Quote:
Originally Posted by NESW20
holy shit you fail.
it's a graph showing how much torque at each RPM will produce 200hp. so when we "know" we WANT 200hp, we can look at the graph and see how much torque is required at a particular RPM to achieve the desired power level. it's not reasonable for any production 2.0L n/a 4 cylinder to make 350ft.lbs, but it's entirely reasonable for it to make 130ft.lbs and rev to 8000rpm.
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First, way to make an ass of yourself.
Second, If we are wanting 200hp, we still don't know what torque or rpm that 200hp occurs at. In other words, we have one known, two unknowns, and one equation; which means we cannot solve the equation exactly. Read up on engines and learn some math before you post shit.
Quote:
Originally Posted by overvolting
If I asked you a question in the form of:
"Hey nate, my engine makes peak power at X RPM. I wanna hit 200HP out of this tune so I can brag to my buddies I make 200HP. How much torque should I aim for?"
It might make your life quite easy to refer to this graph.
I know algebra and maths is hard and it's for the nerds, but it is kind of a simple basic form of maths that has been used since AT LEAST 1700BC. That's almost four thousand years ago. I mean, it's like there's counting and then there's algebra and anything that's worth thinking about is kind of beyond that...
Power[hp] = (Torque [ft.lb] * RPM[w])/5252
Power*5252 = Torque*RPM
Torque = (Power*5252)/RPM
The graph simply plots Torque = (200hp*5252)/RPM
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I know math can be tough, but I'm an engineer and have been teaching calculus on the side for the past four years, so I'm competent in my math skills. All your equations are correct, but the thing is that the relation ship between torque and rpm is not linear. Torque varies with rpm, increasing, then decreasing. What that graph is saying is that ass rpm's increase, torque decreases, and vice versa. However, torque does not increase as rpm decreases past a certain point.
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It represents more than a single car.
It represents ALL cars. ALL engines. In fact, ALL OBJECTS that can rotate and have a coupled force of 200hp.
It's a pretty big axiom.
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This is incorrect for several reasons. Not all cars are the same. Not all engines have the same torque curve (in actuality, no engine has the same torque curve as another since there are slight deviations in machining and assembly-this is the reason Nissan didn't post HP numbers for their engines since it could deviate by 15hp). With spinning objects, things get more complex with mass concentrations, moments, etc.