So I did enough homework on cam decisions to write a doctoral thesis before I made a choice. In all that homework I never ran across any discussion about your torque and HP lines converging right around 5,250 rpm until yesterday in another cam thread in here. And even in that thread it was just a blip.

I looked at my dyno sheet and whattaya know...dead on 5,250. What's the significance of this and what does it mean?

 

Horsepower is just a derived number. Horsepower is not measured, it is calculated from torque. It's based on torque.

Equation is ft lbs of torque x rpm / 5252 = horsepower

So any torque measured at 5252 rpm will be equal to horsepower.

Capische?

Torque curves are all I care about from an engine. Horsepower is for advertising guys.

ETA if you want to be bored stiff... https://en.wikipedia.org/wiki/Horsepower

 

i think the interesting part is the shape of the horsepower curve that the torque curve creates

 

Right on.
Torque is a twisting motion, that creates the rate of acceleration.
Amplify that with the mechanical leverage of a good gearbox, and now it's happening!
Scott

 

The comment in the other thread I saw this on kinda eluded to the fact that the two lines should cross at this point and if they don't, there's an issue. That part doesn't make sense to me. I know I've seen dyno sheets (cars, bikes, what have you) that don't cross there. Just looked at my dyno sheet from my other bike and the two lines converge ~10,500 rpm. Is that coincidence...5,250 x 2 = 10,500?

 

When HP & TQ curves don't cross at the right point, check the scales on the left & right side of the chart. They have to be the same to cross at the right point.

 

Car, truck, motorcycle, etc, all cross at 5252.
Scott

 

Woah....just went back and looked at my Ducati sheet. They crossed at 10,500 like I said...but the torque scale on the right is exactly half the hp scale on the left...which means if they were the same, they'd converge at 5,250! Now that's cool! Never noticed that ever before.

 

What do I win?

 

LOL like I said, horsepower is for advertising guys.