Just out of curiosity, I have a intuitive question. When I downshifted, I think that the rpm of the engine increases and the car's speed decreases and the performance of cooling decreases, but after the warning light of the water temperature lights at the sixth speed gear, it turns off quickly by shift down in the game. Why is that ?
When you downshift, there isn't any combustion happening. The load isn't the same. There's back-torque or engine braking happening, but it's nowhere near the same level of load happening when the throttle is opened and air-fuel mixture is ignited. Combustion heat is less. The cooling is still working with the water/oil heat exchange and conductivity. Not a thermal engineer but err, that's my take on it.
Thank you for fine explanation. I could image that. P.S. Something is bugging me yet. In the game, I feel that it will be cooler when shiftdown to 5th speed than when throttle is closed with 6th speed.
Its probably caused by an increase in waterflow due to the higher rpms, as the waterpump is driven by the engine.
the water pump is driven by an engine usually but coolant temperature should remain constant under all normal conditions as it is regulated by the thermostat. once it gets up to running temperature it opens and lets the water flow through the radiator system at a constant temp. maybe the game has it in the system that if the engine is constantly run at high revs it is causing it to overstress and causing it to fail, high temp light can be the way the game creators warn the player that they are giving the car a hard time.
engine heat's largest contributor is the rpm levels. If you downshift, you also let off the throttle position and thus reduce rpms until the next gear is engaged. Unless you had seriously overheated the engine prior to downshifting, even this brief respite in rpms is enough to begin the cooling. If you kept your throttlle mashed the entire time of downshifting, I doubt the temps would drop.
I agree, I think it is just the brief reduction in rpm during downshifting that causes the drop. The game models these sort of things by mathematical equations, so there is no water pump that is simulated as such. I don't know the exact code, but I could imagine something like: current_water_temperature = previous_water_temperature + rpm_above_threshold * coeff - speed * air_cooling_factor
I turn off throttle just before shifting down from 6th gear. I often do blipping to avoid car posture changes by engine braking. so throttle is little open. As soon as the shift down to 5th gear is completed, the water temperature warning light turns off.
There is one nice video from EngineeringExplained in youtube, about how coasting cools down the engine. Turns out if you are coasting downhill for a long time, you can cool engine a lot bellow its optimum temperature, and that obviously is not ideal for engine.
Downshifting isn't an isolated event. It's bound to be associated with at least some other input changes, and doesn't mean a speed decrease necessarily (unless you're watching one of the Fast and Furious films, in which case gear is roughly proportional to speed). rFactor is overly sensitive to fuel flow, whereas in reality extra fuel can actually cool the engine down. If you have a drop in temperature you're probably using less fuel, by whatever means.
Does rF2 actually simulate a thermostat opening and closing? All the cars I've made so far I had to use trial and error on the cooling lines in the engine.ini file until I got the required results. This way of doing it is probably a bodge though, and there's probably a better way of doing things. I've blown up a lot of engines, usually gradually but sometimes spectacularly when I've put a decimal point in the wrong place!