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CarbonXtreme . Midland Helicopters . HeliProz

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Engines Plugs Mufflers Fuel > heehee hee YOU better do something OS !!!
 
 
Dilbeck
Key Veteran
Location: Springdale Arkansas

Or would not running a colder plug on 30% help do the same as a shim?

If it doesn't fly sell it!
05-15-2008 12:34 PM
 
 
nivlek
Elite Veteran
Location: Norfolk England

[/quote]Or would not running a colder plug on 30% help do the same as a shim?[quote]

It would be the first thing to try .

Maybe my engine running at 300F is still too cool !

http://www.flyrc.com/articles/tune_your_engine_2.shtml

At the end of the day , it gets dark .
05-15-2008 06:49 PM
 
 
the Wasp
rrProfessor
Location: Vt

funny how the guy in the top link says that 250 is too hot for a glow engine but the guy in the 2nd link says 350 to 375 is good

250 is to hot (page 13/23),,
http://members.lycos.nl/helisonly/GlowplugHowTo.PDF


350 to 375 is not to hot
http://www.flyrc.com/articles/tune_your_engine_2.shtml

Jim
Buzz Buzz Buzz
05-15-2008 08:03 PM
 
 
DS 8717
rrProfessor
Location: Here wishing i was somewhere else

Some correct terms
Confusion and a lot of questions exist as to detonation and pre-ignition. Sometimes you hear mistaken terms like "pre-detonation". Detonation is one phenomenon that is abnormal combustion. Pre-ignition is another phenomenon that is abnormal combustion. The two, as we will talk about, are somewhat related but are two distinctly different phenomenon and can induce distinctly different failure modes.
05-15-2008 08:46 PM
 
 
Dilbeck
Key Veteran
Location: Springdale Arkansas

The first article also states for people running more than 25% nitro (for fools only).

If it doesn't fly sell it!
05-15-2008 08:46 PM
 
 
impalacustom
Heliman
Location: Lincoln Nebraska USA

Well as a car guy and an engineer who worked in powertrains, I can tell you there are a few similarities.
Not sure where that guy gets his info but if you have an engine that is running lean you don't go to a hotter plug unless you want to melt the piston. A colder plug is used when you increase the compression in an engine. You also have to retard the timing in an engine with increased compression. That is not possible to do in our little r/c engines since they fire on the glow plug not a spark plug.

Yes pinging will knock rod bearins out in a car engine, which is a possible cause for that bearings failure. I have never seen a roller bearing in a real car engine, the mains and rods have babbit material so they are different. I would be curious as to what the rod bearing looks like on these engines with these bearing failures.

A problem with nitro is you need to have good compression to get it to ignite, so it's kind of a catch 22.

If we knew what we were doing, we wouldn't call it research
05-15-2008 09:51 PM
 
 
lightningrc
Key Veteran
Location: UK

Rod bearings on mine were has new , which points again to poor bearing
05-15-2008 10:11 PM
HOMEPAGE  
 
 
nivlek
Elite Veteran
Location: Norfolk England

Quote 
Not sure where that guy gets his info but if you have an engine that is running lean you don't go to a hotter plug unless you want to melt the piston.

Actually , it can be true - if you have had to lean the engine too much because the plug is too cool , but end up running too lean before you have advanced the ignition enough . I have encountered that situation , the solution is a hotter plug which advances the ignition with a richer mixture .

At the end of the day , it gets dark .
05-15-2008 10:15 PM
 
 
the Wasp
rrProfessor
Location: Vt

a hotter plug will spark the fuel later so an engine will create more compression,,, a colder plug will create more power (why) because it will spark the fuel quicker,,

we don't need a hot plug in our OS Hyper 50 just to run it at 17000 RPMs, a colder plug would work at that RPM,, we use the hot plug because we need to burn all that Oil and Nitro at idle and at spool-up,,

another thing, say your hovering and your carb is 60% open, then you punch the throttle/collective and there is a big load on the engine as the carb opens wide and dumps more fuel in the engine, we need the plug to stay hot to burn all that fuel,,


so, if you had plugs numbered 1, 2, 3, 4, (#4 is hottest)like Enya, you could find # 1 gives you the most power but it may only last for 1 or 2 flights or it may not idle well,, while #4 last for 20 gallons but not give as much power,,, so #3 may last 10 gallons and give more power than #4..

Jim
Buzz Buzz Buzz
05-15-2008 10:46 PM
 
 
Dilbeck
Key Veteran
Location: Springdale Arkansas

I'm not sure how impalacustome came up with that or ever kept an engine running for any length of time. I summit to you that the engine is designed to run (based on there specs) on a certain % of nitro and temperature and plug to get the max rpm/power/longevity out of the engine. Anything less or more constitutes damage. Funny how when they list the specs they don't include % nitro/temp/rpm. I find this post most interesting and one I will be monitoring closely due to the interest I have on the subject. Most of you guys are way sharper than me on the subject matter and I'm listening!!

If it doesn't fly sell it!
05-15-2008 11:17 PM
 
 
Blade_Master1
Veteran
Location: Canada

I tune my engine using my finger on the back plate if I can keep it there for 10 secs with out burning the mixture is about right.
on my OS37 with a toki pipe the main needle is at 1 1/4 turns out
with the stock pipe it was 1 1/2 ~ 1 3/4 and the power sucked.

I wouldn't bother using 30% IMO it just isn't needed and I find you use more fuel and cost more to purchase.

A cold plug will retard the timing and a hot advances it
on 15% nitro you can leave the engine as is
on 30% you should lower the compression ratio ( thats why I say good for older engines)


Has anyone else tried adding duralube directly to the bearings ??

JM2C's :)
05-16-2008 12:58 AM
 
 
the Wasp
rrProfessor
Location: Vt

a glow engine's timing is opposite of a gasoline 4-stroke, in a gasoline engine you advance the ignition timing to increase the power, in the glow you retard the timing to create more compression,, but yes as Delbeck said, you can only go so far with the compression with a given percentage of nitro,,

nitro will work in all sizes of piston engines, but the smaller the engine the better it works, it's inherent in the little 30,000 RPM buggy engines..

Jim
Buzz Buzz Buzz
05-16-2008 02:48 AM
 
 
the Wasp
rrProfessor
Location: Vt

Hyper 50 manual, page 21, upper left, says up to 30% Nitro can be used ..

Jim
Buzz Buzz Buzz
05-16-2008 02:54 AM
 
 
Blade_Master1
Veteran
Location: Canada

Has anyone else tried adding duralube directly to the bearings ??



.

JM2C's :)
05-16-2008 03:00 AM
 
 
the Wasp
rrProfessor
Location: Vt

unless it's a 2 stroke oil that will mix with alcohol wouldn't use it..

Jim
Buzz Buzz Buzz
05-16-2008 03:06 AM
 
 
impalacustom
Heliman
Location: Lincoln Nebraska USA

Hmm an internal combustion engine is similar in all aspects whether it be a glow engine, gasoline, diesel, 2 stroke or whatever. The reason we retard time is to stop pre-ignition. Advance an engine as much as possible to the point of pinging and back off timing a little and you will get the most HP and least fuel consumption. This is because as the flame is ignited BTDC the flame propigation will burn the fuel as the pistom comes to TDC. In a perfect world you want all the combustable to be burned up at the exact moment of TDC or just a degree after. Pinging in an engine is caused improper ignition timing and will cause the hammering that those bearings are showing.
You have to have a higher compression to ignite nitro, it isn't like the methanol or gasoline. Try to burn nitro, you can't do it, not even with a torch. If anyone thinks you don't need compression to ignite nitro I have an old worn out 35 SS Enya your more than welcome to run on 30% it won't even fire but will fire on 5%. The reason older engines run better on higher nitro is because you are giving that engine more fuel to burn but it still has good compression.
I guess it would be hard to tell on these little engines if you are pinging or not so personally if I had a 50 that was eating bearings I would still use 30% nitro and run a cooler plug to retard the timing, and see if that helped. Has anyone run a compression test on the 50's? I would be very curious what the compression is or if anyone has a burette to check the compression ratio.
To me the bearings are getting lubrication, that's not the problem with the failures. If they all look like the one in this post they are being hammered on too much, it's not a bearing problem it's an engine problem.

If we knew what we were doing, we wouldn't call it research
05-16-2008 03:36 AM
 
 
Blade_Master1
Veteran
Location: Canada

^^^^^
totaly agree with impalacustom

and wasp that is a good point using an oil that will mix with methanol maybe klotz would be better to add directly to the bearing,

after further inspection of my egine the duralube is still visible and no sludge build up of any kind found

maybe the next engine I will use klotz oil directly on the bearing

JM2C's :)
05-16-2008 03:55 AM
 
 
the Wasp
rrProfessor
Location: Vt

OK I eited my post above,,

but if you read pages 7/23, 8/23 and 9/23 it tells us we are using to hot a plug,, and page 9/23 tells use we can get pitting on our piston and head if we run to hot a plug with high nitro and or high compression, well I had pitting on my piston and head,, once I get my helis back up I am going to try the Enya 4 and 5 plug,

it all comes together, the OS Hyper 50 has a lot of compression and we use high nitro, (as I said a while back) if we are running to hot a plug then that could be hard on our bearings

http://members.lycos.nl/helisonly/GlowplugHowTo.PDF

Jim
Buzz Buzz Buzz
05-16-2008 07:08 AM
 
 
nivlek
Elite Veteran
Location: Norfolk England

The only reason that people use a hot plug with high nitro is because they are running the engine very rich to keep the engine cool . This cools the plug so you need a hot plug to keep the engine running ! If you change to a cooler plug you will need to lean the mixture to advance the ignition point , the engine will produce more power , but the engine temperature will go up .
The question is , what is the real safe engine temperature ?

I've had no problem at 300F .

I still think that running 30% nitro , then running the engine rich , means that there is more stress on the piston/conrod/gudgeon pin/rear bearing simply because you are trying to compress too much liquid !

At the end of the day , it gets dark .
05-16-2008 07:52 AM
 
 
the Wasp
rrProfessor
Location: Vt

""because you are trying to compress too much liquid""

nivlek, I agree, and the pitting I got points to too much compression, and other people have reported pitting in their Hyper 50s,, so an extra shim would help stop the pitting as well as increase bearing life,,

also I have always had trouble with my Hyper 50s idling well even with an Enya 3 or an OS A5, this too could mean too much compression for the nitro percentage I was using..

Jim
Buzz Buzz Buzz
05-16-2008 08:06 AM
 
 
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