Glow Plug Life

[Steve]

2 washers just reduces the compression ratio, reduces the top end power a touch and increases smoothness.

[jamiem]

How is the exhaust sealed to the engine, of at all? (other than just bolting it to it I mean)

Personally, I tend to blow a plug on my YS91 once or twice per engine bearing change - around 17 5 litre bottles of Optifuel 30 ULV.

[wadders]

Hmmm, interesting! I'm lucky to get a gallon on a plug. OS50 Hyper. It's running cool, It does tend to bog down on stall turns on the climb and fast banking turns....... Today I suddenly started loosing power on a fast banking turn, managed to bring her into a struggling hover and it was bellowing loads of smoke. As soon as I landed it died. I took the plug out and their was almost nothing of the "element" left!!!! Little bit on the top a huge gap and a little bit further in. Never had a blown plug like that before! WTF??? Should have taken a pic....

[pchristy]

Sounds to me like its over compressed. The two plug washers trick is a useful diagnostic tool, but for a permanent fix, I'd suggest shimming the head.

[lee mister]

Thanks for all you suggestions, when we striped it down the other day to do the bearings I was very happy with the condition of the engine the piston ring was showing no signs of wear, it still had its original black color to it, the thing is I had this same problem with my os 50 and its one of the resons I got the 55, so I really don't think I am getting it wrong with two engines, I had great power from the 50, and I can get even better from the 55, I can tell when its slightly down on power Ie if It's losing power on hard tick toks one or to clicks out on the mid, and if It's bogi on full throttle banking turns couple out on the top.
What I'm starting to think is if I think back I'm sure my problem started from birth and oops wrong forum lol, it started when I changed to copter mix 30%, so I'm going to give optI a go see if it helps.
Cheers
Lee

[wadders]

Sounds to me like its over compressed. The two plug washers trick is a useful diagnostic tool, but for a permanent fix, I'd suggest shimming the head.

For my problem too??

[pchristy]

If the engine is over-compressed, the mixture will burn explosively in the cylinder, rather than smoothly - which is what you want! If it is pre-igniting, the resulting bang could well be enough to knock out plugs fairly regularly. In the longer term, it won't do the big and little ends much good either!

To prevent this happening, you need to reduce the compression, and the best way to achieve this is via head-shims. OS always used to provide extra shims with their engines - not sure if they still do!

Any engine will be designed to run with a specific fuel mix. Increasing the nitro content beyond the manufacturers recommendations may well lead to pre-ignition, and short plug life.

Its also worthwhile trying cooler plugs. The rule of thumb should be "Hot fuel - cool plug" and vice versa!

Also remember that Opti measure their ratios differently from other manufacturers IIRC. Most suppliers measure nitro content by volume. I believe Opti do it by weight, which is chemically correct, but means that their figures are not directly comparable with other manufacturers!

And no, I can't recall if this means that Opti has more or less nitro for a given figure......!

[robgt]

OS always used to provide extra shims with their engines - not sure if they still do!

That they do Pete
Cheers,
Rob

[wadders]

If the engine is over-compressed, the mixture will burn explosively in the cylinder, rather than smoothly - which is what you want! If it is pre-igniting, the resulting bang could well be enough to knock out plugs fairly regularly. In the longer term, it won't do the big and little ends much good either!

To prevent this happening, you need to reduce the compression, and the best way to achieve this is via head-shims. OS always used to provide extra shims with their engines - not sure if they still do!

Any engine will be designed to run with a specific fuel mix. Increasing the nitro content beyond the manufacturers recommendations may well lead to pre-ignition, and short plug life.

Its also worthwhile trying cooler plugs. The rule of thumb should be "Hot fuel - cool plug" and vice versa!

Also remember that Opti measure their ratios differently from other manufacturers IIRC. Most suppliers measure nitro content by volume. I believe Opti do it by weight, which is chemically correct, but means that their figures are not directly comparable with other manufacturers!

And no, I can't recall if this means that Opti has more or less nitro for a given figure......!

That's worth a try! Thanks!

[lee mister]

I have already ordered a case of opti so I Will give that a try first just to rule out one thing at a time, I will post back after a couple of gallons the result.
If It's still the same I will shim the head.
Cheers
Lee