06-11-2014, 03:56 PM | #67 | |
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2 x N54 -> 1 x N55 -> 1 x S55-> 1 x B58
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06-11-2014, 03:56 PM | #68 | |
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EDIT: The only thing that I can think of is that the "losses" include the inertia and drag of the dyno rotating components. Last edited by CanAutM3; 06-11-2014 at 04:17 PM.. |
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06-11-2014, 03:57 PM | #69 |
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06-11-2014, 04:03 PM | #70 |
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true forgot about those cars, EVOs and STis get 300 hp out of their 2L turbos CLA 45 amg might be the winner with 177.5 hp/L
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06-11-2014, 04:06 PM | #71 | |
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As I posted previously, I don't think we can compare the WHP number here to typical chassis dynos. The measurement and calculation methodology of this dyno seems quite different. The only numbers that mean anything are the flywheel torque and power numbers (P-Mot and MMot on the graph). Last edited by CanAutM3; 06-11-2014 at 04:12 PM.. |
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06-11-2014, 04:18 PM | #73 |
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06-11-2014, 04:20 PM | #74 | |
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EDIT: My guess is the RWHP is the right number and the math to get to Fly HP is different than what we are used to. 385 RWHP (Prad) * 1.12 (loss factor recapture) = 431 Fly HP. Last edited by phear_me; 06-11-2014 at 04:34 PM.. |
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06-11-2014, 04:25 PM | #75 |
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I think I have a theory. This type of dyno measures how much "brake" power is produced while accelerating the car's drivetrain and the dyno. It then measures how much "brake" power is needed to slow both of them down in neutral. Adding the two numbers together would yield the flywheel power produced. It is legit, but the WHP numbers cannot be compared to other chassis dynos.
Last edited by CanAutM3; 06-11-2014 at 04:37 PM.. |
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06-11-2014, 04:33 PM | #76 | |
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I hope I am wrong because I would love to find out I just got another 35 HP - but somehow I don't think so. |
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06-11-2014, 04:35 PM | #77 | ||
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Also, other BMW turbo engines are known to be underrated, so 35 hp more than their rating wouldn't be out of the ordinary I think. |
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06-11-2014, 04:36 PM | #78 | |
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06-11-2014, 04:44 PM | #79 |
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So why is the whp curve dropping past 6k? No one can answer that and it has nothing to do with math.
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06-11-2014, 04:45 PM | #80 |
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BMW i8 3-cylinder has 154 hp/L (231 hp from 1.5L), so it's not surprising this engine is dynoing around twice the horsepower at twice the size.
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Greg Lake Oswego, Oregon, USA 2023 M2 Coupe - Brooklyn Grey/Cognac/CF, 6MT; 2020 MB GLE 450 Last edited by GregW / Oregon; 06-11-2014 at 05:19 PM.. |
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06-11-2014, 04:47 PM | #81 |
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06-11-2014, 04:48 PM | #82 | |
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The methodology used here is far more accurate as it removes drivetrain losses, tire slip losses, drivetrain, wheel/tire and dyno inertia from the equation. The only variable that it would not account for is the engine inertia (note tha the higher the gear used the less impact it has). |
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06-11-2014, 04:50 PM | #83 | |
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06-11-2014, 04:53 PM | #84 | |
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It all has to do with math and physics. Power needed to accelerate a mass at a given rate increases with speed. The faster the dyno roller spins, the more power you need to keep accelerating it. Same for the drivetrain. This is why you see the P-Schlepp number increase with speed. If the engine produces a constant power output as the speed increases, you will see a decrease in the power measured at wheels on this dyno. |
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06-11-2014, 04:55 PM | #85 |
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Simply because the WHP and "Schlepp" are the actual measured numbers from the dyno to be able to calculate Engine power and torque. WHP is not really relevant. It is seen often because it is the only thing "cheap" dynos can measure.
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06-11-2014, 04:56 PM | #86 | |
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The blue line is WHP, the green line is losses. As the rpm's increase, so does the losses. Just take the P-Mot curve and subtract losses for each rpm and you get P-Rad. The decline in WHP therefore is simply a function of the increase in losses as explained by CanAutM3 above. The engine makes a quite stable flywheel HP reading, but as losses increase the WHP falls (obviously). It's basic maths to calculate the WHP from the P-Mot and subtract P-Schlepp |
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06-11-2014, 05:05 PM | #87 |
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Some info on one type of MAHA dyno:
http://www.maha.de/single-roller-dyn...eLocaleAttr=en 2% accuracy on WHP 1400kg inertia mass |
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06-11-2014, 05:05 PM | #88 |
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might have even more hp once it gets dynoed
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