09-23-2017, 01:55 PM | #23 | |
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09-23-2017, 02:01 PM | #24 | |
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09-23-2017, 02:09 PM | #25 | ||
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09-23-2017, 02:33 PM | #26 | |
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I've posted this many times before, but I'll go at it again here. Modern forced induction engine behave quite differently than engines of yore. The power rating standards used to specify that engines need to be bench tested in steady state (constant RPM) and left to stabilize at each RPM point before the power readings are taken. That remains the best method to obtain the most accurate and repeatable results and was very representative of engine perfromance. However, modern FI engines can actually produce more power in transient state (while accelerating) in the mid to high RPM compared to when they are tested in steady state. Due to this, the SAE power rating standards have been amended to allow the manufacturer to test in transient state to take advantage of those characteristics. The SAE standard however leaves it to the discretion of the manufacturer to test in whatever mode it elects (steady state or transient). This now makes it quite difficult to compare power ratings between manufactures and even more so between FI and NA engines. That being said, since the Giulia QV, C63, RS5 and M3/4 are all EU manufacturers with FI engines, it is very likely they all obtained their ratings using the traditional steady state method. Now, why does the C63S outpace the Giulia QV? The answer is simple: area under the curve. With 38% more displacement the C63S makes (28%) more torque sooner in the RPM range for a beefier powerband.
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Previous cars: M4cs 2019 F82 Limerock Grey / M4 2015 F82 Silverstone / M3 2008 E92 Silverstone / M3 2002 E46 Carbon Black Last edited by CanAutM3; 09-23-2017 at 02:53 PM.. |
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09-23-2017, 03:06 PM | #27 | |
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But I do understand what you are getting at so perhaps a more appropriate definition would be to say that, BMW, specifically the F8X used a measuring method that is more favorable in terms of producing real world performance than other car makers. As for the area under the curve concept, I understand that quite well as I've mentioned in my previous post; I've just got it worded differently. "I do believe however, that a big part of the M3/M4's good performance numbers is from the efficiency of their turbos, not just because they're underrated. The high midrange torque means that versus an NA car of similar peak power, you're making a significant amount of power higher everywhere else other than the peak. This really matters a lot because as much as peak power is great, you gotta get through the midrange to get there." The higher torque of the C63s does sound like a good explanation for that difference. Considering the weight difference however, the difference between its performance in comparison to the Giulia still impresses me. Good discussion all in all. Always enjoyable to discuss these awesome vehicles with a fellow enthusiast |
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09-23-2017, 07:04 PM | #28 | |
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The information and the data is the same, because lbs per hp is what I meant to say. The M3 shows slightly better times vs the weight because of the dct, the power from the engine to the wheels is transferred more efficiently than a conventional torque converter or multi plate wet clutch mct.
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09-23-2017, 08:02 PM | #29 | |
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I don't believe in Internet Bullshit, But that is a good one , I read emperical data that which includes Rear Wheel Dynos of my Stock M3 vs. other vehicles such as a stock C7 on the same dyno, same day I dynoed much higher. However, Since you such as smart guy tell me how how did you account for the R-comps in your Insightful analysis above on the GULIA ??? Oh wait you did not Put all cars on the same drag strip, SAME TIRES, same day, same ambient temps, and maybe you have something. BTW Stock M3/M4 have run in the 11's but that doesn't really mean anthing.. A wheel dnyo is a much better measuring devise IMO. I would love to see a GULIA VS M4 same day Dyno And Yes I have read CAnAutM3's Steady State Explanation as he is quick to remind us every single time this debate arises Last edited by kitesurfer; 09-23-2017 at 08:11 PM.. |
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09-23-2017, 10:36 PM | #30 | |
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Post data from same dynos from same day of stock cars you are discussing.
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09-23-2017, 11:27 PM | #31 |
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WOW how do you have have all the explanations....you must be a powertrain engineer with intimate efficiency knowledge of not only one but of 3 performance transmissions from 3 different manufactures ......or did you just stay at a Holiday Inn Express last night
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09-23-2017, 11:35 PM | #32 | |
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09-24-2017, 11:50 AM | #33 |
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M3/M4 Dynos on 91 octane and some discussion:
http://f80.bimmerpost.com/forums/sho....php?t=1266343 http://jalopnik.com/the-true-power-o...run-1603070524 Alpha Dyno: http://jalopnik.com/heres-how-much-p...lio-1792840088 Granted these are NOT apples to applea comparison Dynos (dynojet 91 oct vs. Mustang xxoct?) between the Alpha & BMW but it is some food for Thought regarding the kind of power these cars are producing. It would be nice to see what the Alpha puts down on a dynojet wiht the same fuel. With all that said....... I would not be surprised if the Alpha that ran the Ring in 7:32 was"Specially Tuned" buy Alpha Engineers before its glory run....I would like to see what Sport Auto time would be with a regular press car. |
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09-24-2017, 02:05 PM | #34 | |
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09-24-2017, 10:30 PM | #35 |
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