ESE's works engine tuner

[TZ350]

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Maybe not as flash as some but two working examples of Kiwi home brew dynos and the ESE boys figuring out how to use a secondhand Dynojet. Nothing too expensive here, but they all do the job.

[Flettner]

Thats an ugly picture
At least its under cover now, hoping to modify it so it can be an inertia dyno as well as load dyno, depending on what you want at the time.

[Flettner]

Pissed around and made a press tool for making tight 90 degree water pipe bends from 1.6mm alloy sheet. Just tig along the edges. 19.6 mm outside dia, 20mm radius.

[SwePatrick]

If someone ever needs a guide how to easily install ignitech ignitionsystems:

[SwePatrick]

And a little progress video.
My Kartengine is coming along nicely.
It has dynoed so far, very rough tuned 42.3rwhp.(howgrinded meteringrod in my 42mm lectron)
And!
Keep in mind, i have just thrown together a pipe from 'feeling', no calculations at all, just for fun.
I´m about to build a pipe designed for this engine, coming up in the future.

https://youtube.com/shorts/OKxjDYwWk44?feature=share

[wobbly]

I am in the process of getting Wiseco to do a proper single ring race piston for the KR180 drag race engine.
It has a 59mm bore , and this is unusual except for several models of 125 engines that were converted with a big bore to become 150cc.
It looks as though the MOQ is going to be 12 units, most of which I dont want or need.
The only people I can think of who would want this piston ( apart from Thai drag racers ) are the several people here in NZ that converted their RS250
engines into RS300 racebikes by putting on NSR150 cylinders that had the same 59mm bore.
I cant remember who these guys were , one of them used to post on here, anyone know who - please PM me, or post it here.

[F5 Dave]

That'll be Sketchy and Richard of i-tools . Both those bikes are probably parked. Sketchy had been fooling fairly extensively with 1/2 an FZR250 and turbo. Had his partner in crime over for a beer Friday and was supposed to go see his turbo at kiatoki on Monday but the 300 Beta had to be ridden.

Amusing aside for electric start 2 strokes.
I washed it and changed dash button battery. Start it to check.
But it wouldn't catch. Making some weird noises. Then hissing after an attempt. WTF? What have I done?!?

Oh. Bung in muffler still from wash. Doh. The hisses explained. Pipe pressure. Not ideL for crank seals but started right up after my embarrassing discovery.

[ApolloMotoMoto]

So, now that I have become the math guru for more than one dyno operator, I need some help from higher level gurus than myself.


How to calculate the moment of inertia of a flywheel...


I have found a few formulas floating around for the mythical "drop test".

Lets see if I can describe what we did, and the math I have found for some "peer review"....


We have a flywheel pinned on a shaft.

The shaft is supported between two pillowblock bearings on a frame.

The shaft also has a sprocket pinned on it.

A complete loop of chain is placed around the sprocket.
(the same chain and sprocket that will be used to drive the flywheel when it comes time to connect an engine)

The chain "drapes" down below the sprocket about 2 feet.

All of this is supported on the frame high enough that the draping chain doesnt touch the ground.

A 3ld weight is hung from a link of "draping" section of chain (near the top).

This 3ld weight is support by a persons hand.

The stopwatch is started the moment the weight is released.

The stopwatch is stopped the moment the weight touches the ground.
(during the full drop, the chain is in a perfectly straight line)

The weight was 3lds (as already noted)
The height of the drop was 1.4375 feet
The time of the drop was 7.3 seconds
The radius of the sprocket was 0.375 feet


I stumbled onto this formula, but I do not know if it correct???

"The formula to calculate the moment of inertia (inertia) of a flywheel using a hanging weight is typically expressed as: I = (m * g * h) / (ω²); where "m" is the mass of the hanging weight, "g" is the acceleration due to gravity, "h" is the height from which the weight falls, and "ω" is the angular velocity of the flywheel."

A a few images are attached to provide some more detail.


My questions:

1. Is the above formula actually applicable to the test I have performaned, and is the formula an accepted method of calculating moment of inertia?

2. Does the drop test I performed provide sufficient data to perform a moment of inertia calculation?

3. We have currently convinced ourselves that using the sprocket and chain during the drop test will ALSO be measuring the resulting moment of inertia of those components as the sum of everything that is being "spun" by the dropping weight. Is this a reasonable assesment?

4. We have further convinced ourselves that this is a good idea, as the engine will be spinning the inertia of these componenets during a pull. Are we missing something?

[husaberg]

Use an acceleration time that is equivalent to what you are going to have when you ride it. Ideal case: the acceleration time in each gear is the same on the dyno and on the road. For that to be the case the roller has do be twice the weight of the bike including rider.

As long as you are unsure about jetting and ignition timing, fuel supply etc, use a shorter acceleration time as it is less likely to destroy an engine with lighter load. Once you are more comfortable with the setting you can switch to longer pulls, using a higher gear. Extra long / longer acceleration times would be the equivalent to driving uphill and vice versa.

You can do what 2 stroke stuffing did and use a ABB electric motor and let Abb do the calcs for you.

[wobbly]

I used this test as well as doing the manual math inertia calculations supplied by SportDevices.
But the drop test is much more accurate if you expand the drop height , and thus the time base.
I wound string several times around the inertia weight up to a pulley in the workshop roof ( 6M height ) with a 1KG weight.
Holding the dyno wheel by hand , as I let it go I hit the dyno run record button , and hit end when the weight hit the floor , this gave the wheel speed and time info needed.
Doing this several times and averaging the result gave accurate info that also includes the roll friction.
The answer gave almost perfect correlation to the manual calc's of the inertia wheel, starter flexplate and brake disc and axle that all form the total run up inertia.

[Noxin]

I just calculated all parts individual inertia and added them together.
Then I spun the flywheel and measured the negative friction and wind drag power when it slowed down.
Then I just add this power curve when testing a motorcycle or moped.

https://youtube.com/shorts/pbGIH3S1t14

[ApolloMotoMoto]

I used this test as well as doing the manual math inertia calculations supplied by SportDevices.
But the drop test is much more accurate if you expand the drop height , and thus the time base.
I wound string several times around the inertia weight up to a pulley in the workshop roof ( 6M height ) with a 1KG weight.
Holding the dyno wheel by hand , as I let it go I hit the dyno run record button , and hit end when the weight hit the floor , this gave the wheel speed and time info needed.
Doing this several times and averaging the result gave accurate info that also includes the roll friction.
The answer gave almost perfect correlation to the manual calc's of the inertia wheel, starter flexplate and brake disc and axle that all form the total run up inertia.

Okay, we did the "manual calc" for all the sub assemblies of the flywheel (hub - spokes - rim) and got 266 pounds per quare foot.

This was done for JUST the flywheel so far, not the sprocket and the chain which are also attached in the drop test.

The math from the drop test produces a resulting 280 pounds per square foot, or 5% higher than the flywheel all by itself.

That seems to be a fairly good correlation; the extra 5% should be the measured friction loss of the pillow block bearings plus the additional inertia of the chain and sprocket.

[ApolloMotoMoto]

Alright, next question...


The measured torque to HP math;

I ran into something I thought I understood, but now I am not so confident about my understanding;

Torque = Total Dyno Inertia multiplied by the measured Angular Acceleration (α) of the flywheel for the given set of data-points.

T = Iα

Now that you have the Torque value for a given set of data-points;

Horsepower = Torque multiplied by (Revolutions Per Minute divided by 5252)

HP = T * (RPM / 5252)


Okay, here is my question;

For the above HP equation, when using an inertia dyno;

RPM of the ENGINE...???

or

RPM of the FLYWHEEL...???


I am having an internal argument in my head and I cant come to a resolution about which one it has to be >.<

Can someone with more empirical knowledge of the math behind an inertia dyno measurement point me on the right track please?

[Vannik]

Alright, next question...

Can someone with more empirical knowledge of the math behind an inertia dyno measurement point me on the right track please?

On the same component where you calculated the torque.

[ApolloMotoMoto]

On the same component where you calculated the torque.

Thank you Neels!