Glow Engines Discuss RC glow engines

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Old 04-23-2019, 02:48 AM
  #40251  
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Thanks Pete, yes I get that but nitro advances the ignition timing and you can only induce so much fuel charge into the combustion chamber with any given engine setup. Higher compression also advances the ignition timing and although it also contributes to higher volumetric efficiency at some point the introduction of higher nitro will bring on detonation.
A fella can keep raising the nitro content in his fuel until no further peak rpm is seen and then back off a percent or two for safety but yes, it will drain the tank and the bank.

What my little project is all about is to raise engine hp through volumetric efficiency and hopefully realize some long term cost savings with little initial investment. Besides, I enjoy engine modding as much as flying. I also like slighting the EPA whenever possible but that's another topic, one that I believe nitro users will be discussing more and more in the not so distant future here in the US.
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Old 04-23-2019, 03:10 AM
  #40252  
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Originally Posted by Hobbsy View Post
Lonnie, here is Clarence Lee's word on the high compression 80: Saito FA-80

And the HC 150: Saito FA-150S
Thanks Dave. I never thought to look at Lee's articles on the high compression engines. Very encouraging to see he was running the fa150 on 18% nitro. He did mention rattling (detonation) when leaned too far at peak rpm but I feel better now about continuing to raise the cr of the 82.
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Old 04-23-2019, 03:10 AM
  #40253  
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Originally Posted by Glowgeek View Post
Thanks Pete, yes I get that but nitro advances the ignition timing and you can only induce so much fuel charge into the combustion chamber with any given engine setup. Higher compression also advances the ignition timing and although it also contributes to higher volumetric efficiency at some point the introduction of higher nitro will bring on detonation.
A fella can keep raising the nitro content in his fuel until no further peak rpm is seen and then back off a percent or two for safety but yes, it will drain the tank and the bank.

What my little project is all about is to raise engine hp through volumetric efficiency and hopefully realize some long term cost savings with little initial investment. Besides, I enjoy engine modding as much as flying. I also like slighting the EPA whenever possible but that's another topic, one that I believe nitro users will be discussing more and more in the not so distant future here in the US.

For any curious folks here is DMRC running a Saito on Davis Diesel fuel.

Last edited by Hobbsy; 04-23-2019 at 03:11 AM. Reason: Add content
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Old 04-23-2019, 04:29 AM
  #40254  
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A fellow sent me a Saito FG 20 that Ibwill be converting back to methanol fuel, retaining spark igntition. Anybody know the C/R of the FG 20, or should I just measure and compare with my FA 125?



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Old 04-23-2019, 04:45 AM
  #40255  
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Originally Posted by Jesse Open View Post
A fellow sent me a Saito FG 20 that Ibwill be converting back to methanol fuel, retaining spark igntition. Anybody know the C/R of the FG 20, or should I just measure and compare with my FA 125?



The FG20 and FA125a show different part numbers for the cylinders and could have different combustion chambers volumes. I'd cc them both. Logic tells me that if there is a cr difference that the gas version would be lower.

Last edited by Glowgeek; 04-23-2019 at 04:51 AM.
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Old 04-23-2019, 05:51 AM
  #40256  
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This is also interesting:

Saito FG 20
Bore===1.24" or 31.7 mm
Stroke==1.02" or 26 mm

Saito 125
Bore===1.24" or 31.7 mm
Stroke==1.02" or 26 mm

Saito FG 21
Bore===1.26" or 32.0 mm
Stroke==1.02" or 26 mm
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Old 04-23-2019, 05:51 AM
  #40257  
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Yep,

I strongly suspect the C/R is lower. I will also check the piston P/N.

For my own purposes, the lower C/R often suits me fine. My HC 150 is sporting a .012" base shim and my HC 80!as well as Enya 80 were fitted with .008" shims.

The fellow I sold the Enya to initially pulled the shim. He put it back after the first day without

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Old 04-23-2019, 05:59 AM
  #40258  
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SAIE115, SAIE115GK, SAIE125A, SAIE125AGK, SAIEG20 The 125 A piston fits these.

The FG 21 is a 1.27
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Old 04-23-2019, 07:13 AM
  #40259  
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Thanks Dave,

No fun doing the searches on this phone. I will try the converted engine with the FG and FA cylinders to check out the differences.

Getting rid of the Saito CDI and using an RCexl in it's place. That will allow the owner to use regular 1/4-32 sparkers.
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Old 04-23-2019, 08:01 AM
  #40260  
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My Saito FG-30's came with RCxcel ignitions. They also have the CM-6 plugs.
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Old 04-23-2019, 08:13 AM
  #40261  
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The FG-20 came with a Saito branded box and a plug connector that fits 1/4-32 Saito plugs..

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Old 04-23-2019, 08:40 AM
  #40262  
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So did the FG-11. It seams like the smaller displacement gas use the same cylinders as the glow, but the larger ones are unique to gas with the larger plug opening. At least the Saito ignitions didn't step idle like the DLE ones did. Those are a royal PITA when trying to land and the idle wont step down.
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Old 04-23-2019, 11:09 AM
  #40263  
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If they made a glow 11, it would be a 66, I wonder how it would compare to the old 65.
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Old 04-23-2019, 12:09 PM
  #40264  
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I think it is based on the 65. I don't know if it still does, but the literature did mention what it is based on.

Oh, NM,

Found it

Uses the proven and reliable FA-62B platform
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Old 04-23-2019, 12:45 PM
  #40265  
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Here's how they list the 82-B=====13.44 cc Bore===1.14" Stroke===.80"
FG 14======================13.8 cc interesting., no listing for the FG 14 bore and stroke

Last edited by Hobbsy; 04-23-2019 at 12:51 PM.
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Old 04-23-2019, 01:02 PM
  #40266  
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The 65 and 62are dimensionally different families.
The "box" I referred to is the CDI box. The Saito box that came with the FG-20 is quite different from the RCexl, aside from the Saito using a Saito connector intended for odd-ball Saito plugs.
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Old 04-23-2019, 01:10 PM
  #40267  
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There are others that use the 1/4-32 plug. The end is easy to change from CM-6 to 1/4-32 cap or the other way. I have spares of each just in case.
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Old 04-23-2019, 01:13 PM
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Originally Posted by Hobbsy View Post
Here's how they list the 82-B=====13.44 cc Bore===1.14" Stroke===.80"
FG 14======================13.8 cc interesting., no listing for the FG 14 bore and stroke
Displacement: 0.82 cu in (13.8cc)
Bore: 1.14 in (29.0mm)
Stroke: 0.80 in (20.4mm)
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Old 04-23-2019, 01:57 PM
  #40269  
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Originally Posted by acdii View Post
There are others that use the 1/4-32 plug. The end is easy to change from CM-6 to 1/4-32 cap or the other way. I have spares of each just in case.
Yep, I change them at times, In this case the Saito system is pretty old so replacing it with an RCexl serves two purposes. I never was too fond of the Saito boxes anyhow.

I also make adapter bushings for the plugs. Unlike most store bought, using bronze rather than brass.

These are the older FG-20 that don't have a great reputation. Hopefully we can correct some of the original Saito shortcomings.

Last edited by Jesse Open; 04-23-2019 at 02:01 PM.
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Old 04-23-2019, 02:18 PM
  #40270  
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Default Question for the Saito Vets

Something that happens with all my saitos is that they won't hold peak. They all settle 100-200 rpm down from peak when I adjust them to check peak. It takes a couple of seconds for it to happen after coming off idle and it happens every time. I always start a little rich and work my way to peak. Once peaked it drops rpm and I cannot get it back up there by adjusting the hsn. I have to bring it back to idle and then go full throttle again to see the highest peak again. The lsn has no effect on the phenomenon. Any ideas?
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Old 04-23-2019, 03:41 PM
  #40271  
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Originally Posted by Glowgeek View Post
Something that happens with all my saitos is that they won't hold peak. They all settle 100-200 rpm down from peak when I adjust them to check peak. It takes a couple of seconds for it to happen after coming off idle and it happens every time. I always start a little rich and work my way to peak. Once peaked it drops rpm and I cannot get it back up there by adjusting the hsn. I have to bring it back to idle and then go full throttle again to see the highest peak again. The lsn has no effect on the phenomenon. Any ideas?
My thought is that its loss of tank pressure that is giving the peak off idle. Throttling up reduces pressure so the HSN leans out just a tad, then steady WOT the pressure equalizes. Just enough to get that 100-200 peak RPM that you just can't get with the needle.
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Old 04-23-2019, 04:05 PM
  #40272  
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Originally Posted by acdii View Post
My thought is that its loss of tank pressure that is giving the peak off idle. Throttling up reduces pressure so the HSN leans out just a tad, then steady WOT the pressure equalizes. Just enough to get that 100-200 peak RPM that you just can't get with the needle.
Thanks, apparently it's normal behavior. I came to the same conclusion, leaning momentarily.

Edited: Odd though that I can't replicate the leaning with the hsn. Perhaps the combustion chamber is overheating at that moment but not enough heat has transfered to outside of the engine where it can be felt by touch? Now that I think about it the peak does hold longer before dropping rpm if I let it cool down at idle longer before going to wot. Hmmm.

Last edited by Glowgeek; 04-23-2019 at 04:35 PM.
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Old 04-23-2019, 07:23 PM
  #40273  
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I think the engines just like messing with you.
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Old 04-24-2019, 01:35 AM
  #40274  
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Okc for the first time i'm in total mental harmony with what you just said,that should worry you right there.

Bruce i get what you are saying but i'm thinking the other way.We all have excess exhaust pressure which gets out the tip of the muffler,it's a natural blowby safety valve because i've squeezed a lot of tanks on the bench when you throttle up quickly and they stay rock hard.First flight of the morning is usually about ten minutes and for the first five the fa82 likes to be run at half to full throttle,it's not a time to be doing throttled back low lazy eights Rest of the flight and all the following one's are perfect engine wise.Maybe we all need to scratch our heads a bit
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Old 04-24-2019, 02:32 AM
  #40275  
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Originally Posted by acdii View Post
Displacement: 0.82 cu in (13.8cc)
Bore: 1.14 in (29.0mm)
Stroke: 0.80 in (20.4mm)
I guess I wasn't clear enough, the FG 14 says the displacement is 13.8 cc and the 82 b says it's 13.44. cc, in their respective specs.
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