how does a dino work?

[starscreamer]

I was at a long beach motorcycle show last week and they had a mobile dino. people brought their bikes and competed in their class to see who had the most horse power. I watched the competition for about an hour( until a busa through a rod and expoded at peak rpm throwing steel and oil everywhere) anyway i realized I don't know how the dyno works. I see the graphs but I when I watched them run the tests they don't change gears. its one twist of the throttle. what gear ar they in???? It dosn't make sense which means i dont understand how they work. anyone got a link -there are plenty of links on dynos - just not on how they work and what they actually measure.

[CLB]

The dyno has two main parts. One is a heavy drum with a known inertia characteristics, the other is a computer.

The bike is usually in high gear as it spins the drum up. This minimizes tire slip and allows more time for data acquisition.
The computer monitors the rate the drum is accelerating and calculates torque from this.
At any given instant power is calculated by multiplying drum torque * drum RPM.

Torque values are translated back to the crankshaft by sprocket and transmission gear and sprocket ratios.

It would be interesting to know the story behind the Busa. I have seen pix of ventilated Sprint castings resulting from bumping redline up.

Originally Posted by starscreamer

I was at a long beach motorcycle show last week and they had a mobile dino. people brought their bikes and competed in their class to see who had the most horse power. I watched the competition for about an hour( until a busa through a rod and expoded at peak rpm throwing steel and oil everywhere) anyway i realized I don't know how the dyno works. I see the graphs but I when I watched them run the tests they don't change gears. its one twist of the throttle. what gear ar they in???? It dosn't make sense which means i dont understand how they work. anyone got a link -there are plenty of links on dynos - just not on how they work and what they actually measure.

[starscreamer]

I was just walking up to the tent that had all sorts of bikes lined up to test. They were giving prises in different categories of bike. They were running the motor up to redline- it coughed and boom- parts and oil and debris everywhere. no one was hurt but it broke the dyno and they had to borrow parts from a local shop.
latter in the afternoon some of the tuners had bikes well over 550 horse power. and an assortment of bikes that sorely disapointed their owners. it was interesting.wish I could know more about how tuning is done.

[caddydaddy]

I had my Sprint on a dyno yesterday. This dyno required an ignition signal to figure the torque, and since I didn't know where to get at something to get that signal, he could only give a horsepower reading for my bike.

[starscreamer]

what have you done to your bike and what horsepower did you get

[caddydaddy]

Originally Posted by starscreamer

what have you done to your bike and what horsepower did you get

TOR muffler and tune, with a K&N air filter. It made 118.76 HP.

[7589]

Originally Posted by caddydaddy

TOR muffler and tune, with a K&N air filter. It made 118.76 HP.

118? at the wheel right?

Stock at the crank is:

Maximum Power: 125bhp at 9,250 rpm
Maximum Torque: 77ft.lbf at 7,500 rpm

Anyone know how to find out what Caddy's BHP at the CRANK is?

--Kory

[CLB]

Rule of thumb is 15% drivetrain loss. It's a worthless figure based on nothing though.

118 sounds good. Isn't ~111 the norm?

[MuzTheInfidel]

How does a Dino work??? The only ones I know of work in the quarry. With Fred & Barney...

Oops..... you meant a Dyno...

Sorry, just my 0430am sense of humour at work there...

[caddydaddy]

Originally Posted by TattooedRedHead

118? at the wheel right?
--Kory

Yes, that's at the wheel on a chassis dyno (Dyno Jet to be exact!).