Making a REAL RC Engine Dyno! - New NR200 Engine Test
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- čas přidán 25. 08. 2021
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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.
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.
@@TimeFadesMemoryLasts Dang, I can’t read half the words your saying
Almost like the decimal needs to be moved 1 spot to the left
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
@@fat_cat8457 Haha, don't worry. TLDR: I can make a very detailed, exact and professional torque and power curve from these dyno runs.
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!
Dyno with 1 to 1 ratio, or as close as you can get to it.
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
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
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?
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).
You need to hold the engine back…. Doesnt seem like the engine is working at all but still cool
Definitely get a bigger flywheel, it’s probably revving up so quick that it’s throwing off the numbers.
Yup. It should take a few seconds, at least, to get through the pull.
Smaller flywheel. 12k rpm during dynk pull is only half of that motors rpm range.
@@Poizdrc Smaller for sure. The engine is trying to rotate too much mass. Gotta make sure you can use the full rpm range.
@@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 🤣
Bigger wheel or remove the gearbox. Likely the engine's own ramp up time is affecting the numbers. Also rpms look unstable.
you're an absolute legend for providing us enthusiasts with this overly specific content
Awesome engine. Cannot wait to get one and install it into a car.
you should probably install one at each wheel..
or maybe two.
Make a tank with one engine and reverse transmission for each track. ❤️
Or a enlarged powerwheels
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.
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!
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
@@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.
motors vary in efficiency at both speed and torque so it will never be a 100% accurate calculation im afraid
@@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.
You need 1/1 ratio with a direct drive or using a real clutch (because a centrifugal clutch spins). And a brake dino setup
👍
Yup especially with a slower four stroke, clutch slip would be my primary concern.
brake dinosaur
The way you used the magnet and the earbud to generate a signal was amazing.
It's part of the instructions for Simple Dyno
2 comment and Lot of like
yeah it’s common, it is cool to see though
I thought the same thing. I was like, "Huh? No way! I never would've thought of that." Good stuff always from JQ90!
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.
Need a roller with higher inertia, RPM rises too quickly to be useful.
Great to see the new nr200! Thanks for the video!
With it being a centrifugal clutch, would there be some losses due it it by nature slipping?
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
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
@@Awkward_Fox Imo, these isn't a need for a clutch, having a direct drive engine to flywheel is my idea of a solution.
@@Awkward_Fox tuning the carb adjusts fuel mixtures...also valve lapping isn't nessesary if the valve seat and valve face are properly machined
@@SlowSTEN I mean to say fuel mixture. Like nitro and whatever other fuel/oil is used
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!!! :-)
Awesome build!
I remember I suggested this a while back. Very impressed!
I never get tired of watching your projects!!
Awesome video! Asmr, quietness. Beautiful! 👍
Remove the gear reduction. All it's doing is lowering your inertia. Also make sure the inertia parameter is correct in your configuration
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.
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.
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
You are one of the best RC ppl I ever seen, thanks for your uploads. :)
Heck yeah! Nice work on the test dyno!
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.
Decimal place value? 3rd grade. Out sick that day?
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
😁
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.
Man this is just the coolest thing I've ever seen..
Very curious about what valve lapping would do for this engine, having seen the video with the other model previously. Just a thought.
Valve lapping isn't nessesary if the valve seats and valve faces are machined properly.
@@SlowSTEN he lapped the valves in the four cylinder and it gained quite a bit higher revs and sounded much crisper in the throttle
@@defaultdriftco00 Yeah I remember that one. Clearly they weren't manufactured to particularly good tolerances for THAT much improvement. Worth a shot here.
Please show us the valves and cams. I think this is a water cooled 2 stroke.
@@fromthebackofmymind its a dohc 4stroke. Much like the inline 4 he has 😅
Mesure exhaust temp so that you can try to lean out your mix without damaging the engine.
@kayo... 🌹 worst freaking attempt at marketing ever
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.
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.
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.
@@chemieju6305 hall effect sensor can give a digital signal so its easier to understrand and process to the computer
Dynos only measure torque. The software does a simple math equation to figure horsepower based off the torque numbers vs rpm.
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
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.
FINALLY thank you...I need to test/tune my engines
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.
Old Xerox machines (the behemoths) had realistic solenoid clutches. I used to have one inside an RC car.
@@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.
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
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!!
Your work is top notch, very good!!
Εξαιρετικη δουλεια φιλε μ!!!συγχαρητηρια!!!!
Seriously you're a mad scientist. That's a complicated thing you've built. Nice job 😎
It is nice to see Johnny. He alwaus makes his own parts. 🇨🇦
Johnny you never size to amaze us with your genius works bruh 👏👏👏
You are the best Francis!!
Cant wait for next one!
FINALLY!! Something to power my pencil sharpener
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.
JohnnyQ90 Great Video! I built my own Inertia Nitro Engine Dyno with a steel Flywheel.
My suggestion is I'll keep watching it because it's really really good! Ty.
super cool build!!!
I've been waiting for a video and here it is keep it up
Finally. He's back!
holy smoked the finish on the 3d printed parts is crazy, I might have to pick up that printer now
Amazing! Kind regards from Brazil
Bravo, Johnny.
I wish you did more uploads. I thoroughly enjoy your videos.
You have a great experience. 👍
Yay new video I love them good work bud
And he does it again. Mind blown.
Great way to test different fuels
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!
já tava com saudades dos seus vídeos tops!!!🤜🤛
More magnets for better rpm resolution. Right now you pick up one signal every two rotation of the engine.
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.
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!
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!
Amazing video❤️
Never understood how a dyno work and you managed to create one... Well done
1:15 That touch felt like the cooking guy that adds salt with his elbow
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.
Nice i waiting for this
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
Freakin amazing work
Very good video 👍
awsome vid!!
your videos are amazing
Pretty cool
this is to cool bro
Please test your previous engine builds on it, would love to see a power/torque comparison between them
I can’t wait to see what she’ll this goes in
It would be cool to lock the clutch To see if any improvement is there. Nice work brother!!
I agree. I wouldn't use a clutch at all. A slipping clutch WILL skew the calculation in the end.
Damn it Johnny take the spring off the clutch.
Dang, that engine seems like it would be good for a rc mini outboard motor for boats, it’s gnarly
finaly. new video
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.
I'm pretty sure the magnet and earbud was supposed to be a hall effect sensor.
@@bisurdaddy effectively, yes. However, using a discrete hall effect would work much, much better. Signal would be far superior.
Sou do Brasil,novo aqui, já me apaixonei pelo se trabalho incrível.
Excelente video, respetos desde Venezuela.💯🤜🔥🤛👍🙏💯💯
Amazing 🤤
Cheers :)
Một chiếc động cơ thu nhỏ thật tinh tế.bạn thật giỏi
this guy has the biggest thumbs ive ever seen!
Youve got some great dyno sugestions. Maybe just a tad more back pressure in the exaust.
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.
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).
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?
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.
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
How badass would it be to build a chassis roller dyno for the car!!
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").
I've watched enough of you videos to know you are brilliant. When is a RR Merlin or Griffin RC scale, gona be on the lath of yours?
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
Nice
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!!!
That would be cool if you produced custom engines for me I have some ideas and your finesse on with your hands and creativity is unique.
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! 😀😎👍
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.
OO hello very good your videos i have been with you for some years now i will leave my like#brasil
When you fix the dyno reading accurate it would be interesting to compare different fuels
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.
What lathe setup do you use? I’ve been thinking about getting one and you always get nice parts from yours.
I feel like someone should make a awsome rc boat with one of these motors.