NA Power Stage 2: Basic Bolt-ons Intake, Exhaust and Timing

[f1yen]

Found this page during a search,

Correct me if I'm wrong, but shouldn't all dyno graphs cross the HP and torque at 5252 RPM. horsepower is just a mathematical function of torque and time, which means that it should cross at 5252rpm ALWAYS. It only looks like 1 graph fits that category.... I am just skeptical of these graphs.

 

[Bmies]

a dyno does not measure with time, but rather with speed of engine and power. Therefore the time variable is not displayed or graphed. and because engines make max torque at low RPMs and max HP at High RPMs. sometimes the differences are so great that the lines will never intersect (65mm turbo civic would be a good example)

 

[the.jack]

a dyno does not measure with time, but rather with speed of engine and power. Therefore the time variable is not displayed or graphed. and because engines make max torque at low RPMs and max HP at High RPMs. sometimes the differences are so great that the lines will never intersect (65mm turbo civic would be a good example)

Mathematically, HP will *always* equal torque at 5252. Disparate peak numbers are not relevant. HP = Torque [ft-lbs] * (RPM / 5252)

The reason some graphs' lines cross at a different RPM or perhaps not at all has to do with the scaling of those graphs. The *values* are not crossing, only the way the lines have been drawn. The software will scale the HP and torque value axes independently to fit them on the same chart. If you look at the graphs and follow the line upward near 5252 then approximate your values from the two vertical axes (make sure to use the correct side) you'll see that the values of torque and HP are indeed equivalent at those points even if the lines themselves are crossing at a different spot. Graph #3's scales just happen to line up near value 140 which is near the 5252 RPM so it appears to be the "good" one. But you'll note even that graph has different scaling: check out the starting values towards the bottom.