PERFORMANCE Upgrade for the 4 Stroke TWIN Cylinder - *VALVE Lapping* - Supercharger Update
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- Опубліковано 14 жов 2024
- While figuring out which supercharging method should I use, I always had the curiosity to know why this particular engine spits so much unburned fuel from the exhaust and the inlet as well. The siplest thought was valve leakage. There's no other way so much fuel can escape both from the inlet and outlet of the combustion chamber. I decided to use the lapping method which is used on full sized engines. In my case I used polishing compound (thicker one) instead of the actual paste that is used for this purpose as it's too thick and harsh for these tiny valves. The result speak for itself. I was never able to rev the engine past 11,000rpm, while now it revs happily almost to 16,000rpm. I still cannot believe that by simply polishing the valves we can have so dramatic changes in the performance of this little engine. Probaply after all the disassembly and assembly process, I accidentally fix the real problem.
About the supercharger. As you can see on the video, it's pretty much impossible to have any gains from an engine that barely works right. I'm surprised though that the blow through setup worked better. As I've said 2 years ago, a positive displacement supercharger would work perfectly fine.
Model engine companies like O.S have released in the past supercharged four stroke single cylinder engines with a roots type supercharger (O.S FS120 supercharged). This alone gives me hope that I will make it work.
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Bored to death with a centrifugal supercharger? Never! I haven't seen one of these things put onto a model engine, and it's super badass! You're so close man! Don't give up!
100% agree, don’t give up on the supercharger! Also agree with some of the other comments, possibly EFI? maybe a team up with a channel that can produce something on RasberryPi etc 🧐
This
@@_Mav Trust me, you wouldn't want to use a Raspberry Pi (SBC) for any engine application. A microcontroller (Ironically, the Raspberry Pi Pico could be used) is what you want.
@@crenn6977 maybe just add fuel pump?
@@crenn6977 just saw the video and at the end, some sort of fuel injection, even if it's just somet to adjust on the fly as the engine revs. Not EFI, "M (manual) FI" lol. Could this little thing have run away boost? Lol. Alright Johnny, time for that micro blow off valve 😬. How would you solve the EFI if not a small computer controlled fuel injection @crenn6977? I'm legitimately curious because Raspberry Pi popped into my head as well.
I can assure you, we are FAR from being "bored" with this project. It's incredible to watch the process. I LOVE this stuff man
What's this "we" shit, you got a mouse in your pocket?? 😜
we also want bigger pulleys
Nah dude I'm not bored at all! I was literally waiting for this video to come out cause it's so cool and uncommon! You make me want to get a pocket nc and a 3d printer so that I can mess around with these little motors!
Been thinking building cnc because yt videos have proven me I need one :D
Me too
I had a PocketNC for a little while, but since moved up to a full size 5 axis machine. But that’s only because my dad and I have a machine shop, and the PocketNC couldn’t keep up. It was a great little machine though, a great tool to learn 5 axis milling, and perfect for hobbyists.
"danger to manifold"
Careful man or your floor pan will blast out
Mate, that comment deserves to be no.1!
@@azzz..6 See but then it’ll randomly spin out before it finishes any races
it's plastic, he can lose as many he can without sparking lol
I wouldn't have expected a difference so big just from lapping the valves....
The sound difference alone is pretty incredible!
Well at this scale a small imperfection in manufacturing is very unforgiving. On an LS3 these flaws would lose maybe 5 to 10 HP over the stock 430, but on this, for like 1 HP it could stand to lose perhaps a quarter HP or so at the worst. So for an LS being a full size motor, that's between 1 to 2 percent power loss, but on this tiny motor that's a 25 percent loss in power. And with so much air flowing between the valves and the valve seats at 12k RPM before the lapping, it was losing a lot of potential power especially since its rated to reach 16k RPM (it is a Toyan L200). So with that defect fixed and even made better than stock, it likely makes somewhere around 1.25 HP without the supercharger and perhaps 3 or more with the supercharger once the AFR is tuned right with the 10 to 1 pulley.
@@Avetho 3 HP from an engine this size would be amazing to see in action
Watch where he points lazer when he checks rpm. He is getting more rpm the second reading because he checks it closer to crankshaft. Lapping valves will increase efficiency and power but not by 4,000 rpm
Jacob Credle you might be confused, the rpm of a rotating body does not change depending where you measure it. A wheel spinning at 60rpm is spinning at 60rpm no matter where you measure it
I’m not bored of this, I’m constantly amazed at what you are capable of designing and engineering and I watch in awe at the scale you work at, keep trying buddy I’m sure you’ll figure it out
Once again, awesome work. You must be a wizard. Great skills mate!
wizard? nah, just hard work and big brain 😉
Watch where he points lazer when he checks rpm. He is getting more rpm the second reading because he checks it closer to crankshaft. Lapping valves will increase efficiency and power but not by 4,000 rpm
@@jacobcredle4807 Yes the laser is further out the second time, but the engine is revving noticeably higher, by the sound pitch it's making. I don't really know much about this kind of laser tachometer, as I've never used one, but if it counts revolutions, it should not matter how far out he checked it. The flywheel/pulley is spinning the same RPM along it's entire radius. It's the pulley speed that changes along it's radius, as the further from the centre, the further it needs to move for the same RPM. So provided the tachometer can somehow know when a complete revolution has been made, it shouldn't matter where the reading was taken.
If it was a tachometer which works out the revolutions by measuring speed at a certain point on the radius, then it would matter.
Like I said, I don't know how this type of tachometer works, usually he uses a tachometer which works by using a piece of reflective tape that reflects the laser, so allowing the tacho to count a revolution. I didn't see him put the tape on this time. Either it's a new type of laser tacho, or he didn't film the application of the tape.
It might be sucking air throught your supercharger bearings if they arent sealed.
@@jacobcredle4807 that's not true, it reads the reflective tape once per revolution. It doesn't matter where the tape is.
to check power gains, you could always run the engine to an electric generator, see how much electricity it makes with and without the forced induction.
I was watching Smarter Everyday's video on power generation the other day, and he had a mini generator attach to a drill to show the effects of rotation speed on frequency loading. He also showed the difference of unconnected poles versus connected poles of said motor. In theory, you could create a load cell of resistors and use either a dmm or even a killawatt type device measure the output of the motor.
No way you've bored us with that. I love the supercharger setup. Just wished you would get it to work. Mount it straight off the front on the crank!
You have to use a geared ratio otherwise you cant get the charger to spin fast enough to produce enough positive air pressure. The crank might spin at 16,000 rpm now, but that charger is probably spinning over 110,000 rpm with the 1:10 pulley used here. With the 8.5 he was at 90,000 at .6 psi.
@@faulcun Dude, 16,000x10:160,000 supercharger revolutions (1:10)
@@darianistead2239 yep you right lol. Wasnt mathing
these replies are big brain, meanwhile i cant even figure out minecraft redstone lmao
You have NOT bored us sir! You make us all aspire to have even half the skill you have. This is one of the best projects I’ve seen
wait wth, valve lapping gave you a 25% increase in RPM?! there was that much pressure loss due to inconsistencies?! that is crazy! I love these videos!!
Johnny this series is super fascinating. I'm always amazed by what you're able to acchieve with this engine. PLEASE continue to upgrade it :D
I suspect your problem is a vacuum leak in the supercharger at the end of the video. I've seen that meany times before. Thanks for the great video.
yes I think through the ceramic bearings
The problem is, the fuel isn't being pushed into the carb like the fuel tank is designed to do. The nipple on the lid of the gas tank is supposed to be connected to a source that can supply positive air pressure.
Couple things come to mind with the draw-through: Ideally you should still be pressurizing the fuel tank with something, but obviously the carb is drawing some fuel on its own.
Second thing to consider is if the supercharger is leaking air from behind the compressor wheel (through the bearings). This is honestly probably the best explanation for why it's running so weird at part throttle. With the blow-through setup this was never a problem, but with draw-through vacuum will pull air through the bearings if the seals aren't up for it. This leans out the fuel mixture.
I belive the reason it was running strange is due to fuel accumulation, fuel is sitting in the bottom of the compressor housing and when it's finally drawn into the engine it's causing your running issue.
I was thinking maybe the carburetor throat was too small and when the engine revs up a strong vacuum forms which begins pulling more fuel through the jet which revs it up more until it begins running lean and then it slows down and repeats.
I think a different style carburetor is in order.
Fuel injection is the way to go. I wonder if they make fuel injectors that small.
Fuel accumulating in the compressor could be it, I was thinking that the intake manifold wasn't distributing fuel evenly as it's not well atomized by that point.
@@Kraknar Yeah, that's my thought too, asking atomized fuel to follow that path and stay atomized is a big ask.
Never bored of your channel. Love the lapping and valve work. Positive increase. Racking my brain as to why the intermittent idle and why the needle valve has no affect on the flow. Could be pulling air through the SC bearings. Great Vid 👍🏼
Sounds like it's running super lean . More air also means more fuel is needed.
I was thinking the same thing. Seemed like the base idle screw needs some adjustment.
Or even a boost referenced fuel pressure regulator. Almost need an electronic fuel pump with a return setup to try and supply the fuel it needs id say
Absolutly way to lean, crank the needle valve up and maybe will work
@@castekracing thats why he went carb before supercharger. this way the carb doesnt see the pressure.
@@rehepeks that’s true. I haven’t done much with draw through.
Adding a pressure bypass when throttle closes may help. Recirculating the pressure back to the intake of the supercharger, this would work best with the blow through design and relieve the compressor loading at idle.
This makes total sense, I just don't know how you can do it on something this small of a scale.
@@onefastslimjim true, but he manages a lot of stuff on a scale that is tiny, a challenge, just not impossible!
@@defaultdriftco00 oh yeah, knowing Johnny, he would find some sort of way!
That valve lift is pretty small, how close are the valves springs to binding? You might be able to make rockers with a more aggressive rocker ratio to gain more lift which will also help with higher rpm.
Would prolly get even more overlap. Which is what he is fighting right now I’m guessing.
@@henryarrington3446 overlap isn't always a bad thing in forced induction, especially in high revving engines. The duration of the overlap shouldn't change though, as without altering the cam profile, although the curtain area/time will be greater, the actual number of degrees per revolution that overlap exists will be the same. If boost drops it'll probably because the intake valves are exessively restrictive. Boost is a means to an end, if you reduce a restrictive valve you may drop boost, but if it means more air actually fills the cylinder then that's actually a beneficial drop.
@@17473039 your right I guess I worded it wrong. Overlap timing would be the same. But the valves would be open more during overlap. There is probably a lot of overlap in that engine to make it easy to start. I don’t know if it’s a flat tappet or roller lifters but if flat tappet you can’t get very aggressive on open and closing of valves. So builders have to put up with a little more overlap to get more duration/lift.
@@henryarrington3446 my guess is that being as cheap as it is, the cam probably acts directly on the rocker so it would act somewhere between the two. There is potential to advance the cam slightly so the intake valve close sooner so piston is closer to bdc when the intake valve closes, and rely on the supercharger flow and the overlap to help cylinder clearing on the exhaust stroke.
@@17473039 agreed bud. I think you and me are thinking the same thing is going on on the little engine. Johnny will get it sorted out I’m sure.
I promise I wasn’t bored at all! This is extremely interesting content
A little tip with boost gauges that like to shake or flutter. Stuff a piece of clay with a wd40 straw (the tiny red ones) through the middle into the pipe used to feed to gauge. The gauge will be slightly laggy (unoticably) but a lot smoother and more accurate. I had to do it on my car's one 😆
They actually make filters for this. Also cotton balls work.
@@benjamindavidson632 yeah I saw the filters but they either seemed too cheap or too expensive 😆 had some milliput and a wd40 straw laying about so improvised 😆
@@MaNNeRz91 Yep RC filter, resistor and capacitor. The restriction is the resistor, and the pipe&gauage volume is a capacitor. Use to do this on boucing pressure transducers mounted too close to a pump set. Even just a length of plastic pipe with a crimp/bend in it works.
@@yeahright3348 i like how knowledge in electronics often can be applied to other fields tech
@@yeahright3348 I never thought about it as an electronic component before but that does make sense. Kind of like the bottle neck explanation for capacity and resistance. (I'm shit at electronics though.. I can repair stuff but I have no clue about working out current and amps)
Johnny, my man, you think we are bored to death with this thing?
Boy are you wrong, there are 3 main reasons people watch these amazing videos of yours:
1-they are incredibly relaxing, 2-watching you make those parts and seeing how good of an engineer and craftsman you are is just incredible (btw, do you ever plan on uploading some videos where you teach us what you do to make these incredible machines of yours and how you do it?), and finally, 3-because watching these things work is, simply put, exciting.
What I mean to say is, there is no project of yours, made in your style, that could ever bore us.
I’ve never clicked so fast
You can fill gauge with oil to damper frequent pressure changes, or buy one with oil in it already. Gauges with oil are made specifically for use like this where there are frequent pressure changes.
It's so nice to see new tools
Don't quit you are just getting started! 3 tips, 1 I think a blow thru with a better carb is in order, 2 use a fluid filled gauge with a restriction in the line, and 3 make a large plenum on the manifold. If you look at what people have done for turbo's on small engines they need a "boost capacitor" basically it's a larger plenum for holding air to dampen the massive changes in pressure caused by low cylinder count.
Love your engine build and tune series. That engine is a PITA to tune and one of the reasons why I went from nitro engines to 2 stroke petrol 1/5th scale rc.
You're ingenuity and ability to make things keeps it interesting.... Keep these videos coming.
I like a lot your videos for the things that you do, you’re one of the best UA-cam es I’ve ever seen
You haven’t bored me bro i am intrigued by your super charger and all the work that goes into your videos keep up the amazing work!!!
to prevent the gauge from being damaged and giving erratic readings ..... us a long length of pipe between the manifold and the gauge.... at the manifold end place a restriction in the pipe, a bush with a 0.1mm hole in it, this will damp the response of the gauge and give the gauge a longer life span .. nice work... cool project
It should not be mechanical to begin with. Theres wayyyy too much fluctuation and its jamming it up. This will happen in any situation which is why ALLLLLLL boost gauges are digital.
totally not bored! this series is insane I love your work!
Would be cool to see if you could port the head.
It's nice to see an "upgrade" is actually an upgrade and not another way to spend money. Thanks for showing the pre-lapped/post-lapped numbers.
It looks like your only tuning the high end needle? There’s a low end needle on the side of the carb as well. You need to tune the high end first to get peak rpm. Then the low end to get good idle and transition.
Also going over to electronic ignition and petrol/gas where it auto advances the timing might help 😊
What was going on there sounded a lot like a vacuum leak to me than a tuning issue. Or maybe some weird interaction between the carb and the supercharger causing an odd vacuum signal. Using an elbow between the carb and the supercharger might not have been the best plan. the more complicated the path between the carb and the engines vacuum the more wonky things get. I once ran what I thought was a pretty simple routing of a flexible (but very stiff) tube between the carb and the engine of my two stroke, and found the engine was virtually untunable. it always ran like trash. Then I eliminated the tube and mounted it as direct as possible, instantly found the right jet, and now it runs flawlessly. And yes I realize this is a 4 stroke of sorts, but these principals do still apply. A carb is a carb. (at least when it comes to 2 and 4 strokes-)
he's missing the pressure line on the lid of the tank. its starving for fuel, which is making it very difficult to tune.
I absolutely love this project! If it were me personally, I’d go back to blow through, keep your current pulley ratio to spin it fast enough, and run your fuel pressure tap from the intake tube between the blower and the carb. That way it should increase fuel pressure on a 1:1 ratio to boost pressure. You may also find that you need a stiffer valve spring. Even with such low boost, there’s still a good possibility that it’s blowing the valve off the seat and making it run erratic. Please don’t give up on it yet!
You need a gauge filled with oil to get a decent reading
I think some kind of restriction orfice also inline?
And a gauge with a stop on the 0 so it doesn't run backwards.
Restrictor should do the job.
I think the shaky gauge had more to do with there still being compression leaking into the intake. Same as if you've ever tried reading vacuum on an engine with a bent or overtightened intake valve. Could just be an RC engine issue ... I've never built a 16K rpm engine ... there could be all kinds of overlap on that cam for all I know.
could also be valve float like crazy..
Duuuude that little torque tool is freaking sweet, didn't even know they made one like that. This guys shop must be a wet dream for hobbyists, I mean just his little 5 axis is 5 grand but his skill is on another level!
Next stiffer valve springs and high duration/lift camshaft for 20000rpm. (and supercharger ofc) Maybe oil system upgrade. Soon the whole engine will be diy upgrades lol.
Great video keep them coming!
Yeah, I've really been wondering if the camshaft has much of any tuning ground into it at all. Not really familiar enough, but my immediate guess would be that (like the rough machined valves) it's only meant to be good enough to let the engine run as a "functional model".
You havn't bored me at all! Love this project. Love this channel. Looking forward to the next update!
If polishing the valves worked that well on that engine do the same to your v4 to see if that gets more rpm also
Not bored ive watched this 3x. Im just amazed at the skill you have building these tiny engines 👍
That is the coolest mini torque/screwdriver thing I've ever seen
I think you need to make an fuel injection system for it
A turbo would be easier to make than that.
@@sepg5084 your not wrong but you know he will find a way to make it
Dude nothing you do is boring! The stuff you do is insanely awesome! 👊😬👍
You're not boring us at all :-)
In 1:1 engines it was determined a long time ago that draw through set ups don’t perform nearly as well as blow through. Go to any drag strip or car meet and they’re all blow through. I do t know it it scales down though? Vacuum leaks will drive you mad. Any unmetered air will cause havoc. God bless you on getting this far.
Iv seen people do this on small motors like for go-carts you need to use a carb with a butterfly not a slide throttle. I dont know why but it just works
Awesome video, quick side note about the pressure gauges you were using. They made fluid-filled gauges that prevent the needle from jumping everywhere under fast changing conditions (and helps them not become stuck as a result) as with the slight resistance of the fluid, it makes the needle show the 'average' pressure compared to the 'instantaneous' pressure.
when running boost you would have to advance or retard your timing ,I know that it doesn't have spark plugs but that would probably be the issue
Would valve float be a concern, I am not a mechanic just a hobbyist
@@LM-uz4pr valve float is an rpm related issue, the only issue you can run in to with changing camshaft timing is valve interference
@@LM-uz4pr Valve leak could actually be an issue that Johnny should inspect for. The valve springs weren't designed to hold positive intake pressure so the boost might be forcing air through them when they are supposed to be closed.
Hard to pull of but definitely cool idea
@@iNubAlert That's true for naturally aspirated cars. In the case of forced induction valve float can also occur when the valve springs are not stiff enough and the sheer air pressure generated by the supercharger/turbocharger manages to push the valves open
To be honest I'm not even "bored to death" with the supercharger. I think it's fascinating, and I would love to see more of it (even if it fails)
I like how you used flush cutters...
But didn’t cut them zippies flush 😂
*cries in mechanic* 😂
Automotive engine builder here. Just to cure your curiosity, since youre reading the pressure at the manifold, the intake valves create a pulsating pressure wave. Jon Kasse has a good demonstration of the pressure waves where he cut a hole in an intake manifold. It will also cause the pulsation in the reading while at boost. I saw your previous video so I know why you did it, just thought I'd explain it!
It's really strange how the engine behaves with the supercharger...maybe it has something to do with the blow through setup but I don't know
I promise I’m not bored of the supercharger videos at all.
I... I can't wait to see this thing on a mini F1 chassis. The thing sounds like a mini F1 at 16k RPM
Put two of them together and you've got something a lot like a mini Cosworh DFV V8...
Nice work! Still awes me every single time about your surgical like precision and steadiness!
Maybe it needs stiffer valve springs.
Bored to death? no this is entertaining to watch and see the progress you make in making smol super chargers. keep up the good work
what if the air that gets "comprimed" is to hot/big? make a tiny intercooler loop se if that helps?
The power increases slowy or no power increased, reason of the existence of Intercoolers doesn't matter its supercharger, turbo or centrifugal turbo.
In case of supercharged engines the cooling is down to the compressor before enters the engine, it's watercooled by a second radiator as intercooler, this also applies in centrifugal turbos used commonly in bikes.
My guess with your blower set up is that you should Box in the entire carburator, not just the inlet port. Maybe there is some blowby throu it that would affect the mixture
Also, maybe the mixture should come down in the engine port, and not "climb in it" we are dealing with a very small air volume here after all...
Not bored, more impressed if anything.
I'm was and will never being bored see your tests and research! Don't hesitate to continue
In this case due to exhaust smoke I could say the fuel is clearly not normally carrying to engine. The engine have it in excess when you open throttle and compressor puzch the "heavy" oil+fuel to engine.
If methanol is easy to transport on the air of your supercharger, oil that's take part of fuel could not be follow a such long tubing before engine
I think your problem is here.
Solution is hard but probably you need to separate air throttle and fuel
Install a fuel sprayer as near as possible to valve and a simple air carb where you want.
I want to see aluminium conecting rods for this engine
I think what youre getting is called Runaway, when the RPMs keep climbing and as a result building more boost and creating a stronger differential pressure. And i believe its that differential pressure thats sucking fuel out of the throttle even though you arent operating it yourself. Basically somewhere near your carb is allowing too much fuel in
watched this litte motor gain 4000 RPM by valve lapping and thought "wow" then i saw the super charger.
The motor has had that supercharger for a while now
Love your work. Really looking forward to positive displacement supercharger too, will love to see how you solve that challenge.
Huge gain ! Never would have thought it would be that big of a difference .. ENJOYED..
I'll never get bored of this stuff and I don't even know what you're doing most of the time
Absolutely not bored with this, I am willing it to work!
We never get bored, this content is too good!!
It doesn't matter what you post. Your videos are hypnotic. Love your content. Do your thing.
I can't believe the valves weren't lapped. Definitely subscribing! Is this a glowplug engine or perhaps magneto? I wonder if fuel pooling is the problem now
You need a plenum chamber, for a twin cylinder about twice the total engine cc, and also as some have commented here some fluid damping in your gauge. The gauge oscillation is quite interesting, perhaps it indicates that the plenum could be even a little bigger than 2x displacement. 2-3x maybe and try to make it so the supercharger does not actually blow into the intake. So say, blow away from the engine with the supercharger, then into the plenum. Then an exit above the plenum entry so the charge exits toward the engine.
That would help to keep pressure pulses at bay. The 1:10 gear looks more like it too. Fantastic builds, keep on keeping on.
Brilliant. I think the 3psi is believable as the boost from a centrifugal blower rises almost exponentially with shaft speed, up to a point.
I did wonder why you went the hard way instead of going with a positive displacement but you explained it at the end.
That noise it makes at 16k tho... awesome.
JonnyQ90, addressing your issue with the vacuum/pressure gage fluctuation quandary, you might employ a ''Fluid Damped'' gage. Basically, the workings of the gage are immersed in a nearly, colourless viscous fluid that slows down the majority of the erratic fluctuations in the gage.
I actually made a fluid damped gage myself, in a far off land, during a critical aeroplane emergency. I prising off the bezel with the lens and filled the gage cavity completely full with a nearly colourless viscous liquid.
We had a local denizen boil up some sugar cane juice until it was about the viscosity between ''light [clear] corn syrup'' and ''type 3 brake fluid''. Then when the gage was filled, sealed the lens to the bezel with ''rubber tree sap'' then wrapped ''black electrical tape'' around the gage housing to seal against the viscous fluid leaking
It worked, but we were still captured anyway...please don't ask where. HaHa!
Amazing what simple polishing did. Didn’t know that could happen!
Not bored at all, JQ. Soon as I see a new JQ vid posted, I’m on it straight away! Can’t help thinking that maybe the “hunting” is due to pressure leaking back from the inlet via the carb and maybe pressurising the fuel system?? Looking forward to seeing this new project car taking shape. Hard to imagine what new ideas you’ll come up with but I’m sure it’ll be awesome!! How about a CVD? Electronic clutch? Viscous coupling?!? That’s it. I’m outta ideas! LOL
Always enjoyable to watch the craftsmanship. thanks for the entertainment at work.
PLEASE READ THIS I think one issue you might be having is with the little amount of boost blowing the valves off there seat Im an engine builder and sometimes see this in cars that have been turbocharged but were factory NA you build boost in the intake and sometimes the pressure is enough to push the valve off the seat loosing compression because of springs not designed for that positive pressure people think you only need aftermarket valve springs when you put a cam shaft in which is not always the case maybe this is why your engine breaks up on the top end of the rpm range you could possible shim under the spring maybe .001 or .002 im not sure because of how small it is for reference on a small block chevy after a valve job we usually throw a .015 shim under the spring just to bring it back to stockish pressure to make up for the material removed from the head and valve during machining hopefully this helps!!!
why I like to polish every moving part or wear part to a mirror finish, or anywhere where flow happens. less resistance to motion, turbulance to flow, and tighter the meet up, usually makes for more power and reliability, and makes the oil and coolant's job easier, especially since polished surfaces reflect heat more and wont absorb it as much, making cooling more efficient usually.
There is something extremely relaxing about your videos
It's seriously worth saying the centrifugal supercharger is not boring, after seeing you make it so long ago I wanted nothing but to see it in action and I'm loving the progress you're making and I know it would be a ton of work but perhaps if you made the impeller larger you could make more boost without spinning it faster? Also a positive displacement sounds dope, with either way keep doing you. I love your content
Just my 2 cents on the tuning issue:
It appears the fuel isn't atomizing enough and it's pooling into the supercharger. That may be why your pressure goes up soo much because fluid doesnt compress. Also causing it to run away on you too, since it's basically a small diesel (no spark plugs). I'd bring the carb down a step and run more fuel with the smaller carb, or go back to the blow through setup you had before. That's what they did on the 80's era Buick's with the v6 turbo. Worked well for a gas vehicle.
On a diesel mindset:
A supercharger that moves air and fluid has more "open" clearances that aren't as tight because the non-compressable fluid and air both running through it. That's a lesson from Gale Banks who's a genius with this stuff. I highly recommend his channel if you haven't seen it yet. Love the content and keep up the good work! 👍
In my opinion, this is the most interesting supercharger kit I ever seen 😌 you are such a talented machinist 😶 Don't loose motivation now, 🙂 it is so close 😊
Btw, how is that draw through setup behaving with smaller crank pulley instead of bigger one you installed in video?
That's blower surge. The engine gets drained of vacuum and then picks up idle to replace the pressure. A blow-off valve will help with that because it will bypass the extra pressure down low when the throttle is closed. The air being forced into the engine constantly is causing it to run lean and when you finally open the throttle and more fuel is added it starts to run away. You need to be able to push more fuel and if possible adjust the timing to keep the intake valve open a little longer to handle the extra pressure from the charger and extra fuel.
Now that's what I'm talking about! If you put a little charge/effort to the engine's output, exhaust gases are going to come out with more pressure and speed spinning the turbo way better, and is going to be easier to tune, you can try putting a small electric generator in the engine as a mean of adding a charge to the crankshaft
Amazing skill my dude! So many people can learn a LOT from you. More people need to take pride in their work like you do.
You sure as hell haven't bored me. I love to see your work.
@JohnnyQ90 with a draw through setup on this type of carburetor, it still likely needs a boost reference line to the fuel tank, because changes in air velocity vs boost are independent of each-other, (given the supercharger isn’t positive displacement), and doesn’t have power-valves and accelerator pump like a Holley, to make the transition from idle vacuum into boost smooth at a consistent air fuel ratio. Adding a tank boost reference line will radically change the tuning of the fuel screw position compared to where it is now and may help a little at idle but my make the engine erratic at a different throttle position of load (won’t know without trying).....a better solution could be to put a boost reference line to the tank with an air screw assembly from a carb in it to restrict air going to the tank so both air screws can be tuned independently......an easier solution would be to cap air velocity by using a much larger carburetor or 2-carburetors of the same size as current in parallel with a y-manifold.....this would lower the air velocity allowing you to richen up the mixture, and have less surging at idle but still have adequate fuel flow at top RPM without a tank boost reference line......the last solution and possibly the best would be to stack two of the current size carburetors in series (each using its own separate fuel tank) and one carbs fuel tank is boost referenced and the other is too atmospheric pressure. This would allow tuning like Holley having both “high” & “low” speed fuel circuits that could be tuned independently......just some thoughts, hope this helps, keep up the good work.
You need a compound gauge, that can read vacuum and boost/positive pressure. Something in the 30 in Hg to 0 then 0 in Hg/psi to 15 psi. They make them because we use them at my work. Also spend a few extra dollars to get one that is glycerin filled to keep it from jumping around and destroying itself. Can find them from grainger or McMaster Carr.
Though I am far from bored with the centrifugal supercharger, I'm beyond geeked to see you do some kind of positive displacement rig. I'm guessing you'll go with a Roots-style setup, but whatever it is, I know it's going to be dang cool. Good luck! Can't wait to see it!
Keep up the awesome work!! So close to the Holy Grail so don't give up. Try finding an oil damped gauge cuz what is killing the gauge is needle oscillations ( it's moving way too fast). Years ago I ran across a book dealing with artificial boost for internal combustion engine design when I was playing around with turbo design for my bikes trying to eliminate most of the turbo lag. If you can find it, or something similar, that may help. Just keep at it cuz it is fascinating to watch you work. You have a talent that most don't. Can't wait to see you begin porting and stroking it (hint, hint).
check valve on the gauge should hopfully block it from reading vacuum
the tuning problem is due to the carb, the supercharger pulls a vacume on the carb side when in a pull through config, because of this it pulls fuel past the needle and air from around the slide, the engine then runs away, the combustion sustains the rpm which sustain the vacume which sustains excess fuel and air flow. a smaller pully on the engine would help with this. you can also hear the supercharger surging which supports this, the engine leans out the revs increase the supercharger pulls fuel and air in which makes the engine pick up. a better carb or efi would help this problem but its all about how far you want to go with a model engine. awesome work eitherway, cant wait to see more
I personally, am not bored with the centrifugal s/c! I like watching you experiment with different setups. Maybe after you make the positive displacement s/c, you should perhaps try to convert the centrifugal s/c to a turbo by making a centre section, turbine (and housing), with a mini waste gate. It would probably be better on the 4cyl engine though.
Also, maybe using those reusable zip ties may be worthwhile, as you wouldn't need to buy so many!😅
Anyway, I always get excited when I see a notification from your channel, so keep those cool videos coming!
Just a suggestion, instead of putting the pressure gouge directly on the outlet port, try running at least a one foot length of tubing with an air snubber/dashpot to stabilize the reading. Maybe even a gauge that is glycerin filled? Great video as always!
For its running issue, it might have something to do with it having a lot of boost after revving that there is no where for it to go. Something that relives pressure when dethrottling would probably work, like a blowoff valve. Also somewhere in the comments said the carb might be to small for the vacuum, and that could also be it, as it would draw in more fuel, and is hard to meter.
Never bored with anything you do Johnny I could watch this stuff allday everyday gr8 video bro....👌👌😉
JohnnyQ90, incredible work you do, always pure joy waching you bring thos engines to life ,,. 1/8th scale twin 4stroke, cant hardly wait,thank you!
I like how clean and productive your work space is, Thank You for the awesome vids too