BMW M52 Tuning

M52B20, M52TUB20, M52TUB24, M52B25, M52TUB25, M52B28, M52TUB28, S52B32

"All you need to know about tuning the BMW M52 engine!"

One engine that keeps cropping up in emails and questions we get sent is the M52, and what parts work best on it. so we've created this how-to guide which goes over what we feel are the primary areas you should tune and outline which modifications we feel are the best.

The BMW M52 makes a really good project engines and with carefully chosen sports parts like remaps, turbo improvements and camshafts you will really increase your driving fun.

Straight-six DOHC petrol engine, developed from 1994 to 2000, BMW M52. The E36 320 was the first vehicle to use it. For the 1998 "technical update" (M52TU), the exhaust camshaft was given variable valve timing (Double VANOS) to boost low-rpm torque.

For certain markets, the Nikasil-coated cylinder wall of an M52 aluminum cylinder block has been problematic due the available fuels used.

TorqueCars will provide a guide to M52 tuning and report on the premier modifications for your car.

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History, Power & Specs of the Engine

• M52B20
• 110 kW (148 bhp) at 5900 rpm 190 Nm (140 lbft)  at 4200 rpm 1994-1998
• M52TUB20
• 110 kW (148 bhp)  at 5900 rpm 190 Nm (140 lbft) at 3500 rpm 1998-2000
• M52TUB24
• 135 kW (181 bhp)  at 5800 rpm 240 Nm (180 lbft)  at 3600 rpm 1998-2000
• M52B25
• 125 kW (168 bhp)  at 5500 rpm 245 Nm (181 lbft)  at 3950 rpm 1995-1998
• M52TUB25
• 125 kW (168 bhp) at 5500 rpm 245 Nm (181 lbft) at 3500 rpm 1998-2000
• M52B28
• 142 kW (190 bhp) at 5300 rpm 280 Nm (210 lbft) at 3950 rpm 1995-1998
• M52TUB28
• 142 kW (190 bhp) at 5500 rpm 280 Nm (210 lbft)  at 3500 rpm 1998-2000
• S52B32 
• 179 kW (240 bhp) at 6000 rpm 325 Nm (240 lbft) at 3800 rpm 1996- 2000

Tuning the BMW M52 and best M52 performance parts.

Best M52 upgrades

The best M52 mods on an engine are typically the ones that give the best power gain for you spend.

We won't be swayed by popular M52 mods, they need to be cost effective.

Altering your M52 camshaft will make a dramatic difference to the engine engines power. Choosing a higher performance camshaft profile raises the engines power accordingly.

Fast road camshafts normally increase the power over the rev band, you could drop a little low end bhp but the higher rpm power will be lifted.

High-rpm power is increased by using race camshafts, but the car's idling and low-end performance suffer as a consequence.

The lumpy idle of a Race camshaft will make the M52 prone to stall, and smooth driving at low rpm becomes impossible with a Competition camshaft. A track car's high RPM range is where you want the power to come from, so it doesn't matter what you do with your RPM range low down so choose your cam depending on your requirements and usage of the car

You should ideally match your bhp range to your cars usage so for a road car stick with a fast road M52 camshaft

Each engine responds better to more aggressive cam durations check your engine on a rolling road.

The engine timing and fuel pump and injectors also will say much on the torque gains you'll hit.

Longer valve durations can alter the torque band and on most engines the exhaust and intake durations do not need to match, although most cams and tuners use matched pairs there are some advantages to extending the intake or exhaust durations.

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Best mods for your M52

1. Flywheel lightening - a reduced weight flywheel will improve the engines rev changes. But not always suitable for all M52 engines.
2. Engine Tunes - A tune/remap offers the most advantage for the money, replacement ECUs, and piggyback ECUs are all alternatives.
3. Forced induction upgrades - forced induction is the most efficient approach to improve intake air supply, this means you are able to use more fuel and make higher power. It is one of the most costly upgrades but provides the best gains.
4. Intake Mods and Performance Exhausts - NB: on their own these mods won't ADD POWER on most cars, but they can help enhance power after other mods by freeing up a restriction.
5. Internal engine mods - crank, pistons, conrods & compression ratio including balancing and blueprinting
6. Fast road cams are significant power adders, but they must be installed by someone who knows what they are doing and tracking one down may be hard but there might be a local firm to regrind a stock cam .

M52 Tuning Stages

Typical stage 1 mods often include:
Sports exhaust header/manifold, drilled & smoothed airbox, Fast road camshaft, Panel air filters, Remaps/piggy back ECU, Intake manifolds.

Typical stage 2 mods often include:
induction kit, Sports catalyst & performance exhaust, Ported and polished head, Fast road cam, fuel pump upgrades, high flow fuel injectors.

Typical stage 3 mods often include:
Twin charging conversions, Competition cam, Engine balancing & blueprinting, Internal engine upgrades (head flowing porting/bigger valves), Adding or Upgrading forced induction (turbo/supercharger), Crank and Piston upgrades to alter compression.

Mapping will help release the full potential of all the upgrades you've fitted to your M52.

(In some cases, as the factory ECU is locked flashing is not an option, so an aftermarket ECU is the route to take, and many of these will outperform factory ECU's but make sure it has knock protection and that you get it setup properly.)

Turbocharged cars typically get approximately 30 percent more power, while NA (naturally aspirated) engines may anticipate to gain around 15 percent, depending on the improvements you've installed and the state of your engine.

In any engine-tuning endeavour, the goal is to push more gasoline and air into the M52's combustion chamber

To begin the squish phase, gasoline is introduced into the engine cylinders via the intake plenum, which transfers air from the filter to the intake valves & engine.

The M52's Intake manifolds may have a significant impact on fuel atomization and engine performance by altering their structure and flow rate.

I've found that headers can be enhanced using racing components, however certain vehicle manufacturers do provide excellent headers and BMW did a good job on the M52.

The amazing byproduct of installing an M52 bigger valve kit and improving port and head flow is the ability to add even more torque to other improvements.

Turbo upgrades for the M52

M52B20, M52TUB20, M52TUB24, M52B25, M52TUB25, M52B28, M52TUB28 & S52B32 Turbocharger Mods

NA (naturally aspirated) engines need quite a lot of work when you add a turbo, so we have a separate guide to help you take into account the pros and cons of going this route on your M52

The more air you can get into an engine, the more fuel it can burn and uprating the induction with a turbocharger upgrade makes massive power gains.

If an engine is fitted with a turbocharger parts are relatively easy and we find turbo charged engines will have harder and stronger components.

However engines will need better parts at higher power limits

We recommend you find these limitations and upgrade to higher quality crank and pistons to utilize the power.

We see many people spending a fortune on turbo charger upgrades on the M52 only to suffer the humiliation of seeing the car explode when it's been finished.

Larger turbo units commonly experience low end lag, and little turbo units spool up quickly but do not have the high rpm engines power gains.

Thankfully the market of turbo units is always moving on and we now see variable vane turbo units, where the vane angle is altered according to speed to lower lag and increase top end bhp.

Twin scroll turbo units divert the exhaust gases into two channels and flow these at differently profiled vanes in the turbo charger. They also increase the scavenging effect of the engine.

It is common that there is a limitation in the air flow sensor AFM/MAF on the when loads more air is being pulled into the engine.

We note 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor limited performance at a much lower level.

Adding a supercharger or additional turbo will make large power gains, although harder to configure. We have this in depth look at twinchargers if you want to read more.

M52 Fuelling Upgrades

You will need to ensure that the engine is not starved of fuel so will have to pay attention to the fuelling when you start extending past 20% of a performance increase.It makes sense to over specify your injectors flow rate.

As a rule of thumb add another 20% when fitting an injector, which takes into account injector deterioration and allows some spare capacity should the engine require more fuel.

We think this one is common sense, but you'll need to match your fuel injector to the type of fuel your car uses as well.

Exhaust Upgrades for the M52

You only need to upgrade your exhaust if the current exhaust is creating a flow problem.

On most factory exhausts you'll see the flow rate is good even on modest power gains, but when you start pushing up the power levels you will need to get a better flowing exhaust.

Sports exhausts can help increase the flow of air through the engine.

But if your exhaust pipe is too large, ie: it's over 2.5 inches bore, you will lose much of the exhaust flow rate and end up losing power and torque.

Usual exhaust restrictions are traced to the filters installed, so adding a faster flowing sports alternative is the answer. This keeps the car road legal and will flow much better due to it's higher internal surface area and design, so has the added benefit of keeping your car road legal. The alternative decat should be considered an off road only mod, as removing a catalyst is illegal in most territories and regions for road registered cars..

Weak spots Issues & problem areas on the M52

These engines generally prove to be reliable and solid as long as they are regularly serviced and maintained.

Carbon build up in the head, particularly around the valves which will sap power or create flat spots, this is a larger issue on direct injection engines but should be looked out for on all engines. We have tips on removing carbon build up.

Some of our members have had issues with flat spots or glitches after applying mods and upgrades or tuning, this is not usually related to this engines design, so instead see our article on diagnosing flat spots and problems after tuning which should help you get the bottom of this issue.

Nikasil Problems were reported on the M52, so please read up on our Nikasil guide.

Keep an eye out for overheating, this will kill the engines if allowed to run away and the fault should be addressed as a matter of urgency.

Water pump failure is a common problem with the plastic vanes which brake off the spine. Another weak area to check for overheating issues are leaks in teh expansion tank and radiators.

Regular oil changes are vital on the M52, especially when tuned and will help extend the life and reliability of the engine.

If you would like to know more, or just get some friendly advice on Tuning your engine please join us in our friendly forum where you can discuss tuning options in more detail with our owners. It would also be worth reading our unbiased tuning articles to get a full grasp of the benefits and drawbacks of each modification.

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This article is flagged for an update, so please pass on specific tips below that I can include. All articles, and content was written by me, Waynne Smith TorqueCars founder. Some outlines are just too general so I appreciate your feedback and suggestions. This entry was filed under BMW. You can leave a response below or join our forum to discuss this article and car modification in detail with our members.

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