Explain HP/T ?

[El Campo]

If HP and T are the same at 5252 RPM does this mean that the torque will never go up from this point? Or do any engines make more torque ever above this RPM than they make below it? What about on turboed engines such as small CI engines (puke imports for example that make 1000 HP at 10000 RPM). I am super ignorant on this sort of thing (damn private school and their no math having ways)
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[Marv D]

No, that just means that torque will be higher than HP below 5252, and HP will be higher than torque above 5252. HP and torque cross at 5252. Look at your dyno sheet again and guarented that's what you'll see. It's a mathmatical equation that can't possibly be any other way. Both can still climb. Not saying that the torque peak can't be above 5252. Case in point a top fuel dragster makes it's peak torque around 6300-6500, both HP and torque numbers continue to climb to 8500,, they think,, no dyno in the world can measure it. The 8000-10000HP is a calculation based on the weight, aerodynamics and speed.

I'm surely no expert, but wil take a stab at this.

Torque x rpm
____________ = HP

5252

Torque is the twist on the end of the crankshaft. To add torque with the 'momentum' of the crank already spinning 5000rpm is a demonstration of power. That's why they came up with horsepower. It adds a time factor (Rev per MINUTE) to the making of torque. Well that's not actually 'why' but it makes a relative measure for us to use in comparing power of one engine over another.

And BTW,,, no question that a stroked BBC is going to be MASSIVE.

Yeah I questioned the huge HP number because the 518 HP at 1500rpm would be 1800 ft lbs of torque,, that's about 1/2 of what a 8500 cubic inch locomotive engine makes (their max rpm is down there less than 1000 as I recall)

Theres a thread below where bcduetch made 1320 pounds of torque (to the rear wheels) with a turbo duramax. The diesel will make frickin astounding torque numbers, but are not going to spin 6000 or 7000 rpm That's why you don't see the truck adds talking about horsepower on the diesels,, only torque because (in stock form) the diesel making 750pounds of torque at 2500rpm a whopping 399HP. That doesn't impress anybody when manufacturer B is talking 750 pounds of torque. It's all about the TWIST on the crank,, HP just adds a time factor to it.

There are dyno sheets all over the net,, and for the most part a mild / upper performing gas engine will make it's torque peak somewhere around 4200-4600. And generally a HP peak around 6200-6400. (at least,, for motors under 400 to 425 inches) More inches that torque peak starts moving down because of frictional losses...

Make sense?

[pockets]

To expand on what Marv said, to put it simply, horsepower is purely a math formula. A dyno measures torque, not horsepower. It takes torque and RPM and calculates the horsepower using torque X rpm / 5252. That is why they are always equal at 5252 RPM, however both can still be climbing (although not very common), but horsepower will always be higher above that RPM.

[El Campo]

Thank you both, gentlemen!!! I will "roll that around" and think about it. Great answers by the way and easy to understand hopefully someone else found this as informative as I did!
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