Modding uprating the BMW M67 engine!

Tuning guide "M67 Modifications"

M67 Modifications Guide

How to modify and upgrade the BMW M67

"Comprehensive guide to performance tuning the BMW M67 engine!"

TorqueCars are frequently getting posts requesting information on how to improve the M67 from people wanting to know what are the ultimate M67 power upgrades. So let us look into BMW M67 mods and outline the best upgrades on this great engine and point out some problems along the way.

Here we examine M67 tuning and point out the best upgrades. BMW M67 are popular engines and with carefully chosen sports mods like ECU maps, turbo upgrades and camshafts you will positively enhance your driving fun.

When talking about the top parts for your M67 engine, we are going to concentrate on the parts that give the biggest return for your cash.

M67 induction kits

Improving air intake on the M67

You need fuel and air for an engine to work. If there is a lack of fuel then it will run lean, if there is insufficient air it runs rich resulting in lost power . We'll pick up on fuelling later in this article but for now we shall look at air supply.

So the aim to any tuning job to force air into each cylinder but this has a knock on effect with the air flow sensor.

It is common that there's a limitation in the air flow sensor AFM/MAP on the M67 when a lot more air is being fed into the engine.

When tuning you may well find you need to get an air sensor or flow meter capable of upto 4 bars to cope with quite large power gains, whereas the OEM air sensor sapped performance at a much lower level.

Intake headers flow the air during the suck phase from the filter and allow it to be fed into the engine and mixed with fuel.

Shape and flow characteristics of the Intake headers can make a substantial improvement to fuel atomisation on the M67.

Many mass produced engine air intake manifolds are ripe for aftermarket parts, although some manufacturers provide reasonably good air intake manifolds.

Adding a M67 larger valve kit, doing a bit of port matching and head flowing will also lift bhp, and more importantly will give you a better bhp increase on other parts.

M67 performance cam tips.

Each engine responds better to more or less aggressive camshaft durations than others.

The engine timing and fuel pump and injectors also will make differences on the power gains you'll get.

A longer valve duration can alter the power 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.

The camshaft profile plays a big part in the engines power output so camshaft upgrades make quite a large difference. The intake and exhaust durations will alter depending on the chosen camshaft profile, so large power band gains are on offer for camshaft upgrades.

NB: Fast road camshafts commonly push up the power throughout the rpm range, you could sacrifice a little bottom end torque but the higher rpm power will be lifted.

Competition camshafts, push up the higher rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

A Competition camshaft won't do well if on the daily commute.

You should ideally optimize your power band to your cars usage so for a road car stick with a mild fast road M67 camshaft

Stage 1, 2 and 3 mods for the M67

Before we break the best tuning upgrades down into stages of tune, let's list the most effective tuning upgrades for you.

  1. Suspension Upgrades - always improve your cars handling
  2. Brake Upgrades - Even before adding power improve those brakes
  3. Intake - make sure the intake is not restricted, use filters and intake upgrades to improve this
  4. Exhaust - as with 3 ensure there is not restriction in the exhaust, cats are the usual bottleneck
  5. Tunes - remapping, piggyback ECU's and aftermarket ECU's can all make decent gains
  6. Fuelling - when you've increased power you'll need to match this with more fuel
  7. Turbo upgrades - Improving the intake with a large turbo and better flowing intercooler will be the biggest power gain you'll see (but one of the most complex).

This video guide to tuning cars is a great starting point to work from in your project.

Stage 1 M67 parts:

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

Stage 2 M67 parts:

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

Tuning tips and articles Engine tuning Transmission tuning Care care Intake & exhaust mods Improve handling Forums

Stage 3 M67 parts:

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

Plan your options and then buy your modifications and set yourself a power target to save yourself from expensive mistakes.

Remapping will help to establish the full potential of all the upgrades you've done to your M67.

You will typically expect to see gains of approximately 20-30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but power output usually depend much on the upgrades you've done and the condition of your engine.

Turbo modifications on the M67

To get a turbo working on a NASP engine there is a lot involved, from lowering compression ratio to improved fuel supply and mapping, so we have found a great guide to helpavoid the common pitfalls or end up with an unfinished project because you were not told what you were getting into by doing this on the M67.

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 the engine is fitted with a turbocharger mods are more reliable and you'll see that turbocharged engines already contain uprated components.

There are practical limits for every engine, with some being very over engineered and some only just able to handle stock power

It is important to find these limits and install more solid crank and pistons to utilize the power.

We've seen mechanics spending a a stack of money on turbocharger upgrades on the M67 only to watch the motor go up in smoke soon after it's been completed.

Larger upgraded turbo units often experience low end lag, and smaller turbo units spool up much more quickly but do not have the high rpm bhp gains.

Thanks to new tech the range of turbos is always evolving and we are seeing variable vane turbos, permitting the vane angle is altered according to speed to lower lag and increase top end bhp.

Twin scroll turbos divert the exhaust gases into a couple of channels and push these at differently profiled vanes in the turbo charger. They also improve the scavenging effect of the engine.

Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large power gains, although more challenging to get working. We have this article on twincharging if you want to read more.

Tips about fuel supply on the M67

Don't forget to uprate the fuel system when you are increasing the bhp and torque - it makes the car more thirsty. Experienced mechanics will tell you to over specify your injectors flow rate.

The accepted safe increase is to add another 15% when buying an injector, helps cope with injector deterioration and gives you some spare capacity should the engine need more fuel.

Don't forget that different fuel grades will usually require different settings, a high octane fuel will burn more efficiently than lower octane fuel for example. A car will trim fuel supply to keep within the ideal air fuel mix but at the extreme ends you may need to adjust your injector capacity, or the mapping or you'll get flat spots and potential lean or rich fuel issues..

Recommended M67 performance exhaust upgrades

You should look to boost your exhaust system with an upgraded one is if your exhaust is actually creating a restriction in flow.

On most factory exhausts you'll see your flow rate is fine even on modest power gains, but on a serious tuning project with a big boost in power you will certainly need to get a better flowing exhaust.

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

But if your exhaust pipe is too big, ie: it's over two and a half inches diameter, you will lose a lot of the flow rate and end up lacking power and torque.

Typically exhaust restrictions can be located the emissions filters installed, so adding a freer flowing race alternative will help avoid this restriction.

Decats (NB:catalysts reduce harmful engine emissions) is illegal in most countries and regions.

Faults issues and things to look out for on the M67

Like most engines an M67, should have few issues if it gets properly serviced and looked after.

We cannot stress enough the need for oil changes with the correct grade of oil on the M67, failure to do this will exacerbate engine wear, on a tuned M67 this is more important than ever and close attention should be paid to your maintenance schedule.

If you are interested in learning more or getting impartial tuning advice for your M67 why not pop over to the forums at TorqueCars where you can chat about M67 tuning options and read about others projects who may be planning to do similar modifications on their M67.

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