HomeMade Dyno

[teasser]

I am thinking of setting up a homemade dyno so me and my mates could test out are bikes and see what jets run best when we upjet are carbs.
I am thinking building a metal ramp with a rod that the rear wheel will spin .
And this rod will be connected to a 24v dc motor then i could measure the voltage to see which set up puts out the most volts.
Does this sound like it would work or is it completely bogus

[Blau Zedong]

Do you write this shit just for the lulz or are you actually a daft twat? Enquiring minds want to know.
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18:54:48 Rob Fzs: jews don't give away stuff for free

18:54:59 Rob Fzs: unless its their clothes/ hair/ golden teeth

[NSR Mick]

It could work but if you live within earshot of neighbors expect some visits from the rozzers.
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If you dont like the way that I ride.......Stop trying to keep up!!!

[Ste]

I think it needs to be a drum that the rear wheel spins, rather than a rod.

I also think dynos are a fair bit more complicated than that.

What bikes are you wanting to put on it?

[Kickstart]

Hi

Basic idea might work, but don't think the voltage from an alternator will be that closely related to the speed it is spun.

You also would need a chunky alternator with a large load on it to keep the wheel accelerates to something reasonable (effectively part of the job a large weighted drum does).

Then you need to work the maths out to get an accurate figure (and the maths would be pretty complicated). However you could simplify this if you do not care about an actual power / torque figure, just want to compare runs.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[Blue_SV650S]

[teasser]

Hahaa thanks for the discerning comments but i am a 16yr old who builds things non-stop and yes i am serious
No the neighbours wont say anything as i live in a semi detached house and im making noise all the time in my garage and the neigbours dont hear a thing.
So yes anyways i will start the build tomorrow and post pictures.
I am going to use two of my mini moto wheels and cut the tyres off.
Put the one infront of the other so the back wheel can sit snugly between them.
and use the the standard cog connected one one of them and connect that to a dc 24v scooter motor with a chain.

[teasser]

Very true about the engine load
The bikes are only little 50 - 70cc mopeds
I will see how it goes and work out all the mathmatics when i get round to it

[Blue_SV650S]

[Kickstart]

Hi

Array of fan heaters?

If you just want comparisons then it just needs to be consistant.

All the best

Keith
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Traxpics, track day and racing photographs - Bimota Forum - Bike performance / thrust graphs for choosing gearing

[robocog]

Bogus unfortunately
You need the bike to "do work" rather than just spin up tha back wheel
a proper rolling road has a load that is variable and is consistent and variable, rather than just a spinning thing

Best I have seen as a low cost tinkerers DIY dyno..

Involved a tape recorder or dictaphone

Small isolating circuit that will convert an electrical pulse as a blip
cannot find the info now but involved a LED and light sensitive diode and a battery , LED and sensor stuffed into a piece of black hose as an isolator so that any high voltage doesn't zap the tape recorder

One wire went into any cylinder's HT lead, every fire it would would make a pulse that the tape recorder would record as just a click

you find a nice clear flat road, hit record, pop vehicle into a suitable gear and accelerate as hard as the machine will go (without spinning wheels)

Make any modifications to the machine in question, do run again and make audio notes or written ones till your happy you have run out of things to try

Now get the analog audio recordings onto the PC

there was a piece of software that you feed the audio recording into and give it some info (like how many cylinders, all up weight, frontal area, co efficiency of drag etc) and it would give approx BHP/torque curve based on the info you put in

Wouldn't have thought it was mega- accurate, but show me 2 RR's that will repeatably give the same figure for the same money

if you did any mods or tweaks between runs you could compare graphically as long as you could repeat the runs in same place under same conditions as far as you could. I guess this would be good enough to get a nice real world comparison of if your tweaks are working or failing, more than accurate bar brag figures

I think the software was called DIY Dyno or Easy Dyno? (was many years ago) and I should still have copies of it here, though no doubt you would have to find an old PC or laptop to run it on
(think it was for win 95?)
I did make the isolator and I don't recall actually using it for real

Things have moved on these days, and I cannot recall the last time I saw a portable tape recorder for sale let alone blank cassettes

I guess there's possibly an app that would run on a mobile phone thingy that would be a million times easier and quicker, these days
Most of the younger people I meet seem to have G meters and what not on their phones, mine rings if someone calls, and I have a camera when I want to photograph stuff but none of the bells and whistles

Failing that just get a stopwatch and time a measured run somewhere safe and away from Joe Public

On my toy car I built an ecu (from instructions..I'm not that clever!) to control the fuelling and spark and it has a serial port on to program it and things like datalogging and tweaking can be done real time the mad bit is it will even program itself to an extent, so I no longer have to order jets and emulsion tubes that will never be quite the right ones or even carry a screwdriver anymore, just a laptop
Magic

Things really have come a long way, but perhaps not as much fun?

Stay safe and have fun

Regards
Rob

[teasser]

Thanks for the info.
The reason for this dyno is to measure rpms.
As when tune the carb it will show an increase or decrease in rpms
I could just point a rpm meter at the back wheel which would be easy and simple but i have just finished school and have plenty of time on my hands so i am goin to experiment and pick up new things from this project.
It is stil worth giving it a try

[carlperkins00...]

[Kickstart]

[Barry_M2]

[Pete.]

The old way to build a home made dyno is using a water brake, easy to make but no real use for measuring torque, only comparing runs and loading the engine for tuning.

Some people make more advanced dynos using eddy current brakes - like they use for slowing down large trucks without overheating/wearing out the brake shoes.

If you want to make a dyno for measuring torque you can buy a known-mass dyno roller and the PC software to go with it - and they are easy enough to make in their most basic form.
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a.k.a 'Geri'

132.9mph off and walked away. Gear is good, gear is good, gear is very very good

[Im-a-Ridah]

Does your bike not come with a tachometer then?

[buddy]

if youre just using it for tuning(and dont really care about accurate readings)

then all ya need is something that will give a consistent load every time and just measure rpm/top speed

since mopeds use a cvt/variator then it only really matters what the maximum hp the engine produces rather athn having to wourry about the entire rev range
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When this baby hits 88 miles per hour... you're gonna see some serious shit.

[stevo as b4]

Nice idea, but sillily over ambitious IMHO. For the cost of all the materials, fabrication, software etc and the time needed to build and test your dyno, how many runs would that pay for on a pro set up using a known and calibrated dyno under controlled and corrected conditions?

Also i don't think your neighbours are going to put up with the noise created for one min TBH! I live about a 650-700m walk, from a motorsport unit with a dyno. They do car's, but most of them are bike engined hill climb/sprint vehicles. Whenever they run one up on the dyno i can hear it easily from my house, and when i walk past the place, the noise is pretty loud TBH.

If your house was on the road side of a long uphill, of NSL road and near say a slow corner, then just think of the noise of lots of bikes with race cans coming out of a slow bend, and then accelerating full throttle through the gears up the hill and past your house. The noise would be a bit much, and thats in the open where it tends to get disserpated more easily. Poor example, but you get the idea.