In a normal diesel engine, air flow is fixed at idle, with some spare air to allow for additional fuel for acceleration without smoke. The excess air is limited, and to prevent or lessen smoke, a mechanical stop on the accelerator may be used, to limit accelerator travel. Or, sensors may be used to calculate the maximum fuel permissible to prevent smoke, but this can result in serious curtailing of engine power. It's probably better to provide more headroom by making more air go into the engine.
A normal diesel engine smokes, indicating that for that particular level of acceleration required, there is not enough air to fire with the fuel at the same time. All the oxygen that is available or can be found in time by the fuel is already used up and that is the natural limit for power. Therefore it is imperative to provide greater air headroom and air flow scaleability to always keep ahead of diesel fuel injection. That is, to let air supply lead fuel supply, like in a petrol engine. But is this possible?
Even if the diesel engine is turbocharged, for sudden acceleration or before the turbo is on, the engine can still smoke. The problem gets worse if there are leaks in the pipes connecting the turbo, intercooler and engine.
With Surbo, this air headroom is increased, shown by a higher idling rpm. This reflects the Surbo's higher air compression and efficiency. With more air flowing through the engine, with some accumulated in the oil chamber which is part of the Surbo system, more fuel can be put in to accelerate harder and to a higher rpm without smoking. Once the accelerator is slightly released and the Surbo is back pressed to generate compressive air jets, less work is required from the engine, which can continue to accelerate without smoke. Therefore, in a Surbo-powered diesel vehicle, the engine is no more entirely fuel-led, but running lean with higher compression due to increased air flow. So, the performance gets a whole lot better.
Even in the case of a leaking turbo pipe, the Surbo can make a difference because the air taken into the engine is above normal intake pressure (reflected by the higher idle rpm). This was the case for a Surbo-equipped Mercedes vito 111, which showed even more power after the turbo pipe was changed. Having all engine-connected air pipes, including the turbo ones, airtight, improves the back pressure required for Surbo charging.
Owners can have the pipes checked first, or come for Surbo installation first, and with our experience we will be able to tell you if your turbodiesel vehicle is in tip top condition.
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.