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  • Mrpikolo's Avatar
    Today, 08:57 AM
    Times seen a little slow to me... And on the depends on the compound. A typical street tire starts is useless "hot" like a drag radial needs to be. I'm sure no one can argue about the science of particular compound and the temperature that is required for maximum fractions. Like snow tires, are pretty sticky cold, and racing compounds are useless cold. Generally your typical performance street tire likes to function at a "warm" temperature. I didn't watch the video(at work), but if they did a huge smoking burnout with street tires, it's pretty much a waste
    18 replies | 1377 view(s)
  • Acheron's Avatar
    Today, 03:17 AM
    I'm talking specifically about the SA CAR guys. Being South African myself I've become rather familiar with how unfortunately flawed most of these guys' tests are and how poor the presentation is, especially when they are essentially SA's biggest car themed magazine. Kinda embarrassing as well when the vids pop up on international websites :laughing-rofl:
    18 replies | 1377 view(s)
  • 93siro's Avatar
    Today, 02:41 AM
    As long as there is not a wide-spread standard for wheel horsepower, the crank horsepower is what that matters. When you say you have 560HP engine, you have 560HP. Everyone know what that is. But when you say you have a 560whp car, then there are several questions to be asked. What was the type of the dyno? What standard was chosen? What gear? Was it weather corrected etc.... I agree with the person who said why would you multiple the drivetrain loss to your dyno numbers? Its just stupid. The drivetrain loss goes up and down in higher and lower loads thats for sure, but it doesnt go up and down with a fixed rate.
    57 replies | 3417 view(s)
  • BlackJetE90OC's Avatar
    Yesterday, 09:50 PM
    Motor Trend has the same comparo coming shortly. Hopefully they took all three to the K&N dyno. I know they took the M3 during its first instrument test.
    6 replies | 430 view(s)
  • subaru335i's Avatar
    Yesterday, 06:47 PM
    We are clearly arguing completely different points. 1) A lot of modern turbo cars are under rated from the factory (crank horsepower). In extreme cases certain cars even show on the dyno almost as much whp as the factory rated crank horsepower. This has nothing to do with the next part. 2) Actual drivetrain losses from REAL crank horsepower output vs REAL whp output might be 20% at stock horsepower levels but not when the car has 2 or 3 times the stock power output. For example a stock 300 bhp car with 20% drivetrain losses will dyno 240 whp. The problem is when people mod this car to have lets say 800 whp on the dyno they incorrectly assume that they still have a 20% drivetrain loss and then they brag that the crank horsepower output must be 1000 bhp. In reality the engine is putting out maybe 920ish bhp depending on the specific car. Drivetrain losses will certainly go up with increased power output (meaning it is not a static loss of lets sat 60hp from the example) but it is not a linear 10% or 20% and any calculations based on the assumption that it is linear will be misleading and incorrect. I kind of like this explanation: With a good conclusion: "So rather than attempting to convert your vehicle's dyno-measured wheel horsepower to a SAE net horsepower figure using a percentage or a fixed horsepower value, you're far better off accepting the fact that these two types of horsepower measurements aren't easily correlated and forego any attempt at doing so."
    57 replies | 3417 view(s)
  • COBB Tuning's Avatar
    Yesterday, 06:36 PM
    Back from Pikes Peak and we just wanted to post up some of the info from the blog. This is a bit of data that we have collected over some the past few months. This same data is what we put into our calibrations to make sure they work no matter the variable! Here is some info from the blog I figured I would post up so you guys can check it out! READING/WRITING OF THE ECU How long does it take? The initial install of the Accessport takes around 6 minutes. Once installed, a map change takes approximately 1 minute. Map changing is done on the Accessport and you can select from calibrations that come preloaded on the device. We have Stage1 maps that are for otherwise stock cars as well as Stage2 maps that are made for cars with upgraded exhaust systems. These calibrations come for ACN91, 91, 93, and 100 octane fuels. We do require that a battery charger be connected to the car for the initial Accessport install process on the 991 turbo. Once installed, a battery charger is not required for map changes. DATALOGGING A great deal of time and resources have been invested to make sure we are offering an exceptional, feature rich, tuning tool. One that can not only flash but also allow the end user to monitor the health and status of their car; something that only the COBB Accessport can do! Data collection is an instrumental part of making a proper calibration. Without data you are only taking an educated guess of the vehicle’s state. The Accessport is able to datalog the most crucial parameters for the Engine Control Unit at a sample rate of 45 samples per second. We currently have the ability to log every single factory monitor as well as a slew of custom created monitors that not even Porsche can see! As we continue to learn more about these cars, we will have the ability to create custom monitors using any data that is reported to, or calculated by, the ECU. Below is an example of a small sample of data monitors we currently have access to, viewed in conjunction with a dyno run from one of the many 991 turbos we have been testing with: Over the previous months we have flown around the country and tested our OTS maps for these cars in varying climates and elevations using a variety of fuel grades. A majority of the R&D was performed out of our COBB SoCal facility which has access to some very poor quality 91 octane fuels as well as 100 octane race fuel. We have also performed a great deal of testing in extreme climates and elevations. From a freezing Pikes Peak to an extremely hot and humid Puerto Rico, we were able to test the cars and calibration files in a variety of relative air densities. Below, we’ll take a look at a few of the quirks we’ve learned along the way: -First, the factory intercoolers leave much to be desired even in stock form. With raised boost pressure we have seen intake temps as high as 185*F while in Puerto Rico and 205*F on Pike Peak pushing the pressure ratio of turbos in an extremely low barometric pressure environment. Intercoolers will be a highly recommended upgrade for these cars in the future as cooling the intake charge will be absolutely vital for making power in a safe manner. -The fuel system on the 991 Turbo seems to be a bit more capable than that of the previous 997.2 Turbo. We have experimented with alternative fuel mixtures and thus far have had great results. We have successfully tested up to E30 in a Stage2 Turbo S without any issues whereas the direct injection fuel system on the 997.2 Turbo car is not capable of maintaining pressure with that amount of ethanol content. We will continue to experiment with alternative fuel blends in order to find and push the limitations of the factory fuel system. -The turbochargers on the 991 Turbo appear to be more efficient than those of the previous generations. We performed some exhaust gas back pressure testing in the 991 and compared the results to those from a 991.1 Turbo. We noticed that the 991 spools earlier as well as holds boost longer with less back-pressure. Back-pressure is still quite high in the upper RPM range but not as bad as the 997.1. Below is a dyno plot illustrating the differences between the 991 and 997.1: The solid line is from the 997.1 and the dashed is from the 991. The blue line is the barometric pressure (InHg), pink is temperature (*F), red is relative boost pressure (psig), and orange shows exhaust manifold pressure (psig). You can see that the 991 spools quicker and makes more boost with less back pressure than with the 997.1. The average boost from 2200RPM to 6500RPM on the 991 in this example was 19.4psi with and average exhaust gas back pressure of 24.2psi. The average boost for the 997.1 over the same rev range was 17.3psi with an average exhaust back pressure of 24.182psi. At 6500RPM the exhaust back pressure of the 991 is just shy of 10psi lower than that of the 997.2. In general, it is preferred to keep exhaust gas back pressure at a minimum in order to keep temperatures under control. When exhaust gas back pressure is too high it puts excessive strain on the turbocharger and effectively lowers the overall volumetric efficiency of the engine. POWER GAINS The 991 Turbo’s gains on the OTS (Off The Shelf) maps are substantial. This is a graph of a bone stock 2015 991 Turbo S with just a flash. As you can see the car picks up a lot all over the power band! Another strong example of a car we have tuned with some basic bolt-on modifications: This is a graph of a bone stock 2015 991 Turbo S with just a flash. As you can see the car picks up a lot all over the power band! Another strong example of a car we have tuned with some basic bolt-on modifications: If you have any questions on the 991 stuff please feel free to email me and ask! Thanks! -Mitch
    1 replies | 165 view(s)
  • Sticky's Avatar
    6 replies | 430 view(s)
  • leveraged sellout's Avatar
    Yesterday, 05:03 PM
    I don't get what there's not to get here...this silly argument that modern turbo cars have these magical drivetrains that are almost 100% efficient is just made the point that cars are not under-rated, we just are somehow measuring the drivetrain losses incorrectly. But this makes no sense...why were these losses showing up as normal for decades and now all of a sudden are not? I don't get this fetish that some people have for trying to prove that somehow modern turbo cars aren't can make any dyno read anything you want, but trap speeds tell the whole story. That's easy to figure out.
    57 replies | 3417 view(s)
  • leveraged sellout's Avatar
    Yesterday, 04:59 PM
    Has to be a ringer, GM SAE certifies its power output so they don't really do the "underrating" game. That trap sped gives it all away, that car is making over 500 hp and there's no way any customers are getting a 500 hp ATS-V. Also, seriously, that car needs a new interior. The engine also definitely sounds the least racy of the 3, imo.
    6 replies | 430 view(s)
  • ezec63's Avatar
    Yesterday, 04:55 PM
    The times really don't make any sense it would almost be believable if they switched the atsv and c63s numbers by mistake lol A private owner has run his bone stock c63s at the strip and hit 11.7 @ 119mph so no way is doing half a second slower and 4mph less trap speed on a Vbox with 1 foot rollout. They also stated they pumped up the c63S tires to something like 48psi which is absurd. So the GTS C&D tested that's ~350 pounds lighter, has less torque but a small amount more top end hp, and DCT instead of mct is running 1.1 seconds faster and 12mph faster trap speed lol
    6 replies | 430 view(s)
  • Sticky's Avatar
    Yesterday, 04:49 PM
    The hazards at the end of course were flashing to make the CLS63 aware of slowing traffic ahead.
    9 replies | 346 view(s)
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