I was thinking it would make a pretty good aspiration pump.

On a slightly different topic, I replaced my transmitter with a frsky x18s. It's a nice transmitter that runs ethos instead of opentx. Problem is the curves only allow you to select integer values and opentx obviously had fractional steps between the I teger values on curves. This lack of curve resolution had me chasing a proper mixture curve and the steps are big enough that it jumps right over the peaked rpm when tuning. I've added a fine tune curve to get the resolution and am currently waiting for it to get above 50f to go attempt to tune the mixture curve. Anyway, be aware of the issue and I'll report back if my solution worked.

It would be nice if they increased the curve resolution to 1024 steps so it aligns with the stick and output resolutions.

The scale is in 0,1% increments, acc manufacturer accuracy is 0,5%
At least on the putt-putt boat engine, the exhaust is 100% oil free. The muffler does not even get warm to the touch, and is fitted with an oil and water drain.
I will still have to figure out how that will turn out with the MUCH hotter running aero engines, most likely I will need an exhaust adapter with an oil absorption set-up, maybe route the gasses through a Viledon filter or similar.

To be honest, I never even considered the effect of ignition timing on CO content. All my engines are timed for 28 degrees. If I have the opportunity, I'll do some experimenting on that.

Am I correct in thinking that advanced ignition reduces CO and retarded ignition increases it? (just a hunch based on advanced ignition resulting in more time for the burn and an intenser burn, retarded timing resulting in a shorter burn time and less intense burn process).

Indeed, The final finetuning in my plane engines were done by carefully observing the exhaust residue, but the issue with that would always be: "WHERE in the curve is that elusive rich spot that causes the black goo" ... I have so far always managed to spot it and remedy it, but at times it was VERY time consuming.
This way of tuning (running the engine through its throttle range while observing the measurement) COULD be of help here..
What is more: on "Non-Electronic" conversions, where the carb needs modification, the meter tells you where the fuel linearity goes.
In case of the small boat, the meter shows fairly conclusively that fuel supply rises at greater rate than air supply when the throttle is opened: CO percentage increases under load while compression pressure and combustion pressure go up (which in theory should make the combustion process more complete)

On the bolded: I agree with Dave, I think that is a VERY good idea...
I'll look into that.

Dang... That is something I would NOT have expected from Ethos... Bummer, hope you solve it.

Yeah, that really socks. Glad I stayed with otx/etx. Recent firmware upgrades have made it possible to run all forms of access rx's on my 2019 SE.

Well, that didn't work. Next up, a new hall sensor. This is annoying the crap out of me now.

...throttle servo is sticking.

What are you working on, Dave?

My cub. I was getting it ready to fly when it's warm and it's giving me hell. I had hoped to just copy the mix curve from my old radio to the new one but I'm having other issues at the moment. I think I need to pull the tank... Hold on....

Goddamnit. It was out of fuel. I think I need a break. I'm off to find a glass of bourbon. Pay no mind to the alcohol. I still prefer gasoline.

I did do this though...

Cool, been waiting for that. Should be a very fun experiment running the mtronic carb on a radio.

I spent 20 minutes messing around and messed up my almost perfect curve one day before I realized I was out of fuel and sucking air... Wouldn't have been that bad but it was on the test stand and fuel level was readily visible...

Yes, hi CO is the result of incomplete combustion... advancing ign increases the burn time, also raises combustion temps... too advanced, NoX forms, but these little engine are more tolerant due to such small displacments... as mentioned in the past, these model CDI systems have a fixed ign curve, configured for a 28 degree base timing... With that small putt putt setup you have in your boat, you probably can get away with it fixed at the optimum timing position, with manual retart for startup... if you could monitor Co2 as well, then that would give you a better reference to combustion efficency.

So I'm going to share some progress and improvments I have made to my CDI with you guys... now running 2 seeeduino's in series, not in cascade, but shares data... first seeed handles ignition timing using ign timing reference tables / cross referencing to rpm with zero interrupts... the other seeed manages rx channel data to manage throttle arm to lockout startup with the throttle stick too hi, similar to how electric esc's function... trying to include sbus2 for other future features... it will have standalone programmability with a separate plug-in device, with program buttons and a small LCD screen, with 8 programmable ign points, and programmable rev limiter... I have someone working with me on it who knows programming a bit better than I... I'm also working with another inividual that may produce theses at a reasonable cost to sell, under $100 USD... a bit larger in size than what we have now ( not by much, just a different shaped enclosure ) and about 1 ounce (28.35g) heavier... 38k spark voltage, multi- spark output with flash over protection, with 3 banks of hi voltage ceramic capacitors switched by the seeed based on rpm... I'm tickled to see this come this far, and it has taken a lot of my spare time.

Mine is still sitting on the endmill table, waiting to be bored out to Bert's solenoid dimensions... I haven't given up on the idea, just been side tracked... my neighbor and I are in the final stages of scratch building a 30% Hostetler Cessna 170 Tundra...its a big bugger, 10' 6" (320cm) wing span... in the process, made some changes to my H9 pa18 .

Ooooohhhhh.... Me LIKEY!!!!

WOW... That sounds good!

Well it's what I've been after since switching over to using CDI... what was holding me back from making it public is the security of the source code, not so much to stop you guys from having a look, but from someone else using it for profit... I don't need to make any money on these, just doing it for myself and the hobby... RCxl, and CH, both are more than capable, based on the complexity of thier milti-cyl radial cdi systems, so I have no worries or concerns with them... it's more about protecting the time spent on developing it... we have away of dealing with that figured out, so the code won't be acessible for the timing side of things... the programmer all it does is reorder and update the lookup table based on your selected ign points, so there's nothing proprietary happing there, nor with the rx channel data / sbus2... potting the electronics for the same reasons, plus vibration protection that's where most of the added weight is... sorry, but I have thought this through for quite some time, and there is so much disregard / disrespect for others in this world these days, I'm not going to just give it away as open source, after spending nearly 4 years on and off, with the help of others involved as well.

Again, this is nothing directed towards you guys, just the world as a whole... I'm sure overseas, there are more than capable individuals to figure it out, but let them figure it out by themselves.

OK, so here's where I'm at right now... I'm building these for just the cost of the components... No source code / sketch will be included... availible in either single or twin units, (including odd fire)... these are wasted spark, I choose to go this route for obvious reasons, not everyone can make the modifications needed to add the additional hall sensor... I still need to come up with a cost, they will be built on a per order bases... if it fails for any reason other than tampering, I'll replace it at no cost... I have one sitting here on the bench performing a durability test that's been operating for several weeks with no issues... I'll let you guys know more when I get everything all sorted out.

John, I have some questions about your cool project.

Do I need only one programmer for multiple CDI units?

Does the programmer have memory so that any given programmed curve can be uploaded to other CDI units.

Does the programmer come with preprogrammed curves?

Does your CDI unit have an rpm output or some way to interface with telemetry?

Does the eight point timing curve address rpm above 4000?

Would we need an exhaust gas analyzer for tuning the timing curve?

Thanks,

Lonnie

John,

Your project sounds impressive and I would like to try one when Its avalible. I admire your effort in this as I know the work involved in creating a reliable ignition system. I played with this back in the day and had a very robust fixed ignition unit developed that I utilized "straight up" or with mechanical advance to do "weedwacker" conversions. My project ended when I got frustrated trying to solve the electronic advance - Packaged development boards were not here yet and PIC programming was my Nemesis. I spent many hours hand winding experimental toroid transformers and coils.

It will come with the plug-in programmer.

When you first plug it in, It will read the current assigned ign table, and store it in the programmer... then with each change you make to the ign map, it will always store the last ign map that was programed, so it stays in sync with the ign map in the cdi box.

It will come already setup with a basic ign map / curve that will run any 2 or 4 stroke engine.

Well above 4000 rpm , due to how the ign advance sys works based on an ever diminishing delay time from the base / static ign timing setup... you setup your base timing anywhere up to 42 degrees advanced, and then set or map each of the 8 ign points to any given rpm / degree point on the table.... if you duplicate a point with the exact same rpm and degree, you will only have 7 ign points, so you can reduce the number of ign points used on the ign table down 2 or 3 if you desire, but the duplicated points have to coincide with each other consecutively in order to reduce the number of mappable points.

No gas analyzer needed, but you will need to retune your needle settings of course, or your solenoid mixture curve .

It has an rpm output... and it will also have sbus2 for telemetry, that's what we are working on now... it also has a throttle servo plug port, so you can plug the throttle servo directly into the cdi box if you dirsire, but not required... I added that just to make it convenient, as most place thier throttle servo up in the nose of the AC.

I'll let you know when I get ready to release them.... PIC is what was used in the original CH ign systems back when Bill Carpenter first introduced CDi to the hobby... todays arduino are even more capable... the method of advance is a diminishing delay time over rpm, down to zero delay, puts your ign timing advance at your static base timing you set the engine up with... the CDI electronic circuit is your basic stepup transformer, charged capacitors, discharged into a mult-wound ign coil... nothing elaborate really... A typical handheld BBQ spark Ignitor works in a similar way, ours has better quality components of course, and a higher voltage output... the cdi is internally regulated of course, 2s 6.6v LiFe minimum required, 3s LiFe, or LiPo will work just fine.

Ignore my complaint about curve resolution on ethos. I tracked my issue to a sticking throttle cable. All is well now and just a bit more tuning and it'll be ready for warm flying days.

That has a short wing tube on it Raleighi'... wing struts are strong I hope.

That's the tube from the kit. Struts are plenty strong when properly attached.

Quick question... since most of you guys are using Frsky radios, and I use Futaba of course... so I'm unfamiliar with Frsky's sbus protocol... is it compatible with Futaba's sbus?... I know its not compatible with sbus2.