Modding upgrading and tuning the BMW M41D17 engine!

The Lowdown on "M41D17 Modifications"

How to modify and upgrade the BMW M41D17

"Comprehensive guide to tuning the BMW M41D17 engine!"

Our friends at TorqueCars often are getting emails about how to improve the M41D17 from people wanting to know what are the optimum M41D17 upgrades. So let us look into BMW M41D17 modifications and outline the best upgrades on this great engine and point out some common pitfalls along the way.

The BMW M41D17 great bases for a tuning project and with a few sensible performance parts like remaps, turbo improvements and camshafts you will really increase your driving experience.

Our aim here is to examine M41D17 tuning and point out the premier modifications for your car.

Just because particular parts are appear in lots of M41D17 projects it doesn't mean its worth having, we will concentrate on the top parts that will give your M41D17 the best power gain for you spend.

Without us subscribing to the common myth of 'if it's shiny and makes more noise it must be good' you seem to get in many tuning magazines and on car forums'.

M41D17 induction kits

Improving air intake on the M41D17

You need fuel and air for an engine to work. If there is little supply of fuel then it will run lean, if there is not enough air it runs rich sapping power . We'll pick up on fuelling later in this article but for now we shall look at air supply.

So Forcing fuel and air into the M41D17 engine is vital to any engine performance tuning project.

It is not unusual that there's a limitation in the air flow sensor (AFM/MAF/MAP) on the M41D17 when considerably more air is being drawn 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 limited bhp and torque at a much lower level.

Engines intake headers flow the during the engines suck phase from the air cleaner and allow it to be drawn into the engine and mixed with fuel.

The bore size, shape and rate of flow of the Intake can make a large improvement to fuel mixing and power on the M41D17.

Most plenum chambers are needing an upgrade, although some makers provide reasonably well designed plenum chambers.

Increasing the M41D17 valve size, doing a bit of M41D17 port enlargement and head flowing will also increase torque, & importantly will make space for raising the torque increase on other parts.

M41D17 performance cam tips.

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

The engine timing and fuelling also will say much on the torque gains you'll make.

Altering 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.

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

NB: Fast road camshafts normally raise the bhp and torque across the rpm range, you may sacrifice a little low down power but the high end rpm power will improve.

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

A Motorsport and race camshaft is not great driving in heavy traffic.

You should ideally match your torque band to your typical driving style so for a car driven daily stick with a shorter duration M41D17 camshaft

Stage 1, 2 and 3 mods for the M41D17

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 M41D17 parts:

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

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

Stage 2 M41D17 parts:

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

Stage 3 M41D17 parts:

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

Carefully think through your options and then source your upgrades and set yourself a power target to avoid wasting your time and money.

Mapping will help release the full potential of all the parts you've done to your M41D17.

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 parts you've carried out and the condition of your engine.

Turbo modifications on the M41D17

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 M41D17.

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.

When a car is turbo charged tuning mods are going to net you a larger power gain and most turbo engines are made with many forged and stronger components.

There are weak spots for every engine, with some being over specified and some only able to handle stock power

See where you'll find these limits and fit stronger pistons, crank and engine components to cope with the power.

We've seen tuners spending a loads on turbo charger upgrades on the M41D17 only to have the motor explode soon after it's completed.

Big upgraded turbos commonly experience a bottom end lag, and smaller turbos spool up really quickly but do not have the peak end power band gains.

We are pleased that the world of turbochargers is always increasing and we commonly find variable vane turbochargers, permitting the vane profile is altered according to speed to lower lag and increase top end bhp.

Twin scroll turbochargers divert the exhaust flow into two channels and flow these at differently designed vanes in the turbocharger. They also help the scavenging effect of the engine.

Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large performance gains, although more difficult to install. We have this article covering twinchargers if you want to read more.

Tips about fuel supply on the M41D17

You will need to ensure that the engine is not starved of fuel so must ramp up the fuelling when you start going beyond 20% of a torque hike. We would recommend you to over specify your injectors flow rate.

As a rule of thumb add 15% when buying an injector, this accounts for injector deterioration and gives a bit of 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 M41D17 performance exhaust upgrades

You should look to replace your exhaust system with an upgraded one is if the current exhaust is creating a flow problem.

On most factory exhausts you'll see the exhaust flow rate is still 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 equal out the flow of air through the engine.

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

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

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

Faults issues and things to look out for on the M41D17

Like most engines an M41D17, 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 M41D17, failure to do this will exacerbate engine wear, on a tuned M41D17 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 M41D17 why not pop over to the forums at TorqueCars where you can chat about M41D17 tuning options and read about others projects who may be planning to do similar modifications on their M41D17.

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