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09-02-2008, 11:14 AM | #91 |
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I don't know yet. This is something we will find out. There is the potential for them to make the same power gain by recapturing the same lost efficiency, however, we will not know what that does to the DCT controller yet.
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09-02-2008, 06:35 PM | #92 | |
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For a well respected tuner such EvoSport to come on here and defend themselves like this takes balls and he is obviously not giving out BS. All responses are well structured and all make perfect sense. Reputation is everything and I doubt Evosport are going to sacrifice their reputation by falsely marketing a product which is only a few hundred dollars. Infact, I am going to import a set of pulley into the UK and independantly test them on my Dyno Dynamics machine.....on which I get very repeatable results. I will point out that we are not an EvoSport dealer and probably never will be due to certain exclusivity deals over here in the UK which unfortunately don't make selling EvoSport products financially viable. A stock M3 makes 410-411 bhp on my dyno. If this product makes X bhp in the USA on a dynojet it's going to make it here in the UK on a Dyno Dynamics under fully controlled conditions. If anyone in the UK is reading this and would like to put themselves forward please contact us. Brad....I'll be in touch. |
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09-04-2008, 08:53 AM | #93 | |
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Quote:
http://www.m3post.com/forums/showthread.php?t=164365
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09-04-2008, 09:14 AM | #94 |
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I am not sure that "more accurate" is correct. That is an age old argument that will not be solved here! There are credible people on all sides of the issue that claim this or that dyno is more accurate.
What is important is the delta and the relationship from one machine to another. The gains seen on that dyno-pack correlate fairly well with what was expected based on the dyno-jet results. Everyone must realize that the dyno-pack may not be the most realistic measurement of your car as it requires you to remove your wheels - and last time I checked, we need those wheels to drive the car on the street or track! Also, when you are talking about a modification that recaptures lost drive-line efficiency, removing one part of that drive-train will lesson the gains to some degree. By far the most accurate way to test motor gains is with an engine dyno. However, with mods like pulleys, flywheels, CF drive-shafts, differentials, lighter rotors, lighter wheels (anything that works to recapture efficiencies lost in the drive-line), you must use a chassis dyno (and as it shoudl be becoming clear, they all have pro's and con's). We use a DynoJet 248c as it is the single most commonly used dyno in the US. You can find one in nearly any town, and you will be able to see gains within 1-3% of advertised on any of these machines anywhere. This allows us the opportunity to have customers see the gains that are sold with the product. Is this the "most accurate" - dunno. Again, that is a bigger argument, and one that will not be solved here. However, we feel it is better then using a dyno that few have access to (like the Maha, which is what a leading MBZ tuner uses to show gains). So net/net, it does not matter which tool you use to measure. You just need to see the before and after and realize how that correlates to the delta from another machine. There are at least half-dozen commonly used dyno's (dynojet, dyno-pack, mustang, maha, etc) - and they ALL read different (arghhh!). I agree that the low-end gains are the most critical as that is where you will feel the biggest improvement - from the stoplight or on the initial application of the throttle. Thanks Brad PS - PencilGeeks test was done in cooperation with evosport. He and I had communicated and I had asked him to do an independent test. Just for full disclosure!
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09-04-2008, 10:55 AM | #95 |
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I am not an expert in dynamometers, but there is definitely such a thing as one instrument being more accurate than another in its ability to measure torque output, and it is not such a gray matter as you seem to present it in your post.
Moreover, my understanding is that a dynapack chassis dyno has the ability to vary the load in real-time during the test to the extent that it can directly measure the maximum possible torque output of an engine at a specific rpm at steady-state. Note that a steady-state measurement at the hubs or the wheels would not take into account the rotational inertia effects associated with the drivetrain or the wheels, and will be the closest indication of output at the engine shaft. (You said above that the most accurate way to test motor gains is with an engine dyno). It is also my understanding that a dynojet dyno cannot do that as it cannot vary the load and simply infers the torque output based on acceleration time under a fixed load. Again, one is a more precise direct measurement method, and the other is based on inference. Correct me if I am misinformed.
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09-04-2008, 11:32 AM | #96 |
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You are right and wrong to some extent IMHO (and this is really opinion). Some opinions are based on more experience then others, but as I stated above, there is no one right answer. In fact, when people try to asset (not saying you are doing this), that one dyno IS the perfect solution, I laugh. They all have pros and cons, they are all a bit right and a bit wrong...
I tried to be clear on this, but if you read what I wrote, you will see that I qualified "more accurate" as to ENGINE, but not car. The Dyno-pack does not measure the power at the wheels - which in reality is where your car puts the power down (as opposed to the hubs). So yes, if you are measureing ENGINE only, then the dyno-pack may be a more accurate tool. However, in the real world, we use 4 wheels to connect the car to the road, and any rotational issues that the wheels add and the drive-line add are VERY real. So if you are attempting to measure the output of the CAR, not just the engine, then a dyno that runs on a roller is superior. As to your "one tool is more accurate" comment - you are right. But my retort, is "how do you calibrate that to know which tool that is?" With any dyno, you simply take a baseline, then mathematically calculate the loss factor, then use that factor moving forward. One step further is the assertion that if a dyno is not emulating the exact conditions your car is really seeing when driving (ie: all 4 wheels on the road), then that is a less accurate tool The dyno-jet does have an option to add load, but load is only an option you use for tuning, not for power runs, or "shootout" mode as per the dyno-pack. The best dyno you can use really is a Superflow. The superflow has the ability to actualy simulate roads or tracks with varying load and allows you to monitor many channels of data. This is what most NASCAR teams use as well as other very high-end race builders. Hope that helps to clear up what I was trying to say. If not, I will try again (I am working on no sleep! lol) This is a great discussion to have, so if you have any additional questions, please feel free to ask. As I stated above, there are as many ideas and beliefs on this topic as there are options, and there is not a right or wrong answer, it is really a matter of opinion. Thanks, Brad
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09-04-2008, 12:46 PM | #97 |
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Thanks for response Brad. I think you are mixing up a couple of issues here. The two issues are the measurement and driving/loading scenario. If we are simply talking about the measurement method, a system that directly measures torque (anywhere, at the shaft, hubs, wheels, it doesn't matter), will simply be more accurate than a system that tries to make the same measurement by way of a inference such as an acceleration time for a fixed load. Again, one is a direct measurement (the basic operating principle of such a dynamometer is to hang a weight on a lever, couple that to the dyno rotor which is clamped to the output shaft--the crankshaft, hub or something else--and balance that), and the other is simply an inference based on some other performance parameter such as acceleration time under a fixed load. The direct measurement will be a more accurate approach than the indirect measurement.
If your the basis of accuracy is what you wrote below (quoting you): "By far the most accurate way to test motor gains is with an engine dyno." Then a chassis dyno making direct measurements will be more accurate than a dynojet with the exception that it will not measure rotational inertia effects associated with the angular acceleration of the wheels. But if your goal is to report steady-state gains at the crankshaft by trying to arrive at the manufacturer's numbers through "estimated" loss/fudge factors, why do you care about the wheels to begin with since manufacturers report steady-state numbers at the shaft, which do not account for any rotational inertia effects. If your goal is to report gains that can be experienced by a real driver during a real ride, then you should only report wheel numbers and leave the numbers at the crank out of it. Then, the loading conditions become a significant issue. A dynojet cannot vary the load in "real-time", but a dynopack can. However, as you are saying, the dynopack does not address rotational inertia effects associated with the wheels, but that can be calculated easily if one really wanted to know via T = I x alpha(angular acceleration). In that scenario, ultimately, I'd still put more stock in the dynopack because it produces a direct torque measurement and can vary the load in real-time.
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09-17-2008, 01:03 PM | #100 |
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We had a DCT car to come in for final steps of dev - but it fell out. So any SoCal DCT's that want a great deal - get a hold of me ASAP!
thanks Brad
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09-17-2008, 03:36 PM | #101 |
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