The phrase "at high engine speeds" is correct and usable in written English.
It can be used when discussing performance, behavior, or characteristics of engines or vehicles at elevated RPMs.
Example: "The vehicle's fuel efficiency decreases significantly at high engine speeds due to increased fuel consumption."
Alternatives: "at elevated RPMs" or "at increased engine revolutions".
Turbochargers are superb power enhancers at high engine speeds but are known laggards at low r.p.m.
At high engine speeds, when the valve is really needed, it opens automatically anyway.
The effects of the higher order dynamics of the crank-slider mechanism on the measured angular motion of the crankshaft have caused the (P ω) method to yield erroneous results, especially, at high engine speeds.
Moreover, the analysis of the experimental data has also confirmed that the Research Octane Number RONN) index is less important than the Motor Octane Number (MON) at high engine speeds and loads, useful to characterize the octane requirement for modern engines.
At high engine speeds, BSFC values are higher because of higher engine friction.
Similarly, the high performance of OCC bowl geometry could result in a high NO emission at high engine speed condition.
Also, the simulation results indicate that in terms of performance SCC is favorable at low engine speed; whereas at high engine speed, OCC is preferred.
This paper reports the numerical investigation on the effects of three bowl geometries on a gasoline/biodiesel fueled RCCI engine operated at high engine speed.
The high combustion temperature at high engine speed becomes the dominant factor, making both heated and unheated fuel to acquire the same temperature before fuel injection.
It is found that the narrow entrance of combustion chamber could generate a strong squish, especially at high engine speed, hence enhancing the mixing of air and fuel.
Therefore, the boost pressure at high engine speed, in which knocking problems are less intense and the volumetric efficiency is lower, is limited by the threshold value defined at medium-low engine speeds, i.e. the pneumatic WG limits the maximum power that the engine can supply.
