I think the key to determining hp by the engine and exhaust note is to tell how many rpm the engine is turning. In F1 the formula is 3.0 Litre V10s right. If you are able to tell the rpm by the note, you can roughly guess the hp since hp is a function of rpm and torque. Since they all have 3.0 litres, they pretty much know the torque range so the question becomes how man revs is someone turning. Last year the BMW V10 broke the 19 000rpm barrier and it is agreed that BMW has the strongest engine in F1 by 20 or so hp.

If force induction is added then it puts a monkey wrench into the model.

Next time, listen to the pitch at 6000 compared to 9000 and listen to F1 cars at 18 000 rpm. Very high pitched at 18 000 for sure. The harmonics is like the doppler effect of red or blue shift in the spectrum.

 

But if a car drove by and you had no idea what size the engine was, how many cylinders it had, and whether it had forced induction would you be able to know how much power it had just from the exhaust sound alone? No way.

 

Ok, I was reading an issue of Street Machine Magazine and it said something like the harmonic sound of the exhaust on the straightway and power can determine the approx HP in a car given the model and make. I wasn't sure if this was true or not and that's why I posted it here...

 

Ahhh, with this "qualification", then there is some validity to the statement. Given the same car and the same type of engine, then yes, you can determine, with a trained ear, that one has "X" HP more than the other. Had you made this more detailed statement in your original post, you would not have suffered quite as many flames.

I think what most posters here were getting at was that you cannot tell how much HP any individual car has by its sound alone. You must have a comparison, a "common footing", to make such a discrete judgement.