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Electronic solutions to modifying glow engines of all sizes to gasoline

Old 09-07-2022, 07:29 PM
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Originally Posted by Glowgeek
Yes, I know the "flyer" of which you speak.

RE nitro: It's my understanding that nitro has little to no effect on engines equipped with CDI. A little more oxygen is brought in with nitro so a tiny bit more power is produced but I haven't heard of any other effects. My 200Ti ran on 15% nitro and GI with no evidence of detonation, even when overly leaned and using the Xoar 18x8.
Well, when running nitro with spark ign... the more nitro content in the mix a strong spark energy is required to ignite the mix, therego the methanol kicks off the nitro when the methanol content is higher than the nitro content... nitromethane is self oxidizing, so the added oxidizer increases the thermal efficiency of combustion, you run a bit on the rich side to take advantage of the increase in burn rate... we run in the opposite mix ratio, 75-80 % nitromethane, and 25- 20 % methanol... running dual 1200mj Digital magnetos.

Lighten the prop load and start from there... I see in the pdf, siato recommend 10-15 % nitro, which is quite a bit for that compression ratio... and then again, the spark energy produced from those Saito ign systems, is rather weak in comparison to the late CH, and RCXel... I took a beating for wanting to produce a CDi system with higher spark energy output, but its done for a reason.
Old 09-07-2022, 07:36 PM
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Originally Posted by Cat 1
First thing we do on the real ones if parameters change and other characteristics don't is suspect the instrumentation... ( 9 times out of 10 its the cause).. Is there a chance one of the temp sensors is having an issue?

Got my ignition setup done - Kinda a Morris mini motors setup using two rings... just the mount left now...


Ok call me intrigued, how did you get that aluminum magnet ring to nestle in the valley of that prop hub without a seam.

Wait a minute, is that thin wall tube, press fit over the prop hub?... looks deceiving, as it looks like its recessed in the groove of the hub, but its not.

Last edited by John_M_; 09-07-2022 at 07:41 PM.
Old 09-07-2022, 08:05 PM
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Originally Posted by Glowgeek
A blade of grass caught in one of the intake runners maybe?
I am thinking along those lines as well. I have had before that a blade of grass somehow got wrapped around the intake valve stem of one of the cylinders. Apparently grass is fairly resilient in sticking where it don't belong.

If the choke would not be necessary for this particular plane, I would allready have installed an air filter, because looking at the mass of dead insects sticking to engine and front of the plane after each day, I an pretty sure stuff will get ingested every now and then.
Old 09-07-2022, 08:16 PM
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Originally Posted by Cat 1
First thing we do on the real ones if parameters change and other characteristics don't is suspect the instrumentation... ( 9 times out of 10 its the cause).. Is there a chance one of the temp sensors is having an issue?
That was my first instinct as well, but I don't see how... Usually these tiny sensors work or fail spectaculairly, they don't "loose calibration".The sensors are still firmly in place, and up to about 100 deg C they are indicating properly AND about "as they should".

Still going to gap the plugs, because whichever way, they have a bit of wear of course, but they are far from worn, and I was actually surprised how clean they were. Basically a thin film of black that wiped off with a fingertip except from the mass electrode, and even the isolator nose was still recognizable as "having been white once".

Right now I am guessing, but I have the feeling that dirt build-up in the intake ports (or something similar) might be the most likely thing, and in all fairness am a bit surprised that the O-rings sealing the intake runners in the plenum (T-piece) have not yet been eaten by the gasoline after 5 years.
Old 09-07-2022, 08:19 PM
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Originally Posted by John_M_
Ok call me intrigued, how did you get that aluminum magnet ring to nestle in the valley of that prop hub without a seam.

Wait a minute, is that thin wall tube, press fit over the prop hub?... looks deceiving, as it looks like its recessed in the groove of the hub, but its not.
I think that is the "Metal Magic" that we have grown accustomed to from Chris... We have officially stopped wondering how he does that...

Old 09-07-2022, 08:45 PM
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Originally Posted by John_M_
Ok call me intrigued, how did you get that aluminum magnet ring to nestle in the valley of that prop hub without a seam.

Wait a minute, is that thin wall tube, press fit over the prop hub?... looks deceiving, as it looks like its recessed in the groove of the hub, but its not.
Originally Posted by 1967brutus
I think that is the "Metal Magic" that we have grown accustomed to from Chris... We have officially stopped wondering how he does that...

picture is little deceiving -I will take a few more to explain as A picture is worth a thousand words and im tired .
Old 09-07-2022, 09:05 PM
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Only trick is a little notch in the original hub to clear the magnet which protrudes on the inside bore - Set screws hold the sensor mount and mag ring in position (2 each) . The sensor ring gets a couple of internal slots to clear the case seams.. Allows for easy set up and fine adjustment..








Old 09-07-2022, 09:59 PM
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Brilliantly done, Chris, really beautiful.

Like I said, that "Metal Magic" that we have grown accustomed to...

And I mean that in the nicest possible way.

Dang it... I have to apologize, I totally forgot, still haven't sent your stuff. Will do today.
Old 09-08-2022, 12:53 AM
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Thats basically what I did with the os boxer using white delrin... press fit with no set screws to hold its position... has not moved since positioning the magnet.

https://ibb.co/L5YLzXf



Old 09-08-2022, 01:25 AM
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OK guys, so I opened up the portside cylinder, the "problematic one"...
This is how it opened up:

Crown before cleaning

Head before cleaning

Single wipe with a piece of dry kitchen paper later...

Ditto. The black wiped off really easy.

I was a bit dissapointed by the scuff marks...

not my favourite thing to see. Not too worried about it either though.

BUT...

The exhaust valve however, had some serious carbon deposits, hard deposits. I fi had to estimate, at least 0,5 mm but impossible to measure.

Three runs in a high powered U-son, AND a "popsicle stick polish" later...

The "popsicle stick polish" is nothing more than chucking the valve stem in a Dremel, and at minimum RPM (which still is fairly fast of course) rubbing the valve disc and stem with a popsicle stick. It removes the hard deposits fairly well without damaging the valve or its landing face.

The valve seats in the head were still perfect, and I was a bit surprised to see that the valve was coked up a bit, but the exhaust port at best a bit sooted and did not require cleaning.
The intake runner turned out to be clean inside, the O-rings still good, and even the sparkplug gap was still a tight 0,5 mm, which surprised me a bit, because they are now about 10 hours in and I would have expected them to have widened a bit allready.
when remounting the head, the valve lash had tightened up considerably (at least 0,05 mm) which puzzled me a bit but I will recheck after one or two runhours.

Whatever the case, a quick testrun showed that the temperatures now remained within 5 degrees from each other all the way up to 125 degrees and full thottle , and there was no distinct tendency for either cylinder to run hotter than the other. They traded places a bit throughout the run-up.
Full throttle RPM was nominal at 7400~7500.

I have a hard time believing that the coked up valve would cause a COOLER run, but what can I say? It is what it is.
The other head I did not yet check or clean.

Bottom line is that I don't like the scuffing marks but I do believe this happened early in the engines life (compression has always been a bit lower on that cylinder), but that I am extremely happy to see that the valves and seats underneath the dirt are in pristine condition, and that piston and combustion chamber do not have any hard carbon deposits. The engine apparently burns pretty clean along the entire throttle range, and the oil I use seems to handle the running conditions well.

This Saturday, weather permitting a tow&glider meet, let's see how the old lady will perform.

Last edited by 1967brutus; 09-08-2022 at 01:29 AM.
Old 09-08-2022, 02:58 AM
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Interesting Bert. The coked ex valve reduced scavenging during the valve overlap period, I suppose. Less fuel=less power=less heat. I'll put that one on my trouble shooting list.
Old 09-08-2022, 03:07 AM
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Originally Posted by Glowgeek
Interesting Bert. The coked ex valve reduced scavenging during the valve overlap period, I suppose. Less fuel=less power=less heat. I'll put that one on my trouble shooting list.
I would have expected a coked up exhaust to cause a cylinder to run hotter, just gutfeeling, because it can't get rid of its hot gasses.
Apparently I am wrong with that. It is the first time that I see a coked up exhaust valve and I have no real explanation as to why, but one possible explanation is that due to the scuffings, this cylinder dumps more oil to the crankcase, leaving less oil to wash the valve.
But that too, is just a gutfeel.
I have so far not yet seen a valve coke up and I do have a 5 cc that has more runhours than the Boxer.
Old 09-08-2022, 03:15 AM
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Originally Posted by 1967brutus
I would have expected a coked up exhaust to cause a cylinder to run hotter, just gutfeeling, because it can't get rid of its hot gasses.
Apparently I am wrong with that. It is the first time that I see a coked up exhaust valve and I have no real explanation as to why, but one possible explanation is that due to the scuffings, this cylinder dumps more oil to the crankcase, leaving less oil to wash the valve.
But that too, is just a gutfeel.
I have so far not yet seen a valve coke up and I do have a 5 cc that has more runhours than the Boxer.
It could just be a reflection in the pic but the cylinder wall appears to have signs of excessive blowby at mid stroke, when the piston is being torqued/tipped by the sharp rod angle. Could it be a less than optimal piston to bore fit, leading to excessive blowby, cylinder wall scraping and inadequate oil for washing the ex valve? Just a thought.

Last edited by Glowgeek; 09-08-2022 at 03:23 AM.
Old 09-08-2022, 04:59 AM
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Bert and all - Can you share a picture of your temp sensor location and mounting - I am putting the parts together to do this on mine with the Graupner telemetry...

Chris
Old 09-08-2022, 05:18 AM
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i can. these are the photos i have without a trip downstairs to the shop...

i use jb weld to secure the RTD and i stuff it adjacent to the head behind the cylinder where it is shielded from the airflow. here's photos of my fs40 and my ft120. if you need more, i can run down and take a few. i use red and blue wires for the RTDs.





Old 09-08-2022, 05:20 AM
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Originally Posted by Cat 1
...I am putting the parts together to do this on mine with the Graupner telemetry...

Chris
openxsensor does Hott telemetry. i believe it's the same protocol graupner uses? you can easily build telemetry devices for a few bucks the same as i do.
Old 09-08-2022, 10:45 AM
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Originally Posted by Glowgeek
Interesting Bert. The coked ex valve reduced scavenging during the valve overlap period, I suppose. Less fuel=less power=less heat. I'll put that one on my trouble shooting list.
Definitely... effects cylinder fill... as does a long restricted exhaust system, like that kelo exhaust with the flat bends Cats got on his boxer... not a fan of that heavy wall aluminum tubing they used.

@ Bert, shame to see the scuff marks as well, especially with that castrol RS 2t oil you run... could be the hard carbon, or it ingested something... Are you running without an air filter?... the boxer is a difficult one a fit an air filter to, but one of those mini boom mic foam windsocks fitted with a wire tie may help... Our rwy is in the midst of the spreading grounds of a flood control basin, and the fine sandy grit gets kicked up on takeoff / landings, plays havoc with the Saito aluminum valve seats.

Last edited by John_M_; 09-08-2022 at 10:58 AM. Reason: added
Old 09-08-2022, 11:52 AM
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Originally Posted by John_M_
Definitely... effects cylinder fill... as does a long restricted exhaust system, like that kelo exhaust with the flat bends Cats got on his boxer... not a fan of that heavy wall aluminum tubing they used.

@ Bert, shame to see the scuff marks as well, especially with that castrol RS 2t oil you run... could be the hard carbon, or it ingested something... Are you running without an air filter?... the boxer is a difficult one a fit an air filter to, but one of those mini boom mic foam windsocks fitted with a wire tie may help... Our rwy is in the midst of the spreading grounds of a flood control basin, and the fine sandy grit gets kicked up on takeoff / landings, plays havoc with the Saito aluminum valve seats.
With some of the Saito AAC cylinders I imagine it would. Older glow Saitos with cast-in liners had bronze valve seats, as does the FA220 (AAC) and all of the FG series gassers (AAC), except the FG20, which has a history of burnt exh valve seats.


Last edited by Glowgeek; 09-08-2022 at 12:15 PM.
Old 09-08-2022, 12:05 PM
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Originally Posted by Glowgeek
It could just be a reflection in the pic but the cylinder wall appears to have signs of excessive blowby at mid stroke, when the piston is being torqued/tipped by the sharp rod angle. Could it be a less than optimal piston to bore fit, leading to excessive blowby, cylinder wall scraping and inadequate oil for washing the ex valve? Just a thought.
I saw that, but that is the soot on the piston top mirrorring in the cylinder wall.
The liner itself has a mirror-like surface (apart from the scratches). There is not a sign of overheating anywhere. Not on the liner, not in the head, not at the valves, nowhere.
There are also no signs of piston ring collapse or excessive blowby (no excessive crankcase pressure). Never have been.
Old 09-08-2022, 12:13 PM
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Originally Posted by John_M_
@ Bert, shame to see the scuff marks as well, especially with that castrol RS 2t oil you run... could be the hard carbon, or it ingested something... Are you running without an air filter?... the boxer is a difficult one a fit an air filter to, but one of those mini boom mic foam windsocks fitted with a wire tie may help... Our rwy is in the midst of the spreading grounds of a flood control basin, and the fine sandy grit gets kicked up on takeoff / landings, plays havoc with the Saito aluminum valve seats.
I am fairly confident, the scuffmarks happened during break in. The engine has always had an uneven compression from basically the start. Probably some production dirt not properly cleaned off at assembly. The engine otherwise shows zero signs of poor lubrication, and the oil from the crankcase is absolutely clear from both soot and metal particles.

I can fit a filter but then will lose thepossiblity to choke before start, and that is very impractical
Old 09-08-2022, 12:18 PM
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Originally Posted by 1967brutus
I am fairly confident, the scuffmarks happened during break in. The engine has always had an uneven compression from basically the start. Probably some production dirt not properly cleaned off at assembly. The engine otherwise shows zero signs of poor lubrication, and the oil from the crankcase is absolutely clear from both soot and metal particles.

I can fit a filter but then will lose thepossiblity to choke before start, and that is very impractical
???? You are running muffler pressure, aren't you?
Old 09-08-2022, 12:25 PM
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Originally Posted by Cat 1
Bert and all - Can you share a picture of your temp sensor location and mounting - I am putting the parts together to do this on mine with the Graupner telemetry...

Chris

Fort 2-strokes I prefer, if possible, this method


In fourstrokes, I jam the probe between the fins of the head (not the cylinder/casting). No glue, just push the probe between the fins. If necessary pry the fins a bit apart.
Old 09-08-2022, 12:28 PM
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No zip tie?

Originally Posted by 1967brutus

In fourstrokes, I jam the probe between the fins of the head (not the cylinder/casting). No glue, just push the probe between the fins. If necessary pry the fins a bit apart.
Old 09-08-2022, 01:00 PM
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Originally Posted by Raleighcopter
No zip tie?
That pic was during installation... (note there also is no throttle rod yet). So... At that point in time not yet..

Rest assured that there is a ziptie now.... And a throttle rod!


Last edited by 1967brutus; 09-08-2022 at 01:06 PM.
Old 09-08-2022, 01:18 PM
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Are those scuff marks deep, or do they just burnish the surface.



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