Volvo B42 Tuning

"All you need to know about tuning and performance parts on the Volvo B42 engine!"

In this article we outline options for your B42 tuning and summarise the greatest upgrades. Volvo B42 provide a fun base for your project and with the best performance parts like remaps, turbo kits and camshafts you will dramatically maximise your driving enjoyment.

History, Power & Specs of the Engine

Tuning the Volvo B42 and best B42 performance parts.

Best B42 mods

When talking about the ultimate modifications for your B42 engine, we are going to concentrate on the mods that give the best power gain for you money.

Altering your B42 camshaft will make a dramatic difference to the engine bhp. Choosing a higher performance camshaft profile raises the bhp accordingly.

Fast road camshafts usually bump the bhp and torque through the rpm range, you may sacrifice a little low end bhp but the top end will improve.

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

On a typical daily driver must carefully try to match your torque band to your usage of the car.

I'd be completely gobsmacked if you find a B42 Motorsport and race camshaft is a pleasure to live with when in heavy traffic because low end power will be very lumpy. Competition cams are designed for maximum power at the top end of the RPM range, a place that most daily commutes will not permit!

Different B42 engines respond better to different cam durations than others.

The map and fuelling also have a large bearing on the bhp gains you'll achieve.

Altering valve 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.

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

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

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

The B42 units respond well to upgrades and we're happy to report there is a lot of parts and performance parts around.

ECU flashing should help to release the full potential of all the modifications you've done to your B42.

(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 the end result often differs on the modifications you've applied and the condition of your engine.

It is the whole point to any tuning project to get air into each cylinder

Intake manifold carry the air from the filter and allow it to be drawn into the engine and mixed with fuel.

The size of bore and shape and flow rate of the Air Intake manifolds can make a substantial improvement to fuel atomisation and engine efficiency on the B42.

Many mass produced engine intake are needing performance upgrades, although some makers provide well optimised intake.

Larger B42 valves, getting 3 or 5 angle valve jobs and porting and head flowing will also boost performance, the fantastic side effect is it will permit an improved performance increase on other modifications.

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 B42

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 your car has a turbocharger parts are more reliable and we find turbocharged engines are made with many forged and stronger components.

However you'll find engines will have power limits

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

There are many guys spending a lots of money on turbo upgrades on the B42 only to watch the motor catastrophically fail on it's first outing after it's been enthusiastically driven.

Large upgraded turbo chargers commonly suffer a bottom end lag, and low capacity turbo chargers spool up really quickly but won't have the peak end bhp gains.

Thanks to new tech the world of turbo units is always improving and we commonly find variable vane turbo units, permitting 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 flow these at differently profiled 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/MAP on the B42 when a lot more air is being drawn into the engine.

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

Adding a supercharger or additional turbo will make large power gains, although more challenging to configure. We have this article covering twinchargers if you want to read more.


You will need to ensure that the engine is not starved of fuel so need to ramp up the fuelling when you start extending past 20% of a bhp and torque increase.Most tuners we speak with say to over specify your injectors flow rate.

The accepted safe increase is to add 20% capacity when buying an injector, this accounts for injector deterioration and provides 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.


You should look to improve your exhaust if your current exhaust is creating a restriction in flow.

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

Please dont run with the biggest exhaust you can get this will slow the exhaust rate - the best for power gains are usually between 1.5 to 2.5 inches. It is the shape and material more than the bore size.

Usual exhaust restrictions are traced to the filters installed, so adding a freer flowing high performance aftermarket one will improve air flow, and rather than doing an illegal decat, will keep the car road legal.

Weak spots, Issues & problem areas on the B42

The B42 engines are generally 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.

Regular oil changes are vital on the B42, 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 B42 engine please join us in our friendly forum where you can discuss tuning options in more detail with our B42 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 them on each model of car. Comments are used to improve the accuracy of these B42 articles which are continually updated.

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