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how do dynos work?

17UCK!

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i see/here people sayin i went in n got my car dyno tuned n they got 40kws out it.. just wondering exactly how it works? and dose it work on a vs commo lollllll:thumbsup:
 

adamc11

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To put it simply... you drive your car up onto the dyno and put your rear wheels (for rwd car) on a set of rollers. When you accelerate though the gears, the rollers spin and the dyno measure the power your car has at the wheels :D
To say someone got 40kw out of it (they probably mean 40rwkw (rear wheel kw as dynos measure in kw at the wheels)) it means that they probably had a tune at the same time... i.e. dyno tune... a professional tuner tunes your vehicle on the dyno so you get the most amount of power out of it.
 

17UCK!

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yeh but like how do they " tune " it?? wat do they axully do 2 make u get more kw? thats wat i dont understand.:bang:
 

greenfoam

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yeh but like how do they " tune " it?? wat do they axully do 2 make u get more kw? thats wat i dont understand.:bang:

Mostly the extra power is from more spark advance, the factorys don't tune cars to all their potential for various reasons. So most cars can have the spark advance increased so that by the time the piston reaches the top of it's stroke the burn is allready well underway and so you get more pressure, more effciency and more power. On modified cars that have had parts changed to get more effciency from the motor they can have more fuel added in those areas to gain a bit more power again. That's about it
 

Not_An_Abba_Fan

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dynos dont measure rwhp/rwkw

they measure torque and calculate the hp/kw from that

Dynamometer - Wikipedia, the free encyclopedia

Beat me to it.

Power is just a calculation. It doesn't really exist. James Watt thought it up when wanting to talk about the effort required from a pony to move coal in a coal mine. At best it was an estimation because horse couldn't sustain the effort over a period of time at the figure that Watt came up with.

It has been passed on through the years as a figure that people use to rate the available power of a machine. An engine doesn't produce power at all, it produces torque (twisting effort), this is measured and converted to hp or kW.

To answer the OP's question a bit more, a dyno loads up the engine by providing resistance to the rollers and measures peak torque. This is when the engine loses it's ability to spin the rollers at certain revs.
 

17UCK!

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cheers greenfoam . that was the kinda answer i was lookin 4 lol..:thumbsup:
 

Weekend Warrior

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Beat me to it.

Power is just a calculation. It doesn't really exist. James Watt thought it up when wanting to talk about the effort required from a pony to move coal in a coal mine. At best it was an estimation because horse couldn't sustain the effort over a period of time at the figure that Watt came up with.

It has been passed on through the years as a figure that people use to rate the available power of a machine. An engine doesn't produce power at all, it produces torque (twisting effort), this is measured and converted to hp or kW.

To answer the OP's question a bit more, a dyno loads up the engine by providing resistance to the rollers and measures peak torque. This is when the engine loses it's ability to spin the rollers at certain revs.


torque is actually "turning force" and is calculated by the force x radius :D hahah good old physics class taught me that one
 

Not_An_Abba_Fan

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Turning force twisting force, same thing. The effort required that causes something the turn or twist.
 

davey g-force

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Beat me to it.

Power is just a calculation. It doesn't really exist. James Watt thought it up when wanting to talk about the effort required from a pony to move coal in a coal mine. At best it was an estimation because horse couldn't sustain the effort over a period of time at the figure that Watt came up with.

It has been passed on through the years as a figure that people use to rate the available power of a machine. An engine doesn't produce power at all, it produces torque (twisting effort), this is measured and converted to hp or kW.

To answer the OP's question a bit more, a dyno loads up the engine by providing resistance to the rollers and measures peak torque. This is when the engine loses it's ability to spin the rollers at certain revs.

Not sure if I mis-read your post but I'm not sure what (watt?) you're trying to say here. Of course power exists and it is very real.

Power (measured in watts) measures the rate of energy use or production per unit of time; i.e. 1 watt = 1 joule of energy per second.

An engine produces BOTH power and torque - hence why all vehicle manufacturers quote both kW and Nm figures. Also why two cars can have the same power, but one can be quicker than the other due to it having more torque.
 
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