hp versus Bhp

[arandle]

Chaps (etc),

As you will gather I'm a technical simpleton but something is bothering me and I hope someone can help shed some light on a simple technical conundrum for me.

As a keen private pilot I own/fly an aircraft that has an engine rated at 150hp (seems small by sportscar standards I know - and it's a 5 litre!). My car gumpf however rates the car's power as Bhp (ie Brake Horsepower) at a certain RPM.

So my questions:-

What is the difference between the hp of an aero engine and the Bhp of a car engine?

How does Bhp relate to RPM - ie why is Bhp quoted at a given RPM, what's the relationship betwen the two?

Thanks a mill....

[arandle]

Thanks for all your replies gents - I've certainly learnt something here although I'm still a little confused as to why Hp is quoted at a given RPM - why is this not just a max RPM or is there a power peak where piston engines are most efficient?....sorry I'm such a numpty on this tech stuff.

Interesting that the marine and helicopter quotes are different again.

Thanks all, interesting stuff.

[arandle]

Phew! I'm glad I started this one.

I do feel somewhat wiser having read through the thread and checked out the websites, thanks all for your input, very interesting stuff (for us saddo's).

Can't recall who mentioned it but yes, the aircraft engine is low revving - normal operating range is 1800-2500 RPM peaking at about 2800RPM at take-off, if my memory serves me right. So this particular engine does fall into the high torque but low power rating category (in HP terms - this is the 150Hp engine that started the debate)....and of course you don't have to change gear when you're flying so all the arguments make sense.

Thanks again all, great stuff.