KP gets an Inertia Dyno

I’ve been looking for a while and it turns out the guy I bought my rental fleet from also has a chassis dyno. It’s an inertia one and for the price I can’t even get a flywheel elsewhere. Arranging shipping for it this week….



It’s a fairly unknown quantity at this point, so I’ll have to calculate the moment of intertia for it at the least. Laptop and I think the analog data box are missing.

Initially I’ll be using an Arduino shield (Daughterboard) called Ardyno (By 2strokestuffing on YouTube) to capture and log the sensor data. It works in conjunction with the free “simpledyno” software to log and display graphs.

  • 1x input for roller rpm, hall sensor
  • 1x input for engine rpm, either hall sensor or capacitive clamp on sparkplug wire
  • 6x analog 0-5v inputs for voltage, temperature, egt, afr, pressure etc.
  • Works with Simpledyno Arduino sketch without modification

Board is about $25 ish, plus components. Probably under $70 total is my guess. Alternatives are in the $400 mark and at this point it’s surplus to my needs.

Longer term goals include adding a provision for straight engine testing as well as adding either an eddy or powder brake with a controller to do steady state and simulated lap runs. At that stage of course we’ll be well beyond using Simpledyno and looking at something spicier.

But for now, I’ll have to get it shipped here and clean it up. Oh yeah probably get a shield around that flywheel too if it doesn’t arrive with one.

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Sweet! One thing that seems like a great idea is using a controller to ensure that motors are all tested or broken-in the same way. I know BBS Engines claims they do that, and I cant see why anybody else wouldn’t! You have the technical know-how to figure that out, so just throwing ideas your way :slight_smile:

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Yep a controlled brake with load cell would be the second or third level. Would be particularly valuable for tuning the EFI system before running it on track.

I might even have something open sourcy made for control… What I’d really like to do is a 24hr simulated torture test and live stream it, but that’s not quite on the horizon yet. This is mostly for the four stroke shifter project I’m working on.

Keep reminding myself that it’s baby steps and to be patient, especially with everything else going on. :slight_smile:

I’ll update this topic as things progress of course.

We can make a this into a science experiment. You livestream the engine running and I’ll livestream my sim racing.

We will see what content is more boring and draws fewest eyeballs.

Watch James get 100 views or something and I get 2.

It will likely be official: watching an engine run is more interesting than other peoples sim racing.

I think “Comment when you think it’ll explode” would add to the spice. Along with “will it be the engine or dyno that lets go first”

I’d likely stream it via FB…

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Well I can’t compete with explosions. I surrender. You win.

KP has an official dyno now, sweet! Need your shipping address! :rofl:

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As long as you’re paying :joy:. I might calibrate it for :duck: power just to mess with people.

Yes, :duck: power is a thing.

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Maybe get some pyrotechnics to go off if you crash badly
And random carbon bits flying at you at 100mph
I’d watch that

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Dyno is on its way. As predicted the transport from VA to MN cost more than the dyno, so I got a kart lift and some spares for the rental fleet thrown in.


It’ll need some TLC, but like I said the entire thing cost less than an inertia flywheel which seems to run $1500 plus a ride and then I still have to fabricate the frame and what not.

The ardyno board arrived too. This will be used to convert sensor data into something computer readable for the dyno software. Engine RPM, flywheel RPM, air fuel ratio, temps and whatever else. I have a choice of six analog inputs I think.

It’s from two stroke stuffing on YouTube.

Getting the components for the board is a chore with no uploadable BOM (component list) that I can find. Someone in Thailand has a few assembled ones so I might just go that way to save time and hassle.

It’s possible the dyno has a box for this already, so I’ll wait to see what I have when it arrives.

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This is the mechanic version of a millstone! That looks heavy.

Team Kalitta’s blower dyno is powered by a small-block Chevy that spins a 4,000-pound flywheel. At the same time, a 50hp electric motor keeps the supercharger at idle (about 2,000 rpm). When the flywheel is up to speed, it instantly kicks the supercharger up to about 12,000 rpm, simulating the launch of the dragster. A series of small turbines measure the output of the supercharger in cubic feet per minute of air; the more cfm, the better the blower.

There are inertia dynos used in RC car racing.

I knew someone who connected a blower/fan to the output to simulate aero load. I’m thinking that a 5 HP blower might do the job.

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I did read something by Pete muller on bobs 4 cycle about a kart dyno that had a GM blower on it.

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Good read. Love reading about all mechanical/analog systems before computers. One thing you learn in Engineering is everything can almost be boiled down to a simple mechanical or electrical system. Pressure=voltage=torque. Flow rate=amps=horsepower. Check valve=diode. Big ass spinning wheel of death=capacitor.

I’ll see if I can find it, but a cool watch is when Ford entered formula 1 just before the turbo era. They had to hand draw the engine, because CAD at the time was too expensive. They were geeking out about sending emails from the US to the UK. Some artisan had to hand carve the engine block by hand to make a sand casting mold. Blows my mind to think about someone saying: “I’ll just draw this complex 3D assembly by hand, CAD is cool and all but it’s too expensive and slow” - some dude at Ford.

this?

I spit out my coffee…

Yes great find! Recommend a watch for everyone.

Cool project! Building test gear for various things has always been a hobby within a hobby for me. I look forward to seeing where this goes!

If you haven’t already, you should really checkout performancetrends.com. This is THE go-to company for all kinds of dyno projects. They have all the hardware and software to bolt right on about any dyno you can come up with, beit inertia or load, in about any HP range. Very resonalby priced stock or custom packages and their software is second to none for DIY dynos.

Their website unfortunatly seems to be circa '08, but the info on the products and packages is there and they even have some online calculators to help with all the flywheel and calibration stuff too; just might have to dig and scroll a bit. Aside from their ancient website, they are great people with excellent customer support that are happy to answer questions through the design/build process. I truly can’t recomend them enough.

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Yeah performance trends is a great resource and I’ve been using their calculators too.
The entry level Datamite is like $500, the tools I’m looking at are <$100.

We’ll see at what point using the DIY type stuff hits an inflection point, but my thought is that $500 would be better off going towards an eddy brake and/or controller in the future. Using their software with the DIY hardware might be a good intermediary option worth exploring.

I’ve been capturing video along the way, including these calcs and whatnot, but it’ll be a few weeks before I start publishing.

http://performancetrends.com/prices.htm

Looks like the google site and drive that was hosting Simpledyno software is no longer available so I’ve uploaded the files that I have to github.

You can download Simpledyno releases from: GitHub - pulsatemedia/SimpleDyno

Also put together a BOM (Bill Of Materials, think of it as a shopping list) for the Ardyno board:

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