What good is a Dyno?

husabutt · Jan 24, 2006

Except for measuring peak horsepower @ WOT why are dyno numbers so important.
If most riding/racing is done between 1/4 and 3/4 throttle is there a way to measure torque/horsepower at say half throttle.
Also how does a dyno help you jet a bike if the bike is always running on the main jet?

logjump · Jan 24, 2006

These are questions I've been wondering myself recently. Seems like dyno numbers are gained in a controlled enviroment so who's to say those numbers will be good when you're out in the woods bouncing around and going through dramatic altitude and outside temperature changes. Seems like jetting while out in the field would possibly give you as good or better results. Maybe there's a good market for mobile dynos.

As a comparison, our automobiles come with estimated Miles Per Gallon numbers on the sticker (city/highway). Well, those numbers were derived in a controlled enviroment but out in the real world, people rarely reach those same MPG numbers even while driving with as light a foot as possible. This has some new hybrid owners furious.

It'll be interesting to read the responses on this subject. Great topic, Eric!

Log

doctorcorey · Jan 24, 2006

The dyno doesn't require wide open throttle. It is a good place to conduct research and science requires a controlled environment. Imagine taking a 50,000 dollar racing engine out on a track and running the s@#$t out of it just to see if it's jetted right; you'd probably blow it up before you ever had a chance to read the plugs. You can test different ignition curves, jetting,etc. Also, how can you be sure of your bragging when you tell your buddies you've got 65 horses under your bum?

That's worth the price of admission right there! Dynos are what engine builders use to save their work from the abuses of lead-footed drivers who destroy their equipment before they have a chance to tune it. :roll:

LINEAWEAVER · Jan 25, 2006

Hi Husabutt,

A dynamometer is only a tool.
Said tool is only as good as it's operator.

(IE Providing the butcher a scalpel does not make for a surgeon)

In the correct hands a "Moment Of Inertia Dynamometer" can closely emulate real world operation.

Wide open throttle is easy. The majority of my dynamometer time is spent tuning transient conditions between idle and 1/4 throttle opening.

I show the peak numbers as whom would be interested in viewing a low rpm, 1/4 throttle, 5 horsepower graph.

I own three types of dynamometers.
Two Moment Of Inertia (one is mobile)
One Rear Wheel Eddy Current Brake
One Engine Brake

The Eddy Current unit allows for a sustained load if required.
The Engine brake is primarily for hard part development.

Hope this helps clear things up a bit.

For the record:
I have tuned bikes here @ sea level to successfully run "Pikes Peak".
Both highlighted finishers were tuned for the hill climb in my dynamometer cell. 8O

750 Class. Pikes Peak.
78 Don Wilson Maple Valley, Washington 1999 Rotax 13:17.1
63 Kenny Perkins Colorado Springs, Colorado 2002 Husaberg 13:28.1
96 Scott Dunlavey Lafayette, California 1967 Triumph 13:28.6
]77 Rick Gunby Milton, Ontario Canada 1987 Hight-Rotax 13:39.1
20 Scott Walz Englewood, Colorado 1996 Woods 13:43.2
10 Teague Sawyer Longmont, Colorado 2002 VOR 14:01.9
311 Tom Specht Woodland Park, Colorado 1983 Honda 14:26.1
178 Brent King Woodland Park, Colorado 1980 Honda 14:48.8
428 Chris Adams Woodlands Hills, California 1996 Husqvarna 14:56.7
191 Joel Heuvelmans Evergreen, Colorado 2000 ATK-Rotax 15:00.3
242 Robin Russell Superior, Colorado 2001 KTM 15:26.1

Pikes peak has a summit elevation of 14,100 ft.

Check it out!
http://www.ppihc.com/

Best Regards,
Dale

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What good is a Dyno?

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