Tuning the BMW M30

"Comprehensive guide to tuning the BMW M30 engine!"

The BMW M30 are fantastic to work on and with the best tuning upgrades like remapping, turbo kits and camshafts you will noticeably improve your driving enjoyment.

Here we look at M30 tuning and provide tips on the optimum modifications for your car.

The ultimate M30 modifications on an engine are usually the ones that give the best power gain for you spend.

We won't be swayed by popular M30 modifications, they need to be cost effective.

Significant gains on the M30 can be made from camshaft upgrades. Altering the camshaft profile alters the intake and exhaust durations on the engine and can dramatically change the engines power and power output.

NB: Fast road cams normally bump the torque through the rev band, you could drop a little low down bhp but your higher rpm power will be lifted.

Motorsport cams, bump the higher rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

A Motorsport camshaft won't do well if driving around busy urban areas.

You should ideally optimize your power band to your preferences so for a car used daily stick with a mild fast road M30 camshaft

Some M30 engines respond better to more aggressive cam durations check your engine on a rolling road.

The ECU mapping and fuel pump and injectors also have a large bearing on the bhp gains you'll hit.

Extending exhaust or intake durations can alter the bhp 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.

Stage 1 mods: Fast road camshaft, Remaps/piggy back ECU, Sports exhaust manifold, Drilled & smoothed airbox, Intake headers, Panel air filters.

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

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

 

The M30 engines respond well to mods and we're pleased to see that there are plenty of upgrades and performance parts about.

 

Mapping helps fully realize the full potential of all the tuning parts you've done to your M30.

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but your mileage will rely on the tuning parts you've fitted and the condition of your engine.

Pulling fuel and air into your M30 is the whole point to any engine performance tuning task.

Headers carry the air from the filter and allow it to be sucked into the engine cylinders.

Shape and flow characteristics of the Intake manifold can make a noticeable difference to to fuel mixing and power on the M30.

I usually find intake headers are in desperate need of an upgrade, although some OEM provide reasonably well designed intake headers.

Fitting big valve kits, doing some 3 or 5 angle valve jobs and porting and head flowing will also improve performance, and significantly will raise potential for a better performance increase on other parts.

Turbo upgrades

NASP 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 M30

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

If your car has a turbo already fitted parts are more reliable and we find turbo engines are made using many forged and stronger components.

However most engines will have power limits

It is important to find these limitations and fit more solid crank and pistons to cope with the power.

We've seen people spending a loads on turbo upgrades on the M30 only to watch the whole thing throw a rod when it's used in anger.

Larger capacity turbo chargers will usually suffer a bottom end lag, and low capacity turbo chargers spool up more quickly but do not have the peak end torque gains.

Thanks to progress the range of turbochargers is always moving on and we commonly find variable vane turbochargers, allowing the vane angle is altered according to speed to lower lag and increase top end bhp and torque.

Twin scroll turbochargers divert the exhaust gases into two channels and push these at differently angled vanes in the turbocharger. They also increase the scavenging effect of the engine.

It is common that there is a restriction in the air flow sensor (AFM/MAF/MAP) on the M30 when considerably more air is being sucked into the engine.

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

Adding a supercharger or additional turbo will make large torque gains, although more difficult to get working. We have this guide to twinchargers if you want to read more.

Fuelling upgrades and mods

Don't forget to raise the fuelling when you are increasing the bhp and torque - it makes the car more thirsty. It makes sense to be generous with your injector capacity.

 

The rule of thumb is to add 20% to the flow rate when fitting an injector, which takes into account injector deterioration and affords a little 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 and mods

Only look to upgrade your exhaust if your current exhaust is actually causing a restriction.

On most factory exhausts you should find that 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 increase the flow of gases through the engine.

 

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

Common exhaust restrictions can be traced to the catalyst and filters installed, so adding a faster flowing race alternative will help avoid this restriction.

Weak spots, Issues & common problem areas on the M30

The M30 engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the M30, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your M30 engine please join us in our friendly forum where you can discuss tuning options in more detail with our M30 owners. It would also be worth reading our unbiased tuning articles to get a full grasp of the benefits and drawbacks of each modification.

Please help us improve these tips by sending us your feedback in the comments box below. We also have an updated more comprehensive M30 tuning article on our .com site.

We really like hearing from our readers, and hearing about which mods were the most effective for them, it helps us improve our recommendations and articles to reflect current trends in modifications and ensures that our M30 guides and tips are kept up to date.

History of the Engine

  • M30B25V
    110 kW (148 bhp) at 6,000rpm 211Nm (156 lbft) @3,700 rpm
  • M30B25
    110 kW (148 bhp) @6,000rpm 215Nm (159 lbft) @3,700 rpm
  • M30B28V
    125 kW (168 bhp) @6,000rpm 235Nm (173 lbft) @3,700
  • M30B28
    135 kW (181 bhp) @5,800rpm 240Nm (177 lbft) @4,200 rpm
  • M30B30V
    132 kW (177 bhp) at 6,000rpm 255Nm (188 lbft) @3,700 rpm
  • M30B30
    149 kW (200 bhp) @5,500rpm 272Nm (201 lbft) @4,300 rpm
  • M30B32
    147 kW (197 bhp) @5,500rpm 285Nm (210 lbft) @4,300 rpm
  • M30B33V
    139 kW (186 bhp) @5,500rpm 289Nm (213 lbft) @3,500 rpm
  • M30B34
    160 kW (215 bhp) @5,800rpm 310Nm (229 lbft) @4,200 rpm
  • M30B35
    155 kW (208 bhp) @5,700rpm 305Nm (225 lbft) @4,000rpm

Tuning the BMW M30 and best M30 performance parts.

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