BadSplice

My Feedback: (1)

As it gets hotter here.... average 90-100 these days, Im having more and more trouble keeping my glow engine running without overheating. I have the Evolution .46nt, with an 11.5x4 prop, in the Hanger 9 FuntanaS .40. I already removed the cowling around the engine, but it still gets very hot. would a different prop help? or maybe different fuel? or some tricky setting with the muffler or needle valve that I dont know about yet? I cant imagine what people in places like Phoenix do to keep their planes running.... have a Large air conditioned building? Any ideas would be greatly appriciated

pilotkelowna

My Feedback: (1)

BadSplice:

Had the same problem when the temp hit 90 a few weeks ago. Switched fuel to 5% nitro - no more problems.

Doug D.

A different prop might be the answer as well. The prop your using seems to be flying the model well for you, it may add a bit of a load in the heat. Try someting different to see. You may add an extra bit of oil to the fuel as well.
[&:]

ballgunner

My Feedback: (1)

In AZ some counties daily averages are 105 - 111 deg. daily for the next couple of months. Try a small increse in your oil content and run the engine richer. Fuel is one of the principal ingredients in engine cooling.

The Ghost

BadSplice,

Richen up the engine 200-300 rpm an the top end and make shore that you fuel is in the 20-25% oil range. It is the oil that helps carry the heat away. Maybe you are a tad lean on the engine. Gets that hot here in the Summer only Winter at the moment around 4deg C at the present. Winter Sucks.

Cheers.

rrragmanliam

My Feedback: (1)

Add Castor Oil to your fuel to bring the % up to 20-25% as ghost noted. It really helps on hot days. If you wan't just mix it in small batches and use it when you need to. I use it year round myself.

Darren

Jim Thomerson

The heat problem is that the hot air is less dense than you are used to. To get the fuel/ air ratio where your engine runs best, you end up setting the engine leaner. Adding oil cuts down the proportion of combustabiles in your fuel. In essence it leans out the engine for you, whilst adding lubrication.

Jim

BadSplice

My Feedback: (1)

Thanks for the tips Less nitro and more oil in the fuel make sense... Ive been messing with the mixture, and it seems to heat up a lot either rich or lean, but it dies if its too rich. I also tried a 10x6 and an 11x4 prop. the 11x4 seemed the best, nest time I'll try the 11x5 also. Is the oil easy to come by? I suppose I could always buy some new fuel for summer but just cracked open a case of the 15-18 kinda hate to buy more

The Ghost

BadSplice,

If the 15-18 is the oil content of the fuel you are using there an't enough oil there. At least 20% allways.

Cheers.

Lenny A

Yes the more oil sounds rite but I don't think less Nitro won't running more nitro give you more power at a richer setting?

William Robison

My Feedback: (3)

BadSplice:

If all else fails, go to your local drug store and buy USP castor oil, sold as a laxative. Add four ounces per gallon.

Bill.

Kimhoff

My Feedback: (22)

As the temp rises the ignition point in a glow engine advances. When this happens the engine starts to run hotter and the ignition advances even more. Less nitro will retard the ignition point. More oil also retards the ignition point. Both are good for a hot running engine. Of course a richer mixture will allow the engine to also run cooler. There is one more element that know one mentioned, the glow plug. Put a colder plug in this thing and your problems should diminish. A colder plug will retard the ignition point.

BadSplice

My Feedback: (1)

I was expecting that the nitro content would affect the engine.... But I handt considered the oil or the plug. Im running an OS #8 plug right now, can anyone suggest a cooler one? Also, how forgiving is the engine to different oils? Do you have to use castor? or is that just the best one?

William Robison

My Feedback: (3)

BS:

Synthetic oils give essentially no cooling, they mostly burn, but not quite so hotly as the methanol. Castor oil doesn't burn, it absorbs the heat and carries it out the exhaust.

To a point more nitro runs cooler, but only because you're taking more methanol in along with it.

Unless I'm mistaken the OS #8 is their hottest plug, the A3 is the colder one.

Bill.

JimTrainor

OS Glow plug info:

http://www.osengines.com/accys/glowplugs.html

The A5 plug is colder than than the A8 according to the above info.

There is also one called an "R5" that is even colder...

nitrospeed3306

HOW DO YOU START A FORUM??? HELLLP

Sport_Pilot

Depends, if the engine doesn't detonate on the higher nitro you are right. But if it is heating up because of detonation you need to lower the nitro. I have an engine that will run fine on 10% nitro till it gets about 85 or so, then I have to run less nitro. Most of my other engines run cooler on high nitro if I run them rich enough.

jaka

Hi!
How do you know your engine runs hot?
When I was in the states in -95 competing in the worldchamps in pylonracing in Muncie Indiana it was real hot, most days around 40 degrees celsius (around 90-100F). And wee ran our 6,5cc Nelsons and IR pylon engines on 80/20 fuel with rpm around 30000 without probems, in our tighly cowled airplanes.....or not so tighly sometimes.....
We used "Rich's Brew" FAI fuel.

Sport engines have no problem of coping with these temperatures (40degrees C) as long as the engines are not set too lean....cowls or no cowls ....so have you opened the highspeed needle and checked if your engine runs OK then?!
11.5x4 APC will be no problem for your engine if you fly at sea level. Also try a APC 11x6.
5%-10% nitro is mostly enough, 15% nitro is overkill and some engine on the market doesn't like that much nitro.
See to that you use good fuel.....best to blend your own so you know what you get.
And use a good sport glowplug like an OS 8 or an Enya 3 plug. Other plugs will work too but these to are the best for sport flying (Not for best rpm though).

Regards!
Jan Karlsson
Sweden

RLDIII

My Feedback: (1)

Jan makes a good point. I know it sounds silly, but exactly what is your definition of "running hot"? Is the engine sagging/detonating and loosing power in the air, or when you say it is running hot, do you mean that it is very hot to the touch after you shut it down? People need to understand that these engines can and do run quite happily at temps that will easily take your skin off! I used to fly an old YS .61 Long stroke in pattern competition that would run like a champ all day long in the Oklahoma and Texas summer heat (100 F+), but after shutting it down at the end of a flight, if someone picked it up wrong and got their arm against the cylinder head...they ended up with a YS brand in their skin for some time!

This is not to say all the suggestions about extra oil, and/or castor is a bad idea, as they are not, I'm just saying that some people don't understand the kind of temps these engines can make it hot weather. As long as the prop is turning, and the engine running, the air blowing across the fins and spent oil in the exhaust are carrying away a lot of heat. But once shut down, the trapped heat inside the engine can actually raise the external engine temps to some pretty scary levels for a few minutes after a flight.

Just something to think about.

smokingcrater

great advice RLDIII!! unless you are actually measuring temp, don't guess that it might be hot. (unless you see symptoms of it...) as others have mentioned, the difference between 75 degrees and 100 degrees basically makes no difference to an engine, since you are already so much hotter then that.

Sport_Pilot

Good point. Someone here once considered their engine to be overheating because their spit sizzled. But water boils at only 212 degrees and our engines run hotter than that. During the spring the engine could easily cool below 212 by the time you walk out and bring it back. But it takes longer to cool down in the summer.