would this work?

To measure HP???

definitively no

## Re: how to test HP

I wanted to make one out of a bicycle trainer. basically taking the systems from goldsprints and converting to torque/hp for a moped. Like rollers with a known resistance and a tach, you could get something pretty representative I think

idk, maybe?

## Re: how to test HP

pretty sure i've seen phone apps that can record g-sensor data

## Re: how to test HP

When we are talking about measurements to maybe 8 horsepower ish, I think you will need good measurements to get within a tollerance of 1 hp. It wouldn't suprise me that with some of these creative methodes, you get a deviation of 3+hp. That could be up to 35% deviation.

At that point, whats even the use? If you want the bragging rights, pay for a dyno. If you want relevant numbers? Just use a speed over time graph measured with gps and see how well your moped accelerates. This will be a more representive way to put the performance on paper. And, depending on weather and road conditions, can be pretty accurate.

## Re: how to test HP

Vidometer is a free app that shows speed, g’s, elevation. If you set it up and make markings on a test area, there would be some very accessible numbers to compare performance.

I saw it here first, so thanks to someone on MA for finding this.

## Re: how to test HP

> Jesse Wallinga wrote:

> -------------------------------------------------------

> When we are talking about measurements to maybe 8 horsepower ish, I

> think you will need good measurements to get within a tollerance of 1

> hp. It wouldn't suprise me that with some of these creative methodes,

> you get a deviation of 3+hp. That could be up to 35% deviation.

>

> At that point, whats even the use? If you want the bragging rights, pay

> for a dyno. If you want relevant numbers? Just use a speed over time

> graph measured with gps and see how well your moped accelerates. This

> will be a more representive way to put the performance on paper. And,

> depending on weather and road conditions, can be pretty accurate.

to me accuracy wouldnt be the goal, just repeatability. I wanna make changes and overlay the response

but yea, the reason i never bothered was I just used speed over time, but the app I used to use would export to excel and you could make meaningful overlays, but they never updated to the new OS, and now i've got nothin...

It was very good, I'd start and end this roughly half mile stretch down my street, flat, consistent, and i'd just line em all up at the 2mph mark so they lined up easy. It was super convenient. I even had plots with a table of changes, timing, jetting etc, and lil calculator to back out 0-20, 0-30, 20-40 or whatever, and top speed. you could plop it into minitab and look at correspondence between multiple changes. Like i'd just download it, run a macro, and plop it into a chart. i wish it still worked.

it even had a little accelerometer readout from the accelerometer in your phone, but that usually wound up pretty unreliable. (edited)

## Re: how to test HP

a fantastic way of finding your horsepower if you havent got a dyno, is to find someone who HAS got a dyno. 50v with av10 parmakit 82cc, low comp 135 psi , doppler streetcup pipe making it rev higher than the 176/126 low tune porting wants to. 12/54 gearing hits 62mph gps. 13 54 goes a bit faster as it pulls all the way on the level.

## Re: how to test HP

Has anyone finished one of the Dynos from 2stroke stuffing's channel? I have a PCB and I'm waiting on one more transistor to solder it all up, but I'm stuck on finding a bigass heavy rotor.

My next idea is to start calling electric motor rebuilders, I've already exhausted all the scrap metal yards in my area

## Re: how to test HP

I started with a 40hp electric motor and quickly found the stator/rotor wasn't going to have enough inertial mass. Added a steel sleeve to get the diameter and weight to get good dyno results. Rotor is about 13" diameter and weighs 320 lbs. My calculations say it's good for 20-25hp.

## Re: how to test HP

What kinda math did you do to get that approximate hp number?

## Re: how to test HP

Will you send me a prototype?

## Re: how to test HP

A prototype of what?

## Re: how to test HP

https://www.performancetrends.com/Calculators/Engine-Inertia-Dyno/Engine-Inertia-Dyno.php

The max speed I felt comfortable spinning the motor/dyno at was 3000rpm. You'll want around a 3-5 second minimum pull for good data. Input your flywheel size, assuming yours is a solid steel flywheel, and then keep turning up the hp untill you get to 3 seconds.

http://wotid.com/dyno/content/view/16/35/

This will show you how to calculate your Moment of Intertia(MOI) which is the most important number besides rpm of the flywheel for calculating hp and torque. every part of the dyno that spins will be calculated. Things like brake rotor and hubs, etc all add up.

## Re: how to test HP

Gotcha gotcha, thanks!

The last transistor I need comes today so I'm gonna get to soldering tonight, then as much Arduino/PC side setup as possible.

## Re: how to test HP

Here is a nice spreadsheet that simplifies everything, including the target MOI you'll need for the required hp and speed of the flywheel.

Trailer was already built, luckily the dimensions were good enough to hack in a 400lb lump. Tongue weight becomes an issue if you can't get it centered well enough. (edited)

## Re: how to test HP

> Joe Schuitema wrote:

> -------------------------------------------------------

> I started with a 40hp electric motor and quickly found the stator/rotor

> wasn't going to have enough inertial mass. Added a steel sleeve to get

> diameter and weighs 320 lbs. My calculations say it's good for 20-25hp.

> >

of this

## Re: how to test HP

Sold the rig to a guy in ohio that raced minibikes with his neighbors. Not much more to it besides a hall effect vane sensor for flywheel rpm, programed arduino and car size brake. I have more pictures of the build on my facebook if you're interested.

## Re: how to test HP

> -------------------------------------------------------

> > Joe Schuitema wrote:

>

> > -------------------------------------------------------

>

> > I started with a 40hp electric motor and quickly found the

> stator/rotor

>

> > wasn't going to have enough inertial mass. Added a steel sleeve to

> get

>

>

> > diameter and weighs 320 lbs. My calculations say it's good for

> 20-25hp.

>

> > >

>

> of this

Are you ok, dude? You have some of the most dissonant posts of anyone here. You post as if you've never interacted with humankind previous to signing up for Moped Army.

## Re: how to test HP

> Dirty30 Dillon wrote:

> -------------------------------------------------------

>

> > -------------------------------------------------------

>

> > > Joe Schuitema wrote:

>

> >

>

> > > -------------------------------------------------------

>

> >

>

> > > I started with a 40hp electric motor and quickly found the

>

> > stator/rotor

>

> >

>

> > > wasn't going to have enough inertial mass. Added a steel sleeve to

>

> > get

>

> >

>

> 13"

>

> >

>

> > > diameter and weighs 320 lbs. My calculations say it's good for

>

> > 20-25hp.

>

> >

>

> > > >

>

> >

>

> > of this

>

> Are you ok, dude? You have some of the most dissonant posts of anyone

> here. You post as if you've never interacted with humankind previous to

> signing up for Moped Army.

I really thought it was a troll account at first, but I think it's just a kid that lives in the middle of nowhere and doesn't really get how the world works. Like, you see someone built a one-off custom dyno that's attached to a trailer and ask them to send you a prototype of it? What? Even if they were producing them regularly, the cost to produce one is in the thousands, prototype or not, and who is going to ship a random person online a several hundred pound piece of equipment for free? (edited)

## Re: how to test HP

Ryan Sadler is a new AI being tested to see if it can blend into the moped community

## Re: how to test HP

Definite troll, like 500 posts with literally nothing constructive what so ever.

## Re: how to test HP

Oh, I actually like the AI theory.

## Re: how to test HP

> Dirty30 Dillon wrote:

> -------------------------------------------------------

> Oh, I actually like the AI theory.

It makes too much sense honestly

## Re: how to test HP

Our responses are training it. Nice.

## Re: how to test HP

Does that mean it's only a matter of time untill he has gathered all our knowledge?

## Re: how to test HP

Eventually it'll know what jet I need

^ 15.5-17.5

## Re: how to test HP

PS I am guessing.

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