26/12/2016
The Citroen CX, a vehicle synonymous with avant-garde design, unparalleled comfort, and technological innovation, reached its zenith of performance with the 25 GTi Turbo 2. While its aerodynamic silhouette and revolutionary hydropneumatic suspension often steal the spotlight, it was the formidable engine lurking beneath its bonnet that truly delivered the exhilarating driving experience. This article delves into the intricate details of the powerplant that defined the ultimate iteration of the CX, exploring its specifications, performance capabilities, and the engineering philosophy that made it a true icon.
The Heart of the Beast: Unpacking the Engine Specifications
At the core of the Citroen CX 25 GTi Turbo 2 lay a meticulously engineered 2.5-litre (2499 cc) inline-four petrol engine. This isn't just any four-cylinder; it was a unit designed for both robust power delivery and remarkable smoothness, perfectly complementing the CX's 'magic carpet' ride. The engine featured a single overhead camshaft (SOHC) controlling eight valves, a common and reliable configuration for its era, known for a good balance of power and low-end torque.
What truly set this engine apart was the integration of forced induction. The 'Turbo' in its name signifies the presence of a Garrett T3 turbocharger, a crucial component that dramatically boosted the engine's output. This turbocharger worked in conjunction with an intercooler, a key upgrade over the earlier Turbo 1 model. The intercooler efficiently cooled the compressed air before it entered the engine, increasing its density and, consequently, the combustion efficiency and power output. Fuel delivery was handled by a sophisticated Bosch L-Jetronic multi-point fuel injection system, ensuring precise fuel metering for optimal performance and emissions control. This electronic fuel injection system was quite advanced for its time, contributing significantly to the engine's responsiveness and efficiency compared to carburettor-fed counterparts.
The bore and stroke dimensions were carefully chosen to provide a good balance between torque and revving ability, contributing to the engine's flexible character. Its robust construction allowed it to withstand the increased pressures and temperatures associated with turbocharging, ensuring a degree of reliability crucial for a flagship model designed for high-speed continental cruising.
Power and Performance: What the Numbers Tell Us
The combination of the 2.5-litre engine, the Garrett T3 turbocharger, and the efficient Bosch L-Jetronic fuel injection system resulted in impressive performance figures for a car of its size and era. The Citroen CX 25 GTi Turbo 2 boasted a healthy power output of approximately 168 bhp (brake horsepower) at around 5,000 rpm. This power figure, while not extreme by modern standards, was more than ample to propel the large saloon with considerable verve.
Equally important was the torque output, which stood at a robust 294 Nm (Newton-metres) or 217 lb-ft, available at a relatively low 3,250 rpm. This strong torque figure meant that the CX 25 GTi Turbo 2 was not just fast at the top end, but also remarkably flexible and effortless to drive in everyday conditions, requiring fewer gear changes. The broad power band made overtaking a breeze and ensured sustained acceleration even at higher speeds.
In terms of outright acceleration, the Turbo 2 could sprint from 0 to 60 mph (0-97 km/h) in approximately 8.0 to 8.5 seconds, a very respectable time for a family saloon in the late 1980s. Its top speed was equally impressive, comfortably exceeding 130 mph (210 km/h). These figures placed the CX 25 GTi Turbo 2 firmly in the realm of genuine performance cars, allowing it to comfortably keep pace with, or even outrun, many of its German and British rivals on the autobahns and motorways of Europe. The sensation of speed, combined with the CX's legendary ride comfort, made high-speed journeys remarkably relaxing and enjoyable.
Engineering Marvel: Beyond the Raw Specs
The brilliance of the Citroen CX 25 GTi Turbo 2 engine extended beyond its raw power figures. It was the seamless integration of this powerful unit with the car's other advanced systems, particularly the hydropneumatic suspension, that truly defined the driving experience. The engine's smooth power delivery and refined operation were crucial in maintaining the CX's reputation for exceptional comfort, even at high speeds.
Citroen's engineering philosophy prioritised a holistic approach, where every component worked in harmony. The engine's characteristics, such as its relatively flat torque curve and smooth response, were perfectly suited to a car designed for long-distance cruising. The turbocharged nature meant that despite its large size and comfortable ride, the CX could transform into a potent grand tourer when required, effortlessly covering ground with minimal fuss.
The engine's design also showcased Citroen's commitment to innovation. While many manufacturers were still grappling with reliable turbocharging, Citroen implemented it effectively, creating a dependable and powerful unit. The careful tuning of the Bosch L-Jetronic system ensured that the turbo lag was minimal, providing an almost linear surge of power that felt intuitive and reassuring to the driver. This meticulous attention to detail in engine tuning and integration contributed significantly to the CX's reputation as a technically sophisticated and highly capable vehicle.
Evolution of Power: Turbo 1 vs. Turbo 2
The Citroen CX 25 GTi Turbo 2 was not the first turbocharged CX; it was an evolution. The original CX 25 GTi Turbo 1, introduced a few years earlier, laid the groundwork. While the Turbo 1 also featured a 2.5-litre turbocharged engine, the Turbo 2 brought significant refinements, primarily the addition of an intercooler and revisions to the engine management system. These changes directly translated into a noticeable increase in power and torque, as well as improved thermal management and durability.
The intercooler was the game-changer, allowing the engine to produce more power more reliably by cooling the intake charge, making it denser and therefore allowing for more fuel to be burned efficiently. This not only boosted performance but also reduced the thermal stress on the engine components, potentially improving longevity. The Turbo 2 also benefited from subtle tweaks to the suspension and braking systems to handle the increased power, further solidifying its position as the ultimate performance CX.
Here’s a brief comparison of the key engine specifications:
| Feature | Citroen CX 25 GTi Turbo 1 | Citroen CX 25 GTi Turbo 2 |
|---|---|---|
| Engine Type | 2.5L Inline-4 Turbo | 2.5L Inline-4 Turbo |
| Displacement | 2499 cc | 2499 cc |
| Intercooler | No | Yes |
| Max Power | Approx. 162 bhp (121 kW) | Approx. 168 bhp (125 kW) |
| Max Torque | Approx. 284 Nm (209 lb-ft) | Approx. 294 Nm (217 lb-ft) |
| Fuel System | Bosch L-Jetronic | Bosch L-Jetronic |
| 0-60 mph | ~8.6 seconds | ~8.0-8.5 seconds |
| Top Speed | ~135 mph (217 km/h) | ~138 mph (222 km/h) |
Maintaining the Legend: Engine Care and Longevity
As with any classic turbocharged vehicle, proper maintenance is paramount for the longevity and continued performance of the Citroen CX 25 GTi Turbo 2 engine. Regular oil changes with high-quality, correct-specification oil are crucial, especially given the turbocharger's reliance on clean lubrication. The turbocharger itself, being a precision component, benefits from careful warm-up and cool-down procedures to prevent premature wear. Allowing the engine to idle for a minute or two after a spirited drive helps the turbo cool down and prevents oil coking in the bearing housing.
The Bosch L-Jetronic fuel injection system is generally robust, but like any older electronic system, it can be susceptible to sensor degradation or wiring issues over time. Regular checks of the ignition system, including spark plugs, leads, and the distributor (if applicable), are also essential for optimal combustion. Given its age, potential owners should also be mindful of the condition of rubber hoses and seals, which can degrade and lead to boost leaks or fluid leaks.
Despite its sophisticated nature, the basic inline-four block is generally considered durable if properly maintained. The availability of parts can be a consideration, but a dedicated community of Citroen enthusiasts and specialist suppliers often makes sourcing components feasible, albeit sometimes challenging. Investing in a good workshop manual and finding a mechanic familiar with classic Citroens or turbocharged engines of this era is highly recommended for any owner.
The Driving Experience: How the Engine Feels
Driving a Citroen CX 25 GTi Turbo 2 is an experience unlike almost any other. The engine plays a pivotal role in this. Upon starting, the engine settles into a relatively smooth idle, hinting at its refined character. As you pull away, there's a gentle surge of power, and then, as the turbocharger spools up, a distinct, yet smooth, push in the back. Unlike some more aggressive modern turbos, the power delivery is progressive and linear, building effortlessly through the rev range.
There's a characteristic turbo whistle that adds to the charm, especially under acceleration. The engine's strong mid-range torque means that overtakes are dispatched with ease, and cruising at high speeds on the motorway feels utterly unstressed. The noise levels are generally well-suppressed, contributing to the CX's serene cabin environment, but a purposeful growl emerges when the engine is pushed hard. This combination of effortless power and supreme comfort solidifies the CX 25 GTi Turbo 2 as a true grand tourer, capable of devouring vast distances with remarkable ease and refinement.
The engine's responsiveness, particularly on the Turbo 2 due to the intercooler, ensures that the car feels lively and engaging, belying its executive saloon dimensions. It's an engine that encourages you to exploit its capabilities, yet never feels harsh or unrefined, perfectly embodying the unique blend of performance and luxury that Citroen aimed for.
Frequently Asked Questions (FAQs)
Q: What kind of fuel does the Citroen CX 25 GTi Turbo 2 use?
A: It was designed to run on Super Unleaded petrol. Given its age and turbocharged nature, using modern high-octane (97 RON or higher) unleaded fuel is highly recommended for optimal performance and engine health.
Q: Is the engine reliable?
A: The 2.5-litre turbocharged engine in the CX 25 GTi Turbo 2 is generally considered robust for its era, provided it has been well-maintained throughout its life. Like any classic turbocharged engine, regular oil changes, proper cooling, and attention to the turbocharger's specific needs are crucial for longevity. Neglect can lead to issues, particularly with the turbo unit itself.
Q: Are parts still available for this engine?
A: While not as readily available as for modern cars, a dedicated network of Citroen classic car specialists and parts suppliers, particularly in Europe and the UK, still stock or can source many engine components. Some specialist parts might require a bit of searching or reconditioning.
Q: What makes the Turbo 2 engine better than the Turbo 1?
A: The primary improvement in the Turbo 2 engine over the Turbo 1 is the addition of an intercooler. This device cools the compressed air from the turbocharger before it enters the engine, making it denser. This results in increased power output (from 162 bhp to 168 bhp), higher torque, and improved thermal management, leading to better efficiency and potentially greater durability.
Q: Does the CX 25 GTi Turbo 2 have turbo lag?
A: While all early turbocharged engines exhibit some degree of turbo lag, the Bosch L-Jetronic fuel injection and careful tuning on the Turbo 2 meant that lag was relatively well-managed for its time. Power delivery is progressive and smooth, rather than an abrupt surge, making it a very usable and enjoyable engine in varied driving conditions.
Conclusion
The engine of the Citroen CX 25 GTi Turbo 2 is far more than just a power unit; it is a critical component that defines the character of this truly iconic vehicle. Its 2.5-litre turbocharged inline-four, with its robust power, generous torque, and refined delivery, perfectly complemented the CX's legendary comfort and aerodynamic prowess. It allowed the CX to be not just a supremely comfortable cruiser, but also a formidable high-performance machine capable of effortlessly devouring long distances at speed. As a testament to Citroen's engineering ingenuity, this engine remains a fascinating piece of automotive history, a powerful heart that continues to beat strongly in the classic car world, captivating enthusiasts with its unique blend of power, sophistication, and Gallic charm.
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