Making a REAL RC Engine Dyno! - New NR200 Engine Test

[@johnnyq90]

Hi guys! Thank you for your comments and all of your suggestions! If you are interested in buying this engine, you can get it here! bit.ly/3ylXSGU You can use the code 'jq90' for 10% discount.

[@TimeFadesMemoryLasts]

Your curve fittings don't fit the measurements. You need at least a 3rd order poly to fit the measurement with its onset and steeper rise. The power numbers will be higher (and more precise) as a result I guess. But a 3rd order poly is "just barely enough". The best fit will most likely be given by a special exponential function but I don't know how advanced the curve fitting tool in the dyno software is. Hit me up if you want me to make a very precise power curve using a zero-phase lowpass filter on the RPM data instead of fitted curves. Therefore you'd know if it's the fit or something else that's keeping the power numbers down. (Friction and deformation in the gears might be another big factor that's adding to this) I'd LOVE to produce a nice power plot for you in Matlab, but in case you want to do this yourself, you can get the power of your dyno by this formula: T = 1/2 * m * r² * dw/dt P = T * w T: torque, P: power, m: mass of flywheel, r: radius of flywheel, w: angular velocity, dw/dw: angular acceleration You need at least a first order lowpass to smooth w (angular velocity) because the derivative of w amplifies high frequency noise linearly. Without filtering, the T and P (torque and power) curve would get noisy and the max. power reading would get unreliable. If you have RPM data from the wheel freewheeling I can also calculate the power loss from friction and air resistance of the wheel so that you can incorporate that into your model to compensate measurement errors. But I suspect the gears have a bigger impact.

[@fat_cat8457]

@@TimeFadesMemoryLasts Dang, I can’t read half the words your saying

[@kevinmasters7189]

Almost like the decimal needs to be moved 1 spot to the left

[@nimabaradari]

You have to calibrate the app before your runs This numbers are absolutely wrong For calibration just click on the Dyno button on screen After that you can fully calibrate your dyno

[@TimeFadesMemoryLasts]

@@fat_cat8457 Haha, don't worry. TLDR: I can make a very detailed, exact and professional torque and power curve from these dyno runs.

[@theafro]

Flywheel weight is everything when it comes to Inertia dynos, you want the engine to take a little longer to get up to speed, the heavier the flywheel, the more accurate the calculations will be., it will give much more consistent results as any errors in the reading will average out a bit more too because of the longer sample time. a better pick-up would cut down on that noise too, but those earbuds will probably work ok as long as it's a fairly clean signal. Did you terminate the unused side of the ear-bud with a resistor or just leave the other bud connected? Those 3d printed flywheel supports gave me the heebyjeebies though, I certainly wouldn't trust them at 10kRPM! Great job as always! thanks!

[@alexchartier3878]

Dyno with 1 to 1 ratio, or as close as you can get to it.

[@manfredbecker9701]

Yeah, and/or heavier, the engine seems like it barely has to work to get that flywheel spinning, that's why it only produced that little horse

[@jamesamalfi9303]

Yes the longer it takes.to sweep from idle to.max rpm the more accurate it will be you want to load the engine down as much as possible. Also I think you can get very small eddy current brakes they would be far more accurate

[@drewcolinnelsen]

I was also going to say this I don’t know if you are taking into account the reduction from the flywheel to the dyno wheel if you multiply the hp numbers by the same as your reduction does that make the hp numbers seem more accurate?

[@Luca_Techy]

Did you consider the 2:1 gear ratio in the software? It's best to have a 1:1 in these types of dynos (open loop) - usually the larger the mass the better - or you should switch to a closed loop/brake hp dyno design with feedback (eddie currents) and field drivers (but maybe overkill for such low power).

[@Loustylz203]

You need to hold the engine back…. Doesnt seem like the engine is working at all but still cool

[@Calthecool]

Definitely get a bigger flywheel, it’s probably revving up so quick that it’s throwing off the numbers.

[@JohnDoe-fk6id]

Yup. It should take a few seconds, at least, to get through the pull.

[@Poizdrc]

Smaller flywheel. 12k rpm during dynk pull is only half of that motors rpm range.

[@kasuraga]

@@Poizdrc Smaller for sure. The engine is trying to rotate too much mass. Gotta make sure you can use the full rpm range.

[@Nordlicht05]

@@Poizdrc but this was the roller rpm? It's seems he used a low gear so it wasn't the engine rpm. In a car you often choose a gear which is near 1:1 with tire rpm. But don't ask me why 🤣

[@johngreen1060]

Bigger wheel or remove the gearbox. Likely the engine's own ramp up time is affecting the numbers. Also rpms look unstable.

[@boyorougesauvage8584]

you're an absolute legend for providing us enthusiasts with this overly specific content

[@pistonhead2k]

You need 1/1 ratio with a direct drive or using a real clutch (because a centrifugal clutch spins). And a brake dino setup

[@Gin_Kush]

👍

[@Maxzillian]

Yup especially with a slower four stroke, clutch slip would be my primary concern.

[@DarkIzo]

brake dinosaur

[@poohssmartbrother1146]

I agree with everyone suggesting heavier flywheel, and 1:1 ratio gears. Given your concern for possible failure and injuries, Perhaps you could build a shield for the whole rig. Set it up so you and the laptop can be 3 feet (about a meter) away from the rig, with a remote fuel cut off switch. You might want to put dampers between the flywheel and the engine in some way. The vibration at idle was enough to rotate the flywheel. A heavier flywheel might fix the problem too. Now if you wanna consider a different dyno method, you could go electric motor based. A brushless battery drill motor would be more than beef enough to handle your engines. 750watts is equal to 1hp. Watts is Volts times Amps. So if the electric motor puts out 24vdc @ 19000 RPM, then all you need to do is measure current. Ideally you would have a variable load on the electric side. This will also allow you to measure Torque.

[@cooperised]

Everything about your idea is good I reckon, except measuring current to figure out torque. There'll be unknown losses in there for sure. It's much more accurate to mount the motor on some kind of hinged rig that lets you measure directly the torque on the motor can. Jeremy Fielding did it with a cheap kitchen scale, but you could use a load cell for the professional look!

[@AntonBabiy]

Motors aren't 100% efficient. Also their efficiency varies with rpm *and* load making them virtually impossible to be used as the dyno without complex measurement post processing

[@cooperised]

@@AntonBabiy isn't that what I said? 😆 Anyway yes you're right. You can use a motor as a load for sure, but you need to measure torque directly rather than inferring it through current.

[@oscarzt1652]

motors vary in efficiency at both speed and torque so it will never be a 100% accurate calculation im afraid

[@cooperised]

@@oscarzt1652 If you're measuring torque separately then motor efficiency doesn't come into it. You're just using the motor as a variable brake, and not relying on its linearity or efficiency or anything else. Power = torque x rotational velocity so if you can measure both torque and speed accurately (and neither is hard to measure) then you're sorted.

[@Calthecool]

The way you used the magnet and the earbud to generate a signal was amazing.

[@AiOinc1]

It's part of the instructions for Simple Dyno

[@AjieDev]

2 comment and Lot of like

[@dtsnjsn6101]

yeah it’s common, it is cool to see though

[@Lickemstick]

I thought the same thing. I was like, "Huh? No way! I never would've thought of that." Good stuff always from JQ90!

[@corym8865]

It's a simple magnetic pick up, most if not all modern engines use them for crank and cam position sensors. On those the magnet is stationary and a toothed wheel is what spins to induse an a/c signal and considering he used headphones he may want to invest in in an A/C to D/C converter considering computers only understand D/C digital signals and not A/C which is what he was producing. Also as a note add more magnets for a better much cleaner A/C signal and it will happen more often giving better data.

[@RCTanksTrucks247]

Awesome engine. Cannot wait to get one and install it into a car.

[@jaggns5774]

you should probably install one at each wheel.. or maybe two.

[@jbirdmax]

Make a tank with one engine and reverse transmission for each track. ❤️

[@nauuwgtx]

Or a enlarged powerwheels

[@RolfRBakke]

Need a roller with higher inertia, RPM rises too quickly to be useful.

[@phoenixeragon6404]

With it being a centrifugal clutch, would there be some losses due it it by nature slipping?

[@Awkward_Fox]

There would be. Ideally it would be a direct drive with the flywheel able to freewheel after the pull. Maybe an automotive style clutch could help? Also, air/fuel ratio could be throwing off the numbers, plus the engine hasn't been broken in. So, a list of things to do would be: -Lap the valves -Tune carb -automotive style clutch rather than centrifugal -play with fuel mixtures

[@Frietpan]

not really, how harder you spin it the better it grips, it slips on lower revs yeah but it will catch up and you would hear that in the engine if it hold mid rpm for some time before reaching max rpm. (my old moped had a 2 speed automatic with centrifugal clutches that even sat in a compartment filled with oil , and like i said they would let you know if they are slipping based on rpm behaviour. and you could see if the actual clutches are glazed by slipping and burning it) his graph shows a smooth line in the dyno, if it slipped it would have shown a flat bit in the graph

[@ThePower1037]

@@Awkward_Fox Imo, these isn't a need for a clutch, having a direct drive engine to flywheel is my idea of a solution.

[@SlowSTEN]

@@Awkward_Fox tuning the carb adjusts fuel mixtures...also valve lapping isn't nessesary if the valve seat and valve face are properly machined

[@Awkward_Fox]

@@SlowSTEN I mean to say fuel mixture. Like nitro and whatever other fuel/oil is used

[@carsonw722]

For suggestions, I think alot of people (including myself) would like to see a bigger flywheel. I think that could definitely be throwing off the numbers. Also 1:1, or a realistic dyno reduction ratio. One last thing, a realistic clutch system would be amazing to see (like clutches that are seen in real cars). Maybe a future project for the channel.

[@aserta]

Old Xerox machines (the behemoths) had realistic solenoid clutches. I used to have one inside an RC car.

[@carsonw722]

@@aserta Oh cool, thanks for that. I have a custom nitro rc trophy truck in the works also. I'll have to check that out.

[@ravencornell7687]

A hall-effect sensor will work with a magnet like you have, and is very accurate. Horsepower numbers rise as rpm rises, more rpm = more HP. Recommend running with a 1/1 ratio, it’ll give you more accurate #’s.

[@chemieju6305]

I might be wrong, but I dont think hall effect would give any significant improvement here. He is just measuring pulses, he doesnt need an analog reading on the magnetic strength.

[@janmrog]

@@chemieju6305 hall effect sensor can give a digital signal so its easier to understrand and process to the computer

[@MrCarnutbill67]

Dynos only measure torque. The software does a simple math equation to figure horsepower based off the torque numbers vs rpm.

[@AntonBabiy]

Yes, the earbud has a certain cutoff frequency possibly making the signal lower amplitude at higher rpms. To really see if this is an issue he'd need to first see the signal on a scope but then keep in mind the audio input also has a finite bandwidth

[@TheObsesedAnimeFreaks]

i thought is was pretty dumb to use an earbud tobegin with. I 100% agree he should switch to a hall effect sensor. they can be configured to put out pulses when the magnet is on top of it or configured to output a digital readout.

[@rickybobby7660]

Reckon you’re out by a factor of 10 (or 20 because you’re running at at half speed) and there basically no load on it, try adding tungsten to the flywheel or remake it in steel and get the mass up to the 5-10kg range, not sure your plastic mounts would hold up 10kg at 10,000rpm through. Typical inertia dyno drums for 100bhp are 100-200kg depending on dimensions

[@foureye7058]

Very curious about what valve lapping would do for this engine, having seen the video with the other model previously. Just a thought.

[@SlowSTEN]

Valve lapping isn't nessesary if the valve seats and valve faces are machined properly.

[@defaultdriftco00]

@@SlowSTEN he lapped the valves in the four cylinder and it gained quite a bit higher revs and sounded much crisper in the throttle

[@IncertusetNescio]

@@defaultdriftco00 Yeah I remember that one. Clearly they weren't manufactured to particularly good tolerances for THAT much improvement. Worth a shot here.

[@fromthebackofmymind]

Please show us the valves and cams. I think this is a water cooled 2 stroke.

[@maxpower700]

@@fromthebackofmymind its a dohc 4stroke. Much like the inline 4 he has 😅

[@mechcntr7185]

You made a dyno! Good job. For more accurate readings, get rid of the reduction gearbox and just make sure the setup can handle 20,000 rpm.

[@fromthebackofmymind]

Decimal place value? 3rd grade. Out sick that day?

[@riccardobartolucci7786]

That's a great work! Well done. For the revs, definitely what we hear isn't 9000 RPM but a lot more. That is because you got a gear in between the crankshaft and the flywheel shaft. Now, you should count the teeth of the big gear and divide the number by the teeth of the small gear. Then multiply the RPM by the gear ratio you calculated. Next, what do you use to calculate torque? I didn't see any sensor there. You could calculate the torque as I x d( omega)/dt where I is the flywheel inertia and omega the angular speed in rads per seconds. d/dt is modifying that angular velocity in angular acceleration. But I wouldn't recommend that. What gets done in 'real' Dynamometer test benches is: 1) you don't have a flywheel 2) that's replaced by an alternator 3) measure the output current of the alternator to estimate the torque Or even better You put a loadcell to stop the alternator spinning, apply voltage to slow down the rotation and simulate the load and measure the force on the loadcell. Then T = Fb Torque is force by the distance between the loadcell and the centre of the alternator. I hope I helped a bit 😁

[@davelowets]

Real dynos use a water brake and strain guages to measure torque, and then calculate horsepower from the measurement of that, and the length of time of the sweep.

[@joshlewis5065]

You probably need to extend the time it takes to achieve max rpm so you can get better data. I would use a steel weighted wheel or try to do an electric resistance testor

[@chris-graham]

Remove the gear reduction. All it's doing is lowering your inertia. Also make sure the inertia parameter is correct in your configuration

[@willmcgo8288]

Inertia will change with the square of the gear ratio. If you have 1:2 ratio and go to 1:1, the effective inertia will change by a factor of 4. Use a shield to catch anything that let's go. I can testify that it's no fun having a disc spinning 9,000 rpm zipping around your work area. I was testing if we could go to 10,000 rpm when a heavy coupling bent a 1.25" diameter dyno shaft 45 degrees, then come flying off. Once that starts, it happens fast.

[@davelowets]

A gear reduction is perfectly acceptable, as long as the math is done at the end to account for it. MANY full size automotive chassis dynos use gear reductions in them.

[@Evolyutsiya]

Mesure exhaust temp so that you can try to lean out your mix without damaging the engine.

[@Evolyutsiya]

@kayo... 🌹 worst freaking attempt at marketing ever

[@davelowets]

And compare it to what? Nobody knows the "safe" EGT for one of these engines. Reading a spark plug would be a much safer way to judge the state of the tune.

[@SirTodd]

Yes, as you said in your video, you need a heavier roller and better pickup. I'm not familiar with that software, but if possible use a Hall Effect sensor. Also, you could apply a brake to the flywheel to apply max load. The goal is to measure the torque required to spin as much weight as possible under as much stress possible to the point of stalling (nearly) the engine.

[@bisurdaddy]

I'm pretty sure the magnet and earbud was supposed to be a hall effect sensor.

[@SirTodd]

@@bisurdaddy effectively, yes. However, using a discrete hall effect would work much, much better. Signal would be far superior.

[@dennisdempseyradiooutofcontrol]

It would be cool to lock the clutch To see if any improvement is there. Nice work brother!!

[@davelowets]

I agree. I wouldn't use a clutch at all. A slipping clutch WILL skew the calculation in the end.

[@wnodzykowski]

More magnets for better rpm resolution. Right now you pick up one signal every two rotation of the engine.

[@Skulljeep00]

Either double up the magnets or do a direct drive. The reduction gearing is causing a mis-read and the numbers to be low. And either add mass to the flywheel or ease into the throttle more slowly. Going ham on it is causing a short recording time for the data log.

[@traxxasslash95]

1:1 like others are mentioning actually doesn't matter, that number is an artifact of dynoing cars on a chassis dyno and attempting to replicate similar speeds and ramp rates. The key with dyno testing, replicability, and comparability, is the actual acceleration/ramp rate. The same as an inertial dyno works back the power required to accelerate the mass of the rotor, there is power loss associated with accelerating the rotating assembly of your engine and all the other rotating masses. The faster the ramp rate of the dyno, the more power is lost to just spinning up the rotating mass of all the engine, clutch, and gears. This is why on load-based dynos, an engine will transmit more power steady-state than from an RPM sweep. On an inertial dyno the only way to slow down the ramp rate is to increase the mass load. You should also attempt to calculate the inertial load from every component of the drive transfer system into the power calculation since small amounts of mass matter on this scale. Edit: Also the way that power is measured on an inertial dyno is based on the acceleration, mass, and moment of inertia. You may need to double check the math this program is using and spread the acceleration time out by increasing the mass or removing the gear reduction as too fast of an acceleration may not provide enough data points for the system or too small of a window for it to accurately calculate.

[@TestECull]

The key to dyno testing is putting an actual meaningful load on the engine under test. This does not accomplish that.

[@jeremyboyce7921]

That’s pretty cool, your machining projects are always great to watch. Regarding the low numbers, maybe the flywheel mass is too small? Certainly seems like that engine should make more power than 0.079 kw. Best luck figuring it out!

[@marendranodi9046]

FINALLY!! Something to power my pencil sharpener

[@dtvtechrp]

Seriously you're a mad scientist. That's a complicated thing you've built. Nice job 😎

[@iangardiner8535]

I used to use this type of dyno on electric motors for model cars. They rely solely on the acceleration of the flywheel and are not best suited to an IC engine. How quickly you open the throttle and any hesitation in pick up will dramatically affect the results. A friction load dyno would give better results where the throttle could be held at a fixed point and the load varied to achieve a desired RPM. Best of luck in building one of those, far more complex. Great channel, love watching the engineering work. Sorry for the late input, only just came across it.

[@davelowets]

Yep. A dyno that can vary the load to the engine and control the engines RPMs at WOT would be the best solution, but an inertia dyno can yield results that are close. The issue with an inertia dyno is getting the weight (flywheel) to be enough so the power output of the engine takes a reasonable amount of time to spin it up to the engines maximum RPMs. A rising RPM curve that happens too quickly doesn't give enough data points or "resolution" for an accurate calculation. If the engine takes longer to spin the weight up to max speed, there are many more data points available and the end result calculation will be much more accurate

[@azypk]

Never understood how a dyno work and you managed to create one... Well done

[@Farmtractor]

Great to see the new nr200! Thanks for the video!

[@bryanpratt3933]

Excellent build! One issue I saw is that your sound card sample rate for the headphone pickup was set to 11,025hz. At that samplerate you are going to have odd results above ~5500 RPM. Setting it to 44,100 or 48,000 should make things more consistent. It should be at least double whatever the maximum RPM is going to be (look up "Nyquist frequency").

[@771racing]

More flywheel weight as others have suggested so your ramp up time is longer. I'd also consider adjusting the clutch to engage as close to just off idle as possible so the motor isn't cheating and doing it's own inertia dump at the start. For the run bring the revs up enough that the clutch is engaged but not increasing revs, wait a moment, THEN do the pull. It'll be tricky because of the one way bearings to get consistent results so you may want to see if you can trim the data to eliminate the initial spike at the start from the calculation?

[@kennethporst1738]

FINALLY thank you...I need to test/tune my engines

[@E-FC3S]

Hey man, love the vids. Serious legend for this little specific stuff. Anything in the transmission line to the measurement side (flywheel) will have an effect on your numbers. Like another said, as scary as it may be you probably need a one to one drive and ditch the clutch. I feel the one way bearings might give you issues too. Maybe find a way to stick together a simple slipper clutch to connect and disconnect everything. Also, not to freak you out, but that shield would do nothing if that flywheel actually popped. Don’t get friendly around it!

[@aSpyIntheHaus]

Great idea putting the arch over the flywheel. If you can spend the time to build a little water dyno that might give you more tangible and easier to interpret results.

[@davelowets]

I have that exact same radio.... You can convert it to the 6-channel version by simply wiring in the extra 2 switches (the spots for them are already on the circuit board), install the switches (the holes for them are right under the stickers above the steering wheel), and then download and flash the 6 channel firmware from the manufacturers website into your radio. You'll get several other features in the 6-channel firmware also... It's as simple as that. The extra channels support a 3-way toggle switch on the circuit board, (center is 0 in the middle of the servo throw, left is -100, and right is +100).

[@jclowe735]

I love how Johnny makes all of the parts needed for what he's doing and I enjoy watching his videos. It's sad that coronavirus sent everyone back a few centuries which impacted what Johnny can do.

[@bard246]

Please test your previous engine builds on it, would love to see a power/torque comparison between them

[@fabricationnation8052]

Stoked to see where this leads.....No matter what you are learning from it, and it WILL be better next time.....cantnwait to see some comparisons between 2 and 4 cylinders engines and many other....Much respect!!

[@geddyt]

I'm not too sure your numbers are all that far off. You're seeing just over .7 hp out of an 8.6cc twin. That's over 80 hp/L. And this is a tiny, relatively crude engine design fueled by a simple carburetor, so it's not like we're talking F1 levels of friction mitigation, tight tolerances, etc. In a larger engine, anything over 100 hp/L is great, especially in a twin cylinder. Also, a tiny engine like that is going to make power by revving. Max power will occur very close to max rpm and will fall off precipitously from there. I noticed that your max unloaded rotational speed was over 19,000 rpm but your highest rpm dyno run topped out at just over 17,000 rpm. That would suggest one of three things: 1.) Your clutch is slipping at high rpm. 2.) Your earbud speed sensor is dropping ~10% of pulses. 3.) The motor lacks the power to rev out to its limit with a mass that large being spun (plus friction in the bearings). Since the rpm vs. time curve climbs steeply and then almost instantly flatlines, I'm guessing it's not the third possibility, and the first two are far more likely. For what it's worth, the manufacturer claims that the motor is capable of 22,000 rpm after carburetor adjustment, and they list the power of the engine at "more than 1 ps," which translates to just under 1 hp. I'm guessing that measurement is both exaggerated and measured a lot closer to that theoretical 22,000 rpm limit (which might also be exaggerated), so you're not that far off! The store you link to that's selling the engine is happy enough with your dyno measurement that they've embedded this very video right there on the product page, so you must be doing something right!

[@fellenXD]

Agreed. RC engine manufacturers seem to be very fond of just pulling some large number out of their ass. Even 0.7 hp from this engine seems like a bit too much. For comparison my car has a 1.5 liter engine and makes 90 hp, it may be from 1995, but power figures hasn't gotten much better since (not counting crazy VTEC engines and similar). With the same power ratio, my car would be putting out 120 hp, which would be very good for an engine that size. These miniature engines are not the most efficient engines out there either.

[@NOTTApro142]

Dang, that engine seems like it would be good for a rc mini outboard motor for boats, it’s gnarly

[@alexx7910]

1:15 That touch felt like the cooking guy that adds salt with his elbow

[@Punnikin1969]

If you can get a pickup from an old electric guitar you might get a much more accurate reading. Since ear buds are designed to output vibrations it might not have the sensitivity you need for an accurate input. Another issue, though seemingly slight, would be the piece of tape you used to balance the flywheel. That could cause a fair amount of drag at high RPMs. A heavier flywheel would help compensate for it, but that drag can ramp up quickly.

[@davelowets]

I wouldn't fuck about with a guitar pick up. Those are frequency limited, just like an ear bud is. A hall effect sensor would be a cheaper, proper, piece to use

[@cavemaneca]

I think it'd be interesting to see a setup for actively balancing the flywheel. Personally I only understand how they work in concept and it'd be pretty amazing if you could make a small one reasonably cheap.

[@Wulthrin]

they use a laser to measure the vibration

[@cavemaneca]

@@Wulthrin that's a lot simpler than I was thinking.

[@davelowets]

Balancing the flywheel would be a simple process compared to the rest

[@flyhigh6591]

Man this is just the coolest thing I've ever seen..

[@transamburnoutdarren1115]

I agree with everyone else's comments that the roller needs to be heavier, its just spinning up too quickly, and the gear reduction is amplifying that issue. Likewise, as someone else mentioned the 3d printed roller supports are a bit scary! I'd also suggest getting rid of the centrifugal clutch somehow to directly connect the engine and flywheel. Perhaps you can make a more traditional clutch or maybe it would even work without a clutch at all? As others have also said, maybe a more accurate sensor would also help?

[@Riddick_4506]

Probably because of the gear reduction you used to slow the fly wheel down.

[@jesse096]

On a normal car dyno, you usually run it in 1:1 gear ratio, with you doing 2:1, your power figure is effectively halved. Run it in 1:1 and you should see the true power figure. Also, if you can put a dynamic load (IE a eddy brake) on the flywheel, it can give you more accurate results, because it will simulate the load it would see pushing a car around.

[@TestECull]

This dyno really doesn't do anything useful. Why the numbers are so meaningless and pathetic. I'd expect somewhere around 1.1-1.3 horsepower from this engine and if he was putting a proper load on it like you're suggesting....I would just direct drive an airplane prop with no clutch at all, take a few simple measurements, and math it out if it was up to me...we'd see something reasonable.

[@davelowets]

@@TestECull How would an airplane prop do anything for that? The varying atmospheric conditions of each day would throw that right out the window. You could use the same prop to somewhat "compare" different engines, but for trying to get an accurate horsepower/torque result out of an engine? That wouldn't work well.

[@blackjackjwh]

holy smoked the finish on the 3d printed parts is crazy, I might have to pick up that printer now

[@rayshutsa6690]

It is nice to see Johnny. He alwaus makes his own parts. 🇨🇦

[@MidwesternRailfan]

Almost 0.1hp! Thats crazy for the size of that thing. 10 of those engines hooked up to one drivetrain could make 1 hp. Imagine if you could make one of those multi-engine pull tractors with those. That would be cool.

[@CharlieSolis]

Heck yeah! Nice work on the test dyno!

[@gfellerman]

This engine must definitely give more HP. The Dyno software calculates the mass you're spinning and the speed it needs to reach max RPM to give you the power in torque and HP. I would look in the settings of the software. The reduction of 2:1 should double the real number close to reality (but not exactly but close enough) and the clutch at that speed shouldn't slip which should not give you a difference. Or ridiculous. Check the input in the software. Movement mass... And one more time awesome built and crazy details. I love the way you make things. Keep on entertaining us the way you do !!!

[@hateforall4012]

I never get tired of watching your projects!!

[@menom7]

Wow,Awesome video JohnnyQ90!!! Have been waiting for You to finish your RC-car with that engine in it!!! But I saw how easy it was to get sidetracked with this new engine!!! Thanks for sharing!!! :-)

[@timjs1018]

Damn it Johnny take the spring off the clutch.

[@BaldSasquatch]

great videos! Really enjoy your work. Watching you install the bearing had me thinking you should look into a small arbor press. Even a jewelers press would be a great addition to your shop. You get a lot more feedback to your hands when you install bearings with a arbor press, and they are way easier to use than a vise to press in small bearings and shafts, and you end up finding all sorts of other uses for them. I use mine to hold glued parts together occasionally.

[@TheSkogemann]

Awesome build! I remember I suggested this a while back. Very impressed!

[@moosemanmagee4495]

My suggestion is I'll keep watching it because it's really really good! Ty.

[@MrNotStock]

Heavier roller 🤙 seems like the tune is a little inconsistent to. Different fuel or Lap the valves maybe?

[@realbogus]

I agree with the 1:1 ratio. It's the standard for chassis dyno testing.

[@davelowets]

A chassis dyno ISN'T a true 1:1 ratio though..... Varying tire sizes blow that "1:1" theory out of the water, and there is a different ratio for every car with a different tire size that goes on it. Yep, the tire size has to be entered into the dyno, but it's no different than having a gear reduction in the mix somewhere, and the dyno computer MUST use the ratio of tire size to the roller size in it's equation.

[@realbogus]

@@davelowets - agreed. this is why chassis dyno's are not the best way of doing business. IIRC, a full sized automotive chassis dyno needs 1:1 in the gearbox, so the tire height can be included into the computer to work that out... in this scale, that is not doable, so the next best solution is to save a set of tires that are the exact same size so as to make equal comparisons. Fair enough?

[@davelowets]

@@realbogus People run what ever tires are on their car. I've never heard of anyone running "dyno tires" before. For a small inertia dyno like the one here, I would run it 1:1.

[@realbogus]

@@davelowets in the scale model world, tire size is stupid important. In the real world, a tire might lose a .25", over a 26" tall tire, who cares?

[@davelowets]

@@realbogus A 29" tall slick may grow by at least 2" at top speed. It's a big deal. Obviously you've never drag raced with slicks before.

[@AsbestosMuffins]

Good thinking with the "Just in case this thing lets loose I'll put a huge hunk of plastic over it" I used to run a high RPM piece of test equipment and it blew up more than a couple of times

[@K_M_M_G]

Suggestions from someone who owns a chassis dyno: The RPM pick up seems to be a problem and if you’re looking to generate numbers like engine horsepower or engine torque we need to use an engine RPM pick up but at the same time you can just double the wheel speed as it’s a 2 to 1 ratio in this case. I strongly suggest a much heavier mass as it jumps from idle speed to max RPM within a second or less. Typically dynos have a calculating frequency (I.e. 5hz...) and the acceleration of the engine might be blowing past what the program is capable of. My first chassis dyno had an optical pick up once per revolution. My new chassis dyno has a magnetic pick up but picks up for signals per rotation. Personally I would start with a different RPM pick up and I would consider a much heavier mass.

[@K_M_M_G]

Just remember, the larger the diameter the greater the mass especially if the weight is at its furthest diameter. If the weight is close to the centroid of the fly wheel it doesn’t help much.

[@harshitbhangre2127]

Finally u've remembered that u hv a yt channel 😅

[@ΔημήτρηςΚαραχάλιος-ι9ο]

my sugestion is bigger and balanced flywheel as you said a 1-1 ratio would be the ideal and also get a hall efect sensor from a car and use it in conjuction with a properly programed arduino board to get the signal!! thanks for the great content man!!!

[@NajtuWorld]

You are one of the best RC ppl I ever seen, thanks for your uploads. :)

[@downunderdan5132]

I think check the signal quality (waveform) from the rpm pickup and see if you are getting any noise. Also check for loss/deterioration of signal throughout the rpm range. Not sure what you get with earbuds but I know signal cables are shielded and typically earthed at one end. Also, how is the laptop hardware and software processing the signal? Any weaknesses? Variations might be caused by inconsistency in fueling? I noticed max rpm varied? Getting the dyno flywheel dynamically balanced might also help. I think you are onto a good thing. I think you’ll get to the bottom of the reading variation, just persevering and refining. Keep up the innovation and outstanding (fantastic!) quality of work! 😀😎👍

[@davelowets]

Yep. I think a hall effect sensor with it's built-in output buffer would yield a much cleaner signal, and make it easier for the P.C. hardware to read it.

[@elismith4961]

I’ve considered this software for small air engines and read that the flywheel should be heavy enough to make the run last 10 seconds or more. It seems like your entire run lasted

[@K_Nasty]

And he does it again. Mind blown.

[@LVDLamVanDuc]

Một chiếc động cơ thu nhỏ thật tinh tế.bạn thật giỏi

[@EBMods]

JohnnyQ90 Great Video! I built my own Inertia Nitro Engine Dyno with a steel Flywheel.

[@brycebjerke3408]

I wish you did more uploads. I thoroughly enjoy your videos.

[@jdmjesus6103]

Change for a steel flywheel? AFAIK, an inertia dyno only really takes a reading as it is accelerating, you can't get a steady state reading from them, once it gets to max rpm, the run is over. Also maybe add more magnets so you can get multiple readings per revolution? The more the better I would have thought.

[@suzesiviter6083]

You could increase power further by adding a soppy flange and knocker knob valve.

[@davelowets]

Yea, great idea! 👌 😕😕😕

[@paulterhaar4862]

You could ask Brent from PFI Speed, he is the best dyno dude on KZbin!

[@Ender_Wiggin]

lol he dynos real motors

[@unknownuser200985]

this guy has the biggest thumbs ive ever seen!

[@jotham123]

is the one way bearing slipping? Bigger flywheel. Maybe make a pronny brake dyno instead? You're also measuring the engine's inertia, which will be slowing it down, the gearing ratio is exacerbating it. Double check inertia numbers. Got correct fuel? Check engine timing is spot on - can be critical, including spark plug gap or just have a play with that.

[@nandor3596]

Great way to test different fuels

[@danjordan1979]

Awesome video! Asmr, quietness. Beautiful! 👍

[@micahrlusk]

as many are saying the ratio plays into it, as well as the flywheel weight or size so you get an actual curve and more load on the engine. another way you can do that is by adding a brake or something to add resistance/load. that would help a lot

[@HomelabExtreme]

I have a couple of sources of errors and a (possibly) better idea: 1: The centrifugal clutch never locks up, so you will have slip and lost power 2: The gearing also causes friction losses, both in the teeth, but also bearings because of the radial load. 3: At these speeds, friction against the air become quite significant, but this is hard to avoid without using a vacuum or a gearbox. I would think measuring brake HP is the better option for small engines, as it is easier to get accurate measurements. A load cell attached to a neodymium magnet, on a slide towards an aluminum flywheel could be a viable solution. The eddy currents induced by the magnet, will brake the flywheel, causing a pull on the magnet which can be measured using a load cell. Varying the distance from the magnet to the flywheel, will vary the drag, so running the engine at max RPM, and slowly moving the magnet towards the flywheel will slow down the engine, as such you can get a nice detailed plot of the rpm and torque at given rpm.

[@Beng177]

try making a load cell dyno instead of an inertia dyno. allows for long runs at a certain rpm can be made wither with a brake system or something like a water pump using a valve as restriction then mount the pump / brake in such a way where you can measure the torque on the brake/pump as well as RPM regulate the valve / brake to control RPM under load

[@TheESS1]

Have some of you guys a link to an example of this? want to look at an example, if it exist, before trying myself... 🙂

[@Beng177]

@@TheESS1 there should be plenty of examples around on the internet for such a dyno setup, just search brake dyno or water pump dyno

[@ΝίκοςΑυγέρης-ο9η]

Imho, apart from the bigger flywheel and better signal mechanism, try using a gear ratio as close as possible to 1:1, maybe even a clutch that is not centrifugal, as they seem to lose a bit hp (i know it's not that much, but in this scale, it may be enough). Also, great job on the channel, love your videos.

[@tnoutlaw73]

Im sending this video to someone who knows exactly what your issue is. However its his decision if he helps. He is a master at this stuff. he knows the science behind how all this shit works. Can anyone guess how the air fuel mixture gets in your cylinders???

[@smoothrider900]

When you fix the dyno reading accurate it would be interesting to compare different fuels

[@Casper_and_Red_Betty]

I can’t wait to see what she’ll this goes in

[@dieselsforlife3847]

Your going threw gears. So gotta figure out your ratio and add to the power. Nice to see a video! Love the creativity! Keep it up!

[@kufman01]

I have an idea for why your power numbers were low. In the simple dyno software there are multiple methods for fitting a curve to your RPM. This is done so that a clean function can be used to calculate the derivative of the RPM or the angular acceleration. The software assumes a very basic function to fit to the RPM (You show this at 10:21). Your angular acceleration is actually higher than the function that was fit and thus your power will be higher too. There is another method in the software that uses more complex functions or it can simply filter you RPM curve and use it directly. Using the raw RPM data directly will probably give a rather crummy curve but playing with the filtering it might work ok. The RPM curve of you engine is rather strange so it will be hard to fit a function to it. Maybe the clutch was slipping at the start? Also, I might have missed it in the video, but did you calculate the moment of inertia of your flywheel and enter it into the software?

[@brianballewsr20]

I’m sure you already thought of these but- 1. Is the mass moment of inertia of the roller calculated correctly and accounted for in the software? 2.does the dyno software account for the gear ratio? 3.is the software sampling the data fast enough? Can you increase the sample rate for better resolution? Your engine is sweeping through the rpm range pretty quickly. Inertia dynos work by accelerating the inertia, so holding it at WOT throttle at a steady rpm at the end isn’t adding more data to the dyno graph. I am not familiar with the software, so I could be wrong on all this.

[@davelowets]

You are on point here....

[@georgedimakis3932]

Εξαιρετικη δουλεια φιλε μ!!!συγχαρητηρια!!!!

[@jiviteshpandab6194]

Hey, you can make a mini electricity generator using one of those engines, use a few bldc or an actual alternator to generate electricity! And a silencer on top and only a button would turn on the generator!!

[@danehutchins3845]

Youve got some great dyno sugestions. Maybe just a tad more back pressure in the exaust.

[@Artiick]

Finally. He's back!

[@twentydixoncider7443]

These little engines are slick as hell I'd love to have one for a display to show people how awesome it is but damn those lol guys are expensive lol just stumbled on to your channel and I dig it very cool man great job you're a wicked smart dude

[@arildolsen6284]

What you need to make is a break-test bed. You need to measure torque (by placing a pressure sensor at a known distance at the side of a flexible engine mount) and rpm. The flyweel needs to be breaked with and "unknown force" - just so the rpm will maintain. The calculation is then simple: HP=(torqueNm x RPM)/7127 or divide by 5252 if using ft-lbs

[@redbeard4671]

How badass would it be to build a chassis roller dyno for the car!!

[@DawahTrucker2024]

Johnny you never size to amaze us with your genius works bruh 👏👏👏

[@christianholmstedt8770]

A few thoughts. The engine is running WAY rich. I'd say a heavier flywheel will work better. Many say the clutch is an issue but I don't think so. I raced 1/8 scale Nitro buggies and the clutch does not slip once the engine gets up to speed.

[@aleks138]

Run an electric motor on the dyno and use a current meter to see if the dyno numbers are even realistic. 750w = 1hp

[@TestECull]

ye a 0.52cid engine revving to 18,000RPM should be pulling somewhere around 1.1-1.3 horsepower.

[@Rebar77_real]

Maybe some threaded through holes filled with molten lead(or birdshot) will get the weight up enough? Then you could thread lock in some caps. (going by everyone else's comments about its mass) Awesome it reads and all that though! :D