oMIKEYo Posted June 29, 2011 Report Share Posted June 29, 2011 Never actually new this one? No idea how the dyno gets the reading, obviously I know it has a rolling road etc lol. Just curious as to the question as I've never known and it's always bugged me I know in reality your car can go quicker lighter but on a dyno does it affect the bhp reading? Shoot me if I'm stupid Link to comment Share on other sites More sharing options...
Adam190 Posted June 29, 2011 Report Share Posted June 29, 2011 No! I reckon your thinking of BHP per tonne! Link to comment Share on other sites More sharing options...
yellowchinaman Posted June 29, 2011 Report Share Posted June 29, 2011 Im not sure about Dyno but in real life weight effects torque. Link to comment Share on other sites More sharing options...
nthnmunky Posted June 29, 2011 Report Share Posted June 29, 2011 A car's weight will have absolutely no effect whatsoever on the power an engine can produce, either BHP or torque. It merely affects the way in which that power can be used. Rotational inertia and mechanical mass of engine components will also play a part but I think in laymans terms a 400kg car making 140bhp with a 1zz engine makes the exact same power a 1200kg car makes with a 140bhp 1zz engine ie 140bhp! Now, on the road the 400kg car will simply kick the ass of a 1200kg car with the same power (gearing dependant obviously) because the power to weight ratio is 3 times better So no, there's no point lightening a car to put it on a dyno lol Link to comment Share on other sites More sharing options...
oMIKEYo Posted June 29, 2011 Author Report Share Posted June 29, 2011 I wasnt planning on doing so I was just curious haha. You've answered my question thanks Link to comment Share on other sites More sharing options...
cooperman Posted June 29, 2011 Report Share Posted June 29, 2011 if you are ligtening engine components or any moving part on the engine, drive train will make a difference to power readings. but apart from that, there is no poing stripping the car out. Link to comment Share on other sites More sharing options...
izzzzythedog Posted June 29, 2011 Report Share Posted June 29, 2011 could you be thinking of unsprung weight ? dynos work by driving you car on , a couple of fellas lash it down and a computer is linked t :)o the coffee machine , while the cars being thrashed on the rollers a readout is taken based on the amount of people who showed up and paid for their cars to be run , if everyones a tight bastard then the figures are low and it serves you right , if everyones got a thirst on or heaven help us buys a bag of crisps then the dyno starts at 200 bhp and goes up ,,, look at spot at rs , no coffee machine ,,, 15 bhp at the fly thats what i think anyway orrr i could google water brake Link to comment Share on other sites More sharing options...
yellowchinaman Posted June 29, 2011 Report Share Posted June 29, 2011 Hold up! Am I the only one who's got the wrong idea about Torque? I was once told that torque on a dyno was calculated by the weight of the car and the HP out put which is not 100% accurate. The formula to work out torque is: Torque = Force x Distance To measure real torque you need a motion sensor in a car to measure how much and how hard it moves when you accelerate. ( a bit like the G force calculator in the new skyline R35) On a dyno you can't cos the car is mainly stationary which is why it is calculated instead. So in reality a lighter car does out accelerate a heavier car with the same horse power because it has a greater power to weight ratio. This also means it can out accelerate the heavier car as it has more torque. Link to comment Share on other sites More sharing options...
dublet Posted June 29, 2011 Report Share Posted June 29, 2011 http://en.wikipedia.org/wiki/Torque#Machine_torque Weight of the car has nothing to do with the torque being output by the engine. Link to comment Share on other sites More sharing options...
CelicaBen190 Posted June 29, 2011 Report Share Posted June 29, 2011 I mean look at that massive humvee on top gear last week, massive heavy as hell machine but loads of torque Link to comment Share on other sites More sharing options...
yellowchinaman Posted June 29, 2011 Report Share Posted June 29, 2011 Foot in mouth. So torque is measured in rotational force of the wheels only not of the thrust of the car. Link to comment Share on other sites More sharing options...
izzzzythedog Posted June 29, 2011 Report Share Posted June 29, 2011 as i understand it it works like this in the real world 2 cars , exactly the same but 1 is producing 50 more torques than the next car ,,,, its been chipped for torque alone in a straight drag race they are exactly the same stick 2 people in the high torque car and drag race again ,, they post the same time stick 1 person into the not chipped car and run again , the high torque wins ,,,,even if you hadnt taken out the 2 people from before bhp can be considered its power output but its out and out pulling ability is down to torque someting like dat anyway Link to comment Share on other sites More sharing options...
dr3bin Posted June 30, 2011 Report Share Posted June 30, 2011 So if you had a car that ran 100bhp but like 10lbs of torque, you'd be wheel-spinning like crazy when trying to drive off? And if you had a car that had 10bhp but 100lbs of torque, you'd set off really slowly but would still be able to pull a trailer?? (like a tractor!) Link to comment Share on other sites More sharing options...
izzzzythedog Posted June 30, 2011 Report Share Posted June 30, 2011 So if you had a car that ran 100bhp but like 10lbs of torque, you'd be wheel-spinning like crazy when trying to drive off? And if you had a car that had 10bhp but 100lbs of torque, you'd set off really slowly but would still be able to pull a trailer?? (like a tractor!) yep , about right , this is why tractors pull 20 ton easily but dont have sod all acceleration , its because there knee deep in torque but not bhp , this enables them to belt up and down hills or pull stumps out of the ground it can be considered torque to be the gauge of absolute power but seeing how theres not many people timing cars from 0-60 uphill then it gets ignored Link to comment Share on other sites More sharing options...
splinter Posted June 30, 2011 Report Share Posted June 30, 2011 10lbs (ft/lbs you mean ) won't get a car any where. But your theory is quite right. Link to comment Share on other sites More sharing options...
dr3bin Posted June 30, 2011 Report Share Posted June 30, 2011 Once 0-60 times on straights get boring then we'll definitely be working on 0-60's up hills Someone's sig on here says something like; "BHP is how hard you hit the wall, Torque is how much of the wall you take with you" Link to comment Share on other sites More sharing options...
splinter Posted June 30, 2011 Report Share Posted June 30, 2011 yeah cant remember whos it is, Understeer is when you hit the wall with the front of the car, Oversteer is when you hit the wall with the back of the car Power is how hard you hit the wall Torque is how far you take it with you!! Classic! Link to comment Share on other sites More sharing options...
izzzzythedog Posted June 30, 2011 Report Share Posted June 30, 2011 and scuttle shake is when youcant see a wall untill you hit it Link to comment Share on other sites More sharing options...
nthnmunky Posted June 30, 2011 Report Share Posted June 30, 2011 10lbs (ft/lbs you mean ) won't get a car any where. But your theory is quite right. Unlike your correction. ft/lb (which should really be written ft-lb) is a unit of force, a foot-pound of force is what is required to move an object of a pound in mass a foot in distance. This is a scalar unit of energy or work meaning that it has only a magnitutde. lb/ft (often mistakenly written as such but more accurately lb-ft) is the rotational force required to move a mass of one pound around a pivot point at a distance of one foot. Torque is a vector unit and thus has magnitude AND direction. I'll get my coat. Link to comment Share on other sites More sharing options...
dr3bin Posted June 30, 2011 Report Share Posted June 30, 2011 Someone's had their weetabix today! Link to comment Share on other sites More sharing options...
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