A SUMMARY:
Driven the usual way, a Surbo-equipped automatic vehicle will accelerate from rest instantly, rev higher (depending on the gearbox program), and be able to kick down gears easily. The improvement will be as in the Dynamometer Test Results, or just about 7 percent.
EXPLANATION:
Accelerator pressure controls the opening of the throttle. The Surbo (in red in diagram below) is fixed tightly in the air pipe and does not move. Its sharp output end faces -> the throttle, so that air flows -> through the Surbo towards the throttle and then into the engine.
Stage 1: to accelerate, press the accelerator to open the throttle, and the engine vacuum will pull the air straight -> through the Surbo's corners and centre, then through the throttle opening.
Stage 2: once the car has gathered speed, if you want to go faster, ease off the accelerator slightly, and the closing throttle causes the air to press <<-backwards towards the Surbo, resulting in a back air pressure, and the straight flows avoid the back pressure and turn anti-clockwise under the Surbo's curved fins and converge to become jets at their sharp tips, matching ->><<- the back pressure.
Stage 3: step on the accelerator slightly again, opening the throttle a bit more, and the compressed air enters ->> the engine and it revs faster. This results in a pressure ahead of the Surbo, so the straight flows continue to duck under the Surbo's sharp tips and jet, maintaining the pressure, and the engine revs higher. This turning of the air causes the round inlet of the Surbo (nearer to the air filter) to form a vortex which sucks more air in, hence the name Surbo (suction-turbo).
So, instead of just the original engine vacuum, we have a 3 force system (1/2 the engine vacuum, jet pressure, and a suction vortex). The higher revs enable easier progress in the following gear (because that will start from a higher rpm where more of the torque is at). Cruising speed is reached sooner, so fuel is saved, at least by 10%. The accelerator will feel lighter all the way.
If the gear is held constant (such as for manual, semi-auto or manual-mode auto gearboxes, or if the automatic gearbox allows high revving), the Surbo can send the engine to the rpm limit with just 1/2 throttle!. So there is a reserve of the other half throttle, and more horsepower can be unleashed by increasing the rev limit. This reserve also helps to increase the top speed, because at the original top speed, the accelerator on a Surbo car will not have reached the floor yet, so there is still some vacuum to keep inducing the air for more power.
Watch the video above showing how an engine revs with Surbo. To return to this page afterwards, click the "back" button. A Surbo-ed motorcycle has been chosen so that the throttle action and revving on the tachometer can be shown together. Note the very slight accelerator movements (turn accelerator/ release accelerator slightly/ turn accelerator) to make the Surbo compress the air. For cars, press the accelerator to open the throttle, release to close it, and press again to open it.
Related pages:
Watch the video above showing how an engine revs with Surbo. Or watch it 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.
More torque and BHP (dyno test)
Quick revving (1/2 throttle to RPM limit)
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