dyno testing tomorrow
#26
Super Member
I remember on the Nissan GTR episode of TopGear they emphasized that each engine was hand built and because of that each engine had different hp numbers. Could that be the case with us? I'm not say that's the situation here, just something I wondered.
#28
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2002 C32 AMG, 2013 GLK 350/4, 2015 E63S AMG Wagon
Here is the same question and an answer by one of the AMG guys at MBUSA:
http://www.mercedes-amg.com/privatel...1&postcount=48
and if you are not a member of that board:
" I certainly would not be concerned about greater deviations in power output from unit to unit because the AMG engines are hand built.
Let’s remember that all of the critical dimensions are machined on CNC equipment so the dimensional consistency from component could not be better. One would be more likely to see deviations in power output from season to season based on fuel formulations and Ethanol content rather than for mechanical reasons."
#29
Super Member
Thread Starter
Chris,
Here is the same question and an answer by one of the AMG guys at MBUSA:
http://www.mercedes-amg.com/privatel...1&postcount=48
and if you are not a member of that board:
" I certainly would not be concerned about greater deviations in power output from unit to unit because the AMG engines are hand built.
Let’s remember that all of the critical dimensions are machined on CNC equipment so the dimensional consistency from component could not be better. One would be more likely to see deviations in power output from season to season based on fuel formulations and Ethanol content rather than for mechanical reasons."
Here is the same question and an answer by one of the AMG guys at MBUSA:
http://www.mercedes-amg.com/privatel...1&postcount=48
and if you are not a member of that board:
" I certainly would not be concerned about greater deviations in power output from unit to unit because the AMG engines are hand built.
Let’s remember that all of the critical dimensions are machined on CNC equipment so the dimensional consistency from component could not be better. One would be more likely to see deviations in power output from season to season based on fuel formulations and Ethanol content rather than for mechanical reasons."
#30
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2002 C32 AMG, 2013 GLK 350/4, 2015 E63S AMG Wagon
No problem. I'll try to explain.
Chris (02C32guy) was speculating that the reason for your higher dyno numbers than what other cars with similar mods showed maybe be related to the fact that AMG engines are build by hand and therefore may have somewhat different HP and TQ numbers. But the guys from AMG disagree that building engines by hand will result in any substantial differences between any two engines.
Chris (02C32guy) was speculating that the reason for your higher dyno numbers than what other cars with similar mods showed maybe be related to the fact that AMG engines are build by hand and therefore may have somewhat different HP and TQ numbers. But the guys from AMG disagree that building engines by hand will result in any substantial differences between any two engines.
#31
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2008 A8L, 2002 996TT X50, 2009 X5
Did you Dyno this in 4th gear or 3rd gear? 3rd gear is going to give you a higher whp since its not a 1:1 ratio.
Your numbers are higher then stock dynojet numbers which reads higher then a dyano dyanmics.
I have a feeling this was dyno'ed in 3rd gear, not the standard 4th gear everyone else does.
Your numbers are higher then stock dynojet numbers which reads higher then a dyano dyanmics.
I have a feeling this was dyno'ed in 3rd gear, not the standard 4th gear everyone else does.
The shop I go to also dyno's these vehicles in 3rd. Again, it's a data point, so as long as you're consistent, it's fine IMHO.
Last observation - Dynojet numbers usually read higher than Dyno Dynamics - but not always (which your post seems to suggest); it all depends on the individual shop and how they set up their dyno.
#32
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My point would be that there have been a hundred if not hundreds of C32 dyno's and they all dyno in the 280-294whp stock. A intake no matter what design will result in no gain to maybe 5-10hp at best.
#34
Registered User
try keeping tire pressure up . i hear it increase hp #'s as well on a dyno . @ the track higher psi "within tire parameters of course " gives you a higher mph so i think it should work out
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03 g35 coupe...........02 c32 Sold
While I agree fully that dyno'ing in the gear that's a true 1:1 ratio will give the most accurate results, your claim that a non-1:1 ratio will dyno higher than 1:1 is not universally true. Look at the C63's that just dyno'd at a group dyno day in Seattle - their 5th gear (i.e. 1:1 ratio) results were noticeably higher than 4th gear results.
The shop I go to also dyno's these vehicles in 3rd. Again, it's a data point, so as long as you're consistent, it's fine IMHO.
Last observation - Dynojet numbers usually read higher than Dyno Dynamics - but not always (which your post seems to suggest); it all depends on the individual shop and how they set up their dyno.
The shop I go to also dyno's these vehicles in 3rd. Again, it's a data point, so as long as you're consistent, it's fine IMHO.
Last observation - Dynojet numbers usually read higher than Dyno Dynamics - but not always (which your post seems to suggest); it all depends on the individual shop and how they set up their dyno.
I disagree. A dynojet is basically a roller dyno. It measures acceleration based on many revolutions the car can spin the roller in a given pull. Then reverses the math to get hp and tq numbers.
Using a more agressive gear such as a 1.41 in 3rd gear will multiply the tq the car is putting down by 1.41 rather then 1, therefore spinning the roller much faster then in the same given pull. This is deceptive because now, your not measuring just the tq of the engine but the tq created by the gearing of the transmission.
A dyno dynamics is basically resistance roller. The dyno applies resistance or a brake to the roller and measures how much force was applied to move the roller. This is why tuners consider more accurate numbers since its considered to stimulate real life conditions more accurately because of the extra load.
I understand your point that the delta is the main factor. But since he didn't take a baseline dyno, he's basically posting a dyno on in my estimate a dyno a 3rd gear vs others who dynoed in 4th gear.
Basically making a apples to oranges comparison.
If a dyno dynamics shop posts higher dyno numbers with the same car then a dynojet then i think there's something wrong with the software or the operator..
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#36
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03 g35 coupe...........02 c32 Sold
here's a great write up on differences between a dynojet and dyno dynamics.
here's a quick copy and paste
You can read the rest here
http://www.mazdas247.com/forum/showt...hp?t=123629978
here's a quick copy and paste
This discussion revolves around chassis dynamometer's and is intended to be informative and thought provoking. There are two types of chassis dynamometers on the market, inertia and loading. An inertia dynamometer (such as DynoJet) does not measure torque, but measures acceleration. A loading dynamometer applies resistance that is measured (using some type of strain gauge.)
The most often heard discussion is that what factor can be applied to rear wheel horsepower to reflect crankshaft horsepower. This is where we need to understand how the rear wheel horsepower number was derived. Since the DynoJet seems to be widely used and numbers quoted are those from a DynoJet, we are going to use them as our inertia dynamometer example.
First it is important to have an understanding of how DynoJet gets their horsepower numbers. Power in mechanical terms is the ability to accomplish a specified amount of work in a given amount of time. By definition, one horsepower is equal to applying a 550 pound force through a distance of 1 foot in one second. In real terms, it would take 1 HP to raise a 550 pound weight up 1 foot in 1 second. So to measure horsepower, we need to know force (in pounds) and velocity (in feet per second). Dynojet's inertial dynamometer measures power according to the terms just described. It measures velocity directly by measuring the time it takes to rotate two heavy steel drums one turn. It measures force at the surface of the drum by indirectly measuring it's acceleration. Acceleration is simply the difference in velocity at the surface of the drums from one revolution to the next. The force applied to the drums is calculated from acceleration using Newton's 2nd law, Force = Mass * Acceleration. Since the mass of the drums is know and acceleration has been measured, Power (horsepower) can now be calculated. Torque is then calculated using the horsepower number: Torque = Horsepower * 5252 / RPM.
Once they have these numbers a series of correction factors are applied, some made public, some hidden as proprietary secrets. The public correction factor is the SAE correction factor. This formula assumes a mechanical efficiency of 85%. The formula used is: Where: CF= 1.18 * (29.22/Bdo) * ((Square Root(To+460)/537)) – 0.18. To = Intake air temperature in degrees F, Bdo = Dry ambient absolute barometric pressure. This correction factor is meant to predict output in varying atmospheric conditions and is a +/- 7%. The proprietary correction factor is supposed to reflect the loss of power from the crankshaft to the rear wheels.
A Loading Dynamometer applies resistance to the dyne's roller(s) , typically using either a water brake or a current eddy brake. In either case, the amount of force is measure using a strain gauge. The measured force is torque which is a real, indisputable measurement of the actual output at the wheel. Horsepower than can be calculated: Hp = Trq * 5252 / RPM.
A Dynamometer can only measure actual power at the output location. Actual power produced AND delivered by an engine will be highest if measured at the crankshaft, lower at the transmission output shaft and even lower, but more meaningful, still, at the rear wheels. The power that you use is the power at the rear wheels. Some Dynamometer companies add to measured rear wheel power readings a factor that is based on ESTIMATED rear wheel power losses (under what power conditions? 3.0 ltr.? 5.0 ltr.? Under coasting conditions? with a 185/70/15 radial tire? a 335/35/18 radial tire? New heavy radial tire vs. worn old, light, racing tire? Who knows?) In short, there is NO meaningful "average" tire to get a correct rear tire power transmission loss measurement for all cars - so obviously, unless they actually measure the power lost in the rear tires, under driven load conditions, NO dyno company should BE ADDING incorrect power figures into the measured power. It's simply wrong. The fact that they add varying amounts of power to the actual, "true" amount of power delivered and measured to the surface of the drive roller creates a situation that makes it an onerous task to compare power figures from different brands of dynamometer systems. On simple inertial dynamometers, some (most) companies use an average for the inertial mass value of the engine, transmission, driveshaft, axles and rear wheels. This is saying that a 4 cylinder, 2.0 ltr. Porsche 914 has the same rotating mass and same rear wheels as a 8 cylinder, 5.0 ltr. Porsche 928 S+4. This simply is not so and wrong.
The most often heard discussion is that what factor can be applied to rear wheel horsepower to reflect crankshaft horsepower. This is where we need to understand how the rear wheel horsepower number was derived. Since the DynoJet seems to be widely used and numbers quoted are those from a DynoJet, we are going to use them as our inertia dynamometer example.
First it is important to have an understanding of how DynoJet gets their horsepower numbers. Power in mechanical terms is the ability to accomplish a specified amount of work in a given amount of time. By definition, one horsepower is equal to applying a 550 pound force through a distance of 1 foot in one second. In real terms, it would take 1 HP to raise a 550 pound weight up 1 foot in 1 second. So to measure horsepower, we need to know force (in pounds) and velocity (in feet per second). Dynojet's inertial dynamometer measures power according to the terms just described. It measures velocity directly by measuring the time it takes to rotate two heavy steel drums one turn. It measures force at the surface of the drum by indirectly measuring it's acceleration. Acceleration is simply the difference in velocity at the surface of the drums from one revolution to the next. The force applied to the drums is calculated from acceleration using Newton's 2nd law, Force = Mass * Acceleration. Since the mass of the drums is know and acceleration has been measured, Power (horsepower) can now be calculated. Torque is then calculated using the horsepower number: Torque = Horsepower * 5252 / RPM.
Once they have these numbers a series of correction factors are applied, some made public, some hidden as proprietary secrets. The public correction factor is the SAE correction factor. This formula assumes a mechanical efficiency of 85%. The formula used is: Where: CF= 1.18 * (29.22/Bdo) * ((Square Root(To+460)/537)) – 0.18. To = Intake air temperature in degrees F, Bdo = Dry ambient absolute barometric pressure. This correction factor is meant to predict output in varying atmospheric conditions and is a +/- 7%. The proprietary correction factor is supposed to reflect the loss of power from the crankshaft to the rear wheels.
A Loading Dynamometer applies resistance to the dyne's roller(s) , typically using either a water brake or a current eddy brake. In either case, the amount of force is measure using a strain gauge. The measured force is torque which is a real, indisputable measurement of the actual output at the wheel. Horsepower than can be calculated: Hp = Trq * 5252 / RPM.
A Dynamometer can only measure actual power at the output location. Actual power produced AND delivered by an engine will be highest if measured at the crankshaft, lower at the transmission output shaft and even lower, but more meaningful, still, at the rear wheels. The power that you use is the power at the rear wheels. Some Dynamometer companies add to measured rear wheel power readings a factor that is based on ESTIMATED rear wheel power losses (under what power conditions? 3.0 ltr.? 5.0 ltr.? Under coasting conditions? with a 185/70/15 radial tire? a 335/35/18 radial tire? New heavy radial tire vs. worn old, light, racing tire? Who knows?) In short, there is NO meaningful "average" tire to get a correct rear tire power transmission loss measurement for all cars - so obviously, unless they actually measure the power lost in the rear tires, under driven load conditions, NO dyno company should BE ADDING incorrect power figures into the measured power. It's simply wrong. The fact that they add varying amounts of power to the actual, "true" amount of power delivered and measured to the surface of the drive roller creates a situation that makes it an onerous task to compare power figures from different brands of dynamometer systems. On simple inertial dynamometers, some (most) companies use an average for the inertial mass value of the engine, transmission, driveshaft, axles and rear wheels. This is saying that a 4 cylinder, 2.0 ltr. Porsche 914 has the same rotating mass and same rear wheels as a 8 cylinder, 5.0 ltr. Porsche 928 S+4. This simply is not so and wrong.
http://www.mazdas247.com/forum/showt...hp?t=123629978