Magnum GP40 with 0% nitro fuel. Some question (Full Version)

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neuroza -> Magnum GP40 with 0% nitro fuel. Some question (3/16/2008 9:17:12 PM)

Hi!
I have Magnum GP40 engine with air bleed carburetor.
I use my own fuel (20% castor oil, 80% methanol, 0% nitro).
Is it possible that because is without nitro the engine sometimes just die on high RMP (the needle is set very carefully)???

Have another question, when the engine run on minimum,
I turn the nose up and the engine increase in RPM, then when I put the nose down the engine die.
Is this a air bleed problem - did need to be adjusted??? How???

Because I use 0% nitro, do I need to increase compression, how??? Can I put out the thin ring that come under the cylinder head???

Thanks for any help!



jetpack -> RE: Magnum GP40 with 0% nitro fuel. Some question (3/16/2008 9:46:15 PM)

Not sure about the carb, but taking the head washer out is a good idea. No nitro likes a higher compression and a warmer glow plug.



neuroza -> RE: Magnum GP40 with 0% nitro fuel. Some question (3/16/2008 10:05:38 PM)

Ok, thanks!

I have another question, on some other forum i find that if there is no nitro I can add some acetone... Is that right??? How much???



jetpack -> RE: Magnum GP40 with 0% nitro fuel. Some question (3/17/2008 12:15:18 AM)

3% if the alcohol your using doesn't already have some in it.



neuroza -> RE: Magnum GP40 with 0% nitro fuel. Some question (3/17/2008 12:19:41 AM)

No, I use pure Methanole, and medicinal pure castor oil.


So is this the right mixture???:

20% Castor oil
77% Methanole
3% Acetone


Thanks!!!



XJet -> RE: Magnum GP40 with 0% nitro fuel. Some question (3/17/2008 1:03:49 AM)

I doubt you'll need (or notice) the effect of the acetone.

I ran a wide range of engines without any nitro for many years back in the 1960s-1980s and they all performed perfectly.

The Magnum GP40 is an engine that should run just fine on 0% nitro. I'd recommend an OS#8 plug -- they seem to work very well with low nitro levels.



downunder -> RE: Magnum GP40 with 0% nitro fuel. Some question (3/17/2008 3:56:03 AM)

It should run just fine on zero nitro but use a hot plug, even a 4 stroke plug. Small amounts of acetone (in that 3% range) is supposed to act somewhat like 5% nitro as far as starting and idling go. It won't hurt the engine so it's just a matter of trying it and see. Taking out the head shim will help a tiny bit by raising the compression slightly but you may get some leakage at the head joint because the shim is also a gasket.

The only thing I can't be sure of is how well an engine runs on zero nitro in cold weather because that's something we don't have here.



neuroza -> RE: Magnum GP40 with 0% nitro fuel. Some question (3/17/2008 1:26:36 PM)

Ok, thanks!

Have another question...
I try to use several synthetic oil but every one drop to the bottom of fuel mixture (the mixture is not homogenic)...
What do I need to pay attention when I buy the right synthetic oil???[X(]




XJet -> RE: Magnum GP40 with 0% nitro fuel. Some question (3/17/2008 9:08:56 PM)

You can't use a conventional automotive oil (synthetic or otherwise) because, as you've discovered, it won't mix with the methanol.

Your oil choices for a methanol-based fuel are far more limited than for gasoline-based fuels and since the 40GP is a plain-bearing engine it demands a good level of castor oil in the fuel anyway.

I'd try the good old formula of 18%-20% castor oil and 80%-82% methanol.

Synthetic model oils are not well suited to plain-bearing engines but if you're flying in very cold conditions you can use 10% of a suitable synthetic (Motul Micro, Aerosynth, Aerosave, Klotz Techniplate or Morgans CoolPower Blue) and 10% castor. This will make it easier to start your motor -- because straight castor gets real thick at low temps.

Regular automotive oils (synthetic or otherwise) will not mix with methanol -- you need one specifically designed for methanol use.



neuroza -> RE: Magnum GP40 with 0% nitro fuel. Some question (3/17/2008 11:02:03 PM)

Thanks!



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