Volvo B6254 Tuning

"All you need to know about performance parts and tuning the Volvo B6254 engine!"

Our aim here is to provide a guide to B6254 tuning and summarise the ultimate mods that work. Volvo B6254 are popular tuning projects and with the right tuning upgrades like remaps, turbo upgrades and camshafts you will maximize your driving opportunities.

History, Power & Specs of the B6254 Engine

B6254FS 2.5 L

170 PS (125 kW; 168 hp) at 5700 rpm with 230 Nm (170 lbft) of torque at 4400 rpm.

Applications:

  • 1995–1997 Volvo 960 badged as 960 2.5 or 960 24V
  • 1997–1998 Volvo S90 badged as S90 2.5 or S90 24V
  • 1997–1998 Volvo V90 badged as V90 2.5 or V90 24V

B6254G without catalyst

Tuning the Volvo B6254 and best B6254 performance parts.

Best B6254 parts

When talking about the greatest modifications for your B6254 engine, we are going to concentrate on the upgrades that give the best value for money.

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.

Fast road camshafts normally boost the performance throughout the rpm band, you could sacrifice a little low end bhp but higher rpm power will be higher.

Motorsport and race camshafts, boost 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, really you should, ideally aim to optimize your engines power to your preferences.

You'll never have found a B6254 Motorsport cam 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 B6254 engines respond better to extreme camshaft durations than others.

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

Extending exhaust or intake 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.

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

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

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

The B6254 engine blocks respond well to upgrades and thanks to their popularity there are plenty of modifications and performance parts around.

ECU mapping allows a tuner to to establish the full potential of all the tuning mods you've done to your B6254.

(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 your results usually differs on the tuning mods you've applied and the condition of your engine.

It is the main goal to any engine upgrade task to pull air and fuel into the B6254 engine

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

The bore size, shape and flow rate of the Headers can make a big improvement to fuel engine efficiency on the B6254.

It's not uncommon that intake headers are needing aftermarket tuning parts, although a few manufacturers provide decently flowing intake headers.

Fitting big valve kits, getting B6254 port enlargement and head flowing will also boost performance, and importantly will allow you to get increasing the performance increase on other upgrades.

B6254 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 B6254

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 make more power and most turbo engines will have harder and stronger components.

There are common areas of failure for every engine, with some being over specified and some only just able to handle stock powerWe recommend you find these limitations and upgrade to more solid crank and pistons to utilize the power.

We've seen mechanics spending a lot of money on turbo charger upgrades on the B6254 only to suffer the indignity of watching the whole thing literally blow up on it's first outing after it's been finished.

Bigger upgraded turbochargers often suffer a bottom end lag, and smaller turbochargers spool up quickly but won't have the top end torque gains.

Thankfully the choice of turbo chargers is always developing and we commonly find variable vane turbo chargers, allowing the vane profile is altered according to speed to lower lag and increase top end torque.

Twin scroll turbo chargers divert the exhaust gases into two channels and push these at differently angled vanes in the turbo. They also boost the scavenging effect of the engine.

It is not unusual that there is a limit in the air flow sensor MAP/MAF/AFM on the B6254 when loads more air is being sucked into the engine.

You'll see that 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor sapped torque at a much lower level.

Adding a supercharger or additional turbo will make large performance gains, although more difficult to install. We have this article on twincharging if you want to read more.

Fuelling

Don't omit to increase the fuel system when you are increasing the bhp - it makes the car more thirsty. It is important to over specify your injector capacity.

As a rule of thumb add 20% when buying an injector, which takes into account injector deterioration and gives you some 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.

B6254 Performance Exhausts

Only look to improve your exhaust if your exhaust is actually causing a restriction in flow.

On most factory exhausts you'll see 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 can help increase the flow of air through the engine.

But if the exhaust pipe is too large, ie: it's over 2.5 inches bore, you will lose a lot of your flow rate and end up losing power and torque.

Typically exhaust restrictions come around the catalyst installed, so adding a better flowing sports alternative is the answer. This keeps the car road legal and will flow much better due to it's higher internal surface area and design, so has the added benefit of keeping your car road legal. The alternative decat should be considered an off road only mod, as removing a catalyst is illegal in most territories and regions for road registered cars..

Weak spots, Issues & problem areas on the B6254

The B6254 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 B6254, 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 B6254 engine please join us in our friendly forum where you can discuss B6254 tuning options in more detail with our B6254 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.

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 modifications work best for them on each model of car. Comments are used to improve the accuracy of these B6254 articles which are continually updated.

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