Diagram below shows the air pressure accumulation within the Surbo system as the Surbo is activated through Stages 1 to 3.
where P1 is the initial inlet vacuum, P2 is the Surbo's pressure setting, and P3 is the back pressure formed by the temporarily decreased acceleration.
| Stages/ {Surbo System Component} | {Surbo (red), presses air into grey pipe} | {Oil chamber, in orange} | {Governer, controlled by accelerator, in white box} | {Intake manifold, in light grey} | {Engine, bottom block in pink} | {Exhaust, no colour. Exhaust gases flow around turbocharger, spinning it so that it compresses air} |
| initial acceleration (Stage 1) | air flows straight through | is pressed to inject diesel for acceleration | normal absolute pressure | is sole energy source | ||
| pressure accumulation (Stage 2) | begins to cross-jet and form vortex | fills up with engine back pressure | is held still for 1 second to reduce engine acceleration, to generate a back pressure towards the Surbo | fills up with engine back pressure | cylinder pressure increases due to lessened acceleration but air still rushing in | exhaust back pressure increases, ready to blast air out. Turbocharger picks up speed due to exhaust pressure |
| vortex (Stage 3) | spins air at full speed | acts as air pressure accumulator | is pressed slightly more and varied slightly around half way point | half accelerator pressure means half as much diesel injected | higher cylinder compression because of moderately increased air pressure | blasts air out instantly because exhaust already under full back pressure. Turbocharger spins faster than usual, for increased boost. |
| scavenging: pulling gases through (Stage 3 and afterwards) | vortex's suction pulls air in harder than before | half accelerator pressure prevents over-fueling and smoke | higher air density imparts more force to air to overcome flow friction losses | abundance of air to completely burn the diesel injected | higher mass flow to push through exhaust and spinning turbocharger harder than before |
Read the similar study for petrol vehicles.
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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