This page describes how the Surbo works in detail. For simple animation, click on the upper window and press PageUp and PageDown to see how the system changes through the stages (designed on a 15-inch screen, with display at 640x480. To enable this, minimize all active screens, open "My Computer", select Control Panel, Display, Settings, and scroll Screen Area to 640x480 pixels).

To start, please scroll the upper window above to its top (Stage 1). Press PageDown to bring yourself to Stage 2, and once more to Stage 3 (if you want to know the details, please scroll down).

Focus on different parts of the diagram, and see how they change as you go up and down. This gives you a understanding of what happens, and the way to press the pedal to get the most benefit from the Surbo. i.e. get maximum revving power with just part throttle (or change gears once you have revved enough).

The colours show the air travel, and in order:
1. Black air filter
2. Red Surbo
3. Grey airpipe
4. Throttle (opening adjustable via accelerator, which is shown by the thin lines below the black filter )
5. Pink manifold (which distributes air to the cylinders)
6. The Yellow area is the engine oil-cooling air loop. The lower oil breather L allows the hot air to be sucked away while the upper breather U supplies the engine with cool air. As there must be no air leak, the engine oil dipstick and the oil cap have to be shut tightly.
7. The White meter is an air pressure boost guage (optional). You can read the Boost Gauge page together with this one for a deeper understanding of the Surbo system. This gauge shows the air density in the pink area. The Golden fuel pressure regulator also receives the same air signal via the black vacuum line. Our aim is to raise the air pressure to increase engine compression and thus power, and with more power the driver is likely to press less on the accelerator, thus reducing the fuel injected.
8. The Blue meter is the rpm meter, which shows the engine speed.
9. The Green purge system (p) normally releases air pressure, but we can stop the air loss to give maximum compression, power and economy. (About this purge system: this was originally designed to release air pressure so that fuel pressure does not build up too high (via the regulator) and lead to unburnt fuel and high emissions. However, with the Surbo in place, engine compression and thus power is up so the accelerator needs to be pressed less, lowering consumption and emissions. Emissions have been measured at levels lower than the original (see the Environment page).

This system pleases the driver the most as the throttle opening required is much smaller than before. Your passengers will also have fun as they will feel a tingling sensation in their backs.

Stage 1, 2 and 3: Details

Stage 2: When the back pressure P3 is generated due to the decelerating cylinders (engine already got this pressure as it is built back from there) and the throttle closing relatively to Stage 1, the airflows along the corners avoid the higher P3 and turn into the 4 helically-curved cross blades (virtual, alternate air channels), scale up the range of P2 (taking cover from P3 by flowing under the blades) and squeeze out of the sharp pins at the end of the blades as jets to form a high speed vortex. The jets and vortex together raise the pressure exiting the Surbo to match P3 as they are in the same chamber.

Stage 3: The throttle is opened again relative to Stage 2. Remember that the engine has got P3 already as it was a backward pressure, and runs immediately at this pressure upon acceleration. Since this pressure P3 is higher that that of the atmospheric air coming in through the Surbo, the incoming air must still avoid the higher P3 via the pins, and therefore the jetting continues and the pressure is maintained. This results in higher air compression and extra engine power.

Note: repeated slight pumps (opening and closing the throttle by about half a cm) on the accelerator after the initial activation keeps raising the net air pressure with higher and higher P3 backwaves that the Surbo must match. This method is especially useful for automatics, with a few slight pumps after the initial quick takeoff for a continous surge.

Common question: how is the vortex going to get past the throttle and all the bends to the engine?
Answer: It isn't going to! The spinning will end inches after the vortex. Where it ends, there will be high density flow, at pressure P3. It was the backward P3 that formed the vortex, and not the other way round!

Notes:

P3>range of P2>P1, and air flows into area of lowest pressure. That is why in Stage 1, the airflows go straight only (and avoid the blades which are higher at P2). When P3 is formed, the straight flows turn into the blades once P3 is higher than P2, and as the blades are pointed the pin outputs are high speed nozzles (much like dividing a number by near zero-you get a large number). 4 crossed nozzles result in a high speed vortex, which pressurizes air.

For a Twin Surbo system, another (upper) Surbo can be attached just before the (lower) one in the diagram, and as the lower one is activated, there is internal crossflow, and the upper one is also drawn into a spin. This is provided they are close together within 1.25 inches in a straight line and nothing is in between. If there is insufficient space then both can be installed before the filter in a straight line. (As this is a back-pressure system, fitting before the filter does not matter as even our dynamometer-tested car had Surbos before the filter, and the results were positive. A pressure-drop analysis will also show the before-filter and after-filter Surbo systems to be similar, as the after-filter case must also suffer a pressure drop across the filter before reaching the Surbo.

Note: if you have an automatic car, please read our Auto page for more details. For diesels, due to the absence of a throttle, the back pressure is generated momentarily by the decelerating cylinders only.

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