I know now why I had low Dyno Numbers!!
12-12-2002, 01:16 AM
#1
Happy CL-S Pilot
Thread Starter
I know now why I had low Dyno Numbers!!
I know now why I had low Dyno Numbers!!
The "not so careful" Shop owner... Dynoed my CLS in the 2nd....
The Gear ration ( RPM/MPH ) was 81.27 so that is
81.27 * 60 = 4876.2 Rev per Mile now... the Nitto tires has 821 Rev per Mile....
Therefore the Gear Ratio was: 4876.2 / 821 = 5.939
The final drive ratio on my CLS is = 4.428
So the Gear Ratio is 1.3413
Which very close to the second gear of 1.552 !!!
Finally, looking at the the Dyno graph we can see the best Torque is shown in the Gear closest to 1:1....
And here are some Dyno tips:
Dyno Tips:
It takes a few minutes to get the engine and drivetrain warmed up on the chassis dyno, so you will need to take several runs before the data becomes consistent. I like to just run the car on the dyno for about 5 minutes before taking any data.
Make certain that you have a strong fan blowing air into the radiator or you will overheat the engine.
In first and second gears, the inertia of the engine and gearbox will reduce your horsepower readings. Third gear is a good choice for getting accurate data. All of my data is always taken in third gear. By the time you get up into fourth and fifth gears, the drivetrain losses are significant and reduce the horsepower.
When you start making data runs, go full throttle at a little over 3000 rpm and run it up to 6000 rpm. Do that over and over until the results stabilize and give power curves that are the same within 1 hp.
Source: http://wahiduddin.net/race/dynotest.htm
Which is BTW, a good Tech Talk!
And another Dyno FAQ:
http://www.awe-tuning.com/pages/faq/...ain.cfm?FAQ=22
Finally, another Thought of loss of power... and user error in dyno testing:
http://toyotaperformance.com/dyno.htm
The "not so careful" Shop owner... Dynoed my CLS in the 2nd....
The Gear ration ( RPM/MPH ) was 81.27 so that is
81.27 * 60 = 4876.2 Rev per Mile now... the Nitto tires has 821 Rev per Mile....
Therefore the Gear Ratio was: 4876.2 / 821 = 5.939
The final drive ratio on my CLS is = 4.428
So the Gear Ratio is 1.3413
Which very close to the second gear of 1.552 !!!
Finally, looking at the the Dyno graph we can see the best Torque is shown in the Gear closest to 1:1....
And here are some Dyno tips:
Dyno Tips:
It takes a few minutes to get the engine and drivetrain warmed up on the chassis dyno, so you will need to take several runs before the data becomes consistent. I like to just run the car on the dyno for about 5 minutes before taking any data.
Make certain that you have a strong fan blowing air into the radiator or you will overheat the engine.
In first and second gears, the inertia of the engine and gearbox will reduce your horsepower readings. Third gear is a good choice for getting accurate data. All of my data is always taken in third gear. By the time you get up into fourth and fifth gears, the drivetrain losses are significant and reduce the horsepower.
When you start making data runs, go full throttle at a little over 3000 rpm and run it up to 6000 rpm. Do that over and over until the results stabilize and give power curves that are the same within 1 hp.
Source: http://wahiduddin.net/race/dynotest.htm
Which is BTW, a good Tech Talk!
And another Dyno FAQ:
http://www.awe-tuning.com/pages/faq/...ain.cfm?FAQ=22
Finally, another Thought of loss of power... and user error in dyno testing:
http://toyotaperformance.com/dyno.htm
12-12-2002, 08:22 AM
#5
Happy CL-S Pilot
Thread Starter
Maybe yes... the thing is the next nearest dyno is asking $150 for a baseline run.... no way.. I will look for $60 deal with a dyno-day club thing...
How soon, by next spring...
How soon, by next spring...
12-12-2002, 08:38 AM
#7
Happy CL-S Pilot
Thread Starter
Looking from the graph of the baseline... it shows the gear ratio is 00.00....so not sure if it was the same as I was not behind the wheels when dynoing...
Assuming that both were in the 2nd, the gain would scale the same, but both numbers are lower due to more losses on the 2nd gear...
Assuming that both were in the 2nd, the gain would scale the same, but both numbers are lower due to more losses on the 2nd gear...
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12-12-2002, 12:24 PM
#8
Suzuka Master
When you dyno in a lower gear the theory points to greater contribution of "engine side" inertial losses. (Grab a control theory book, it is pretty clear on this issue.)
However, ask Scalbert about his 3rd vs. 4th gear dyno run in his 6-speed.
You would help yourself out by getting a 2nd and 3rd gear dyno run to VERIFY your assertions. (Having the ECT, IAT, and fuel-air would be nice too...)
3rd gear is the norm for the auto.
However, there some engine management and air charging/mass flow issues that might come into play depending on the sweep time.
The manifold vacuum will vary depending on load
However, ask Scalbert about his 3rd vs. 4th gear dyno run in his 6-speed.
You would help yourself out by getting a 2nd and 3rd gear dyno run to VERIFY your assertions. (Having the ECT, IAT, and fuel-air would be nice too...)
3rd gear is the norm for the auto.
However, there some engine management and air charging/mass flow issues that might come into play depending on the sweep time.
The manifold vacuum will vary depending on load
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