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Steve's DIY Dyno
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Thursday, 18 July 2024
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Steve's Dyno Home Page Print

Welcome to my "Do It Yourself" dyno pages.

Have a look around the site and if you're thinking of building your own dyno hopefully you'll find some information that helps out.

I've sold the dynamometer. These pages will remain, but will be static, no more updates, testing or experiments. Everything I have to offer is here. It was fun while it lasted, but now it's over. Good luck if you're building your own dyno.

Why WOTID? When I started work on the dyno software I named it WOTID - Wide Open Throttle Inertia Dynamometer)

It could have been called Aergia. Inertia comes from the Latin word, "iners", meaning idle, or lazy. The Greek Goddess of laziness and sloth is Aergia.

Contact: I've made it hard to contact me, because I don't have anything more dyno related to offer. It is all here. Thanks, Steve

Here are a couple of short videos of the dyno in use. (Right click "save-as")

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My friend's old '01 GSXR1000 getting a run up through the rev range. (657kb)
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Running the old TLS up through the gears to 4th. No WOT, no limiter. (1.2mb)

A few more videos are here on Youtube.

How it all started.

Many many years ago I was at a motorcycle dyno shootout day and thought I could build one of these. So the seed was planted. Then in 1997 I got my hands on Visual Basic 4 (VB4) and thought I'll use this to write the frontend.

It was a project that took me 3 years from when I started to when I did my first run on the dyno with the old KLR250. 3 years that used up a lot of free time. If you're going to build your own dyno, don't expect it all to come together overnight and be prepared to do some work & go a little mad. You're going to have to spend some money too. My drum is K1045 bar, 460mm (18.1") in diameter and 600mm (23.6") long and weighed 786kg (~1733lbs) cost me $1676.40AUD in 2000. The machining cost $528AUD and the pillow block bearings (CBC UC216) cost another $300AUD. The trailer I built during lunch times at work, the powder coating etc was free. It would have cost a few more dollars for the axle, wheels and tyres. Add the Basic Stamp, software, other miscellaneous electronic components and it all adds up.

I worked out how to get VB to do math, draw a graph, open and close files. So I moved on to data acquisition. I wrote a heap of little non related VB programs to work out how to send and recieve data over a parallel port and soon moved to the RS-232 serial port. After searching for various options on the internet I decided I'd call on some of my electronics training and see what I could do myself. I stumbled onto the Basic Stamp which really accelerated my development time. I had it communicating with VB in no time.

Before I spent some serious money on the drum, I wanted to know with some confidence that it would work. That's when I used a variable speed drive (VSD) hooked up to a motor. I could simulate doing dyno runs by getting the VSD to accelerate a disk at different rates and different speeds too. Using excel spreadsheets I'd written to help me, I'd experiment by simulating different diameters, widths, mass, MOI, horsepower speeds etc. I wrote many programs for the Basic Stamp and built various versions of the data acquisition unit.

Somewhere in there I taught myself all about rotational physics, mainly by using Google. The physics was the easy part. Calculating the moment of inertia is straight forward with the drum configuration used. Calculating power is just one more simple step.

Eventually I put it all together and did that 1st run on the KLR. It was then that the interest and motivation fell right off. I'd achieved what I set out to achieve and that was it, 3 years work. I never really had plans to build and sell dyno's or make money from it, I did it simply as a hobby to keep me occupied and because I thought I could. I did a little more development after those 1st runs but not much. So this year after 7 years of doing nothing other than pulling it out once in a while to do some bike testing, I bought the Dyno46 set-up off eBay.

So it went something like - teach myself how to use and write programs using Visual Basic, then some rotational physics, brush up on my electronics to build a data acquisition unit, design a drum, put it all together and start doing runs. It was a lot of fun.

Here are a sample of pictures from the photo gallery. Click on any of them for a larger image.

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