BMW Performance Tips: E30 M3, E36 M3, M5 Series

E30 M3 1987 - 1991

Maintenance

Areas of the E30 M3 to keep a close eye on are:

• Intake manifold gaskets: The gaskets are fitted between the intake manifold and the cylinder head. Due to the vibratory nature of the S14 engine, in time the gaskets will leak, causing a rough idle. The gaskets are especially prone to leaking if the intake manifold bracket was removed (as sometimes happens when a sloppy mechanic replaces a starter motor).
• Front subframes: If motor mounts are not replaced at specific mileage intervals, the motor mounts eventually fail, causing the engine's considerable vibration to be transmitted undampened to the mounting point of the subframe. The subframe develops cracks radiating away from the motor mount stud hole. If the cracks are not repaired in time, steel is torn away, resulting in a large hole, and an unsupported engine. Stress cracks generally show up first on the passenger side mount, since the S14 engine naturally leans to the right, putting more stress on the right side motor mount. The best solution to this problem is to have a knowledgeble shop weld reinforcing steel in key areas of the subframe before the cracks develop. However, motor mounts will still need to be changed on regular service intervals.
• Cam chains and tensioners: S14 cam chains and cam chain tensioners can become unreliable after 100,000 miles. In some instances, the cam chain or the tensioners can break apart, resulting in complete devastation of the motor's internals.
• Transmission shift shaft seals: Shift shaft seals usually seep lubricant after 50,000 miles or so.
• Driveshaft flexible couplings: Driveshaft flexible couplings deteriorate over time and should be replaced at the first indication of wear.
• Rear subframe bushings: Rear subframe bushing become noisy when they wear. If the bushings are not renewed, eventually unwanted changes in the rear suspension geometry will result, and poor handling.
• Service indicator light: The service indicator light on the instrument cluster should not be trusted. A nickel-cadmium battery powers the service indicator light. If the light is unlit after the service mileage has come up, then it is highly likely that the battery has failed. Also, it is not recommended that only a new battery be soldered in. It is best to replace the light's circuit board.

Modifications

• Exhaust Cam Sprocket: Installing the cam sprocket from an Evolution 3 M3 will improve low-end engine response and the transition to top-end power will be smoother. This is possible because the Evo.3 exhaust cam sprocket is designed to retard the exhaust cam timing by 3 degrees. Overall, a small amount of top-end performance is sacrificed, but it's a good trade off for a broader powerband.
• Rear Shock Tower Plates:
The rear shock tower plates/reinforcements from the BMW Z3 can be installed on the E30 M3. The reinforcement plates dampen the forces that are produced during shock rebound. In stock form, there are only two small washers acting to spread out the stress generated by the shocks. Stress concentration on the shock mounting points could lead to eventual fatigue cracking of the towers. The Z3 reinforcement plates alleviate the stress by spreading out the load during shock rebound, as well as in compression. The part number for the Z3 rear shock tower reinforcement is: p/n 51 71 8 413 359
• S50/S52 Timing Chain Tensioner Conversion:
The S50/S52 timing chain tensioner from an E36 M3 has a much stronger spring, and it simply screws right into the cylinder head. The result is a reduction in timing chain rattle on cold start ups (when oil pressure is low). Additionally, the S50/S52 tensioner has a double-piston design which produces a "rising rate", so increasing force can be applied to the timing chain tensioner under high RPM conditions, where it is most needed.
• M Roadster Differential Cover Conversion:
The fins on the M Roadster differential cover are longer to help lower operational differential temperatures. The differential cover simply bolts right into place and costs about $140 from a BMW dealer. The part number for the M differential cover is 33 11 2 228 335. Also required is the differential gasket: part number 33 11 1 210 405, and two crush washers: part number 07 11 9 963 355.

E36 M3 1995 - 1999

Modifications

• Performance Software:
The stock M3 is tuned/programmed to handle average driving conditions. The Engine Management System (EMS) can be reprogrammed to deliver higher torque, smoother power curve (broader powerband), and higher rev limit with the change of a EPROM chip (on the 1995 M3 only). The 1996 and up model M3s require a software flash upgrade to the on board computer (not a simple chip installation like the 1995 M3). Either the whole car or the EMS must be sent to a performance shop so that they can download the high performance map to the EMS via the service data port.
• Exhaust System:
On an otherwise stock engine, the performance gains will be slight. However, for drivers that really like to hear their engine, it is a big audio improvement. Also, an aftermarket exhaust system will most likely be lighter, and made out corrosion resistant stainless steel (should last the life of the car). To experience bigger performance gains from the free flowing exhaust you will need a free flowing intake system (see below). In other words, you need a balance between intake and exhaust.
• Intake System:
Installing a K&N filter is a very common and simple modification. These filters are less restrictive, allowing more oxygen to enter the intake system, improving combustion, resulting in more horsepower from the engine. The gains like the aftermarket exhaust system are modest, but the cost to install a K&N filter is low. The intake system will be a bit louder, but some drivers like the increased intake sound, and others do not. Something to keep in mind is that an intake system that pulls air from under the hood will be less efficient than a cold air system, which pulls cooler air from under the car. Hot air is less dense, therefore, combustion efficiency is decreased. The drawback to a cold air system is that they are not legal in every state, and they can take in water in flood prone areas. Water/liquids do not compress like gasses, so a gulp of water in your cylinders will destroy your engine (cracked pistons, bent or broken connecting rods, twisted crankshaft, blown head gasket, cracked block, etc.).
• Cooling System:
In general, cooling systems are not a BMW strong point. The M3 series is especially prone to water pump failure (shattered impeller: the pieces lodging into water jackets and the radiator - expensive to correct). As a result, it is very important to keep your eye on the engine temperature gauge. If the gauge needle creeps above half, then pull over (safely) and have the car towed to an experienced/authorized mechanic to diagnose the problem. Installing an oil cooler from the BMW Euro spec car (includes a new oil filter housing with hook-ups to run a loop to a small oil cooler radiator. Special ducting is also included to channel airflow from the front spoiler to the oil radiator) will help the car stay cool, but it will not make up for a faulty water pump or other cooling system problems.
• Underdrive Pulley:
The underdrive pulley replaces the stock engine crank shaft pulley that drives the accessories (air conditioning, water pump and alternator). The pulley has a slightly smaller diameter and is made of lighter material (aluminum). The smaller diameter will drive the accessories at slightly less speed. This all adds up to less parasitic drag on the motor, and more power is put to the rear wheels, instead of to the accessories. The extra horse power is available throughout the power band. It is best not to use an underdrive pulley in conjunction with a lightweight flywheel. A harmonic balance problem can turn up that can cause the crank shaft to fail.
• Suspension:
Replacing the shocks and springs for a lower and firmer ride is a common modification, but you will need to take care over speed bums and steep driveways. Coil Over springs can be adjusted (where the stock McPherson suspension is non-adjustable) to raise or lower ride height, but remember that your wheel camber will go more negative as you lower the car. Too much negative camber, and your tires will hit the struts. Also, the 1996+ M3 has different suspension parts than a 95 M3, so keep that in mind when ordering parts. A nice addition is a strut tower brace to minimize tower flex due to the unibody construction.
• Brake System:
The M3 brake systems are excellent and sufficient for daily hard driving. Floating and slotted rotors with big calipers are an option for extreme braking power. Also, stainless steel brake lines are a nice improvement to the stock brake system. Be sure to check wheel to caliper clearance due to the large size of the calipers. In some cases, spacers on the hubs are required to provide clearance for the top and front of the caliper.
• Transmission:
Stiffer transmission mounts can increase your shifting precision (reduce the chance of a missed shift). Some modification will be needed to enlarge the mounting holes on the E36 gearbox tabs and cross brace by about 1mm.

M5 (E28, E34, E39)

Modifications

Many of the same modifications available for the M3 series are also available for the M5 series. The basic modifications include:

• Engine Management Software/Chip:
Depending on the program of chip, gains of 20-40 horsepower, and an additional 30-40 lb/ft of torque can be expected.
• Cam Sprockets:
Typically, these cam sprockets retard exhaust and intake cam timing, or retard the exhaust cam timing and advance the intake cam timing. In effect, this set up increases valve overlap for better low-mid range power (power that you can really use, since most people do not spend much time near the redline anyway). Gains of up to 55 horsepower are possible depending on how much valve overlap is present.
• Intake Systems:
A simple drop-in filter like a K&N OEM replacement filter will result in a couple of horsepower increase. A cold air system that draws air in from under the fron of the car will produce more power (5-10 horsepower, depending on other modifications). Most of the cold air systems use a K&N cone-style filter, which can be cleaned and re-used.
• Exhaust System:
Aftermarket exhaust systems seem to improve sound more than anything else. Another benefit is that most are constructed out of Stainless steel, so they should last the life of the vehicle. Depending on the state of tune of the engine, gains from a free flowing exhaust system will be in the range of 5-20 horsepower.

BMW Codes

BMW Acronyms	Translation
BMW	Bayerischen Motoren Werke (or Bavarian Motor Works)
C	Coupe
CS	Coupe Sport
CSi	Coupe
CSL	Coupe Sport Lightweight
M	Motorsport
S	Sports or Special
Ti	Touring International (twin Carb.)
Tii	Touring International, Injected
X	Four-wheel drive
SA	Special Model
L	Long wheelbase
i	Fuel injection
BMW Engine Codes	Translation
	Z8 V8 M motor
S70	5.6 liter V12
S65B50	5.0 liter V10
S62	V8 4.9 liter M5 motor
S54	3.2 liter I6
S52 B32	Euro spec. 3.2 liter motor
S50	3.0 liter "M" I6
S14	M3 4cyl. 16 valve
S38	New version M88/3 for M5 and M6
N62	3.6-4.4 liter V8
N42	1.8 - 2.0 liter I4
M102	745i turbo engine
M88/3	M1 street motor and early M6
M88/2	M1 Group 4 race motor
M88/1	M1 Group 4 race motor
M88	M1 24 valve DOHC motor
M73	5.4 liter V12
M70	12 cyl. motor
M67	3.9 liter diesel V8
M60	V8 motor 3.0-4.0 liter
M54	3.0 liter I6
M52 B32	US spec. 3.2 liter M3 motor
M50	New small 6 cyl. 4 valve motor
M44	1.6 - 2.0 liter I4
M43	1.6 - 2.0 liter I4
M42	1.6 - 1.8 liter I4
M40	1.6 - 1.8 liter I4
M30	Big 6 cyl. 2.8-3.5 liter
M21	Diesel motor
M20	Small 6 cyl. 2.0-2.7
M10/M12	4 cyl. 1.6-2.0 liter motor
M06	2.5 - 2.6 liter I6
BMW Chassis Codes	Translation
Z8	Z series V8 M motor 2001-current
Z4	Z series 2003-200?
Z3	Z series 1996-2002
Z1	Z series 1988-1991
M1	M series supercar 1975-1981
E90/91	5th generation 3 series 2005-200?
E87	1 series 2004-200?
E83	X3 SAV 2004-200?
E70	2nd generation X5 2007-200?
E65/66	4th generation 7 series
E63	2nd generation 6 series
E60	5th generation 5 series 2004-200?
E53	BMW X5 SAV years 2000-200?
E46	4th generation 3 series 1999-2004
E39	4th generation 5 series 1996-2003
E38	3rd generation 7 series 1995-2001
E36	3rd generation 3 series 1992-1999 (including Z3 series 1996-2000)
E34	3rd generation 5 series 1989-1995
E32	2nd generation 7 series 1988-1994
E31
8 series 1991-1997
E30	2nd generation 3 series 1984-1992
E28	2nd generation 5 series 1983-1988
E26	M1 1979-1980
E24	6 series 1977-1989
E23	1st generation 7 series 1978-1987
E21/5	1st generation 3 series 1.8 motor 1980-1983
E21	1st generation 3 series 2.0 motor 1977-1979
E12/6	1st generation 5 series 3.0 motor 1975-1978
E12/5	1st generation 5 series 2.8 motor 1979-1981
E12	1st generation 5 series 4cyl.
E10	2002 turbo 1973-1974
E9	2.5-3.0 CSi/L 1968-1976
E6	1600-2002 Tii 1967-1974
E3	2.5-3.3 Li
Type 121	2000-2000Tii
Type 118	1500-1800 Tii
Type 114	1602-2002 Tii