Engine doesnt perform as expected

Hello,

i tried to create an engine for the Gavril Grand Marshal based on the BMW M5 (e34) 3.8l inline six cylinder engine but somehow the transmission aswell as the engine dont exactly perform as expected. Here's an overview of the performance -> http://www.e34.de/e34/tests/Test-m5-4.jpg
And here's the result out of BeamNG:

As you can see the max hp is not at 6900 rpm and "only" about 304HP @ 6000 rpm, but the real engine has about 340hp @ 6900 rpm
Also, the transmission delivers about 83 kph and not 58 kph in the first gear (Depends on wheel size?)
Do i have to change sth on inertia/friction/...?

Here's the source code (based on the hatch)

Code:

"enginetorque":[
        ["rpm", "torque"]
        [0, 0],
        [1000, 145],
        [1500, 175],
        [2000, 200],
        [2500, 250],
        [3000, 325],
        [3500, 350],
        [4000, 380],
        [4750, 400],
        [5000, 395],
        [5500, 375],
        [6000, 360],
        [6500, 325],
        [7000, 295],
        [7500, 250],
    ],
    "engine":{
        "idleRPM":1000,
        "shiftDownRPM":3000,
        "shiftUpRPM":6900,
        "maxRPM":7500,
        "inertia":0.08,
        "friction":16
        "brakingCoefRPS":0.15
        "burnEfficiency":0.5
        "throttleSensitivity":1.2
    },


//.......some code in between


//Transmission:
"engine":{
        "transmissionType":"manual",
        // -1, 0 (neutral), 1, etc
        "gears":[-3.71, 0, 3.51, 2.08, 1.350, 1.00, 0.810]
        "clutchDuration":0.12
        "clutchTorque":500
        //temporary until manual is coded
        "viscousCoupling":4
        "lockingTorqueLimit":115
    },

 

As far as I can see, your torque curve isn't very accurate. You have 200nm at 2000rpm. In the graph it shows it should have 300nm at 2000rpm. The angle of the first part of your torque curve heavily changes what amount of horsepower you get. On top of that, you've got a huge dip in your torque curve, which shouldn't be there. And a good tip for the straight parts of the curve: try to take bigger steps(ie 750 or 1000rpm per step, if possible). That way it'll turn out much smoother which usually works better.

I believe Gabester once told me that for every engine this applies: When the RPM Is 5252rpm, torque equals horsepower... So the angle of the first part of your torque curve needs to be dead on correct to get the right hp rating. I managed that on both my Cadilllac and my new project, so it's definitely possible to accurately simulate any engine...

I'm not sure about the gear thing. Are you sure you used the real life gear ratios(both differential and drive-gears)?

 

Like Mythbuster already has said, the torquecurve in this magazine is not very accurate. To be exact, the BeamNG drive values are absolutely correct.

Like you might know horsepower can be calculated from the engine rotations and torque.

P = 2 x Pi x n x M

P = power in W
Pi = 3.14...
n = rounds per second
M = torque in Nm

If I now insert the values from the torquecurve (that you also have used in the code for your car) I get exactly the result as Drive. The torque curve in that magazine is really inaccurate :\

2 x 3.14159 x (6500 / 60) x (325Nm) = 221kW or ~300hp
At 6500rpm you'd need about 375Nm to get 340hp.

Also wheel size is an important factor for the vehicle speed in each gear, make sure to use real wheel sizes for realistic performance. With larger wheels you'll get a significantly higher top speed as well (as long as your engine is powerful enough)

 

Ok with max torque 420 and inertia 20 the car brings around 320 hp and as Mythbuster said, i made the steps bigger, so the curve is much smoother now


And for the gear, i have forgotten to change the transmission of the differential, it's now about 66 kph at 7000 rpm and it should be 58 kph, so quite nice so far

Is there still something i could change in order to get more precise to the real engine?

Code:

"enginetorque":[
        ["rpm", "torque"]
        [0, 0],
        [800, 260],
        [1000, 310],
        [2000, 320],
        [3000, 345],
        [4000, 400],
        [4750, 420],
        [5000, 415],
        [6000, 380],
        [7000, 300],
    ],
    "engine":{
        "idleRPM":1000,
        "shiftDownRPM":3000,
        "shiftUpRPM":6900,
        "maxRPM":7500,
        "inertia":0.08,
        "friction":20
        "brakingCoefRPS":0.15
        "burnEfficiency":0.5
        "throttleSensitivity":1.2
    },