Dyno calculation
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Joined: Jan 2006
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From: Oxfordshire
Dyno calculation
Hi
I know from the comparison between the ECU+ dyno analysis & those drived from rolling roads that ECU+ is pretty close. I wonder how ECU+ calculates the figure. I ask, because ECU+ gives me about 255hp with 20% tranny loss, from my nearly stock JDM Evo VII.
Does ECU+ use the slop of the graph or is the recorded road speed used. In the UK to get around the speed limiter on imported cars, an electronic device is placed at the output wire on the gear box, making the speedo read in MPH, I have noticed that ECU+ see my speed as 55MPH in 3rd at 7000, the speedo reads 90MPH which is about the same as the logs from USDM cars. I gues therfor that gearing is not an issue.
If anyone has a 3dr gear run from a stock Evo could they post it up. My car takes about 10 secs to go from 20 to 90 on a slight incline.
MB
I know from the comparison between the ECU+ dyno analysis & those drived from rolling roads that ECU+ is pretty close. I wonder how ECU+ calculates the figure. I ask, because ECU+ gives me about 255hp with 20% tranny loss, from my nearly stock JDM Evo VII.
Does ECU+ use the slop of the graph or is the recorded road speed used. In the UK to get around the speed limiter on imported cars, an electronic device is placed at the output wire on the gear box, making the speedo read in MPH, I have noticed that ECU+ see my speed as 55MPH in 3rd at 7000, the speedo reads 90MPH which is about the same as the logs from USDM cars. I gues therfor that gearing is not an issue.
If anyone has a 3dr gear run from a stock Evo could they post it up. My car takes about 10 secs to go from 20 to 90 on a slight incline.
MB
It uses the engine RPM scaled appropriately by the wheel/tire size to compute dyno MPH. With that information, the vehicle weight and some math, you get the results. In general, it's a bit off in that it doesn't take drag into consideration, but other'n that it should be about right.
Tom
Tom
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From: Oxfordshire
Originally Posted by Warrtalon
255whp is very strong for a stock Evo7.
I'd be realy happy if that was the whp, but I quoted estimated crank hp as I couldn't remember the estimated whp.
My car has only an HKS cat back exshaust & walbro pump, hardware wise, I have used ecuflash to copied in a ralliart ignition map, as I was getting knock issues with the JDM map. It is now much smoother & no knock.
In the UK we are much more use to quoting crank figures, I know there is great deal of debate about things like that on these boards, but I am more familiar with the estimated crank figure, so those stick in my mind.
MB
Oh, I thought you said it was 255hp after the 20% drivetrain loss. You're saying this is before drivetrain loss? Hmm. Oh, you're not stock either.
We don't quote crank, because it can't be measured without an engine dyno. Why bother with guesswork when a dyno tells you the actual power to the wheels? There is no exact drivetrain loss % that is the same for all cars, and it is not linear as power increases, so that's why I prefer to speak in terms of wheel horsepower.
We don't quote crank, because it can't be measured without an engine dyno. Why bother with guesswork when a dyno tells you the actual power to the wheels? There is no exact drivetrain loss % that is the same for all cars, and it is not linear as power increases, so that's why I prefer to speak in terms of wheel horsepower.
Thread Starter
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Joined: Jan 2006
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From: Oxfordshire
Hi
Yae I am aware of the arguments about crank hp. ECU+ dyno feature uses a nominal 20% tranny loss so I leave my setting there, it can be adjusted to give 0% tranny loss & a good estimate of whp.
Like I said, in the UK we are much more use to seeing estimated crank figures.Given the variation in dynos, fuel, air temp, ventilation, atmospheric pressure, etc. the variations possible from the same car under different conditions make any hp quotes subject to variation anyway.
MB
Yae I am aware of the arguments about crank hp. ECU+ dyno feature uses a nominal 20% tranny loss so I leave my setting there, it can be adjusted to give 0% tranny loss & a good estimate of whp.
Like I said, in the UK we are much more use to seeing estimated crank figures.Given the variation in dynos, fuel, air temp, ventilation, atmospheric pressure, etc. the variations possible from the same car under different conditions make any hp quotes subject to variation anyway.
MB
