in that range the stock airbox is not the limiting factor. I assume if there is a problem (the cylinders could be filling to capacity) that it is the intake manifold in that range. Above 4800 rpm the DISA setup has changed over the butterfly in the manifold and the stock airbox was limiting flow again.

As an aside I also tested the intake air temperature. According to my center console computer it was 70 degrees during the test. The intake air temp. (as read from the DME using OBDTOOL) was 75 degrees while just cruising around and when I floored it for a few seconds it dropped to 73 degrees and stayed there.

I’ve tested a similar mod on a 318ti and recorded about a 5% airflow increase. That car was a ’97 with the additional throttle body in the airflow (read extra restriction) and it the rest of the engine was totally stock.

I’ve also done before/after 0-60mph runs using a G-Tech Pro. With just the Remus exhaust I was able to get a best time of 8.1 seconds. After the airbox, throttle body and Garrett Lim’s software (with stock 6500 rpm rev-limiter) my best times dropped to 7.45 seconds. My software was overwritten last December, by the way. Since then I have run stock software with the box.

Tools you need to build it:

Something to cut a hole in the plastic airbox. You could use a 4 1/8″ hole saw, reciprocating saw, Dremel or whatever else you feel comfortable with.

A Dremel with a heavy duty cutting wheel, a grinding stone and if you are using it to make the main hole the dime sized metal bladed circular saw and one of the grinding stones.

Eye protection (you are going to need it!)

10 mm socket and socket wrench

Hot glue gun with extra strength glue

Regular screwdriver

Permanent marker

Scissors and Wire cutters

Optional but recommended: Propane torch and plumbing solder, only needed if you are going to install the rodent screen in the inlet

Stuff to buy:

Go to the nearest Home Depot or the like and in the ventilation section get an aluminum 5″ to 4″ duct adapter. This is a tubular piece to allow a 5″ hose to plug into a 4″ hose and should cost about $3.

Optional but recommended: While at Home Depot in the ventilation department you need a ‘Rodent Blocker’ which is just a square piece of heavy mesh which is meant to go on your clothes dryers exhaust to keep mice from getting into you house. Figure a buck or two for this.

Go to a Pep Boys or whatever and in their ventilation section they should have a 4″x72″ air intake type of plastic hose for under $15. Anything similar should work OK but make sure it’s flexible. The stuff at Pep Boys worked really well and is very smooth on the inside for better air flow. Also get a 4.25″ hose clamp for a buck.

Very optional: can of flat black spray paint… high temperature outdoor gas grille paint works OK

Making the inlet:

First thing you need to do is to make the 4″ inlet out of the adapter you bought at Home Depot. To do this on the expansion funnel (between the 4″ and 5″ tubes) you need to cut/drill the two rivets. This lets you separate the adapter into 3 pieces, the 4″ tube, the expansion funnel and the 5″ tube. We only need the 4″ tube with the ‘rib’ on the side that was connected to the expansion funnel which opened up to the 5″ piece. The 4″ diameter tube will become your inlet into the airbox.

Optional but recommended: Cut down the ‘Rodent Blocker’ to a circle that will just barely fit inside the ‘rib’ on the inlet and solder it in place. This is a safety step to be sure a rodent doesn’t climb up your airhose and decide to make a nest in your airbox.

Very optional: spray paint the intlet. Paint doesn’t stick very well so it will take multiple coats. I’ve found that it helps if after each coat of paint you ‘bake’ it on with a hot air gun but even then it can come off fairly easily.

Completed inlet along with the airhose and hose clamp. This is all the parts required for the Fogged airbox.

Adapting the airbox:

It would be helpful if you have the car up on ramps or jack stands but it isn’t required. You need to get the bottom half of the airbox out of the car. To do that release the four clips holding the top of the airbox on and move the top aside. Take out the air filter and put it somewhere clean till you are done. On the fender side of the airbox there are two 10 mm nuts holding the air box in place. Remove them.

Above the radiator is the big black plastic box which holds the stock intake hose. Take the cover off of this by removing the (4) 10 mm bolts. Two are right in front of the plastic box in plain sight, the other two are right behind the plastic box. Lift the cover of that off and put it out of the way. You will now see the stock hose and where it connects to the snorkel on the airbox. Just pull that hose off and the bottom of the airbox can be removed from the car. While you are at it disconnect the other end of the stock hose and remove it from the car as it’s not needed.

Now with the bottom half of the airbox out of the car remove the external snorkel from the box. There is a clip on it that will let the snorkel slide off the box. Notice how tiny the hose is at the end of the snorkel! Next the internal funnel needs to be removed. There is a clip on the top of that and another clip on the opposite side of the box that lets you take the plastic frame out along with the sound deadening material. Don’t worry if you break some of the plastic frame pulling it out… I left mine out and it’s not a problem.

Now comes the fun part, you need to cut a 4″ hole where the stock hole is. Put the 4″ side of the inlet over the hole, on the outside of the airbox, and draw a new circle on it with the marker. Don’t center the new hole over the old one. You basically want the new hole to be as far forward on the airbox as you can make it. You need the inlet to be forward so it can clear your steering reservoir when you reinstall the box.

Now PUT ON YOUR EYE PROTECTION!!!!! – Using whatever method you decided on, cut out that 4″ circle. This is the most time consuming part of the project as hot, nearly liquid plastic is going to be flying around so be careful! Be sure to also look inside the airbox as in a couple of places there are plastic ribs and such that you need to cut from the inside for the hole to come out. After you get the hole cut out test fit the inlet into it. The inlet should fit through the hole but stop at the ‘rib’ on the inlet. For the test it is easier if you just put the 4″ side through the air box from the outside but this isn’t how it will be when you are done. If you can’t get it to fit use the grinding wheel to smooth and enlarge the hole. It should be as tight a fit as you can make it without distorting the inlet. After you have the inlet fitting in the hole remove the inlet from the airbox. Scrub out the inside of the air box with a brillo pad or something similar to remove all the plastic bits that got thrown around when you cut the hole. After you get it all cleaned out dry it.

Now put the inlet into the airbox for real. The side with the rib goes inside of the box with the 4″ tube pointing out the hole. Only have the tube protrude from the box up to the rib on the tube hitting the inside of the airbox. The rib will keep the inlet from pulling through the box if you cut the hole properly. Now from the outside of the box seal the inlet to the box with the hot glue.

A slight air leak here isn’t critical, as it’s still before the air filter, but do the best you can. Do NOT use a silicone glue as it could cause problems with your O2 sensors.

After the glue has set, slide the 4″ air intake hose over the inlet protruding from the airbox. It is a very tight fit but if you take your time and work it around the inlet you will get it on. Secure it in place with the hose clamp. Do not overtighten the hose clamp as you could deform the inlet. You could cut the length down to about 3-4 feet now or you can wait till it’s installed then cut it.

Now reinstall the airbox into the car. The tube and hose should just fit into the car but it will fit if you cut the hole in the proper position. You can either put the old air intake cover back over top of the radiator and put back in the (4) 10 mm bolts or pull the bottom half of the plastic assembly off of the fan shroud and out of the car. I took it out of my car but if you want your intake to look stock leave it all in place.

Reattach the (2) 10 mm nuts holding the airbox in place. Put the air filter back into the airbox and secure the cover with the 4 clamps. Be sure you get a good seal. Now would be a good time to replace your air filter if you haven’t in 10k miles or so.

Route the hose pretty much straight down along the side of the radiator. This is easier to do from under the car but is manageable from above. Run the hose into the opening that leads into the front bumper, right in front of the wheel and place the hose opening behind the foglight. Trim the hose as needed to do this. You may want to disconnect your battery for a few minutes to reset the long term fuel trim (adaptation) that occurs in your DME but it isn’t really needed.

At this point you are done. You too now have a Fogged Airbox. Go take your car for a spin and run it up to redline a few times! You are going to love it!

Fogged Airbox FAQ:

(Q) Why not put the hose in front of the radiator or below the car or add a scoop or where ever?

(A) I’ve tried a scoop and it resulted in no measured airflow increase. It also greatly increases your chances of hydro-lock. Putting the hose behind the fog light gives good airflow and you would need to drive through a VERY deep puddle (several feet) before you would have a problem. Hydro-lock occurs when you fill your combustion chamber with enough water to stop the piston on its compression stroke. When this occurs you cause major damage to your engine. Even if you submerged your hose in water I don’t think the M44 creates enough vacuum to suck water up the 4″ diameter hose, then fill the airbox and finally draw it into the combustion chamber. If it was 1″ diameter hose, yes but not the 4″ hose. Your airbox has a drainage hole in it that would act as a vacuum relief if the main hose was submerged. Having said that it doesn’t mean I recommend that you drive through very deep puddles. You are not a U-Boat captain after all. You also want to limit the number of bends the hose needs to make as each bend will cause some restriction. Keep it simple and put the hose behind the foglight, it works.

(Q) Won’t rain get behind the fog light and get into the intake?

(A) Yes, but small amounts of water isn’t a problem. This can happen on the stock setup during driving in the rain or on very foggy nights. It basically wets your filter and since it is still a paper filter there is no problem.

(Q) Won’t I get check engine lights? IE… Dinan says that if the mod worked it would cause Check Engine lights as the DME won’t know how to deal with the airflow. They also claim the engine will run lean with any air intake on it and no ‘Stage II’ software in the car.

(A) Simple answer: No

Much longer answer: I’ve put around 15k miles on my car and never had a Check Engine light. No other Z3 owner that has done the mod has had lights that were caused by the Fogged airbox either. Remember how your fuel injection works, the HFM directly measures the airflow into your engine and injects the appropriate amount of fuel. It ‘knows’ how to deal with the increased airflow. This is assuming proper air mass metering by the HFM. I have done wide open throttle (WOT) runs recording my O2 sensor data vs. RPM to see what mixture I’m running at. At WOT my engines goes rich (O2 data at 0.8v) from right off idle and stays very consistent (+/- 0.05v) all the way to the rev-limiter. IOW, with the Fogged airbox the HFM is properly metering the airflow increase and the DME is adding fuel as needed throughout the rev range. This is with stock BMW software in my DME. If this was not the case the O2 voltage would drop off (go leaner) as I got above 4k RPM where the airflow increase occurs. On other types of fuel injection: air-flow metering or speed/density the DME would NOT be able to measure the additional air and they would need a ‘chip’ or ‘software’ to properly deal with the increase flow. On our cars this is NOT the case.

Even IF what Dinan claims was true (in that it applies to ALL intakes, it is not true) why wouldn’t the ‘Stage I’ software (which makes your engine run slightly richer at WOT and slight advances your timing) be enough? A theory on that: Assume for a second you have two intakes.. their actual airflow into the engine is the same. But one intake has smooth laminar flow at the HFM and the other intake has turbulence at the HFM. What would happen when you put them on your engine? Again, if you look at the inside of your HFM you will see that it actually only samples a small fraction of the air that passes through it. Based on that small sample it calculates the total air mass. This works fine if the airflow through the HFM is nice and smooth. In the case of the intake with smooth airflow through the HFM if you increase the airflow through the HFM your DME will properly measure the airflow increase and add fuel as required. In it’s maps it says for ‘A’ amount of air inject ‘X’ amount of fuel. Because the metering is accurate you are running at the proper air to fuel ratio.

Now what happens if you put on the intake that flows the same amount of air but causes turbulence at the HFM? Because the HFM only samples a small part of the airflow if the airflow through the HFM is turbulent the HFM will NOT properly meter the mass of air flowing through it and the DME will inject fuel based on the INCORRECT metering. You could end up running richer or leaner depending upon which direction the metering was off. The DME reads that you are taking in ‘B’ amount of air so it injects ‘Y’ amount of fuel. Since you are actually injesting ‘A’ amount of air (it was just mis-metered by your HFM because of turbulence) you should be injecting ‘X’ amount of fuel. But because it is in fact injecting ‘Y’ amount of fuel you are NOT running at the proper air to fuel ratio.

So, what can you do about this? Either smooth out your airflow for proper metering OR add a ‘correction’ (re-calibration) into the DMEs maps so that when it meters ‘B’ amount of air (still actually flowing ‘A’ amount) it in fact injects ‘X’ amount of fuel. This would result in you running at the proper air to fuel ratio.

If you ran that ‘correction’ on a car that meters its air properly (say a stock airbox, or an intake with smooth airflow that metered properly) you would end up running at the wrong air to fuel ratio. Hence, ‘Stage I’ and ‘Stage II’

(Q) What is laminar airflow and why is that important to your HFM?

(A) This is an attempt to explain it, not the best example but it was all I could think of. Picture six lines of people all running parallel to each other waiting to get on a subway.

Subway

A B C D E F

A B C D E F

A B C D E F

A B C D E F

A B C D E F

A B C D E F

A B C D E F

A B C D E F

RULE: When lines C and D move forward 1 person lines B and E move forward 1/2 a person and lines A and F move forward 1/4 of a person. Knowing this and starting at the front of the lines by watching the people in any single row (A,B,C,D,E or F) you can determine how many people total have gotten on the subway. For example if the first person from row A just got on the subway you can calculate that a total of 14 people have boarded the train. You use a small sample to determine the total knowing the ‘flow’ characteristics. This is what your HFM does but for air mass flowing into your engine.

(Q) Will I really feel the difference? Can it really work that well for so little money?

(A) Yes!!!

I have a very hard time convincing people that this works as well as it does. I’ve never heard from a person that has done it and not been thrilled at the difference. Above 5000 rpm it feels like a totally different engine. Now your engine pulls HARD all the way to redline. You might even hit the rev limiter a few times while you get accustomed to the difference.

(Q) Do you really think BMW screwed up on the airbox design that much?

(A) I think they met their design goal, so in that sense they didn’t screw up at all. Their engineers had to make a compromise between noise and airflow. The stock airbox acts like a ‘muffler’ for intake noise. Just like any other muffler this limits airflow somewhat in the pursuit of reduced noise. The Fogged mod is sort of like putting on a straight pipe for your intake. It lets air in easier but it also lets intake noise out easier. Under acceleration you will get a little bit of an intake roar but it sounds great and is perfectly appropriate in a sports car.

(Q) What do you get out of all of this?

(A) Besides the satisfaction of helping out other M44 Z3ers, nothing. 😉 To that end if you do Fogg your airbox please e-mail me or preferably post a message on the Z3 message board with your opinions on it.

(Q) But xxxx tried a K&N and noticed a huge difference in performance, why?

(A) Most of the people I’ve talked to that tried a K&N decided to give it a try when it was time to replace their paper filter. The reason they felt the increase in performance wasn’t from the K&N itself but because their paper filter was clogged and needed to be replaced. If they had just put in a new paper filter they would have felt the same thing. I replace my filters every 8-10k miles, I can tell when they need to be replaced as my gas mileage starts to drop.

Photographs courtesy of Rich Carlson, Robert Leidy and Tom Mosteller, thanks guys!

The Fogged airbox is copywritted by Shawn Fogg and is for individual use only.

Discuss this article and other Performance upgrades in the

///MZ3.Net discussion forum.

Dissecting the M Air Intake Box

Turns out the air intake box on the M roadster is slightly different than the air intake box on the 2.8 liter Z3. The difference stems from the fact that the M roadster has an additional air intake “snorkel” that is connected down to the hole on the front bumper where the 2.8 liter Z3 fog lights are installed.

I was curious to see how BMW redesigned the air intake box to account for this additional air intake. Dissecting the M air intake box might also be informative to 2.8 owners who are looking to increase the airflow to their roadsters. It appears you could even retro-fit the M air box into a 2.8 and install your own snorkel, but I’ll let a 2.8 owner try that one.

First step was to remove the air filter so I could see inside the box. Two plastic clips hold the filter housing in place. After the clips are unclipped, the entire filter housing slides out (FYI: this is also how you replace the filter). I believe I’m still on my factory filter and have over 11,000 miles on my M roadster. The filter still looks fairly clean, but I knocked some dust off since I had it out anyway.

Once the filter is removed you can look into the wide slot on the top of the air box. The following pictures are of inside that open slot, but because it is dark in there it is difficult to make out what you will be seeing. Just remember you are looking down into the now open slot where the air filter used to be.

First notice the debris that had accumulated in the air box. It was mostly sand and dirt, but I did find one pebble about 5/6th the size of a dime (guess this is why we have air filters). But the important thing to notice in this picture is the tube inside the air box. This tube is what carries air INTO the air box.

Getting the camera positioned just right, you can actually find the right angle and see down into the air box, through that air tube, down the snorkel, to the bumper and catch some daylight. I’m sure this is probably the path that nearly dime sized pebble took, but the point is it is also the path that a LOT of air took.

The other air intake position is just to the left of the driver’s side headlight. Although this area is not directly exposed behind the kidney grill on the hood, it is pretty close and should catch a lot of incoming air. This air intake is identical to the air intake on the 2.8 liter Z3, although in the 2.8 it is the sole air intake. In the M this intake works in addition to the other one. They are both connected to the air box via the same tube I showed you inside the air box (so there is a “Y” connection somewhere just outside the air box).

Looking back in the air box (remember the air filter is removed in this picture) you can see a second tube that would normally be on the other side of the air filter. This tube moves air from the air box into the engine. Just out of frame but to the right of this picture is a air flow meter that monitors the airflow and passes the information onto the roadster’s CPU.