English to Hungarian Tech/Engineering Engineering (general) autó

The air filter plays a fundamental role, operating upstream from the combustion process.
It ensures that a sufficient amount of clean air is delivered where it is needed.
Offering extreme performance, the filter traps 99.96% of particles, down to 1 micron in size.

Hogyan értelmezzük itt hogy "upstream"?

Előre is köszönöm.