Mazda RX8 rotary engine: technical characteristics, pros and cons

Engine characteristics Mazda Skyactive 2.0

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Since the Mazda RX8 rotary engine often operates under extreme conditions, it must be carefully maintained. In particular, this concerns the regularity of oil changes. It is advisable to perform this procedure once every 5,000 km. Considering that the oil change in this engine is partial, this should not be a problem. It is highly not recommended to tighten it, as you may end up with a new engine, and even a major overhaul will not help.

As noted a little above, the apex is one of the most loaded elements of the system. This plate is a seal between the combustion chambers. Therefore, it is constantly under load from temperature and pressure changes. The designers partially managed to solve the problem with its wear by using high-alloy steel. However, the apex is usually the first to fail.

Malfunctions and repairs of the Mazda Skyactive 2.0 engine

The Mazda SkyActiv 2.0 engine belongs to the first SkyActiv series, which appeared in 2011.
The 2.0 liter engine replaced Ford's Duratek 2.0, which was installed on Mazda under the name MZR LF. Skyactiv 2.0 has good power indicators - 165 hp, in some markets it is throttled to 150 hp, due to the optimization of tax payments, along with power, the engine has become an order of magnitude more economical. The engine is equipped with all modern systems, including direct fuel injection and a variable valve timing system on two shafts “Dual S-VT”, hydraulic compensators so as not to adjust valve clearances, naturally, so that the engine operates at such a high compression ratio (14), a lightweight ShPG is used with pistons having shapes to improve the combustion process, at the exhaust there is a 4-2-1 spider with a catalyst, the length of the spider is designed so as to ensure purging of the cylinders and this entire set allows the Skyactiv 2.0 engine to run on SZh 14 on 95 gasoline and not detonate.

According to reviews from owners, SkyActives are a little noisy at idle, there are vibrations, but as they warm up, everything disappears.

No other complaints were found, everything is quite reliable, however, Motor-X is constantly monitoring the SkyActiv family and if new information appears, you will be the first to know about it. In general, the Skyactive 2.0 liter on the Mazda 3 behaves very quickly and looks like a much more attractive purchase than the Sky 1.5. If the engine is chosen for larger cars, like the Mazda CX-5 or Mazda 6, then the 2.5 liter representative of the SkyActiv series will be more pleasant.

Tips and recommendations from the manufacturer

Due to the high degree of compression, a gasoline power unit can detonate, so it is very demanding on the quality of fuels and lubricants. The manufacturer advises using a grade of gasoline not lower than AI-95, since a low octane number can cause premature failure.

Particular attention should be paid to engine oil. The technical documentation recommends using Ultra 5W-30, since it is most suitable for the engine design and allows for economical fuel consumption.

Do not forget about timely replacement of spark plugs. Their contamination can cause destructive engine detonation.

You also need to be careful about the air filter of the Mazda CX-5 engine, which will prevent damage to the piston group parts and extend the life of the power unit.

Engine tuning Mazda 3/6/CX-5 Skyactive 2.0 l.

Chip tuning SkyActiv 2.0

Everyone knows that the European SkyActiv 2.0 engine produces 165 hp, in some countries the power is reduced to 150 hp, but judging by the measurements, the power is reduced only on paper. Therefore, you need to remove the catalyst, do chip tuning and get 170 hp. without reducing resource. It will not be possible to install a turbine on SkyActive, due to the very high coolant and the need to replace the piston with a forged one, followed by converting the engine from SkyActive to a regular 2 liter. Any methods of supercharging on SkyActive will lead to serious consequences for the engine.

Is there Renesis tuning?

Many car owners would like to slightly modify the Mazda RX8 rotary engine. Reviews say that tuning is inappropriate. This is primarily due to its high cost and complexity. The resource of the RPD also affects it, which is already quite low, and hardly anyone would want to reduce it even more.

That is why they often try to install a different engine on a given car rather than tuning this one. True, in most cases such attempts lead nowhere. The RPD has a small mass, in this case 110 kg. The only more or less sane option is to install the RPD from the RX-7, which is considered more durable. Although 90% of owners ride what was installed at the factory, that is, stock, and are very satisfied.

Technological features of compression ignition

The problem with HCCI is that there is a very narrow range of RPM and throttle positions at which the technology can be applied. It works best with light engine load and moderately low speeds. Outside this range, burning time is chaotic and difficult to control.

If detonation does not occur according to the standards stipulated by the technical parameters, then, at best, efficiency is lost, and at worst, the engine is destroyed. So, there are 2 supporting points:

1. There is a narrow range in which HCCI can be used. 2. Outside this range, spark ignition is required.

Thus, there is a need to solve the problem of easy switching between spark ignition and compression ignition.

But what if you don't need to switch completely? What if you always used a spark plug? That's exactly what Mazda engineers did. In ranges where compression ignition is not possible, the SkyActiv-X engine operates like any other petrol unit. The piston moves upward, compressing the air/fuel mixture to top dead center, where the spark plug ignites the mixture and the flame moves outward, pushing the piston downward, creating the power stroke.

When possible, the engine operates in the same way as diesel engines, albeit with pre-mixed fuel and direct fuel injection. The air swirls as it enters, creating a homogeneous environment when the piston reaches the top of its stroke. Ideally, the air-fuel ratio at this point is about 37:1. This is about the same as traditional gasoline engines. Here, the direct fuel injector reduces the gasoline flow, lowering the air-fuel ratio to a spark plug-appropriate ratio of approximately 29:1.

These two separate areas of mixing play an important role. As the piston moves upward, the fuel gets dangerously close to igniting from the heat and pressure from compression (understand that this is regular octane fuel with a compression ratio of 16:1). Before the mixture detonates, the spark plug is activated. The thinner area of ​​air near the plug burns, creating a small, expanding fire.

With the additional pressure from this fire, the surrounding very dry air can no longer remain in its original state. Almost instantly the entire mixture explodes. This is where Mazda's design makes so much sense - using the spark plug for optimal combustion time and using compression ignition for incredibly high efficiency.

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But what about a supercharger, low octane fuel, and any Miller cycle? Everything that at first seems contradictory has a rational explanation.

Ion sensors, direct injection, fuel pump and injectors

The shape of the piston alone cannot be used here and will not eliminate detonation under certain loads. Therefore, certain ion sensors were built into the ignition coils.

It is these sensors that help the engine operate on the verge of detonation, and contribute to the complete combustion of the fuel mixture. However, it should be noted that there are also ordinary elements that monitor detonation

The operating principle here is as follows - the ion sensor monitors the fluctuation of the ion current in the gap of the spark plugs after ignition of the fuel mixture. When it burns, ions are formed that make the medium conductive, the sensor sends pulses of electricity to the electrodes of the candle and then measures them. If there is any deviation, then he orders the ECU to adjust the ignition (it’s difficult to understand, but it works). Thus, detonation is practically eliminated.

The fuel pump, here it is a high pressure pump (HPF), supplies fuel with increased pressure up to 200 BAR (on old engines there was only 100–115 BAR). The injectors are built into the block itself, each on its own cylinder (that is, direct injection), and at the end they have six points for simultaneous injection (instead of one, as was usually used).

This approach to nozzles and increasing pressure also has its effect. BEFORE mixing the fuel mixture (as you and I know, here air is supplied through the manifold, and fuel through the injectors and they are mixed in the cylinder, but for some time the fuel is alone without air), the gasoline that was supplied to the cylinder cools it a little, removing excess temperature. Which also reduces the detonation a little. Moreover, there are 6 injection points, which creates a larger cloud that covers a larger cooling area.

What is lubricant waste

Oil consumption is a normal part of its operation in an engine. It is due to the fact that the motor elements have minimal gaps into which the lubricant penetrates; they are necessary precisely for these purposes, otherwise friction processes will lead to the wear of parts. The penetration of lubricant into these gaps leads to a gradual decrease in its level in the system. Getting on the surface of moving parts, the lubricant forms a protective film, and it, preventing the working surface from being worn out, burns itself out, being promptly replaced with a new portion of oil.

The manual for the Mazda CX 5 indicates the permissible amount of lubricant consumption for waste, it is 800 ml per one thousand kilometers. It is important not to exceed these values; it is recommended to avoid the following factors during operation:

• Increased load - it is not worth overloading the car beyond the stated requirements; often using it as a towing vehicle is also not recommended;
• Heavy traffic – when driving with frequent stops and starts, especially uphill;
• Idling – in this mode there is an increase in waste;
• Driving at high speeds – sporty driving style increases the consumption of all engine resources.