Volvo B234 Tuning

"All you need to know about tuning the Volvo B234 engine!"

The Volvo B234 really good project engines and with the best sports modifications like a remap, turbo kits and camshafts you will really increase your driving fun.

We shall detail the best approach to B234 tuning and highlight the premier upgrades.

History, Power & Specs of the B234 Engine

1989–1992 B234

2.3 L (2,316 cc) DOHC 16-valve — Volvo 740, Volvo 940

Tuning the Volvo B234 and best B234 performance parts.

Best B234 modifications

Just because particular tuning mods are appear in lots of B234 projects it doesn't mean its worth having, we will focus on the best tuning mods that will give your B234 the biggest power gain return for your cash.

Significant gains on the B234 can be made from camshaft upgrades. Altering the camshaft profile alters the intake and exhaust durations on the engine and can dramatically change the power band and power output.

Fast road cams commonly boost the torque through the rev band, you could drop a little low end power but the high end rpm power will be better.

Race cams, boost the high end rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

A Competition cam is not great in heavy traffic.

You should ideally optimize your power band to your preferences so for a car driven daily stick with a fast road B234 cam

Some B234 engines respond better to extreme cam durations so set your engine up on a rolling road.

The ECU mapping and fuel pump and injectors also will make differences on the power gains you'll make.

Longer valve durations 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 Engine Mods for your car

  1. Mapping - remapping provides the most advantage in terms of cost savings,  aftermarket ECUs, and piggyback ECUs are all alternatives.
  2. Fast road cams are one of the most significant mechanical changes, but they must be installed by someone who knows what they're doing and they are not always easy to source but you might find a local firm to regrind a stock camshaft.
  3. Intake and Exhaust - Note that on their own these mods will NOT ADD POWER in most cases, but they can help enhance power after other mods by removing the restriction.
  4. Upgrades to turbochargers and superchargers - forced induction is the most efficient approach to increase air supply, allowing you to burn more fuel and make more power. It is one of the most costly upgrades but provides the best gains.
  5. Head work - The goals of porting and flowing the head are to get air flowing into the engine while removing flow restrictions and turbulence.
  6. Typical stage 1 mods often include:
    Remaps/piggy back ECU, Panel air filters, Fast road camshaft, Intake manifolds, Sports exhaust header/manifold, drilled & smoothed airbox.

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

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

    The B234 units are great to work on and thankfully there are increasing numbers of mods and tuning parts around.

    ECU mapping should help to establish the full potential of all the parts you've done to your B234.

    (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 NA (naturally aspirated) engines, but figures achieved will vary depending on the parts you've done and the condition of your engine.

    It is the whole point to any engine upgrade task to push air into your B234

    Your intake manifold will direct the air from the air cleaner and allow it to be drawn into the engine cylinders.

    Shape and flow characteristics of the Plenum can make a noticeable improvement to fuel atomisation on the B234.

    Most intake manifolds are needing performance upgrades, although some makers provide fairly well optimized intake manifolds.

    Adding a B234 larger valve kit, getting port matching and head flowing will also raise performance, the fantastic side effect is it will raise potential for increasing the performance increase on other mods.

    B234 Turbo upgrades

    NA (naturally aspirated) 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 B234

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

    When your motor is fitted with a turbocharger parts are relatively easy and turbo engines use better components.

    However you'll find engines will have power limits.It is important to find these limitations and install better quality crank and pistons to handle the power.

    It's not unheard of drivers spending a fortune on turbo charger upgrades on the B234 only to experience the motor literally blow up on it's first outing after it's used in anger.

    Bigger upgraded turbo chargers tend to experience a bottom end lag, and smaller turbo chargers spool up quickly but do not have the peak end torque gains.

    Thankfully the selection of turbo units is always moving on and we commonly find variable vane turbo units, permitting the vane angle is altered according to speed to lower lag and increase top end bhp and torque.

    Twin scroll turbo units divert the exhaust flow into 2 channels and feed these at differently profiled vanes in the turbo charger. They also increase the scavenging effect of the engine.

    It is common that there's a limitation in the air flow sensor MAP/MAF/AFM on the B234 when a lot more air is being drawn into the engine.

    Going up you'll find 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 harder to configure. We have this guide to twinchargers if you want to read more.


    Don't forget to pay attention to the fuel delivery when you are increasing the bhp - it makes the car more thirsty. Most tuners we speak with say to be generous with your flow rate on the injectors.

    As a rule of thumb add 20% when specifying an injector, helps cope with injector deterioration and provides a bit of 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.

    B234 Performance Exhausts

    You should look to replace your exhaust if the existing exhaust is creating a restriction in flow.

    On most factory exhausts you should find that your flow rate is ok 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 balance the flow of gases through the engine.

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

    Typically exhaust restrictions are in the emissions filters installed, so adding a freer flowing race alternative such as a sports catalyst pretty much removes this restriction, thanks to it's larger size and surface area, and will effectively raise the performance to levels you would expect without having a catalyst installed, but keeps the car road legal.

    Weak spots, Issues & problem areas on the B234

    The B234 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 B234, 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 B234 engine please join us in our car forums where you can discuss B234 tuning options in more detail with our B234 owners. It would also be worth reading our unbiased Volvo tuning articles to get insights into each modification and how effective they will be for your car.

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