Acceleration curve vs torque curve vs HP curve.
#21
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
3 Ways to Calculate Acceleration - wikiHow
Unless i'm misunderstanding your **** though.
#22
Elite Member
Thread Starter
Join Date: Apr 2010
Location: Newcastle, Australia
Posts: 2,826
Total Cats: 67
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Yes, it will be different units and scale but yes. Matter of fact thats how Drum dynos work to calculate HP/tq. They know the mass of the drum and they measure how quickly your car accelerates the drum.
3 Ways to Calculate Acceleration - wikiHow
Unless i'm misunderstanding your **** though.
3 Ways to Calculate Acceleration - wikiHow
Unless i'm misunderstanding your **** though.
#26
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Basically if you can get some data points. Ie Speed, RPM @ set 0.1 second time intervals then it would be easy to graph against a dyno plot for that engine.
I think acceleration = HP graph. Speed = area under HP graph (multiplied by a constant which is something like Diff * gear / mass of vehicle)
#27
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
18psi sort of gave a representation above. Problem is the x-axis for acceleration is time, while for torque and HP it is RPM. You would have to skew one curve or the other to get an overlay.
But, the answer is clear. F=ma (somebody already said that). For example, VD calculates torque from the acceleration curve taking into account aerodynamic drag plus a fudge factor for road and drivetrain resistance. It then multiplies torque by RPM to derive HP.
But, the answer is clear. F=ma (somebody already said that). For example, VD calculates torque from the acceleration curve taking into account aerodynamic drag plus a fudge factor for road and drivetrain resistance. It then multiplies torque by RPM to derive HP.
#29
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
That's because it isn't an acceleration curve. It's a speed curve. Acceleration would be the first time-derivative of the curve your showing. I don't think it's a logged parameter from the MS though. When VD does it's calculation, it is calculating linear acceleration in little chunks of time based upon the change in speed.
#30
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Oh, well that makes more sense.
And that log is not made by MS, it's made by an OEM ecu![](https://www.miataturbo.net/images/smilies/smile.gif)
I just screenshot everything in MLV because I like how it looks.
I have hundreds of logs and dyno plots from all sorts of cars with the speed/torque plotted, but if what you're saying is true then none of it will be of any use for this particular question. And I doubt many (any?) other people will have accel curves for that matter. It's just not something people.....record?
And that log is not made by MS, it's made by an OEM ecu
![](https://www.miataturbo.net/images/smilies/smile.gif)
I just screenshot everything in MLV because I like how it looks.
I have hundreds of logs and dyno plots from all sorts of cars with the speed/torque plotted, but if what you're saying is true then none of it will be of any use for this particular question. And I doubt many (any?) other people will have accel curves for that matter. It's just not something people.....record?
#34
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
https://www.physics.uoguelph.ca/tuto...ro.angacc.html
All the other stuff you enter like Cd, tire diameter, rear end and gear ratios and the basic speed vs. time data are meant to create the numbers from which you can calculate torque from the above Newtonian formula. Once you have torque, it's a simple matter to multiply by RPM and get HP.
#36
Elite Member
Thread Starter
Join Date: Apr 2010
Location: Newcastle, Australia
Posts: 2,826
Total Cats: 67
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
Now its feeling like a clever conversation.
Anyone with an overlay that includes G force can probably do this right?
Preferably the person would have a non flat torque curve with an easy to see obvious knee point.
Dann
Anyone with an overlay that includes G force can probably do this right?
Preferably the person would have a non flat torque curve with an easy to see obvious knee point.
Dann
#39
Elite Member
Thread Starter
Join Date: Apr 2010
Location: Newcastle, Australia
Posts: 2,826
Total Cats: 67
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
As hornet said if you wanted the exact number you can calculate it either direction, but just a torque curve thats kinda unique and a matching acceleration curve thats kinda unique would do because you can just stretch the images to get the scaling comparable for a visual check.
I want to do this so I can show others that infact the math is totally correct, and explain how torque curve shape affects driveability and how a flat hp curve within a given range is worse than a constantly increasing HP curve (with the same are under the curve) for reasons of driveability, and loading components/things likely to break (conrods, clutches, gearboxes, diffs, axles, and finally traction).
Dann
I want to do this so I can show others that infact the math is totally correct, and explain how torque curve shape affects driveability and how a flat hp curve within a given range is worse than a constantly increasing HP curve (with the same are under the curve) for reasons of driveability, and loading components/things likely to break (conrods, clutches, gearboxes, diffs, axles, and finally traction).
Dann
#40
Former Vendor
![](/mt2011/images_td/ranks/supporter1.gif)
iTrader: (31)
Join Date: Nov 2006
Location: Sunnyvale, CA
Posts: 15,442
Total Cats: 2,103
![Default](https://www.miataturbo.net/images/icons/icon1.gif)
This is the fundamental equation being used:
https://www.physics.uoguelph.ca/tuto...ro.angacc.html
All the other stuff you enter like Cd, tire diameter, rear end and gear ratios and the basic speed vs. time data are meant to create the numbers from which you can calculate torque from the above Newtonian formula. Once you have torque, it's a simple matter to multiply by RPM and get HP.
https://www.physics.uoguelph.ca/tuto...ro.angacc.html
All the other stuff you enter like Cd, tire diameter, rear end and gear ratios and the basic speed vs. time data are meant to create the numbers from which you can calculate torque from the above Newtonian formula. Once you have torque, it's a simple matter to multiply by RPM and get HP.
If you've ever used a Dynojet and had trouble with the RPM pickup, you'll understand what I'm saying. Dynojets don't need to know RPM to generate an accurate power curve, and they never ask for tire diameter or gear ratios at all. They measure raw power based on the time it takes to accelerate a known mass (the drum), then use RPM to back-calculate torque output from there.