motor torque vs. hp question boosted 17.5 vs 10.5
01-26-2012, 12:59 PM
#1
motor torque vs. hp question boosted 17.5 vs 10.5
I'm trying to understand the output of these motors a bit better now that I've discovered that while my top speed with my 17.5 w/ tons of timing may rival a 10.5 it doesn't appear to have the same torque or initial pickup. Reason I even delved into this was due to a triple at my track that I could not clear no matter what. I geared way up and added max timing and I was still not able to clear a jump that a 10.5 motored car could. I thought maybe I was spinning a bit w/ max timing so I lowered it but I still didn't clear this triple. This is in a 4wd buggy so forward traction usualy isn't an issue so I doubted this but tried anyway. Is it in fact true that a boosted 17.5 won't be able to clear what a non boosted 10.5 would? Does the 10.5 spin up faster thus requiring less land to reach top rpm? Realistically giving no tire slipage how many feet should these motors take to reach peak rpm at recommended FDR?
FYI, these are what I tried (TEKIN ESC, linear throttle curve, timing added via boost 5k start 20k end):
7.51 FDR w/ max timing
6.54 FDR w/ max timing
6.54 FDR w/ 35 degrees of timing addded
Stiffening springs front/rear to see if it'd help me clear this jump. It helped but I still couldn't clear this jump.
The car I am comparing to is my exact 4wd buggy w/ a very high (11.26) FDR but running a 10.5.
My driveline is free and has no binding and the motor is in great shape.
Thanks guys and if you have any other suggestions I'd appreciate them.
Dave
FYI, these are what I tried (TEKIN ESC, linear throttle curve, timing added via boost 5k start 20k end):
7.51 FDR w/ max timing
6.54 FDR w/ max timing
6.54 FDR w/ 35 degrees of timing addded
Stiffening springs front/rear to see if it'd help me clear this jump. It helped but I still couldn't clear this jump.
The car I am comparing to is my exact 4wd buggy w/ a very high (11.26) FDR but running a 10.5.
My driveline is free and has no binding and the motor is in great shape.
Thanks guys and if you have any other suggestions I'd appreciate them.
Dave
Last edited by TT_Vert; 01-26-2012 at 01:10 PM.
01-26-2012, 02:01 PM
#2
While timing can boost Kv through the roof, it cannot overcome the limitations of wattage output a lower wind motor is capable of. A 10.5 just has more power outright. Timing advance relies on rpm, it's hard to get a benefit out of it at lower RPM. That's where the lower turn motor will always win.
01-26-2012, 03:31 PM
#4
Davidka pretty much nailed it right on the head. I once compared dyno graphs of a Novak 13.5 and a Novak 7.5 and I posted it below for you to see. It shows that even though a Novak 7.5 will have lower initial torque than a Novak 13.5, it has much higher power and RPMs.
Taking these two motors as an example, if in the same vehicle, using the exact same pinion, the 13.5 will slightly out-accel the 7.5 but once the 7.5 reaches 10,000RPM, all gloves are off and the 7.5 doesn't begin to lose power until about 22,000RPM whereas the 13.5 begins to lose power around 12,500RPM.
-Matt
Taking these two motors as an example, if in the same vehicle, using the exact same pinion, the 13.5 will slightly out-accel the 7.5 but once the 7.5 reaches 10,000RPM, all gloves are off and the 7.5 doesn't begin to lose power until about 22,000RPM whereas the 13.5 begins to lose power around 12,500RPM.
-Matt
01-26-2012, 03:46 PM
#6
usually when adding boost/timing it will come in at a set rpm (esc dependant)
until the boost comes in the motor is non boosted and getting no timing benefits.
usually if you lower the boost start below a certain rpm it will just bog the motor down causing excessive heat.
so until boost starts actually working your running a non boosted motor against a motor with more watts
until the boost comes in the motor is non boosted and getting no timing benefits.
usually if you lower the boost start below a certain rpm it will just bog the motor down causing excessive heat.
so until boost starts actually working your running a non boosted motor against a motor with more watts
01-26-2012, 03:55 PM
#7
Not much waiting on a 7.5 to get going on offroad!
01-26-2012, 05:36 PM
#8
ok, how far does the vehicle have to move to achieve top rpm? Is there some way to calculate this? I'm not able to tell when my car reaches it's top speed. I know my gear ratio and I can measure my rollout also.
Dave
Dave
Last edited by TT_Vert; 01-26-2012 at 05:48 PM.
01-26-2012, 07:34 PM
#11
Gene that isn't going to be signifigant enough to make a difference. I went to a stiffer spring to see what it'd do and I still couldn't clear it. I may see if I can borrow a 10.5 to try from someone at the track. I was racing w/ another zx5 the other day and we were fairly even until the triple and he would make up about 10' a lap tripling while I doubled.
I'd really like to know how long it takes these motors to spin up under load.
Dave
I'd really like to know how long it takes these motors to spin up under load.
Dave
01-26-2012, 09:18 PM
#14
Vert,
You are asking some pretty technical questions, and there is really no easy way to answer it without getting into torque, inertia, physics, etc..., but here I go....
Firstly, I don't have any recent data, all of it is over 2 years old. I had a ton of plots but my HDD crashed and I lost so much data
Anyhow, I am planning on firing up the dyno again soon because I have been itching to put some of these motors and manufacturer claims to the test especially concerning 550 can motors vs 4 pole motors.
Here is some data taken from a Novak 13.5t motor using a flywheel that weighs 365g and is 3.427" in diameter with a moment of inertia equaling 0.0003458121Kg-m^2s^2
Basically, what this data is telling me is that with this load, it is taking 1.6s to spin up to 10,000rpms with an output torque between 310 and 183 N-m x 10^3.
Everything you want to figure can be calculated, but I am not getting paid for it and it is past my bedtime and I shouldn't even be posting this, so you're going to have to figure it out yourself, but here are some tips. You can calculate the speed necessary to make the jump by using the distance required to make the jump and the angle of the face of the first jump. Then you can calculate the acceleration you will need based on the speed you will carry into the corner and the distance to the jump and your final speed, then taking that acceleration times your rollout will give you the torque at the motor.
I didn't say it was going to be easy 
You are asking some pretty technical questions, and there is really no easy way to answer it without getting into torque, inertia, physics, etc..., but here I go....
Firstly, I don't have any recent data, all of it is over 2 years old. I had a ton of plots but my HDD crashed and I lost so much data
Anyhow, I am planning on firing up the dyno again soon because I have been itching to put some of these motors and manufacturer claims to the test especially concerning 550 can motors vs 4 pole motors.Here is some data taken from a Novak 13.5t motor using a flywheel that weighs 365g and is 3.427" in diameter with a moment of inertia equaling 0.0003458121Kg-m^2s^2
Basically, what this data is telling me is that with this load, it is taking 1.6s to spin up to 10,000rpms with an output torque between 310 and 183 N-m x 10^3.
Everything you want to figure can be calculated, but I am not getting paid for it and it is past my bedtime and I shouldn't even be posting this, so you're going to have to figure it out yourself, but here are some tips. You can calculate the speed necessary to make the jump by using the distance required to make the jump and the angle of the face of the first jump. Then you can calculate the acceleration you will need based on the speed you will carry into the corner and the distance to the jump and your final speed, then taking that acceleration times your rollout will give you the torque at the motor.
I didn't say it was going to be easy Code:
Output Results Time RPM Power Torque Efficiency Power angular Predicted Angular Predicted Torque Output Output Input velocity Angular V Acceleration angular s rev./m W N-m x 10-3 % Watt rad/s rad/s (Rad/s2) accel. (rad/s2) N-m 0.0 -67 -2.21 314.51 #DIV/0! 0.00 0.00 -7.04 909.48 0.3145 0.1 788 25.14 304.79 3.05 825.24 0.00 82.50 0.00 881.36 0.3048 0.2 1616 49.98 295.27 6.58 759.13 0.00 169.25 0.00 853.86 0.2953 0.3 2419 72.43 285.97 9.89 732.32 0.00 253.29 0.00 826.95 0.2860 0.4 3196 92.66 276.88 13.14 705.07 313.84 334.66 3138.45 800.65 0.2769 0.5 3948 110.80 267.98 15.73 704.21 411.13 413.44 972.85 774.94 0.2680 0.6 4676 126.97 259.30 18.58 683.49 509.15 489.67 980.18 749.82 0.2593 0.7 5380 141.31 250.81 21.26 664.68 596.69 563.42 875.46 725.27 0.2508 0.8 6061 153.94 242.52 24.00 641.49 677.01 634.75 803.20 701.30 0.2425 0.9 6720 164.96 234.42 26.87 613.96 751.57 703.70 745.60 677.89 0.2344 1.0 7356 174.50 226.52 29.82 585.24 828.86 770.34 772.83 655.04 0.2265 1.1 7971 182.65 218.81 34.17 534.53 898.81 834.73 699.53 632.75 0.2188 1.2 8565 189.51 211.29 38.61 490.89 965.10 896.91 662.88 611.00 0.2113 1.3 9138 195.17 203.96 42.40 460.33 1026.57 956.95 614.70 589.79 0.2040 1.4 9691 199.73 196.81 46.36 430.87 1086.99 1014.89 604.23 569.11 0.1968 1.5 10225 203.27 189.84 50.48 402.67 1142.39 1070.79 553.97 548.96 0.1898 1.6 10740 205.87 183.05 54.01 381.20 1196.74 1124.70 543.50 529.33 0.1830 1.7 11236 207.61 176.44 58.52 354.78 1244.17 1176.67 474.38 510.21 0.1764 1.8 11715 208.55 170.00 62.08 335.91 1290.15 1226.75 459.72 491.59 0.1700 1.9 12175 208.76 163.73 66.64 313.26 1331.09 1275.00 409.45 473.48 0.1637 2.0 12619 208.32 157.64 69.87 298.16 1374.86 1321.47 437.73 455.86 0.1576 2.1 13046 207.27 151.71 72.34 286.54 1411.94 1366.19 370.71 438.72 0.1517 2.2 13457 205.68 145.96 74.77 275.08 1451.00 1409.23 390.60 422.06 0.1460 2.3 13852 203.61 140.36 77.23 263.62 1488.90 1450.62 379.09 405.88 0.1404 2.4 14232 201.09 134.92 80.98 248.34 1517.60 1490.42 286.93 390.17 0.1349 2.5 14598 198.19 129.65 82.34 240.69 1555.19 1528.67 375.94 374.91 0.1296 2.6 14949 194.94 124.53 83.64 233.06 1586.61 1565.41 314.16 360.10 0.1245 2.7 15286 191.39 119.56 84.91 225.41 1615.20 1600.70 285.88 345.75 0.1196 2.8 15609 187.57 114.75 85.11 220.39 1640.43 1634.58 252.37 331.83 0.1148 2.9 15919 183.52 110.09 85.28 215.19 1666.61 1667.08 261.80 318.34 0.1101 3.0 16217 179.29 105.57 85.87 208.78 1693.53 1698.26 269.13 305.29 0.1056 3.1 16503 174.89 101.20 86.99 201.05 1721.38 1728.15 278.55 292.65 0.1012 3.2 16776 170.36 96.97 86.40 197.18 1745.26 1756.80 238.76 280.42 0.0970 3.3 17038 165.73 92.89 85.73 193.32 1764.84 1784.25 195.83 268.60 0.0929 3.4 17289 161.03 88.94 86.77 185.59 1784.95 1810.54 201.06 257.19 0.0889 3.5 17530 156.26 85.13 87.86 177.85 1810.71 1835.70 257.61 246.16 0.0851 3.6 17760 151.47 81.45 85.17 177.85 1831.76 1859.78 210.49 235.52 0.0814 3.7 17980 146.67 77.90 85.19 172.16 1853.43 1882.82 216.77 225.26 0.0779 3.8 18190 141.87 74.48 85.34 166.25 1869.98 1904.85 165.46 215.38 0.0745 3.9 18391 137.10 71.19 84.43 162.39 1892.49 1925.91 225.15 205.86 0.0712 4.0 18583 132.37 68.02 82.51 160.42 1903.91 1946.03 114.14 196.70 0.0680 4.1 18767 127.70 64.98 79.60 160.42 1927.26 1965.26 233.52 187.90 0.0650 4.2 18942 123.09 62.05 78.65 156.51 1945.17 1983.62 179.07 179.44 0.0621 4.3 19110 118.56 59.25 77.70 152.59 1957.32 2001.16 121.47 171.32 0.0592 4.4 19270 114.12 56.55 76.75 148.68 1975.75 2017.90 184.31 163.54 0.0566 4.5 19422 109.78 53.98 75.83 144.77 1994.60 2033.88 188.50 156.08 0.0540 4.6 19568 105.54 51.51 74.93 140.86 2007.37 2049.13 127.76 148.95 0.0515 4.7 19707 101.43 49.15 74.07 136.94 2020.25 2063.68 128.81 142.12 0.0491 4.8 19839 97.43 46.89 71.15 136.94 2039.94 2077.56 196.87 135.61 0.0469 4.9 19966 93.55 44.75 70.33 133.03 2053.24 2090.81 132.99 129.39 0.0447 5.0 20086 89.81 42.70 67.51 133.03 2066.75 2103.45 135.09 123.47 0.0427 5.1 20202 86.21 40.75 66.76 129.12 2073.55 2115.51 68.07 117.84 0.0407 5.2 20312 82.74 38.90 66.08 125.21 2087.38 2127.03 138.23 112.48 0.0389 5.3 20417 79.41 37.14 63.42 125.21 2101.30 2138.02 139.28 107.40 0.0371 5.4 20517 76.22 35.48 62.84 121.29 2115.55 2148.52 142.42 102.59 0.0355 5.5 20613 73.18 33.90 60.34 121.29 2122.67 2158.55 71.21 98.04 0.0339 5.6 20704 70.29 32.42 59.88 117.38 2137.12 2168.13 144.51 93.74 0.0324 5.7 20792 67.53 31.02 57.53 117.38 2151.67 2177.30 145.56 89.69 0.0310 5.8 20876 64.93 29.70 57.22 113.47 2159.11 2186.08 74.35 85.88 0.0297 5.9 20956 62.46 28.46 54.41 114.80 2174.08 2194.49 149.75 82.31 0.0285 6.0 21033 60.14 27.31 54.26 110.84 2181.62 2202.55 75.40 78.96 0.0273 6.1 21107 57.96 26.22 52.91 109.55 2196.91 2210.29 152.89 75.83 0.0262 6.2 21178 55.92 25.22 52.33 106.88 2204.56 2217.72 76.45 72.92 0.0252 6.3 21246 54.02 24.28 51.14 105.64 2212.31 2224.88 77.49 70.22 0.0243 6.4 21312 52.26 23.42 51.37 101.73 2220.16 2231.77 78.54 67.71 0.0234 6.5 21375 50.63 22.62 49.19 102.92 2228.02 2238.43 78.54 65.40 0.0226 6.6 21437 49.13 21.88 48.29 101.73 2243.93 2244.86 159.17 63.28 0.0219 6.7 21496 47.75 21.21 48.25 98.97 2252.00 2251.09 80.63 61.34 0.0212 6.8 21554 46.50 20.60 46.99 98.97 2260.06 2257.13 80.63 59.57 0.0206 6.9 21610 45.37 20.05 47.76 95.00 2268.23 2263.01 81.68 57.98 0.0200 7.0 21665 44.36 19.55 46.69 95.00 2276.50 2268.73 82.73 56.54 0.0196 7.1 21718 43.46 19.11 45.74 95.00 2276.50 2274.32 0.00 55.26 0.0191 7.2 21770 42.67 18.72 46.87 91.04 2293.05 2279.79 165.46 54.12 0.0187 7.3 21822 41.98 18.37 46.11 91.04 2293.05 2285.15 0.00 53.13 0.0184 7.4 21872 41.40 18.08 45.47 91.04 2301.53 2290.42 84.82 52.27 0.0181 7.5 21921 40.91 17.82 44.94 91.04 2309.91 2295.61 83.78 51.54 0.0178 7.6 21970 40.52 17.61 46.53 87.09 2318.49 2300.73 85.87 50.93 0.0176 7.7 22019 40.21 17.44 46.18 87.09 2327.08 2305.80 85.87 50.43 0.0174 7.8 22067 39.99 17.31 48.11 83.13 2335.67 2310.82 85.87 50.05 0.0173 7.9 22114 39.85 17.21 47.94 83.13 2335.67 2315.81 0.00 49.76 0.0172 8.0 22162 39.78 17.14 47.86 83.13 2344.46 2320.78 87.96 49.57 0.0171 8.1 22209 39.79 17.11 50.25 79.17 2353.16 2325.73 86.92 49.47 0.0171 8.2 22256 39.86 17.10 50.34 79.17 2362.06 2330.67 89.01 49.45 0.0171 8.3 22304 39.98 17.12 50.50 79.17 2370.96 2335.62 89.01 49.50 0.0171 8.4 22351 40.17 17.16 50.74 79.17 2362.06 2340.58 -89.01 49.63 0.0172 8.5 22398 40.40 17.23 53.72 75.21 2370.96 2345.55 89.01 49.81 0.0172 8.6 22446 40.68 17.31 54.10 75.21 2379.96 2350.54 90.06 50.05 0.0173 8.7 22494 41.01 17.41 54.52 75.21 2388.97 2355.56 90.06 50.34 0.0174 8.8 22542 41.36 17.52 55.00 75.21 2388.97 2360.61 0.00 50.67 0.0175 8.9 22591 41.75 17.65 55.51 75.21 2398.08 2365.69 91.11 51.03 0.0176 9.0 22640 42.16 17.78 56.06 75.21 2407.30 2370.82 92.15 51.43 0.0178 9.1 22689 42.60 17.93 56.64 75.21 2407.30 2375.98 0.00 51.84 0.0179 9.2 22739 43.05 18.08 60.41 71.25 2407.30 2381.19 0.00 52.28 0.0181 9.3 22789 43.50 18.23 61.05 71.25 2416.51 2386.44 92.15 52.71 0.0182 9.4 22839 43.97 18.38 61.70 71.25 2425.94 2391.73 94.25 53.16 0.0184 9.5 22890 44.43 18.53 66.01 67.30 2416.51 2397.07 -94.25 53.59 0.0185 9.6 22942 44.88 18.68 66.69 67.30 2435.26 2402.45 187.45 54.02 0.0187 9.7 22993 45.32 18.82 67.34 67.30 2435.26 2407.87 0.00 54.43 0.0188 9.8 23046 45.74 18.95 67.97 67.30 2444.79 2413.33 95.29 54.81 0.0190 9.9 23098 46.14 19.08 68.56 67.30 2435.26 2418.83 -95.29 55.16 0.0191 10.0 23151 46.51 19.18 69.11 67.30 2444.79 2424.36 95.29 55.48 0.0192 10.1 23204 46.84 19.28 73.96 63.34 2444.79 2429.93 0.00 55.75 0.0193 10.2 23257 47.14 19.35 74.42 63.34 2454.31 2435.51 95.29 55.97 0.0194 10.3 23311 47.38 19.41 74.81 63.34 2454.31 2441.12 0.00 56.13 0.0194 10.4 23365 47.57 19.44 75.11 63.34 2454.31 2446.74 0.00 56.22 0.0194 10.5 23418 47.70 19.45 75.32 63.34 2463.95 2452.36 96.34 56.25 0.0195 10.6 23472 47.77 19.43 80.45 59.37 2463.95 2457.98 0.00 56.20 0.0194 10.7 23526 47.76 19.39 79.52 60.06 2473.69 2463.60 97.39 56.06 0.0194 10.8 23579 47.68 19.31 80.30 59.37 2473.69 2469.19 0.00 55.84 0.0193 10.9 23632 47.51 19.20 80.01 59.37 2473.69 2474.76 0.00 55.51 0.0192 11.0 23685 47.25 19.05 79.57 59.37 2483.43 2480.29 97.39 55.08 0.0190 11.1 23737 46.89 18.86 83.64 56.06 2483.43 2485.77 0.00 54.54 0.0189 11.2 23789 46.42 18.64 83.77 55.42 2493.27 2491.20 98.44 53.89 0.0186 11.3 23840 45.85 18.37 77.22 59.37 2493.27 2496.55 0.00 53.11 0.0184 11.4 23891 45.16 18.05 81.48 55.42 2493.27 2501.81 0.00 52.20 0.0181 11.5 23940 44.34 17.69 80.01 55.42 2493.27 2506.98 0.00 51.15 0.0177 11.6 23988 43.40 17.28 77.41 56.06 2493.27 2512.04 0.00 49.96 0.0173 11.7 24035 42.31 16.81 76.35 55.42 2503.22 2516.97 99.48 48.61 0.0168 11.8 24081 41.09 16.29 74.14 55.42 2503.22 2521.75 0.00 47.11 0.0163 11.9 24125 39.71 15.72 70.83 56.06 2503.22 2526.38 0.00 45.45 0.0157 12.0 24168 38.17 15.08 68.88 55.42 2513.27 2530.84 100.53 43.62 0.0151 12.1 24208 36.47 14.39 65.06 56.06 2513.27 2535.10 0.00 41.60 0.0144 12.2 24247 34.60 13.63 62.44 55.42 2513.27 2539.15 0.00 39.41 0.0136 12.3 24284 32.56 12.80 63.26 51.46 2513.27 2542.98 0.00 37.02 0.0128 12.4 24318 30.33 11.91 58.26 52.06 2523.33 2546.55 100.53 34.44 0.0119 12.5 24349 27.91 10.95 53.62 52.06 2513.27 2549.86 -100.53 31.66 0.0109 12.6 24378 25.30 9.91 49.16 51.46 2523.33 2552.88 100.53 28.66 0.0099 12.7 24404 22.49 8.80 43.70 51.46 2523.33 2555.58 0.00 25.45 0.0088 12.8 24427 19.47 7.61 37.83 51.46 2533.48 2557.96 101.58 22.01 0.0076 12.9 24446 16.24 6.34 31.56 51.46 2533.48 2559.98 0.00 18.35 0.0063 13.0 24462 12.79 4.99 24.57 52.06 2533.48 2561.62 0.00 14.44 0.0050 13.1 24473 9.12 3.56 19.21 47.50 2533.48 2562.86 0.00 10.30 0.0036 13.2 24481 5.23 2.04 10.88 48.05 2533.48 2563.67 0.00 5.90 0.0020 13.3 24485 1.10 0.43 2.30 48.05 2533.48 2564.03 0.00 1.25 0.0004
01-26-2012, 10:57 PM
#15
wow. Some good info there. way past my thinking, lol
easy fix. get a larger motor.
We have classes for Mod 4wd buggy and 13.5T 4wd buggy.
On a small track the 13.5T is faster
but my 6.5T in my buggy is hella fun small track or not lol
easy fix. get a larger motor.
We have classes for Mod 4wd buggy and 13.5T 4wd buggy.
On a small track the 13.5T is faster
but my 6.5T in my buggy is hella fun small track or not lol