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Old 12-17-2012, 07:03 PM   #120
roger 04 rt OP
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Joined: Nov 2011
Location: Massachusetts
Oddometer: 2,095
I figured out how to get Excel to add two Stock Dyno runs to the same chart so I'm reposting.

As I mentioned earlier in the thread, I realized several months ago that a GS-911 can be used as a personal Dynomometer. The key things you have to know are the vehicle's weight including rider (~800 lbs.) and aerodynamics (Cd=0.66, Frontal Area 8 sq-ft), gear ratios, and rear tire diameter (25.59" for PR2 in motion). You log the GS-911 to a data file, import it into Excel, run some math on the numbers and you have Torque, Horsepower and Acceleration. Working out how many feet/second of velocity are created per RPM in a gear is tedious but not difficult (0.01956667 for 4th gear).

It has been my belief based on the feel of my 2004 R1150RT that it has gained torque in the lower RPMs from running Closed Loop at 13.5:1 and fuel pressure at 52 psi. Spend some time looking at the charts below. The Excel chart is a scatter plot of 6 test runs that I took in 4th gear, no wind, 3 in one direction on the highway, 3 in the opposite. Some runs were better than others but I used them all. There are significant torque gains below 3500 RPM, especially between 2000 and 2500--this tracks my driving experience. My RT produces about 55 lb-ft at 2500 RPM compared to 45 lb-ft on Ron's sample. Note: The numbers I measured are actually 5% higher but, as with a Dyno, I reduced them by a factor of 0.956 to account for weather conditions.

Between 3000 RPM and 5000, my bike accelerates at about 12 ft/sē. Anything over 10 ft/sē gives you reasonable acceleration. In fourth gear that requires 48 lb-ft of engine torque, the curves on my RT show that at 2000 RPM. There are also gains at higher RPMs.

While I believe my data is accurate, the one thing I would say is that I was careful to get the run prepped for low RPMs by running along at idle in 4th or 5th gear, then crank open the throttle. I did not run quite to the Rev Limiter, choosing to let go of the throttle at around 7000 RPM. So my numbers might be a bit better due to the care of low RPM starting but I don't think that explains it all.

Enjoy the curve, I've got some more coming.



Stock bike from Ron Hankison's web site.

http://www.r1150rts.com/DynoData/Dyno_004b.htm
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