asmund

Hello, this weekend I burnt out/blew the OS F plug in my YS fs .63 when running it really hard on 60% nitro and WOT operation for several tank-fulls. The only plug I had in my fieldbox that day was a "Tower plug" so I put it in there and fired it up again. I did some checking and testing on the ground and to my surprise I could not detect any difference to the OS F at all. I still had the same looow steady idle, instant spool-up and tremendous power. I continued to fly with that plug the rest of the day and I don`t think I will bother to change that plug until it eventually fails.
Anyone else had great results with normal two-stroke plugs in four-stroke engines??

gkamysz

My Feedback: (19)

Not many run 60% nitromethane. This will result in very different plug selection.

earlwb

As you increase the nitro content the glow plug gets colder.
So the OS F plug is not good with that much nitro in the fuel. Using a different plug would be a good choice then.

rambler53

My Feedback: (494)

I run OS A3 plugs in my 4 strokes, and Saito and Surpass never gave me problems using it. I'm in a hot climate, at sea level, tuning to 10,000 rpm routinely, and go at least a season without worrying about the plugs. I never ran a 4 stroke YS.

MJD

My Feedback: (1)

But how generally relevant do you think your results are when you run that much nitromethane? Engines behave way differently on that brew. Increased nitromethane content generally improves idle, transition and mixture tolerance or so I thought.

I notice a tremendous improvement in handling of my Saito .72 with an OS F plug, compared to several other plugs I ran. And believe me I hate paying for them, and don't think I show any symptoms of OS worship. Some ran generally okay, but none seemed to have the all-round handling qualities of the OS F - reliable idle, good transition, good top end, easy starting, whatnot. That's running fuels in the more normal 10-20% nitromethane range.

asmund

Aha, all the nitro of course, I didn`t think of that as I switch fuels alot because I like to try different blends (synt/cast -high nitro/low nitro- high oil/low oil). Yes, I agree that it will affect the choice of plug.

I will try this on regular 15% too and see how it behaves, if not good then back to the F plug. Around here they cost the same as other plugs anyway.

I didn`t do this to try and save buck, I did it because I had too that particular day and it worked fine, on 60% that is

cutaway

High nitro on a very hot plug can produce pre-detonation. If you ever hear a sound like eggs or bacon frying, that's pre-detonation. It can destroy an engine quickly.

NM2K

My Feedback: (14)

There is no such thing as pre-detonation. There is preignition (incorrectly called spark knock) and there is detonation. Both are distinctly different phenomena. It would be nice if some modeling publications hired folks that knew what they were talking about.


Ed Cregger

pe reivers

Bravo Ed. Well said.

60% nitro? WOW. More nitro however adds extra oxygen to the mix. More oxygen means more cumbustion gas, confined in the same combustion chamber space. This can, and will cause detonation, unless extra shims are added under the head. Detonation can be cause of rough hot running,throwing props, or frequently burning out plugs.
First get the engine to handle the nitro properly, then experiment with different plugs. You may damage your engine if you do the sequence the other way around.

Hobbsy

My Feedback: (102)

Asmund, I keep two OS-fs here for testing purposes and so far have never seen them make any difference over a Fox Miracle, Saito SS, a Glo_devil 4c Special or a Taipan 4 stroke plug. It just doesn't happen. The OS-f was better than some of the McCoy fourstoke plugs but so were the others I listed here.

jaka

Hi!
Why on earth Asmund use 60% nitro???? That fuel would cost an arm and a leg...And I'm sure you engine will not like it any more than 15% nitro...
Yes! OS F plugs (or others like it) are necessary if you use the more common 0-10% nitro blends that we use over here i scandinavia.

earlwb

You would need to use a jeweler's Loupe and inspect the bad glow plug closely to see what the damaged coil looks like.
Then you can determine what might be the problem better.

blw

My Feedback: (3)

He was having fun from the sound of it.

MJD

My Feedback: (1)

Interesting - I bet I can't remember all the other plugs I tried but I believe they were the McCoy, Saito SS, and Fox Miracle. I ended up thinking the OS had the best all-round handling and most reliable idle. But that's just my experience with one engine.

rambler53

My Feedback: (494)

I have two gallons of it, cost me $17 on clearance at Hobby Town. I spike my FAI fuel with it and make 30%.

60% is boat engine fuel from what I was told.

Jezmo

Don't let Jan fool you. He knows perfectly well that an engine running 60% nitro will trounce one running 10% if the compression ratio is set up right. He's a racer and any good racer knows these kinds of things. I haven't tried 60% percent in any of my Saito's but they sure do like 30% and make much more power on it than 15 or 20% with a noticeably smoother idle. Just my two cents. LOL

asmund

Yeah, it is a boat fuel I use in my boat, 60% Rapicon, actually it is not that expensive compared to several other brands of 15%. I just wanted to try it in my YS because I keep reading about how they use 60% in YS engines when racing. As I said, I like to try different things, it`s just a hobby and as long as I`m having fun I`ll keep on going. My engine really loves it and shows no sign of detonation or running too hot, the F plug that blew was several years old and had to fail sooner or later. I think I would know if my engine wasn`t happy

Now I am going to run a couple of my cars on it too, and shoot them with my Bushnell radar-gun to see if I can detect any more speed than from lower nitro