BMW M70 Tuning

"All you need to know about tuning the BMW M70 engine!"

Now we will provide a guide to M70 tuning and report on the best modifications for your car. BMW M70 offer good returns when tuned and with the optimum uprated parts like a remap, turbo kits and camshafts you will dramatically maximize your driving pleasure.

We were asked questions for more information on tuning and building a modified M70 and particularly which turbo upgrades work best, so we've created this web page that covers our go to upgrades for this engine and what we feel are the optimum value upgrades you can do.

The M70 is an awesome car modification project to carry out. If you do your research then you can create an awesome M70 but don't be fooled there are lots of uprated modifications out there that will simply not suit it read our unbiased guides first.

History, Power & Specs of the Engine

The M70 is a SOHC V12 petrol engine, which was BMW's first production V12 in 1987 and production ended around 1996.

Each cylinder bank used a separate ECU and MAF sensors with drive by wire and hydraulic valve lifters.

M70B50

220 kW (295 hp)  at 5,200 rpm 450 Nm (332 lbft)  at 4,100 rpm 1987-1994

  • 1987–1994 E32 750i/750iL
  • 1989–1994 E31 850i/850Ci

S70B56

280 kW (375 hp)  at 5,300 rpm 550 Nm (406 lbft)  at 4,000 rpm 1992-1996

  • 1992–1996 E31 850CSi

S70/2

461 kW (618 hp)  at 7,400 rpm 650 Nm (479 lbft)  at 6,700 rpm 1993-1998

  • 1993–1998 McLaren F1

S70/3

427 kW (573 hp)  at 6,500 rpm 670 Nm (494 lbft)  at 4,500 rpm 1998-2000

  • 1998–1999 BMW V12 LM racing car
  • 1999–2000 BMW V12 LMR racing car
  • 2000 BMW X5 LM racing car

Tuning the BMW M70 and best M70 performance parts.

Best M70 tuning mods

Just because particular tuning parts are appear in lots of M70 projects it doesn't mean its worth having, so we'll ultimate tuning parts that will give your M70 the best value for money to power increase.

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

Fast road cams commonly bump the bhp over the rev range, you could sacrifice a little low down torque 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.

For a car driven daily you need to match your engines power to your preferences.

I would be surprised if you have ever thought or claimed that a M70 Motorsport cam is a pleasure to live with when driving in heavy traffic. The low end idle will be very lumpy and irregular, so something you would notice on a track when you drive in the upper third of the rpm band, but on roads this is a serious issue and we've heard from lots of drivers lamenting their decision to add an extreme competition cam profile to their engine.

Some M70 engines respond better to less aggressive camshaft durations check your engine on a rolling road.

The engine timing and fuel pump and injectors also have an effect 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.

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Best mods for your M70

  1. Internal engine mods - crank, pistons, conrods & compression ratio including balancing and blueprinting
  2. Intake Mods and Performance Exhausts - Be aware on their own these mods will NOT ADD PERFORMANCE on most cars, but they enable you to lift power after other upgrades by losing a restriction.
  3. Lightened Flywheels - a lower mass flywheel will enhance the engines ability to rev freely. But not always suitable for all M70 engines.
  4. Fast road Camshafts are generally the biggest mechanical mod upgrade, but should always be installed by someone qualified to set them up properly and they are not always easy to source but there is usually a local firm to regrind a stock cam for you.
  5. Remaps - A remap gives the biggest gains with respect to your investment, replacement ECUs, and piggyback ECUs are all alternatives.
  6. Upgrades to turbochargers and superchargers - A New Turbo is the most significant way to raise the intake air supply, which permits you to combust more fuel and make better power figures. It is one of the most challenging upgrades you'll see massive gains.

M70 Tuning Stages

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

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

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

Carefully think through your options and then source your tuning parts and set yourself a power target to save yourself from expensive mistakes.

Remaps should help to unlock the full potential of all the mods you've done to your M70.

(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.)

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

It is the aim to any tuning project to shove more fuel and air into the M70 engine

Intake manifold transmit the air from the filter and allow it to be drawn into the engine cylinders.

Design and flow rate of the Air Intake manifolds can make a large difference to fuel delivery on the M70.

I usually find headers are needing aftermarket parts, although a few OEM provide decently flowing headers.

Fitting big valve kits, getting port matching and head flowing will also improve performance, and as an added benefit will give you raising the performance increase on other parts.

M70 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 M70

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 your car has a turbo already fitted tuning parts are giving better power gains and turbocharged engines already contain more solid components.

However engines will have power limits and depending on how well made it is you might have more leeway in your project. Lowering the compression ratio is important if you plan to add forced induction to your M70.

It is important to find these limitations and install more solid crank and pistons to handle the power.

It's not unheard of people spending a lots of money on turbo upgrades on the M70 only to see the whole thing explode soon after it's completed.

Big capacity turbos commonly experience low end lag, and smaller turbos spool up really quickly but won't have the high rpm power band gains.

Over the last 20 years the choice of turbo units is always evolving and we now see variable vane turbo units, allowing the vane profile is altered according to speed to lower lag and increase top end torque.

Twin scroll turbo units divert the exhaust flow into 2 channels and direct these at differently designed vanes in the turbocharger. They also improve the scavenging effect of the engine.

It is common that there is a restriction in the air flow sensor (AFM/MAF/MAP) on the M70 when a lot 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 bhp gains, although harder to configure. We have this feature on twinchargers if you want to read more.

Fuelling Mods for the M70

Don't overlook the need to look at the fuelling when you are increasing the torque - it makes the car more thirsty. It makes sense to be generous with your injectors flow rate.

As a rule of thumb add 20% when buying an injector, this takes into account injector deterioration and allows some spare capacity should the engine need 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 on the M70

You may need to increase your exhaust if your exhaust is creating a restriction.

On most factory exhausts you should find that the flow rate is still 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 gases through the engine.

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

Typically exhaust restrictions can be traced to the catalyst installed, so adding a faster flowing performance catalyst removes the restriction. We note that performance cats perform similarly to decats and have the added benefit of keeping your car street legal, as decats or catalyst removal is illegal in most territories for road going cars.

Weak spots, Issues & problem areas on the M70

The M70 engines are generally reliable and solid units, as long as you follow the manufacturers service schedules, and use a good quality oil to ensure longevity. Few problems should happen 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.

Regular oil changes are vital on the M70, especially when tuned and will help extend the life and reliability of the engine.

Lifter tapping is an issue as the bolts loosen up.

If the idle is erratic, check for split vacuum lines and O2 sensor issues also the plastic VCV can be sticky so is worth watching along with the PCV.

If you would like to know more, or just get some friendly advice on Tuning your M70 engine please join us in our friendly forum where you can discuss tuning options in more detail with our M70 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 love to hear what our visitors have got up to and which parts work best for you on your car. Which helps us keep our guides and tips up to date helping others with their modified car projects. Your feedback and comments are used to keep this page up to date, and help improve the accuracy of these M70 articles which are continually updated.

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