Due to gaps along the air intake and connected tubes and chambers, from wear and tear, imperfect design, or third party servicing or modification, air suction is not entirely directed at the air filter. Air velocity through the air filter drops and the gaps mean some of that air will not enter the engine for combustion. In fact, some dirt enters instead. To create more air suction, the accelerator has to be pressed more, causing more fuel to be injected, resulting in over-fueling that can cause hesitation, carbon deposits, and even knocking. The rpm achieved may not be very high. Some fuel is wasted, often in the form of emissions. For diesels, black smoke might be seen.
A shortage of air causes automatic gearboxes to shift up too soon, because in a higher gear, the engine requires less air. This also makes downshifts more difficult, as the engine requires more air for higher rpm in a lower gear. So, often the accelerator has to be pressed deeply to allow more air into the engine to induce a gear shift down. The result is increased emission and fuel consumption, and foot fatigue for the driver.
In a petrol engine, when the accelerator is pressed more, the vacuum in the engine manifold drops. However, the vacuum is the only force that draws air into the engine. When the accelerator is pressed fully, the vacuum falls to zero, and air induction force is minimized. Also, with the accelerator on the floor, fuel injected is maximized, and over-fueling occurs. Acceleration quickly becomes zero for the gear, and a gearchange up is necessary for further acceleration. Acceleration begins to slow significantly from third gear, and in the top gear, the rpm limit cannot be reached. Therefore, the top speed of a typical 1.6 litre sedan is only about 190kph.
During installation of the Surbo, the gaps in the air intake and connections are covered. If a loose tube is connected to the engine vacuum, our tightening it means the vacuum is restored. Less accelerator pressure is required to pull the air through the air filter and into the engine, so initial acceleration is improved. The lesser fuel injected due to reduced accelerator pressure means over-fueling is prevented. More air goes into engine for proper combustion, increasing low rpm torque. So, acceleration becomes faster initially, and some of the time saved can be used to compress air through the Surbo, for even more power. How so?
By slightly easing pressure off the accelerator for 1 second, a backward air pressure is formed towards the outlet of the Surbo, causing it to twist air and jet it at the outlet to match the back pressure, and the twisting results in a vortex within the Surbo. Upon subsequent acceleration with a slightly larger throttle opening, due to the air pressure that is still ahead, the jetting and vortex continue, and air is gorged into the engine, so that the rpm limit is achieved with just 1/2 accelerator pressure!
When the air is charging between the Surbo and the engine, the engine also puts out exhaust gases of increased pressure, thus helping the exhaust system to blast out the burnt gases from a lower rpm (which aids low end torque). For turbocharged engines, since the turbocharger is driven by the exhaust, the response time of the turbo is reduced so the full turbo effect comes earlier and with less effort from the engine. The result is a quick flick of the rpm meter from 3000 rpm to the red line. Read about reduced turbo lag.
For automatic vehicles, since the Surbo feeds the engine with more air, the engine is allowed to rev higher before changing to a higher gear, and this gives more speed and makes better use of the original max engine torque available at the upper mid rpm range. Similarly, due to more air on standby, downshifts are easier to induce with just a slight press on the accelerator. Once the Surbo is on, a second downshift can also be induced for even more acceleration.
Since the accelerator is never floored, manifold vacuum does not fall to zero, but continues to draw air into the engine forcefully together with the jets and vortex, so acceleration is extended till the rpm limit is reached. With this 3-force air induction system, the Surbo-assisted vehicle is so strong that it will reach the rpm limit even in the top gear, and top speeds of 220 kph for 1.6 litre sedans are routinely reported by customers. While not everyone will drive at such a high speed, a higher top speed means that cruising is easier and fuel savings apply.
At very high rpm, as the accelerator never has to be floored, the manifold absolute pressure is lower than without Surbo, so the cylinders have an easier time compressing the air, and can therefore accelerate faster. Fuel pressure (which is proportional to air pressure) will be less, resulting in lower fuel consumption and emissions. There will be less carbon deposit on the valves to cause knocking, and reduced combustion heat, so your engine is likely to last longer. For diesels, black smoke will be reduced, and noxious NOx will be less due to lower combustion temperatures. The sooner you adopt Surbo technology, the better for your vehicle!
Watch the video above showing how an engine revs with Surbo. Or watch it in conjunction with the How it works page.
Above: video of Volvo XC90 T8 with Surbo, sprinting to 130 kph.
Above: video of Volvo XC90 T8 with Surbo, sprinting to 211 kph.
Above: video of Volvo XC90 T8 with Surbo, sprinting to 224 kph.