|Pros:||Fairly easy to replace, same wattage, brighter light, whiter light|
|Cons:||Can’t see more any more road, same coverage area as stock bulbs|
I’ve always been unhappy with the headlight performance on my 1998 M roadster. The brightness of the headlights was okay but the light coverage area was terrible. BMW has apparently designed the headlights with more concern for oncoming traffic than the Z3 driver. There is a dead space (I call it the black hole) that is just left of center. The problem is that if I was driving on a road that was turning to the left (like in the picture above) the black hole ended up being RIGHT in the middle of the lane I was trying to drive in. I’ve never been comfortable driving my car at night because of this. Even after repeated attempts to adjust the aiming of the headlights I still wasn’t comfortable with the results. Not knowing what else to do, I decided to start throwing money at the problem and see if that would fix it.
PIAA makes replacement headlight bulbs (model number 9006) that are the same wattage (51 watts) as the stock Sulvania bulbs, but claim to produce brighter, whiter light without producing additional heat. The pair of bulbs cost a hefty $70 but my frustration with the stock headlights made the purchasing decision easier to swallow. I waited until after dark and then drove the roadster to a dark road so I could take before and after pictures. Replacing the bulbs wasn’t simple, but only took about 10 minutes for each side (picture to the right was taken after upgrading only the left side). It would have been a lot easier if I had tiny hands, but the PIAA instructions repeatedly warned about not letting anything touch the bulb so it was difficult to maneuver everything in the tight space. (I’m sure working on a dark road also made it more difficult but it was necessary for this article.
After getting both headlight bulbs replaced my first reaction was “Wow”. But then I took a longer look and went back to my before and after pictures to confirm my suspicions. I think everyone will agree that the PIAA bulbs are whiter and brighter, but if you look at the pictures closely you will notice that the PIAA bulbs don’t light up any additional area, which is what I really intended to do with this upgrade. So now I have brighter and whiter headlights, but my roadster really isn’t any safer to drive at night.
|Pros:||Reduced shift throw, solid shifts (no “play” in linkage)|
|Cons:||Requires some crawling on the ground if you don’t have access to a lift|
|Cost:||List price: $300 (from UUC motorwerks)|
The UUC motorwerks M roadster/coupe short shift kit comes with all the parts you need to reduce the shift throw of your M roadster or coupe by 15-20%. The kit includes a replacement M roadster shifter lever with a custom bend in it, a CNC machined adaptor to mate the shift lever to the shift selector rod, all clips, pins, washers, and lubricant needed for the installation, replacement Delrin bushings for the shift carrier, and a special tool for removal of the shifter cup.
The kit also comes with a 17-page booklet detailing every aspect of the installation. The instructions are detailed, but it is wise to take some time to familiarize yourself with all the different terms used before beginning, and to constantly go between looking at the parts on the car and the pictures and descriptions in the booklet. If you don’t know what all the parts are (I didn’t when I started), it may not be immediately obvious what the “carrier” is, for example.
Besides all the parts in the kit, you will need some tools. An 8mm hex bit or 8mm allen hex wrench is absolutely necessary. You will also need some blue “Loctite” threadlock. A small hammer may be necessary to tap some things into place, and a flashlight is a must. A large flat-bladed screwdriver is needed, and snap ring pliers (tips to the side, not straight out) and work gloves are recommended although not absolutely necessary (I made do without them, but having them would have made the job easier). You will also either need access to a lift (recommended if you have any chance to get your car on one) or jackstands to lift the front of the car. Two final notes before beginning: First, make sure the car is cool. You will be working all around the exhaust. Second, some parts of the installation are almost impossible without two people. For example, sometimes one person will need to be under the car, working to attach something to the bottom of the shift lever, and at that time it is very useful if you have someone else above the car to hold the shift lever in place and keep it from flopping around.
Step 1 is to remove the shift knob by pulling up on it forcefully. Be careful not to mash your nose, and also be careful not to rip loose the wires for the lighted shift knob that M roadster and coupes feature. After you have the shift knob loose, pull on the leather boot on the sides towards the center and lift the boot up. This will expose a foam insulating insert which covers the connection to the lighted shift knob.
Tug the foam insert up out of the way and unplug the connector for the lighted shift knob. You should now be able to set the shift knob, leather boot, and foam insert to the side.
If you feel like having a little fun at this point, you could try driving your car around the block using just the stub of the shift lever–the effort is noticeably increased, but you get a great Miata-like feel to the shifter. This just makes you look forward to getting the short shift kit fully installed!
Notice in the pic of the bare shift lever that there is a rubber boot around its base. Your next step is going to be to pull up on it to remove it.
Once the rubber boot is off, you can see the top of the aluminum carrier. In this is the nylon cup which holds the ball of the shift lever in place.
Now that the rubber boot is out of the way, push the shift lever to the right and look down on the left hand side of the carrier underneath it. You should see a circlip. This clip is what is holding the selector rod in place in the hole in the bottom of the stock shift lever. You can push the clip off with a screwdriver, use a pair of snap ring pliers to remove it, or push it off with a gloved hand. After removing it, remove the small yellow washer and you should then be able to push the selector rod pin out of the shift lever.
I was naive about how the shifter lever in an M roadster actually connected to the transmission. I had no idea what a “carrier” was. The carrier is a metal piece that attacnes to the top rear of the transmission and extends rearward into a rubber fitting behind the shift area. The shift lever itself has a round ball that mounts into a nylon cup which fits in the circular area of the carrier. The bottom of the shift lever is under the carrier and attaches to a selector rod which extends forward to the transmission. The UUC instructions are about to tell you to remove the nylon cup and then to remove the carrier. This is a picture of the carrier next to the car so you can realize how long it is–this will keep you from a little bit of puzzlement as you try to figure out where various clips are (that you need to remove) in relation to the shifter lever.
I’m going to fast forward a bit in the installation. The instruction booklet from UUC contained better pictures than I could take with my camera–since I didn’t have the car on a lift, I just didn’t have room to try to take any pictures from under the car. The UUC instructions clearly take you through removing the shifter cup (either with the supplied shifter cup removal tool or, in a pinch, with a pair of small screwdrivers). The instructions then take you through removing a clip/pin that attaches the front of the carrier to the top of the transmission. Take your time feeling out where the carrier ends and where this clip is. It is not immediately obvious and is hard, if not impossible, to see–you just have to feel along. The clip can be hard to pry up–as the instructions say, “some cursing and swearing tends to make the job easier”. I really recommend trying this tip, as it really works!
Once you have the carrier out of the car (see picture above of it laying next to the car), you can remove the stock rubber bushing shown already out at lower right in this picture) and replace it with the Delrin bushings shown on either side of the hole in the carrier in this picture.
Before reinstalling the carrier, you need to flip the selector rod (which is currently still attached at the transmission end) from side to side and end to end. You will need to remove a circlip from it at the transmission end just like you did at the shift lever end. Make sure to note where yellow washers are used when you take it off and put new ones (supplied with the UUC kit) in place when you reinstall the selector rod. When you take the selector rod out, you should see that in its original position, it had its pins pointing towards the left side of the car, and had a “kink” or bend in it near the transmission end, which bend “pointed” up, giving the rod a little clearance over the driveshaft. When you flip the rod end to end and side to side, you will be reinstalling it with the pins pointing to the right side of the car. If done properly, the kink will now be towards the rear of the car and will still be pointing “up”. This is important to maintain clearance of the drive shaft.
After moving the selector rod, you now need to reinstall the carrier. Again, the clip that fastens it to the transmission is going to give you fits. UUC provides a replacement clip, which you need because you will probably destroy the original clip when you remove it. Make sure to get the replacement clip snapped down all the way when you install it.
Once the carrier is back in place, you should slip the UUC-provided new nylon cup over the ball of the shift lever, slide the cup into the hole in the carrier, and snap it into place as per the instructions. Use the provided grease to lubricate the ball of the shifter before placing it in the nylon cup. Unlike the stock lever (shown at bottom of picture), the UUC lever (top of picture) has a bend in it. Make sure that the lever leans towards the back of the car, and that the bottom part of the lever is also pointing towards the back of the car.
You now will install the supplied adaptor onto the bottom of the shift lever. Note that it can be installed in one of two positions. You should install it in the 15% reduction position to match the way you have now flipped the selector rod. Continue with the instructions to attach the selector rod to the adaptor.
Back to the rubber boot–after you have the shift linkage reassembled, and you have tested your way through the gears, you need to reinstall the rubber boot. The instructions do tell you to make sure to get the bottom of the rubber boot around the top “lip” of the carrier. However, they don’t say that the best way to do this is probably from beneath the car. Get your fingers up in there and tug the boot down around this lip–this is important to keep dirt from getting in the pivot point of the shift mechanism. After reinstalling the rubber boot, reinstall the foam insulation, reconnect the lighted shifter wires, and reinstall the leather boot and shift knob, all in the opposite of the order in which you took them off.
gear pair Stock
4-5 3 11/16″
3 11/16″ 3 3/16″
3 1/4″ 1/2″
7/16″ So, what is it like when you are done? I took the following measurements. In general, the UUC short shift kit reduces the throw about one-half of an inch between each pair of gears. This may not sound like a lot at first, but it certainly feels different when shifting and is a very nice change. The shifter feels like it should have come this way from the factory.
The animation below shows the stock shifter on the left and the UUC shifter on the right. This gives you some idea of what it is like to shorten your shift throw the UUC way.
All in all, I recommend the UUC short shift kit. The installation is difficult for a first-timer, but having been through it once, I think it would be much easier the second time around now that I know where all the components are and what they look like. It feels great in my car, and I have been enjoying it each day since I installed it.
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|Pros:||Performance, Exhaust Sound|
|Cons:||Not a “Do It Yourself” Install|
BabyZ wanted to get her exhaust modified for two basic reasons. One for increased performance and two, so she would sound like the high performance sports car she is. Three things hindered performance of the OEM exhaust system. First of all the OEM unit is very heavy (approximately 30 lbs.). The reason it is so heavy is that there is a lot of baffle material in it to make the engine very quiet. This results in the second performance problem that this material creates a large backpressure that reduces engine horsepower. The third problem is an additional source of backpressure in the exhaust pipe. Where the pipe goes under the rear axle it has a large kink put in it to apparently increase the clearance from what look to be quite ample with a full diameter pipe to an even greater clearance.
The kink is not easily seen in this picture of the OEM system as it is right behind the massive hangar and in front of the shinny resonator (close-up of this kink follows in a bit). The second basic desire was to hear the engine. BabyZ didn’t like being a wolf in sheep’s clothing. She’s bad and doesn’t mind anyone knowing it!
Well we have a pretty good idea why BabyZ wants new pipes now, so the next problem is deciding what to put on instead. The first requirement was the system had to be all stainless like the OEM one. In some areas this may not be as important as it was to me but with the rain, humidity and chemicals present in Houston, this was a must. This eliminated the Remus as it is not stainless, a nice sounding unit for sure, but not stainless. The stainless units available were Supersprint, B&B and Borla. With Supersprint and B&B you can get a cat back bolt on system that uses the OEM hangars while the Borla is a weld up modular system. If you want to do this all yourself, and assuming you aren’t a stainless welder, you would not be able to do the Borla. This however may not be a total disadvantage if you don’t mind letting a muffler shop in on the fun. Two reasons balance out the ability to do it yourself are the cost of the system and the sound. Borla is cheaper even after the shop install and gives more sound with a deeper tone than either the Supersprint or B&B (IMHO). Based on the extremely detailed research done by theBaba, where he determined that the Borla did make a muffler (PN 40651) that fit the system and satisfied all BMW requirements (even though they did not list the Z3 on their application list) and testing out his fine ride, Hans, this was the system decided on for BabyZ. Another advantage for BabyZ is that she could keep the resonator which was felt desirable given her automatic tranny (of course you can drop the resonator for a manual if you like).
In the photo of the OEM and Borla mufflers on the ground the difference in size is apparent, but what you see is only part of the story. The weight difference is incredible with Borla weighing in at well under half of the OEM. The smaller size should also help with heat dissipation and reduce the heat exposure to the floor of the trunk and the battery. You can also see that the inlet and outlet to the muffler line up around the centerline of the muffler exactly at the same points as the OEM so the tips will line up with the bumper cut out without any modification.
This is a close up of the infamous “kink”. It actually is more of a smash. The pipe looses fully half of its diameter to go under the rear axle and meet the BMW engineers specified clearance. This smashed pipe is eliminated in BabyZ’s new pipe. In over 2 years of operation since installing the Borla with a full diameter pipe I do not see any indication on the pipe that it has ever been hit by the axle. This includes street, cross-country, track and autocross driving.
This shows the full diameter pipe going under the axle and you can hopefully see that there is plenty of clearance. Also, a new hanger was used on the pipe and attached to the original mounting point. (Note. The second OEM mounting point on the left of the muffler was also used but the third on the right rear of the muffler was not used.)
The shop foreman fabricated the stainless steel “Y” for the dual tips. It was quite a battle to see who would get to install the muffler on BabyZ, I guess this proves that “Rank Has It’s Privileges”. The tips are Borla Turbo Intercooled (PN 20102) and are also stainless steel.
The tips are staggered at the ends to follow the contour of the bumper. This is a personal preference as theBaba and others have theirs straight across and both ways look fine. Another thing to note is that the tips are not positioned on the centerline of the opening in the bumper cover but are moved toward the right side of the opening. This was done to give the maximum room for the tips to move left as the exhaust pipe warms up and expands. This will prevent the tips from touching and melting the surrounding bumper material. The tips are also positioned close together to further maximize the safe area for tip movement.
The finished product is and all stainless steel system with the resonator left in place to compensate for the low rpm preference of the automatic transmission. The Borla is the easiest available system to customize this way and can be installed with or without the resonator (true cat back) as per your preference.
Borla is also the loudest of the systems and depending on your desires this is either a positive or a negative. One drawback is that it is the loudest at 2300 to 2800 rpm’s. This equates to 50 to 60 mph and can resonate quite a bit with the top up. There are two other things wrong with that scenario in the first place; i.e. why is the top up and what are you doing going less than 60mph for any way, so it isn’t much of a consideration for me.
Installation of the Borla resulted in a nice performance boost that was most noticeable in the low rpm range especially in accelerating. The Borla was the first performance upgrade on BabyZ so there were no other mods that could have interfered with the effect of the exhaust upgrade. Since this time the chip has been upgraded with Dinan programming and the airbox has been “Fogged”. Each of these upgrades had an additional effect and I recommend that the full trifecta be done to get the maximum effect from all of the upgrades. One interesting side effect of the addition of the airbox upgrade is that the tone of the exhaust changed and a particular resonate tone was eliminated. I take this as an indication that a definite restriction in airflow was eliminated with this upgrade and that the exhaust was happy to accommodate the additional airflow.
One other benefit is that you won’t need “no stinkin stereo upgrades” when you are listening to the sweet Z3 engine music played through a Borla.
Cost of the muffler and tips is about $300. Installation, including all the needed pipe was $100 and it took about an hour and a half even with a substantial amount of discussion and picture taking. . The Borla is made of T-304 stainless and has a one million mile warranty. Borla’s website is at http://www.borla.com.
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When I bought my ’99 2.3 in March from dealer stock there was one option missing that I would’ve ordered – fog lights. I had considered after market PIAA’s. But when BMW came out with a retrofit kit, I ordered one right away. And the installation is pretty easy, since the car is pre-wired from the fog light connectors all the way to the switch connection behind the dash.
The part # for both 1999 and 2000 Z3s is 99 00 0 001 658. The suggested retail is $229, but they are available from Circle BMW for about $161 plus shipping (www.circlebmw.com)
The kit comes with easy to follow instructions that are well illustrated. The only tools required are simple hand tools, but a hook awl is handy to remove the existing fog light mount covers. I’m not very handy with tools around the house or cars. I usually have to be retrained each time I remove or replace my Stonegards. So I got a friend to help me, and I’m glad I did. Despite interruptions for picture taking and running into a glitch or two, it took about 50 minutes from unpack to drive away.
The preparatory instructions called for disconnecting the battery ground cable, but we decided against it to keep from reprogramming the anti-theft radio.
I began by removing the plastic fog light mount covers with a small pick bent to form a hook awl. They pull out easily.
Install the silver Tinnerman clips over the fog light mount as shown with the smooth surface facing you. (LH light opening shown.)
The RH fog light connector is located behind the bumper adjacent to the receiver dryer. Pull up on the wiring harness to cut the tape holding the connector to the harness. The instructions said to secure any other connectors that were loose with cable ties (not provided) to prevent wire chaffing or interference with the A/C compressor pulley. This did not appear to be a problem so we skipped it. Then pull the connector through the opening and push the RH fog light connector into the RH fog light assembly.
Position the RH fog light assembly in the opening and press the assembly flush against the Tinnerman clips. Then secure with two of the 4.2x16mm hex head screws provided.
The LH fog light is installed in the same manner, except there was no need to secure any wires with cable ties.
To access the fog light switch connector you have to drop the driver’s side lower trim panel (knee bolster). With a small screw driver, pop off the caps that cover five M6x12 hex head bolts and remove the bolts and washers. Then push out the oval knock out panel from the alcove where the switch will be mounted just left of the steering column. The fog light switch is easy to find behind the panel and is larger than the oval knockout opening. Now came the only tricky part of the installation. I couldn’t reach the connector and hold it up against the oval opening in order to push in the fog light switch to connect it. So we strung a wire around the connector and pulled it flush with the back of the oval opening and held it while we pushed the switch in. The round switch button should be positioned on the left.
Next, reassemble the knee bolster and lower trim panel.
Under the hood, remove the cover from the power distribution box and plug in the provided relay in position K47. There should also be a 5 Amp fuse in position 22. If missing, use a spare fuse. Mine was already in place.
Functional check of fog lights is next
Turn ignition to position 2 and switch low beams on. Switch fog light switch on the green fog light indicator on instrument cluster should illuminate when fog lights are on. Then select high beams – fog lights and indicator should go out. There is a screw adjustment on each light assembly to adjust the vertical beam – no adjustment available to side.
Last step is press in the black plastic covers supplied to fill in the opening.
Note: Two things are different from the factory fog lights:
The lens is crystal clear instead of a ribbed surface. Personally I like the appearance better.
The fog lights will only come on with the low beams, period. You can’t turn them on with only the parking lights selected as the factory installation allows. That I don’t like. I suspect the relay is the problem. My service rep promised to get me an answer about this oddity. Maybe the relays are defective or maybe the factory relay can be substituted. I’ll provide an answer as soon as I find out.
This was an easy installation that any 1999 or 2000 2.3 driver could do in 45-50 minutes. You’ll save $100 over the factory lights and have a unique set of fog lights. Now, go out and shine your light!
The battery in the BMW Z3 is NOT a maintenance free battery; it needs occasional servicing. The leading cause of battery failure in the Z3 is from a lower water level. Fortunately it’s pretty easy to check the level and add more water.
The first step is getting access to the battery. For all but very early 1996 models the battery is in the trunk. You will have to raise the trunk liner and remove the plastic cover over the battery but then you will looking at the top of the battery.
Along the top of the battery are six plugs that unscrew from the battery. Remove the plugs but take care since you’ve just exposed corrosive liquid. You can look down into the battery, but don’t get to close (the water vapor can’t be very good for your eyes).
When you look down into the battery, you will see a little metal tab in each hole. The water level in the battery should be just over this metal tab. In the picture above, the battery needs water.
BMW Techs have a special water can that makes filling the battery easy and accurate, but there really isn’t anything fancy about this procedure. Richard Carlson suggested that the perfect substitute is a turkey baster. Just gradually add water and keep rechecking the water level until it covers the metal tabs. It’s best to use distilled water so no mineral deposits will be left from the evaporation of ordinary tap water.
When the battery is properly filled, the tab will still be visible, but obviously under water. Regular checking of the water level should greatly extended the life of the battery, especially during the hot summer months when the water will evaporate at a faster rate.
Update: Ron Styger reports that his 9-1-1999 build date M Coupe has a different battery. Not sure when BMW actually made the change but it is nice to see that they have a different battery now (maybe the new one will have a longer average life span).
Update: Tom Bilken sent me this note regarding the new battery (pictured above)…
I have a 1999 2.3 (build date of 3/99). I read a lot about the battery problems (low water) on the MB, and your article. When I looked at mine, it was the same as the added updated picture on the Mz3 site for Ron Stygers battery. But, under the decals on the top were the battery plugs. If you look in the picture that you posted of Rons battery, you can see the outline of one of the plugs. Mine has the “eye”, but after I peeled back the decals, and opened up the plugs, I had to add a lot of water. I just wanted you to know (and maybe you already do) that these batteries still have the plug caps, and my levels were still low.
|Pros:||Very convenient location, holds 12oz cans and slim 20oz bottles, flexibly material so its easy to install and uninstall|
|Cons:||Condensation can drip into door pocket|
|Cost:||$24.95 (from Z3 Solution)|
“Here I am driving one of the most fun automobiles in the world, yet I can’t find a good place to put this can of coke while I shift into 5th gear.” This has been a common statement ever since the introduction of the Z3. The BMW roadster is an amazing automobile, a near perfect balance of modern day technology and classic “retro” styling, but it doesn’t have a cup holder. This is where Z3 Solution enters into the story. Pictured below is a cupholder that Z3 Solution makes that snaps into the side door pocket.
This design is simple and functional, its a single piece of molded plastic/rubber material that was custom made for the Z3. The flexible material lets the unit snap into place in the door pocket. Once installed the cupholder holds standard 12oz cans and the newer styled slim 20oz plastic soda bottles. It sticks out from the door slightly more than the door pocket, so there is a slight loss of leg room. However the positioning doesn’t affect the driver, on long drives I even find myself resting the side of my knee on the soft rubber since its more comfortable than the door pocket.
I find myself using the cupholder to also hold my sunglasses and other items when I don’t have a drink in there. I needed to come up with some “cons” for this article, so I got really picky and found one. Condensation from the can ends up dripping down into the door pocket since there is no bottom to the cupholder. If you keep items other than the cup holder in the plastic door pocket they could get water dripped on them (so its not a good place to keep paper). I’ve learned to keep something like a napkin under the cupholder so this isn’t much of a problem.
Performance Exhausts for the BMW Z3
May 31, 1999
By: Robert Leidy
Inside each cylinder, the BMW Z3’s electronic control module injects a calculated mixture of air and fuel. This mixture is then ignited which produces power. However a by-product is also produced from this process which is commonly referred to as exhaust. The burnt gas fumes (exhaust) exit the cylinder and travel through a pipe commonly referred to as a header. The header pipes from each cylinder are then combined and channel the exhaust fumes from the engine into a catalytic converter. The catalytic converter is a device filled with a metallic-mesh-like filter that removes some of the pollution from the exhaust fumes. Once the exhaust has passed through the catalytic converter, it is channeled through a single pipe to an exhaust resonator, which reduces some of the sound produced by the engine. Once the exhaust has passed through the resonator it is channeled to a muffler to “muffle” additional sound from the exhaust. Once the exhaust travels through the muffler it exists the Z3 via tail pipe(s) under the rear bumper.
The theory behind performance exhausts is that each device that the exhaust fumes pass through cause resistance, which in turn increases the amount of air pressure inside the exhaust. The pressure built up also effects the cylinder because “back pressure” from the exhaust is putting additional effort on the cylinder as it is handling the next mixture of air and fuel. A performance exhaust is designed to reduce the amount of resistance in the exhaust making the exhaust flow more freely and reduce and amount of “back pressure”. In order to accomplish this, those devices within the stock exhaust that cause resistance can either be removed or redesigned to be less restrictive. However each component of the stock exhaust is there for a reason. The muffler is designed to remove sound at the cost of exhaust resistance. You can redesign a muffler to have less resistance but in general you will also be decreasing the mufflers ability to “muffle” sound. As with most things in life it is a give and take relationship. Finding the correct balance of give and take is a judgment call, so it can be different for different personal tastes.
There are varying degrees an owner can take to reduce the pressure in the exhaust and increase performance of the engine. Perhaps the easiest way is to just replace the muffler. Or for a little more performance, replace the muffler and resonator. Professional racers like Mark Hughes remove all of these resistance-causing devices. However removing the catalytic converter would keep a Z3 from being street legal (which is not a problem for the Z3 Race Team). The most common after-market exhaust systems are called “cat-back exhausts”. With the design of the Z3 these “cat-back” systems bolt right onto the stock catalytic converter and replace everything “back” from there (keeping the Z3 street legal). The new pipes are larger, the resonator is removed and the muffler is less restrictive, so exhaust can exit the engine/exhaust with less resistance. This has two effects on the Z3, it increases the performance and it makes the Z3 louder (more sound from the exhaust).
So now that we’ve covered the theory behind performance exhausts lets look at the type of decisions an owner would need to make in evaluating after-market performance exhaust systems:
Stock Engine/Exhaust Design:
The theory behind performance exhausts is that reducing the amount of pressure increases performance. So it only makes since that the amount of potential performance gain is directly related to the amount of resistance/air-pressure-buildup in the stock exhaust. In other words if the stock exhaust is very restrictive then there is a lot of potential performance gain.
Assuming that between the different Z3 engine configurations the restrictiveness of the various BMW stock exhausts components is roughly the same, we can make some general observations looking at the different designs. The 1.9 Z3 is a 4-cylinder engine, the exhaust output from all four cylinders is combined before entering the single catalytic converter. So roughly 1.9 liters of exhaust output is sent through the stock exhaust each time the gas inside the cylinders is ignited.
Compare that to the 6-cylinder 2.8 Z3, which has the exhaust output from all six cylinders combined before entering the single catalytic converter. So roughly 2.8 liters of exhaust output is sent through the same pipe. Comparing these two it would appear that the 2.8 would benefit more from a performance exhaust than the 1.9 would since 47% more exhaust is traveling through the exhaust.
To continue the comparison, the 3.2 Z3 is also a 6-cylinder engine. However the exhaust output is split in half, the output from three cylinders is sent to the first catalytic converter, with the exhaust output from the other three cylinders is sent to a second catalytic converter. The exhaust output from each half is never mixed so in reality the each exhaust is only handling 1.6 liters of exhaust output. Comparing this output it would appear the 3.2 engine would benefit the least from an after-market exhaust.
There are also differences in the type of metal used in exhaust systems, the big differentiation is it, or is it not stainless steel. The big advantage to stainless steel is its durability. If you live in an area where salt is used on roads then you know that rust can eat up car parts. For these areas stainless steel will last a lot longer so the increased price is easily justified. The other advantage to stainless steel is that it conducts 2/3 less heat than mild steel, which helps to keep temperatures in the exhaust to a minimum. However stainless steel also expands 40-45% more than mild steel when heated so fitting a stainless steel exhaust is slightly more difficult. (The stock exhaust system is not stainless steel).
Choosing exhaust tip style is usually a 90% cosmetic decision. However the type of exhaust tips also effect how the exhaust will sound. If the exhaust tip is angled up the sound will generally be louder, if the exhaust tip is angled down the sound will generally be quieter. Most exhaust tips point straight back just like the stock exhaust does.
In the United States, five different engine configurations have been built in the Z3:
M44: model year 1996-1998
The M44 1.9 liter engine was the first Z3 sold in the United States. Several companies make performance exhausts for this Z3. However this engine configuration is no longer being made for the US market so it is doubtful that any additional aftermarket performance exhausts will be added to the list.
M52: model year 1997-1999
The M52 2.8 liter engine was the second Z3 engine configuration to be sold in the United States. Several companies make performance exhausts for this Z3. However this engine configuration is no longer being made. BMW now has a new M52TU 2.8 liter engine that is different in design, so exhausts for the M52 Z3 will not work on the M52TU Z3 and via-versa.
S52: model year 1998-2000
The S52 3.2 liter engine was the third Z3 engine configuration to be sold in the United States. Several companies make performance exhausts for this Z3 (officially called the M roadster and M coupe).
MXXTU: model year 1999-2000
The MXXTU 2.3 liter engine is the forth engine configuration to be sold in the United States. MZ3.Net does not know of any M52TU Z3 “cat-back” performance exhaust systems at this time.
M52TU: model year 1999-2000
The M52TU 2.8 liter engine is the most recent engine configuration to be sold in the United States. Supersprint is the only company that MZ3.Net has heard that currently has a cat-back exhaust ready for the new 2.8 liter engine. Supersprint’s part numbers for the new exhausts are 78.67.06 or 78.67.66. I assume the two different numbers are for different exhaust tip options.
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|Pros:||Protects the fragile paint on the Z3. Hard to detect from a distance of 4 or more feet.|
|Cons:||Moderately hard installation|
|Cost:||Contact XPel at http://www.xpel.com/ or 800-447-9928|
|The Days Events
The BMW Z3 is painted with EPA backed “environmentally friendly” paint. The makers claim that the new paint is less susceptible to fading and oxidation, but an apparent downside is that the new paint is much more brittle. While BMW has never openly admitted this, the evidence is overwelming. Rock chips are appearing on nearly all BMW Z3s and there really isn’t a solution to stopping them. While owners can’t win the war in the long run they can protect themselves and prolong the life of their paint using a product developed by 3M.
3M makes a thin clear layer of protective film which can be applied directly over the paint. With this protective layer of clear skin the Z3 has additional protection against rock chips. It appears 3M decided to not market this new product directly to consumers but rather they offered the product to vendors that could make custom kits specifically made for certain vehicles. This is where X-Pel enterers the picture.
X-Pel has kits made for the Z3 and M roadster that fit over the more vulnerable areas on the Z3. The front bumper and front 1/3 section of the hood are the most frequent places where the chips occur. The X-Pel kit covers all this area. In addition X-Pel also offers additional (optional) kits for the headlights, foglights, rearview mirrors and rear fender flares.
Installing the kit requires patients and lots of water. The Z3 is watered down with soapy water so the thin layer can me float and move easily during the fitting process. A Squeegee is then used to press the film against the paint and remove the water from under the film. With the film in direct contact with the paint it adheres to the surface and stays in place. The film itself is not water tight so any remaining water trapped under the film eventually evaporates.
Once installed, the thin layer can be seen on close inspection, but its difficult (you have to be looking for it). From a distance of four or more feet the kit can not be seen. On closer distances it is possible if you look for the edges. Occasionally you can catch it at the right angle and see the difference in refection. I stood over Larry’s car for several minutes trying to find that “just right” angle to show this to you in a picture. In the picture on the right you can see a flatter and slightly more yellow tint from the covered area. The yellow tint is really more of trick of the camera than an actual trait of the X-Pel kit. To the naked eye I never saw this yellow tint (sometimes cameras see things we don’t).
X-Pel said that once applied, wax and wash the car the same as you usual. Except you should take a little more caution around the edges so you don’t get wax buildup on the leading edge of the kit. The expected life of the kit is four to five years.
The Z3 club in Texas had a gathering in Dallas that didn’t involve driving but rather car care. The club invited X-Pel to come along and demonstrate the kit. By the time the event was over X-Pel had installed their kits on several Z3s and M roadster and each owner was pleased with their purchase.
|The Days Events
It all started with a casual conversation at the conclusion of the Texas River Run drive. I made a comment to Rory that we should have a non-driving Z3 get-together, maybe a Z3 fix-it day or something. One thing led to another and eventually we came up with a paint chip fixing day. We contacted a paint touch-up guy that Moritz BMW recommended, and a company that sells and installs invisible bras. Unfortunately, we had to limit the guest list because we could only handle so many Z3s at Rory’s house. Priority was given to Z3 owners that live in Dallas, however I bet there will be future events similar to this one so others can attend.
This has got to be a record. Click on the picture to the right for a larger view of 11 BMW Z3s parked in one Z3 owner’s driveway. There were actually 12 Z3s at the event but Phil left in his Boston green Z3 before we took the picture. For fun, the Texas Z3 group would like to challenge other Z3 groups to take a picture with more Z3s in a residential (Z3 owner’s) driveway.
Fixing Paint Chips