Is anyone interested in collecting acceleration data on their cars? I built up a 3 axis accelerometer board (from a sample I got at work) which will record X, Y and Z accelerations at 280Hz (280 samples/second). I tested it on my friend's car with some really interesting results. I was able to extract peak acceleration (m/s/s or Gs) through each gear and shift times too. In theory, we'd be able to extract shift points (in MPH) from the acceleration data, but I can't clean it up enough to make that work well enough (yet). The test car below is a Mitsubishi Lancer Evo 8. He had it tuned and dynoed at DB performance and it came in at 318whp (peak). What other data would be interesting to collect? I never hear too much about this statistic, and I figure it's not talked about much because it's hard to get or nobody cares. I can bring this to Firestone sometime if you guys want to measure your cars. You'll get some acceleration plots, and I'll get to ride in some fast Subarus. That's a good deal to me. Anyway, here's what I measured below. Reid
You can see pretty clearly where he shifts by the negative acceleration. You can also see where he lets off the gas in preparation for a shift. Also notice the oscillation after he gets back on the gas. You can feel this in the car too. I think it's from a bad/quick shift. It's a new clutch too, so that may have something to do with it. Braking acceleration was not great because it was snowy out. The ABS kicked in a few times. The acceleration through the gears was lacking a little too because the wheels would slip every now and then. This was done on wet pavement.
It looks like a fun toy. I could be very useful...for accel, decel, cornering, whatever, maybe even for suspension if you measure verticle movement, maybe even independent front/back movement if you had two. What about compensating for body roll?
ECUTEK Delta Dash does the same thing: Code: Time(s) RPM Speed(m/s) ChangeInDistance(m) Cumulative Distance(m) Acceleration(m/s^2) Accelerative Power(W) Drag Force(N) Drag Power(W) Wheel Power(W) Wheel Torque(Nm) 0.83 2280 12.68 0.78 6.35 1.77 31405.1 61.9 784.2 32189.3 134.8 0.89 2299.5 12.78 0.8 7.15 1.68 30125.4 62.9 804.3 30929.7 128.4 0.95 2319 12.89 0.8 7.95 1.79 32232.7 64 825 33057.7 136.1 1.02 2339.3 13.01 0.81 8.76 1.83 33299.2 65.1 846.9 34146.1 139.4 1.08 2359 13.12 0.82 9.58 1.69 31009.5 66.2 868.5 31878.1 129 1.14 2379.5 13.23 0.81 10.39 2 36981.2 67.4 891.3 37872.5 152 1.2 2400 13.34 0.81 11.2 1.75 32608.7 68.5 914.6 33523.3 133.4 1.26 2419.5 13.45 0.82 12.02 1.81 34014.9 69.7 937.1 34952 137.9 1.32 2440.1 13.57 0.82 12.84 1.94 36924.4 70.9 961.2 37885.6 148.3 1.38 2460.5 13.68 0.83 13.67 1.76 33638 72 985.4 34623.4 134.4 1.44 2481.7 13.8 0.84 14.51 2.12 40909.7 73.3 1011.2 41920.9 161.3 1.51 2503.5 13.92 0.85 15.36 1.86 36164.5 74.6 1038.1 37202.6 141.9 1.57 2524.1 14.03 0.85 16.21 1.89 37057.1 75.8 1063.9 38121 144.2 1.63 2545.5 14.15 0.88 17.09 1.91 37916.4 77.1 1091.1 39007.5 146.3 1.69 2567.9 14.28 0.91 18 1.99 39831.4 78.5 1120.2 40951.7 152.3 1.76 2591.4 14.41 0.92 18.92 2.1 42269.6 79.9 1151.3 43420.8 160 1.82 2614.7 14.54 0.94 19.85 1.91 38867.6 81.4 1182.6 40050.2 146.3 1.89 2638.7 14.67 0.95 20.81 2.17 44623.7 82.9 1215.4 45839.1 165.9 1.95 2664.2 14.81 0.96 21.77 2.17 44894.6 84.5 1251 46145.6 165.4 2.02 2689.3 14.95 0.97 22.74 2.1 44022.6 86.1 1286.7 45309.3 160.9 2.08 2715.5 15.1 0.98 23.73 2.35 49680.8 87.7 1324.6 51005.4 179.4 2.15 2741.2 15.24 0.99 24.72 2.03 43222.7 89.4 1362.6 44585.3 155.3 2.21 2766.8 15.38 0.99 25.71 2.38 51358.9 91.1 1401.2 52760.2 182.1 2.28 2793.8 15.53 0.99 26.7 2.31 50214.2 92.9 1442.7 51656.9 176.6 2.34 2821.5 15.69 0.98 27.67 2.62 57593.2 94.7 1486 59079.2 200 2.4 2849.2 15.84 0.96 28.63 2.42 53756 96.6 1530.2 55286.2 185.3 2.46 2877.8 16 0.97 29.61 2.77 62077.4 98.5 1576.7 63654 211.2 2.52 2908 16.17 0.98 30.59 2.74 61981.4 100.6 1626.9 63608.3 208.9 2.58 2938.1 16.33 0.99 31.58 2.73 62432.6 102.7 1677.9 64110.5 208.4 2.65 2970.1 16.51 1 32.59 3.09 71527.5 105 1733.3 73260.9 235.5 2.71 3002.4 16.69 1.01 33.6 2.79 65152.6 107.3 1790.5 66943.1 212.9 2.77 3035.3 16.87 1.03 34.63 3.19 75442.7 109.6 1850 77292.6 243.2 2.83 3071.8 17.08 1.04 35.66 3.46 82680.6 112.3 1917.6 84598.2 263 2.89 3107.4 17.28 1.06 36.72 2.95 71439.1 114.9 1985 73424.1 225.6 2.95 3144.6 17.48 1.07 37.8 3.75 91726.4 117.7 2057.1 93783.5 284.8 3.01 3183.7 17.7 1.07 38.87 3.37 83560.8 120.6 2134.8 85695.6 257 3.07 3222.8 17.92 1.09 39.96 3.75 94006.9 123.6 2214.4 96221.3 285.1 3.14 3262.9 18.14 1.1 41.06 3.55 90268.2 126.7 2298.1 92566.3 270.9 3.2 3303.5 18.37 1.11 42.17 3.86 99128.4 129.9 2385.1 101513.5 293.4 3.26 3346.5 18.6 1.13 43.3 3.96 103155.3 133.3 2479.3 105634.6 301.4 3.32 3389.5 18.84 1.14 44.44 3.89 102582 136.7 2576.3 105158.3 296.3 3.38 3435.4 19.1 1.16 45.6 4.47 119411.4 140.4 2682.3 122093.7 339.4 3.44 3483.1 19.36 1.17 46.78 4.22 114384.4 144.4 2795.5 117180 321.3 3.5 3530.1 19.63 1.19 47.97 4.34 119287.8 148.3 2910.2 122198 330.6 3.56 3580.5 19.91 1.21 49.17 4.83 134642.7 152.5 3036.6 137679.3 367.2 3.62 3631.5 20.19 1.24 50.41 4.35 123057.3 156.9 3168.2 126225.5 331.9 3.69 3683.5 20.48 1.26 51.67 5.02 143973.1 161.5 3306.4 147279.5 381.8 3.75 3737.3 20.78 1.26 52.93 4.77 138614.7 166.2 3453.3 142068 363 3.81 3790.4 21.07 1.28 54.21 4.9 144488.9 171 3602.6 148091.5 373.1 3.87 3843.9 21.37 1.3 55.5 4.84 144795.7 175.8 3757.3 148553 369 3.93 3896.9 21.66 1.31 56.82 4.81 145788.5 180.7 3914.9 149703.4 366.8 3.99 3948.2 21.95 1.33 58.15 4.53 139318.8 185.5 4071.6 143390.3 346.8 4.05 4000 22.24 1.35 59.5 4.91 152739.6 190.4 4234.1 156973.7 374.7 4.11 4053.1 22.53 1.37 60.87 4.75 149806.3 195.5 4404.8 154211.2 363.3 4.18 4106 22.83 1.39 62.25 4.87 155726.1 200.6 4579.4 160305.5 372.8 4.24 4157.8 23.12 1.4 63.66 4.57 147787.1 205.7 4755.2 152542.3 350.3 4.3 4209 23.4 1.42 65.08 4.76 155841.6 210.8 4933.1 160774.7 364.8 4.36 4259.3 23.68 1.46 66.53 4.29 142248.4 215.9 5112 147360.4 330.4 4.42 4308.6 23.95 1.49 68.02 4.48 150346.8 220.9 5291.6 155638.4 344.9 4.48 4360 24.24 1.49 69.51 4.76 161429.1 226.2 5483 166912.1 365.6 4.54 4411.6 24.53 1.49 71 4.65 159649.7 231.6 5680.3 165329.9 357.9 4.61 4463 24.81 1.51 72.51 4.71 163521.8 237 5881.2 169402.9 362.5 4.67 4515.5 25.1 1.52 74.03 4.84 170095.8 242.6 6091 176186.8 372.6 4.73 4566 25.38 1.54 75.57 4.35 154651.3 248.1 6297.6 160949 336.6 4.79 4614.8 25.66 1.56 77.13 4.53 162543.5 253.4 6501.6 169045.1 349.8 4.85 4663.1 25.92 1.58 78.71 4.27 154937.1 258.8 6708 161645.1 331 4.91 4712.6 26.2 1.59 80.3 4.75 174183.8 264.3 6924.1 181107.9 367 4.97 4764.5 26.49 1.61 81.91 4.7 174261.6 270.1 7155.4 181417 363.6 5.03 4816 26.77 1.63 83.54 4.66 174591.4 276 7389.5 181980.9 360.8 5.09 4868 27.06 1.64 85.18 4.81 182118.7 282 7631.5 189750.2 372.2 5.16 4917.7 27.34 1.68 86.86 4.15 158668.4 287.8 7867.8 166536.2 323.4 5.22 4966.9 27.61 1.72 88.58 4.61 178322.3 293.6 8106.4 186428.7 358.4 5.28 5018.3 27.9 1.73 90.31 4.53 176748.2 299.7 8360.5 185108.7 352.2 5.34 5067.5 28.17 1.73 92.05 4.32 170330.5 305.6 8608.8 178939.2 337.2 5.4 5116.7 28.45 1.73 93.78 4.64 184834.6 311.5 8862.1 193696.7 361.5 5.46 5166.1 28.72 1.75 95.52 4.35 174976.5 317.6 9121.3 184097.8 340.3 5.53 5214.9 28.99 1.76 97.28 4.53 183680.2 323.6 9382.1 193062.2 353.5 5.59 5263 29.26 1.78 99.06 4.24 173854.7 329.6 9644.5 183499.2 332.9 5.65 5309.1 29.52 1.8 100.86 4.14 170931.5 335.4 9899.9 180831.4 325.3 5.71 5356.3 29.78 1.81 102.67 4.46 185903.3 341.4 10166.5 196069.7 349.6 5.77 5404.7 30.05 1.83 104.5 4.34 182709.6 347.6 10444.3 193153.9 341.3 5.83 5454.2 30.32 1.84 106.34 4.67 198432.9 354 10734.2 209167.1 366.2 5.89 5501 30.58 1.86 108.2 3.83 164002.7 360.1 11012.5 175015.2 303.8 5.95 5544.1 30.82 1.88 110.08 4.03 173858.1 365.8 11273.8 185131.9 318.9 6.01 5590 31.08 1.89 111.97 4.32 187812.6 371.8 11555.7 199368.3 340.6 6.08 5636.1 31.33 1.9 113.87 4.1 179646.5 378 11844.5 191490.9 324.4 6.14 5682.2 31.59 1.92 115.79 4.29 189812 384.2 12137.1 201949.1 339.4 6.2 5728.1 31.85 1.94 117.73 4.07 181470.9 390.4 12433.7 193904.6 323.3 6.26 5774.2 32.1 1.95 119.68 4.32 194374.7 396.7 12736.3 207110.9 342.5 6.32 5819.8 32.36 1.97 121.65 3.98 180253.2 403 13040.3 193293.6 317.2 6.38 5863.5 32.6 1.98 123.63 3.99 182257.8 409.1 13336.8 195594.6 318.5 6.44 5906 32.83 2 125.63 3.74 171895.2 415.1 13628.6 185523.8 300 6.5 5947 33.06 2.01 127.64 3.73 172579.5 420.9 13914.4 186493.9 299.5 6.56 5988.5 33.29 2.03 129.67 3.84 178925.1 426.8 14208.1 193133.2 308 6.63 6031.9 33.53 2.04 131.7 4.05 190212.5 432.9 14518.6 204731.1 324.1 6.69 6075.2 33.78 2.08 133.78 3.76 177675.8 439.2 14834 192509.8 302.6 6.75 6118.6 34.02 2.1 135.88 4.05 193055.7 445.5 15154.2 208210 325 6.81 6161.1 34.25 2.09 137.96 3.67 176145.9 451.7 15471.9 191617.8 297 6.87 6202.7 34.48 2.1 140.06 3.9 188118.9 457.8 15787.3 203906.2 313.9 6.93 6244.2 34.71 2.11 142.18 3.66 178120.7 464 16106.7 194227.4 297 6.99 6285.6 34.95 2.13 144.31 3.87 189420.5 470.1 16429.3 205849.8 312.7 7.05 6327.9 35.18 2.14 146.45 3.81 187840.8 476.5 16762.6 204603.4 308.8 7.12 6368.9 35.41 2.16 148.6 3.66 181267.2 482.7 17090.9 198358.1 297.4 7.18 6409.9 35.64 2.17 150.77 3.81 189863.6 488.9 17423.1 207286.7 308.8 7.24 6453.4 35.88 2.18 152.96 4.11 206527.3 495.6 17780.3 224307.6 331.9 7.3 6495.9 36.11 2.2 155.16 3.62 183208.7 502.1 18133.9 201342.5 296 7.36 6534.8 36.33 2.21 157.37 3.45 175468.2 508.2 18461.3 193929.5 283.4 7.42 6571.5 36.53 2.25 159.62 3.16 161424.9 513.9 18773.9 180198.9 261.9 7.48 6608.1 36.74 2.26 161.88 3.44 177011.4 519.6 19089.7 196101.1 283.4 7.54 6645.7 36.95 2.25 164.13 3.41 176307.9 525.6 19417.7 195725.6 281.2 7.61 6682.5 37.15 2.26 166.4 3.28 170828.9 531.4 19741.8 190570.8 272.3 7.67 6718.5 37.35 2.28 168.67 3.28 171317.8 537.1 20063 191380.8 272 7.73 6755.2 37.56 2.29 170.96 3.39 178341.7 543 20393 198734.7 280.9 7.79 6794 37.77 2.3 173.26 3.68 194679.6 549.3 20747 215426.6 302.8 7.85 6832.4 37.98 2.31 175.58 3.3 175541.1 555.5 21100.5 196641.5 274.8 7.91 6866.5 38.17 2.33 177.9 2.91 155637 561.1 21418.3 177055.3 246.2 7.97 6899.5 38.36 2.34 180.24 3.09 166159.1 566.5 21728.6 187887.7 260 8.03 6936.6 38.56 2.35 182.59 3.66 197425.5 572.6 22080.9 219506.4 302.2 8.09 6975.9 38.78 2.36 184.95 3.48 189108.9 579.1 22457.7 211566.6 289.6 8.16 7013 38.99 2.4 187.36 3.21 175109.6 585.3 22818.7 197928.3 269.5 8.22 7049.5 39.19 2.44 189.8 3.27 179383 591.4 23175.9 202559 274.4 8.28 7085.6 39.39 2.46 192.26 3.17 174693.9 597.4 23534.6 198228.5 267.2 8.34 7122.2 39.6 2.44 194.7 3.41 188948 603.6 23900.6 212848.6 285.4 8.41 7156.4 39.79 2.48 197.18 2.7 150208.8 609.4 24246.9 174455.7 232.8 8.47 7187.6 39.96 2.55 199.73 2.73 152633 614.8 24565.2 177198.2 235.4 8.53 7220.4 40.14 2.56 202.29 2.97 167106.3 620.4 24902.8 192009.1 253.9 8.6 7255.2 40.34 2.57 204.86 3.09 174611.8 626.4 25265.2 199877.1 263.1 8.66 7291.4 40.54 2.56 207.41 3.26 185269.1 632.6 25644.7 210913.7 276.2 8.72 7326.4 40.73 2.54 209.95 2.96 168893.9 638.7 26015.7 194909.7 254 8.79 7358.1 40.91 2.55 212.5 2.68 153644.1 644.3 26355.2 179999.3 233.6 8.85 7391 41.09 2.56 215.07 3.18 182954.4 650 26710.9 209665.3 270.9 8.91 7425.3 41.28 2.57 217.64 2.92 168591.3 656.1 27084.2 195675.4 251.6 8.97 7457.1 41.46 2.59 220.23 2.74 158756.2 661.7 27433.3 186189.5 238.4 9.04 7486.3 41.62 2.62 222.85 2.41 140544.6 666.9 27757.2 168301.7 214.7 9.1 7514.8 41.78 2.61 225.46 2.66 155329.1 672 28074.9 183404 233.1 9.16 7542.7 41.93 2.56 228.01 2.43 142793.3 677 28389.4 171182.6 216.7 9.22 7571 42.09 2.57 230.58 2.72 160392.4 682.1 28710.3 189102.7 238.5 9.28 7601.4 42.26 2.58 233.16 2.8 165930.3 687.6 29057.1 194987.5 245 (truncated because the post was too long)
Do you have that thing mounted to something or are you holding on your lap? You could get some weird dampening effects if you're holding on to it. Probably wouldn't be that much, but still. Doesn't the ecutek kind of piggyback onto the stock ecu. At least in the sense that it only has the stock sensors to read off of. I would say that a stand alone accelerometer would be a more accurate gauge of whats going on, rather than some sort of interpolated results from the factory ecu. Just my guess though, I don't know anything about ecutek. Edit: I just noticed that it was the ecutek (brand) delta dash (model). Which is probably one of those radar detector looking things that measures g-force/0-60/ 1/4 mile times etc. So never mind. I'd still probably wager that a stand anlone accelerometer would be better, but you can't really say that without knowing the specifics of either. Either way, carry on!
ECUTEK Delta Dash is a computer interface with your ECU. It monitors, displays and datalogs every single sensor, relay and output from your ECU. Every single one; it can tell you things as random as: Is the rear window defroster on or off? How many steps is the idle air control valve at at any given moment, etc etc. Provided that there is no wheel spin and your speedometer is accurate, the data should be perfectly accurate. With wheelspin of course the program will think you are accelerating faster than you really are. On a level road in 3rd gear (the way the test is normally performed) it is said to be within a % of what a dyno reports. Plus it doesn't just look at acceleration data... I can look at time vs rpm vs air fuel ratio vs ignition timing advance vs boost vs throttle position vs coolant temperature, etc etc etc... Very powerful tool; I wouldn't live without mine It also allows you to adjust idle rpm, ignition timing retard, and a couple of other things too.
You can probably do something similar with the Enginuity logger as long as you log vehicle speed. It would give you time, just not g's.
Hey, I'm not doubting that as a useful tool. All I'm saying is that the outputs are only as good as the inputs are. I'm not sure of what kind of accelerometers are used in cars these days (airbag sensor? abs actuator?). All I'm saying is that if you use speed and time to calculate acceleration, it won't be as accurate as measuring acceleration with an accelerometer. The airbag sensor is probably more of an on/off threashold accelerometer, and the abs probably doesn't even use an accelerometer (I don't know what kind of systems they use). All I'm saying is that interprolated calculations will have more error than a calabrated accelerometer. And if the ecutek is drawing off of sensor data from the car, I'm just saying that I'm unaware of what the capabilities of factory accelerometers are.
I double stick taped it to the center console. It held it quite rigidly. Damping would be a primary concern if we were trying to measure the vibration profile of the car (which we can do using an Fast Fourier Transform). 280Hz would be enough to capture vibe profiles up to roughly half that. The advantage of a dedicated accelerometer is it's a measure quantity, not a calculated one. The ECU unit is essentially doing calculus based on the ECU data. (Speed 2 - Speed 1) / (Time between speed 1 and speed 2). However, that's probably not that important in this situation because we really don't care about the absolute accuracy of the reading. Also, the output is not being fed in to anything else, so errors only compound once (in the calculus). I like the idea of an integrated ECU device. It'd probably be good enough. This has the advantage that it's portable and doesn't rely on anything else but me and my laptop. BTW, I'm not ECE....Aero. Engineering FTW! Reid
Does anybody here have a G-tech meter or anything like it? I got one this fall from my girl friend. I had my doubts, and still do about good accuracy, but it is fun to mess around with. The G-tech uses an accelerometer and input read from the cigarette lighter to give you speed and acceleration numbers along with engine rpm. I can check 1/4 mile, 0-60, lateral G's, shift point, rpm vs. time, ...whole bunch of stuff. It also data logs your best runs and saves about 20 to 30 so that you can go back and review them when you get bored. Before it snowed, my friends and I were having a good time trying to best eachother's times on the meter. We would just put the meter in each car and see what it can do. I forgot to add, it does rough horsepower calculations after you plug in vehicle weight. I read that the baseline values you read off that are pretty bad, but it is good for checking the difference that different modifications make. There's my $0.02 on the topic.
Uh? Accelerometer? Dude I just explained that it runs off ECU data. I'm not going to repeat my post, re-read it if you didn't understand. This is exactly what ECUTEK uses to tune their cars. It comes off within one percent of dynos.
I understand. ecutek uses ecu data to calculate acceleration, that's fine and there's nothing wrong with that. I was just making sure you knew/understood the distinction between calculating and measuring acceleration. As you can see from graph posted above, acceleration is a pretty dynamic thing to measure. Let me illustrate what I'm trying to say so that you understand it. I can roughly (very roughly) calculate the acceleration of an sti if I know the trap speed and 1/4 time. I can use that to calculate the hp. I can then put that same sti on a dyno and measure it's actual hp. I can do this 5, 10, 500 times in a row. And then I can take hp(measured)/hp(actual) and average that over my sample group to get a calibration multiplier. And I bet you could probably do that and get results that are within whatever percentage of the actual dyno. There's nothing wrong with that whatsoever, if that's what you think I'm implying. I'm just stating that this is all thats going on. If you really look at the science of measurement, everything is treated this way. How accurate do you think a dyno is? Nothing that is measured is hard and fast. Theres always a statiscal element to it.
