I took an average of 6 dynos from magazine articles on 07's.
66hp/80tq.

 

If you didn't end your dyno run with an idle-down with your clutch pulled, you only measured WHEEL TORQUE & POWER, while the torque stated on the specifications is the Crank torque and power.

 

You didn't read my post properly. As I said: If a TC96 puts out 78 lb-ft on the rear wheel at the dyno, then H-Ds crank number is too high. If we assume that H-Ds crank number is correct then the difference between crank and rear wheel torque is 16%. Do you honestly think that a Harley has 16% transmission losses?

I have never seen that 92.6 lb-ft number before. Does it really say so in the manual? H-D say on their website that a TC96 has 86 lb-ft of torque in the engine. That seems reasonable considering what it puts out the rear wheel.

 

Harley web site...touring....see full specs.... FWIW





Engine Torque


92.6 ft. lbs. @ 3500 rpm


like it's already been said, dynos vary greatly...watch a TV show where they are upgrading a car or truck motor and using a dyno, they always do a base run first and then use the same dyno to measure the power gains

 

I see. I just didn't get what you meant.
Well... you can't compare what the dyno says to the manual.
To do that, you'd have to use a crank dyno (which attaches directly to the engine crank).
There are various factors that contribute to make a wheel dyno less accurate.
That is: that 16% is made up by the actual transmission and tire loss plus whatever error the dyno put in, and it can be as big as 5%, and that's an optimistic value assuming a good dyno which has been properly set up and maintained, certified and all.
I'm not an expert in bike transmissions, so I really don't know if 16% is way over or optimistic. I know that, for a front drive car, that would be pretty good indeed. But you have a bigger gear transmission and the differential.
On a bike, if I was to take a wild guess, I'd say from 10% to 15%, depending on primary, secondary, transmission and tire.

 

Ahh, thanks! I checked the wrong model...

 

I know a couple of people who build and wrench, and those numbers are pretty much in line with what they've told me.

 

The other factors that might not be accounted for in different dealers and dynos is Altitude. There is a major difference of SL compared to ABSL of say 3000 FT in making power. As Pointed out there is a big difference between crank, versus rear wheel, orperisitic losses.

If I take my bike to a dealer and dyno it at SL, and then they say take it to Denver where the altitude is roughly 5000 feet ABSL my power numbers on the dynowill be a hell of alot less then they were at SL.

 

Note: modern dynos take that into account, but the model they use to compensate may differ from actual engine behavior.

 

99Octane

Am I understandingcorrectly that a Dyno examplein Denver at 5000 feet would report correctedHP and Torque at SL rather then say its actualmile high altitude performance where the test run was made?So it would report numbers inTQ/HPequivalent to SL? But in reality issomething at the rear wheel that was something much, much,less because of the mile high altitude?

I would be surprised if Techs/dynoswere reporting corrected to0 SLnumbers. It would be very mis-leading to what the actual bike was putting to the ground in those circumstances.

In Portland ouraltitude is somewhere around 90 feet ABSL. That said, what they usually correct for is barometric pressure againstABSL/BLSLgiven the generally accepted known altitude in the area.

I know at times that 90 feet ABSL in Portland accounting for barometric pressure to an engine, can look much better, or much worse based on atmospheric conditions at the time of the test run. These changingconditions will have huge effects on peak numbers.

Barometric pressureis likely the only thing thatis being corrected back to thespecificelevation in the area where the test run is conducted. So, I still say my bike, would reflect lower numberson the dynoin Denver then it does in Portland as a result of known elevation to the area. Riding it would also tell the same story seat of the pants.

This is my understanding of it. But if I am wet, let me know. All ears!