1) ignition timing, each fuel has a different burn rate and that means power will be applied early, late, or on time. 2) spark plug gap varies with fuel and compression. 3) different fuels require different carb jets.

One idea to possibly make the engine run better, and be a bit more _scientific_ is to give the engine a load. I think the best idea is to use some kind of generator hooked up to a multimeter, so you can directly compare the different fuels.

Biggest issue you have is the lack of fine tuning on the fuel injection side - all those fuels have different stoichiometric ratios for combustion as you mentioned in the video so you need to adjust the carb/jet to inject more of the methanol/nitrometh fuels (and possibly adjust the gas injection too - you could just be dealing with misfires)

Tomatoes are disgusting! Nice video. My idea is a 3D printed inverted Wankel engine, maybe a transparent one made with resin.

idk if you have done this in the past, but could you make a piston engine powered by the pressure generated from sublimation of dry ice? You might be able to 3d print almost all of the components

An integza upload. Hell yes, exactly what I needed right now. Thanks for the smiles buddy.

Distributes on cars have always had a mechanism to advance the timing when at higher RPM's . As the engine revs up the pistons move faster and the spark needs to happen earlier to catch the fuel and compression at that perfect spot that allows the fuel to ignite before the exhaust valve opens. Great video as always, thanks for sharing!

As others have mentioned the fuel/air ratio and ignition timing are probably a factor. The lack of a head gasket might be playing a role too, at 10:05 you can see exhaust gases poofing out of the seam which would suggest its not getting as good compression as it could.

Yo, when you switch fuels like that, you have to retune the engine timing and carb flow rates (i.e. rejet) for that fuel type. Also, engines running race fuels tend to run at higher than normal cylinder pressures than their stock counterparts. That little green o-ring on that piston probably not gonna cut it. Maybe vent the crankcase to monitor blow-by with a pressure guage. Just a few tips from a fellow engine enthusiast. Happy Brapping!

Hey integza, I’m a car and motorist enthusiast myself, so perhaps I can explain some of your inquiries. The reason rpm decreases as more highly combustible fuels are used is because the fuel expands with more energy. This means that the force applied to the piston is greater thus a greater torque is produced. The rpm decreases to compensate for the increased torque because the force is applied over a shorter length of time meaning that the impulse of the piston will decrease (dp=Fdt). Even though the respective force has increased, it is applied over a much shorter time. This means that the object will accelerate slower yet apply more turning force (torque) to the axel. Furthermore, the reason you weren’t getting the 4 cycles may be due to (as you’ve alluded to) the spark plug timings. In a car, a vital component for efficiency is the timing belt which dictates the spark plug’s the moment of ignition. If the spark plug is ignited before the fuel is compressed enough then it will fail it’s cycle. This is common in smaller engines (especially I4’s) because the piston has to travel further in order to compress the fuel enough and have a successful ignition. Also check for seals. Metal is good for engines because of its high melting point but also because it can create a good seal with itself. Plastic, being a polymer, is not too good at making seals (especially with metal) so this can lead to leaks and a decrease of pressure in the combustion chamber. This may also be the reason for the drastic decrease in rpm for higher energy fuels.

You need to adjust the timing of the motor. So it sparks a little early. The way your spark will be in time with higher RPM. Same as with the top fuel drag racers. They run terrible at low RPM, but a high RPM they run super smooth.

Hi Joel, The reason why this engine is not doing a power stroke every 4 strokes could be that it might have speed governing, specifically hit and miss where it doesn’t combust the fuel when it is running above the set speed. Just something to consider :) Kind regards Hunter

My guess as to why it's firing inconsistently, is that the air fuel mix is VERY rich. As is often the case with engines as small as that. If there isn't a mixture screw on the carburettor, there's not much you can do about that, aside from removing the "jet" (which will be a small tube in the centre of the carby in this case) and replace it with a new tube with a smaller hole in the end in order to lean out the A/F ratio. You can either do a lot of maths to work out how much to reduce the jet size, or you can just do it by trial and error. I'd wager that if you reduce the jet orifice by 10%, it will fire much more reliably. It will also run hotter, and may not have enough lubrication. You could try restricting the flow of fuel with a valve, that might allow you to tune it.

First thing would be mixture, as all of these fuels have different air/fuel ratio. Bad mixture would cause the engine to run poorly, if it even runs. Second thing, it would provide better data to use some form of engine load to better test the performance of each fuel.

I like the sound of these engines and it is so satisfying to see the the piston moving😀

If the cylinder weren’t exhausting the entire contents of the cylinder during the exhaust stroke, the plug may be firing into a dead charge unable to ignite the cylinder until the next cycle clears it. Typically scavenging from the exhaust pulses plays an important role here. You may try adding a bit of positive pressure to the intake to overcome this. Would make for an interesting video.

When the power stroke occurs creates massive pressure. The opening of the release valve might not be enough to release all that compressed pressure ,so the fuel entry valve when opened, because there is still compressed material in there, instead of fuel entering it will be repelled.

Video idea: build a transparent electric motor and put magnetic powder around the stator coils. That way we could see the operating motor and the activation of each individual coil. I'm a huge fan of 3D printing, engineering, motors and (obviously) integza!

A 3D printed see-through fire piston which demonstrates how diesel engines work, would be a fun project to see. You can ignite small pieces of cotton or tissue this way. It's a cool way to teach how a quick change in volume can increase temperature.

Thank you so much for making this video! My six-year-old wants to make an internal combustion engine, so we are learning all we can about them preparatory to getting our hands dirty. Thank you!

your engines/rocket content just keeps getting better, love the videos

I think it has to do with timing, by changing the octane of the fuels as you are, you change the ignition point in the cycle, you'd have to tune the timing to match the ignition time, useful for increasing compression to avoid detonation (Lower octanes self detonate under higher compression).

Honestly super impressed you made that animation for such a small part of the video

A 3d printed transparent transmission would be great to see. I know most of us understand how gears work, but to see a sun gear engage and run through individual gears would be awesome 😎

All the alcohols you tested have a different stoichiometric ratio, which you briefly touched on. Gasoline is 14.7:1, and while I don’t know about methanol or nitromethane off the top of my head, I do know that ethanol in 9.7:1. So you need much more fuel to combust with the same energy. Where the benefit comes from with these alcohols is in high performance engines with extremely high cylinder pressures. Gasoline will burn too hot and too fast, which can cause problems such as pre ignition, and melt pistons. When you start to get into high compression ratios, advanced ignition timing, and forced induction, these alcohols have their place. They burn cooler, and slower (the slower a fuel burns, the higher the octane rating). Running pump gas under these extreme conditions will often be detrimental to a cylinder, but the alcohol fuels make it much safer to run. Edit: also, an added benefit is, alcohol burns much cleaner. If you ever disassemble an engine that’s ran on alcohol vs gasoline, you will notice that on the piston, valves, and cylinder head will have lots of carbon deposits, whereas the alcohol engine will look clean as a whistle!

I would speculate the stroke missing has to do with the load on the engine. A load would pull the RPMs down and thus the cycles would complete in the allowed time to meet the next power stroke. This would mean the powerstoke is only missing because the engine is using inertia at the point the second powerstroke would hit so it essentially becomes another suction phase that would cause a combustion failure. but the inertia in the system wouldn't be great enough to maintain a speed that can skip a third powerstroke cycle.

keep up the good work, and with style!

Thank you for showing a preview at the beginning before diving into the content. I can't stand modern youtubers that give their life story before diving into the raw content.

Suggestion: You should make a musical flame table incased in infinity mirror and place it in background or use it for epic tomato burning montages

it has to do with how fast the air fuel mixture burns as the flame front moves at different rates depending on the fuel, also i don't think you adjusted your carb to run richer to take advantage of the ability to burn more nitromethane and as you said it's less energy dence so given the same air fuel ratio you make less power.

Great channel. One thing I’d like to see is some of your previous experiments which were limited by materials like the jet engine but with the failure points replaced with metal to see what you could achieve with them. Also you could do a whole metal themed dress up thing which you would enjoy. Thanks for the great content!

Fun to watch your videos, wish I had more time to do fun stuff like this.

I love your content I show it to my 4 son's, and I have to say thank you because your videos has made their love of science equal to or surpass my love of science.

Valve and ignition timing (IE when the valves open/close and when in the stroke the spark happens) may all need to change with the different fuels. In addition, the carburetor is built assuming the required air/fuel ratio for the original fuel. Those ratios, as you pointed out, are different for any other fuel.

Lovely project!

I loved your video and very awesome to see. Please note: Compression, Carbeuration (for amount of fuel) and timing of the spark all come into play for proper 4-stroke performance.

Love the see-through mini engine! Awesome project Joel! 👏

Integza, all your skipping cycles troubles are related to the fuel-air mixture. Different fuels have different density, therefore if you don’t adjust the carburetor, it won’t work properly. I don’t know if you have adjust on that carb, but if not, you have to adjust some how the fuel metering jet… for metanol it should be smaller, as metanol is less dense than gas…. Modern multifuel engines today do that by adjusting the injectors opening time, thus adjusting for less or more fuel per volume of air.

Try measuring the output of the hall effect trigger to see if the triggering signal is slew rate limiting in response time. Also do the same at the ht spark end. Create a capacitive divider network to reduce the HT voltage your trying to measure with your oscilloscope to something within the voltage range of the oscilloscope. You can create a capacitive voltage divider clip with a giant plastic peg to clip to the spark plug, and use insulated wire coiled, to create two capacitances for a voltage divider.

Always knew you were a very smart person, being an enginehead wasn't surprising at all

I once again recommend you look at turbo prop engines. They provide a mix of power and efficiency with smaller aircraft. It also has a really interesting design for compression and air intake

I'm always just amazed by what you are able to create and I always wanna do something like this myself whenever I see your content, keep up the great work!

I like the sound of these engines and it is so satisfying to see the the piston moving

Towards the end of the radial engine/propeller age, aircraft engines began using a power recovery turbine, which recovered some of the waste exhaust gas energy through a turbine that mechanically connected to the propshaft to add power. Pretty neat what they came up with at the absolute limit of radial engine development

I'd love to see a video 3D printing steam engines, the gasoline ones are really cool but I've always wanted to see the inside of a steam engine working!

You should try an transparent piston with a 2-stroke engine, that`d be fun to watch.

When you first put the clear cylinder on, we could see bubbles coming out from gaps between the cylinder and the head. Put a gasket in there. Also print your cylinder small and polish to the proper dimension. Just a thought.

When dealing with compression you also have to remember there's a difference between Dynamic compression and static compression. Static compression is the typical one used to measure the compression of an engine. It only refers to the Piston at bottom dead center and the Piston at top dead center. However this is not always the proper way to measure. When the Piston is at bottom dead center the valves are still open, which means that it's not actually compressing any air. As the Piston moves up in the bore, the valve is still open for a bit, then fully closes. The measurement of the volume that is compressed in the combustion chamber when the valves are fully closed is called the dynamic compression ratio.

Suggestion: Stress test a transparent pulse jet by putting a tomato in it. I once saw someone put sand in engines to destroy them and it went for a very long time, lasted surprisingly well. I'd like to see something similar to that with transparent parts on something with fire in it vs tomatoes instead of sand.

One of the coolest looking see through engine I've ever seen!

I think an interesting video idea would be comparing different cylinder / piston shapes. Such as hemispherical, conical, and flat cylinders. Certain configurations have different power, efficiency, and manufacturing advantages (such as spark plug placement)

Hey Integza, you should make a video describing how a carburetor works. It would help with understanding different fuel types and help in understanding the reasons for some fuels running better than others.

Hey Integza, I think it would be an interesting video to see if you can use the waste heat from the gasoline engine to power a steam engine and somehow combine their outputs if possible. Squeeze all the power you can out of those dinosaurs :)

Love the videos, I would like to provide my two cents on why she wasn't running right: As a qualified and experienced small engine tech, and what you have there is essentially a small vintage briggs and stratton engine, I reckon your fuel mixtures were off (too rich) The reason you got better combustion with the 25% nitro is (as you perfectly explained) the nitro requires less air to burn, so a rich mixture actually helped its combustion. If you adjust the fuel mixtures, I suspect gasoline would end up running mint.

Hi Joel Hunter again, Another reason why the engine is doing only one power stroke per eight strokes could be that the Hall effect switch/sensor might not be registering some of the strokes because of how fast the engine is running. Kind regards Hunter

I love the little engine

Perhaps the different fuels are not reaching optimal stoichiometric ratios with the same carburetor settings? You could try forced intake so you can dial it in to get the most power maybe. Very cool demo engine mate. Nice work on the 3d print cylinder.

It would be really cool to use an arduino or similar to adjust the spark timing manually, controlled with a hall effect sensor. You could also put a capacitor in series with the spark plug for a hotter spark, see what results you get from different fuels

Your content is always exceptional! And you are right we want the real deal no cartoons, so thanks for the real deal dispight the work you had already done. You should put it in the intro. Keep it up!

Love 4 stroke engines!

Love the video as always! I would love to see you build a carburetor using clear 3D printed parts and explain how they work. Thanks as always!

In keeping with the same theme, could you do a clear two stroke engine? I’ve always wondered what that would look like.

I don’t know where you got that shirt man but I absolutely love it from the sponsor you and also passed you lol

You’ve come very far with your videos Integza!

Would be interesting to measure and compare the amount of torque the different fuels produce. (Especially if the engine is fixed so it fires every 4 strokes!)

"Engines tend to be made out of metal, and metal tends to be opaque." Not many understant this pain.

my theory is that the nitromethane is expanding slower than the others, but with more force behind the expansion and thus is slowing the piston down on the exhaust stroke.

I was actually thinking about something like this a few weeks ago. Really impressive work 👍👍 Good job

when you change the fuel, you need to tune the carburetor. if not, the engine will run with either too much fuel or not enough depending on what fuel you're using. in the case of nitromethane you want more fuel than air.

I’d love to see a 2 stroke version of this video

Air/fuel ratio & spark timing, & possibly a flywheel, keep up the great work :)

I had 1 idea recently because of gas prices . What do you think about useing hydrogen to power the engine , in my opinion this is one of the future fuels and it's the cleanest one . But to that you would have to do HHO generator first , for person who build rocket engines in past this shouldn't be a problem. I hope that this idea gonna get most likes

Well of course the next step would be to build some other miniature engines with a transparent cylinder, right? Being able to look at the differences with a two-stroke engine (like how differently lubrication works) with a transparent cylinder would be great, or a diesel engine (how it doesn't use a spark plug, etc.) Something I've always found fascinating is how different cylinder configurations have different characteristics, how they have to be timed with one another and be balanced. Like for example, every piston in an inline engine needs a counterweight, but in boxer engines, pistons are arranged to oppose each other and balance each other out. I've never seen this outside of an animation. I'd also love to see you play with moving energy storage, like using flywheels or reaction wheels.

I love the vrooms they make, especially my cars

Jan Ridders made some great little glass cylindered motors about 8-9 years ago. Will Trudell has a real motor with a glass cylinder and Latheman's crazy machines has some glass cylinders made from syringes. Seeing the flames inside a motor is pretty insane.

A common misconception about octane is that it makes your fuel more explosive. In actuality, they add octane to calm the volatility of petrol (gas) to help the engine run more smoothly and with less misfire ping. Also better atomization of the fuel as it leaves the carburetor will increase performance and fuel economy as it helps the engine fire more reliably.

I'd love to see a transparent rotary engine, it would be so cool if you could even build it from scratch!

I really appreciate the forethought to address my comment without having possibly knowing I would comment it . I remember complaining about how inefficient automobile engines were on a previous video.

I really like your channel, it's a lot of fun. Also glad you gave a shout out to Warped Perception and Smarter Everyday, which are both awesome channels. I see you like jet engines and they could definitely give you some tips. Good luck buddy. Very cool video

Would be interesting to power something with your 4-stroke, and perhaps measure real-world impacts of the various fuels. Also I do think that your issue with missed powers strokes is the ignition. Perhaps you could rig up your own ignition and an artificial load?

Each fuel requires a particular ratio of the carburetor for a perfect combustion, moreover variables like weight, diameter, cm2... can make vary the parameters of admission What I would like to see is to compare the different fuels by installing a solution that gives them more kinetic energy with for example the installation of a flywheel ( "volant d'inertie" I'm not really sure about the translation )

Wowsers!! I absolutely LOVE that multicolored shirt! It makes you look even more awesome!

I'd also guess its because of the mechanical nature of the reed contact thats used to pickup the Crankshaft's position. keep in mind, it's not only igniting at the Powerstroke, but at every incidence the Piston is at it's highest point. Those reed contacts need to be accelerated and decelletated twice to create one negative flank that indicates passing the upper endpoint. Could be just about losing the sweetspot in those higher rmps. Depending on the nature of that Spark plug circuitry, try a hall sensor instread. You may even need a power transistor to energize the coil if it's a regular ignition coil setup. This will also require a reverse diode to protect the Hallsensor and Transitor from the peak voltage, even better, a set of HV-Caps (WIMA MKP). For a transitor, something that switches really quick is important. the steeper the flank, the better the ignition. That's why mechanical contacts remained for so long in combustion engines. good luck, and thanks for the nice video.

Actually, a benefit of 4-stroke Gas Engines are that they reduce fuel consumption because fuel is only used once every 3 strokes. But it does make the runtime a bit faster. Just look at the 4 stroke Air Engine by Axel Dayton. It can only run for a few seconds without pressure regulators. And now look at Tom Stanton’s 2-stroke air engine. It can last very long.

Exhaust stroke is slower when there's actual exhaust to be pushed out. Different fuels also have different detonation speeds which don't necessarily correlate to power. Test again with a static load, or some kind of muffler on the exhaust and you'll have a better time plotting the power of each fuel.

One thing I noticed is that all of the 3D printed cylinders are leaking at the top so it could still be a compression issue. The metal cylinder is likely machined to be a perfect fit so maybe adding a little silicone or something as a gasket/ seal where the cylinder meets the head would help.

One hypothesis I would suggest for performance/fuel is that mix ratio is important and unless the carburetor is controlled for the specific mix ratio with the butterfly valve, you will not get adequate performance for each fuel. In this case, my favored hypothesis would be that 4 strokes may not provide an adequate mix ratio with the valve setting and the pressure to ignite properly. Another thing to consider is that different fuels will require different compression ratios to ignite adequately. Compression is a fuel dependent design variable in a 4 stroke engine but the general philosophy is more is better till you reach a weight limit for structural strength to hold the pressure in. There is however a minimum pressure for many fuels to ignite repeatably. You seem to have a major leak on the cylinder head (looking at those bubbles), I would recommend adding a gasket and see if it improves the ignition because if pressure leaks, that means you may not have enough pressure built up to ignite some fuels properly.

Video idea: You should try to print an axial type compressor and see if it's possible to get it self sustaining if used in a jet engine. EDIT: i've seen one video of a printed axial copressor but never used for an engine

@11:00 The issue is with your magneto timing, valve timing and piston ignition timing.. The fuel isn't igniting properly because of the energy output of the fuel being provided. If you change your magneto, valve, and intake/compression phases to match the fuel potency requirements, i think it will help. You hate Tomatoes, I love Tomatos :-D

Was wondering why I haven't seen an integza video recently. Didn't get the notification for this one.

It’s the compression of the engine, that’s why different engines use different fuel octane levels, for a fuel that doesn’t ignite every time you need more compression to assist the ignition process

Try to make a plastic rocket engine as usual, but chemically coat the plastic with metal to make it stronger and more resistant to temperature.

My idea is to make the engine run on hidrogen withch is also combustible.

I think I saw something: To me, it looked like some of the fuels ignited well past the cylinder starting the power stroke - It seemed to flash at the mid stroke position - which would lose you a lot of energy, as the explosion would work against the piston when it's going into its exhaust stroke. If my eyes aren't deceiving me, that's a timing issue and may be related to the missing power strokes issue. From my limited knowledge of combustion engines, I seem to remember that you need to tune the engine according to what fuel you're using to get the action to work right. So that might be worth tinkering with. For the missing power stroke issue, I think you need to do more tests. See if there's pressure escaping around the top of the cylinder, what happens if you move the ignition timing around, etc.

Ok, so, a couple things. Nitromethane has a stoichiometric fuel to air ratio of about 1.7 to 1, so even if it does have only 1/4 of the energy per mass, you can burn about 8 times as much as it per stroke as gasoline, resulting in about twice as much energy output for the same volume of air. Even then, the drag cars that run it run it much above stoichiometry, so much so that raw, unburned fuel leaves the exhaust as a thick fog of fuel, it’s not smoke. To get that engine to run correctly, you are going to have to increase the fuel jet size by many times, assuming the carburetor can even flow that volume of fuel. Same goes for methanol, lower energy density, but you can shove a lot more of it in the motor. I think you will have more luck running methanol/nitromethane then gasoline, because methanol and nitromethane can take a ridiculous amount of thermal energy with them as they leave the engine. So much so, in fact, that drag cars that run on nitromethane don’t have any means of cooling otherwise. They are not equipped with radiators, coolant, or fans. This might give you a bit more life out of that cylinder. Also, you’re cylinder can’t hold onto any oil, because it is smooth. If you look at cylinders in any engine, you will find that the cylinders are crosshatched intentionally with scratches to hold onto oil as the piston slides up, since you can’t do this because it would ruin the transparency of the resin, I would mix oil into the fuel at 16%. The extra oil in the cylinder will help seal the piston to the sleeve. This is how it’s done on rc cars that run nitromethane, as they don’t have rings of any sort. They rely on the taper of the cylinder to seal it off as the piston approaches top dead center. Typically, in engines of that size that are designed to run nitro fuel, have a glow plug instead of a spark plug, as when you have that much fuel going into a cylinder, it can be pretty tricky to ignite. Glow plugs are typically made of a platinum or platinum coated wire that catalysis with the methanol in the fuel to creat ignition. For drag cars, they run so much current through their spark plugs, that they all melt off about 2 seconds into the run. At that point, the exhaust valves are hot enough to auto ignite the nitro, effectively turning the engine in to a diesel mid track, so yeah, nitro isn’t the easiest to properly run. Oh and to add to the fun it’s corrosive and hydrophilic. As for making it run more reliably, check the seal of the valves. This will cause low compression and can be fixed by lapping the valves. I personally think you either have a weak, or inconsistent spark, or poor homogenization of the fuel and air in the carb, or the mixture is off all together. These Chinese engines are known for having ignition issues though. As some other people have mentioned, it seems your running quite rich. Reply if you got any questions (or if you even see this). I have always wanted to do this and I thought it was a great video. I’ve been trying to see if I can make 3d printed engine parts as well, and have made a couple functional camshafts. Good luck!

My idea to make would be a steam powered bike that would be great 👍

11:09 The air to fuel mix is off. Along with the air pressure and fuel injection. Remember. Different fuels require different air to fuel mixtures. But the engine has a "fixed" amount of air and compression. Im not an expert, feel free to correct me.

Warped perception makes heaps of clear engines and Steve mould makes clear fluid dynamic demos

One possibility could be that force is given by speed times torque or is defined on motors. This means that the nitromethanol triggers more torque in the engine than the other fuels and therefore, conversely, has more energy.

Now that you've done a video on a 4 stroke engine, a follow up video on a transparent 2 stroke engine would be really interesting. This video does a excellent job of explaining how the motor functions and how amazing and complicated modern 4 stroke engines are.