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(meaning high volume : PV=NRT - Boyle&Mariotte law) from a 1.5 liter bank at, say, 1 bar (absolute pressure, ie no boosting) and 4000 RPM, to go through a pipe 4 feet long and 2.5" diameter ? OK, let's try : -> 1.5liter at 4000RPM (4-stroke so 2000 cycles) = 1.5*2000 = 3000l/mn = 50l/s -> This cold air enters the cylinder at, say, 300Kelvin (no boosting). The exhaust gas temp (mean value) along the exhaust line before the end f the TP (where the sensor is) is, say, 900Kelvin, and mean pressure could be 2 bars. -> So the air breathed at 50l/s is flowed at 75l/s. -> Let's say DP+TP's length is 1.5m (I don't remember exactly), and ID is 60mm. Section is Pi*R²=28cm², volume is section*length = 28*150 = 4200cm^3 = 4.2l -> Finally, if the gas flow is 75l/s and the piping's volume is 4.2l, it takes 4.2/75=0.056 second for the flow to go from the DP to the end of the TP. I'm sure there are many approximations in my values (especially the exhaust temp and pressure), but hey, even if I'm wrong with a 2x ratio, I'm pretty sure the sensor itself will not react quicker than 1/10s.
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