MENUVolvo D5252T Tuning
"All you need to know about tuning the Volvo D5252T engine!"
The Volvo D5252T are good project engines and with the optimum modified tuning mods like a remap, turbo upgrades and camshafts you will definitely increase your driving enjoyment.
TorqueCars will consider D5252T tuning and summarise the best modifications.
History, Power & Specs of the D5252T Engine
2.5 L (2,461 cc) Audi Turbocharged Direct Injection (TDI) inline five-cylinder SOHC, 103 kW (140 PS; 138 bhp)
- Volvo 850
- Volvo S70
- Volvo V70
- Volvo S80s
Application list
103 kW (140 PS; 138 bhp) (41.9 kW/L); 290 Nm (214 lbf⋅ft) at 1,900 rpm
Volvo D5252T: Volvo 850, Volvo S70, Volvo V70, early Volvo S80s
Within the VW group this engine was fitted in various configurations and Badged 2.5 R5 TDi.
65 kW (88 PS; 87 bhp) (26.4 kW/L); 195 Nm (144 lbf⋅ft) at 1,900 rpm
Volkswagen Transporter (T4)
74 kW (101 PS; 99 bhp) at 2,600 rpm (30.1 kW/L); 275 Nm (203 lbf⋅ft) at 2,500 rpm
Volkswagen Marine TDI 100-5
75 kW (102 PS; 101 bhp) (30.5 kW/L); 250 Nm (184 lbf⋅ft) at 1,900 rpm
Volkswagen Transporter (T4)80 kW (109 PS; 107 bhp) (32.5 kW/L); 280 Nm (207 lbf⋅ft) at 1,900 rpm
Volkswagen LT85 kW (116 PS; 114 bhp) (34.5 kW/L); 265 Nm (195 lbf⋅ft) at 1,900 rpm — Audi C4 10088 kW (120 PS; 118 bhp) at 3,250 rpm (35.8 kW/l); 275 Nm (203 lbf⋅ft) at 2,500 rpm
Audi C3 100
Tuning the Volvo D5252T and best D5252T performance parts.
Best D5252T parts
When talking about the greatest modifications for your D5252T engine, we are going to focus on the tuning mods that give the best power gain for you money.
Altering your D5252T camshaft will make a dramatic difference to the engine engines power. Choosing a higher performance camshaft profile raises the engines power accordingly.
Fast road cams usually increase the bhp across the rev range, you may lose a little bottom end power but higher rpm power will improve.
Competition cams, increase the higher rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.
A Motorsport camshaft won't do well if in heavy traffic.
You should ideally optimize your torque band to your driving style so for a daily driver stick with a shorter duration D5252T camshaft
Each engine responds better to less aggressive camshaft durations so view each engine as unique.
The engine timing and fuel pump and injectors also have a large bearing on the bhp gains you'll get.
Longer 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.
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Best Engine Mods for your car
- Engine Tunes - engine tuning/remapping provides the most advantage in terms of cost savings, aftermarket ECUs, and piggyback ECUs are all alternatives.
- 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.
- 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.
- 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.
- Head work - The goals of porting and flowing the head are to get air flowing into the engine while removing flow restrictions and turbulence.
Typical stage 1 mods often include:
Sports exhaust header/manifold, drilled & smoothed airbox, Intake manifolds, Panel air filters, Remaps/piggy back ECU, Fast road camshaft.
Typical stage 2 mods often include:
Fast road cam, fuel pump upgrades, high flow fuel injectors, induction kit, Sports catalyst & performance exhaust, Ported and polished head.
Typical stage 3 mods often include:
Competition cam, Adding or Upgrading forced induction (turbo/supercharger), Crank and Piston upgrades to alter compression, Engine balancing & blueprinting, Twin charging conversions, Internal engine upgrades (head flowing porting/bigger valves).
Remaps should help to fully realize the full potential of all the tuning mods you've done to your D5252T.
(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 power output will depend much on the tuning mods you've fitted and the condition of your engine.
It is the whole point to any engine modification project to force fuel and air into your D5252T
Intake manifolds carry the air from the air filter and allow it to be sucked into the engine cylinders.
Design and flow rate of the Intake manifold can make a noticeable effect on to fuel mixing and power on the D5252T.
Most intake manifolds are needing aftermarket tuning parts, although a few OEM provide reasonably well designed intake manifolds.
Larger D5252T valves, carrying out 3 or 5 angle valve jobs and porting and head flowing will also boost torque, and more importantly will make space for increasing the torque increase on other tuning parts.
D5252T 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 D5252T
The more air you can get into an engine, the more fuel it can burn and uprating the induction with a turbocharger upgrade makes impressive power gains.
If the engine is turbo charged modifications are relatively easy and most turbocharged engines will have uprated components.
There are weak spots for every engine, with some being very over engineered and some just sufficiently able to handle stock powerSee where you'll find these restrictions and upgrade to better pistons and crank to handle the power.
We've seen people spending a a stack of money on turbocharger upgrades on the D5252T only to have the motor go up in smoke soon after it's first rolling road session.
Larger upgraded turbo chargers tend to experience low end lag, and smaller turbo chargers spool up much more quickly but don't have the high rpm engines power gains.
Thanks to new tech the choice of turbochargers is always increasing and we commonly find variable vane turbochargers, where the vane profile is altered according to speed to lower lag and increase top end bhp.
Twin scroll turbochargers divert the exhaust gases into 2 channels and flow these at differently profiled vanes in the turbocharger. They also improve the scavenging effect of the engine.
You'll commonly see there is a restriction in the air flow sensor MAP/MAF/AFM on the D5252T when loads more air is being pulled into the engine.
You'll see that 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor sapped bhp and torque at a much lower level.
Adding a supercharger or additional turbo will make large performance gains, although more complex to install. We have this article covering twinchargers if you want to read more.
Fuelling
Don't forget to boost the fuelling when you are increasing the bhp and torque - it makes the car more thirsty. 
It is important to be generous with your flow rate on the injectors.
As a rule of thumb add 20% to the flow rate when buying an injector, this allows for injector deterioration and affords a little 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.
D5252T Performance Exhausts
You only need to uprate your exhaust if the current exhaust is actually causing a flow problem.
On most factory exhausts you should find that the flow rate is fine 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 will certainly help air flow through the engine but do not go too large or you could very well end up with a reduced flow rate. So generally speaking, keep to 1.5 to 2.5 inches as a rule of thumb.
Common exhaust restrictions can be traced to the filters installed, so adding a faster 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 D5252T
The D5252T 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 D5252T, 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 D5252T engine please join us in our car forums where you can discuss D5252T tuning options in more detail with our D5252T 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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