03-21-2004, 03:49 AM
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#1
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turbo-charged-supercharged bhp-torque
what mean this very known terms
why is bhp and not hp?
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03-21-2004, 04:20 AM
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#2
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bhp is the power produced at the crankshaft...i.e. not subject to drivetrain losses whereas HP is usually measured at the wheel.
turbocharging and supercharging are two different means of what is called, "forced induction" where more air is compressed and forced into the cylinder than would naturally be possible.
a turbocharger is a turbine driven by exhaust gasses that then drives a second turbine that pumps fresh air into the engine.
a supercharger is a mechanically driven turbine (usually driven by the crankshaft) which forces fresh air into the engine.
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03-21-2004, 05:20 AM
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#3
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i though bhp and hp were the same.. bhp being brake horse power and hp beign horse power. the idea is the same though, its the power needed to hold the engine at a constant rpm. as for drivetrain losses i thought that was whp... wheel horse power. could be wrong tho
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03-21-2004, 05:58 PM
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#4
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deth you are correct. HP is just a unit of power. BHP and WHP are just distinctions in where the power is measured.
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03-21-2004, 06:51 PM
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#5
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precisely.
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me-- "Sometimes you feel like a nut, sometimes you don't. Sometimes I feel like the moon is made of cheese"
my Hindibonics-speaking Indian roommate--"Dawgs, do you have any idea how much bacteria that would take?"
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03-22-2004, 12:57 AM
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#6
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Originally Posted by jasc
deth you are correct. HP is just a unit of power. BHP and WHP are just distinctions in where the power is measured.
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umm....the brake in brake horse power refers to the fact that there is a needed amount of horse power to 'brake' the engine, and hence hold it at a given rpm.......it doesnt necessarily have to be measured at a given place ie crank vs wheel
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03-22-2004, 01:04 AM
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#7
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Originally Posted by deth
umm....the brake in brake horse power refers to the fact that there is a needed amount of horse power to 'brake' the engine, and hence hold it at a given rpm.......it doesnt necessarily have to be measured at a given place ie crank vs wheel
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umm....so you're telling me that no power is lost in the drivetrain? The power needed to "brake" the engine at the crankshaft is the same as at the wheels? :roll:
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03-22-2004, 01:06 AM
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#8
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a supercharger is a mechanically driven turbine (usually driven by the crankshaft) which forces fresh air into the engine.
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Whats the difference between a roots type, and a centrifugal? The centrifugal looks more like a turbocharger right?
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03-22-2004, 01:17 AM
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#9
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centrifugal or roots is what they mean by the turbine type
A centrifugal turbine is the same as the one used on a turbocharger, the only difference is that a turbocharger has another turbine that is driven by exhaust gas, and this turbine turns another turbine (the centrifugal compressor), whereas in a supercharger this centrifugal compressor is driven by the engine directly through a belt or gears.
A roots type supercharger, correct me if i'm wrong, looks like two gears in a casing, or any other pump like an oil or water pump.
The difference between the two is that the roots type produces pressure in a progressive manner whereas the turbine is more efficient at a given rpm..
If you look at a pressure curve per rpm, the centrifugal turbine is steeper than the roots turbine.
Difference between one and other, the centrifugal is cheaper to produce I suppose, as well as much less complex than the roots. Also I think the roots has the ability to compress the air fuel mixture whereas the centrifugal just compresses the air before it mixes with fuel..
Please correct me in anything i'm wrong.. 
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03-22-2004, 01:55 AM
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#10
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Originally Posted by fedezyl
centrifugal or roots is what they mean by the turbine type
If you look at a pressure curve per rpm, the centrifugal turbine is steeper than the roots turbine.
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I beg to differ...i have a roots type supercharger...and full boost is instantaneous(i have usable boost from idle- 8 psi @ about 2000 rpm or less straight through to redline)..so i would think the roots type would have a steeper graph...
The advantage however of the centrifugal is its efficiency...and the ability to run higher 'boost' levels.. 8)
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03-22-2004, 02:30 AM
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#11
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10x a lot guys
this was really clear for me?
Another question: why it is said that Wankels aren't so eficient in time?(durability)
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03-22-2004, 02:38 AM
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#12
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Roots and centrifugal should produce similar horsepower and torque curves, as they are both mechanically driven whereas there is definite lag w.r.t. the volume and speed of exhaust gas necessary to spin a turbo.
check out this website, it might help settle things:
http://www.rcspoolers.com/Root_vs_Cent_vs_Screw.htm
deth wrote:
umm....the brake in brake horse power refers to the fact that there is a needed amount of horse power to 'brake' the engine, and hence hold it at a given rpm.......it doesnt necessarily have to be measured at a given place ie crank vs wheel
umm....so you're telling me that no power is lost in the drivetrain? The power needed to "brake" the engine at the crankshaft is the same as at the wheels?
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I don't believe that is what deth was trying to say...
I think he was explaining what has only haphazardly been explained already. That in fact brake horsepower is the amount of power necessary to keep the engine running at a constant speed with a given load (originally measured with a flywheel brake). There is of course something on the order of 15% drivetrain loss in the end, so f/rwhp is a more interesting number as far as performance nuts are concerned. HP is an ill-defined measure, as it is difficult to tell from one manufacturer to another at which point they are measuring power...SAE net is probably the best indicator in the end as far as that is concerned.
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me-- "Sometimes you feel like a nut, sometimes you don't. Sometimes I feel like the moon is made of cheese"
my Hindibonics-speaking Indian roommate--"Dawgs, do you have any idea how much bacteria that would take?"
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03-22-2004, 02:40 AM
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#13
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Wankels tend not to be reliable over long periods of time because they require a very tight seal between the rotary piston and the walls of the "combustion chamber"...as time goes by, and lubrication becomes poorer, the seal gets worse, power is lost and eventually the engine is more or less useless.
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me-- "Sometimes you feel like a nut, sometimes you don't. Sometimes I feel like the moon is made of cheese"
my Hindibonics-speaking Indian roommate--"Dawgs, do you have any idea how much bacteria that would take?"
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03-22-2004, 02:44 AM
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#14
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Don't Wankels only have 3 valves? Would 2 be for exhaust to provide better throttle response?
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"You can get a lot much farther with a kind word and a gun, than you can with a kind word alone"
-Al capone
"Time is a versitile performer: it flies, marches, heals all wounds, runs out and will tell"
-Franklin Jones
^The definition of grip. Nav+Bose (standard) Arctic Silver on Blue, Heaven on Earth. '05 911 Turbo^
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03-22-2004, 02:46 AM
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#15
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It depends on the engine...if you look up the construction of the RENESIS engine in the RX-8 you'll find that on one version there are 3 and the other there are only 2 (or something like that, I can't remember the numbers for certain.)
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me-- "Sometimes you feel like a nut, sometimes you don't. Sometimes I feel like the moon is made of cheese"
my Hindibonics-speaking Indian roommate--"Dawgs, do you have any idea how much bacteria that would take?"
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