engine overheating help
 

First of all let me state I've been flying 3 years and know how to properly tune a glow engine on the low and high end to prevent overheating. I like this forum because of quick response and a willingness to help. Here Goes:

Engine overheating with 2 deadsticks. Everything tweaked for maximum rich/cool operation.
I have an Aeroworks Edge 540T .46-.61 size with a Tower Hobbies .75 ABC 2 stroke glow engine.
The engine was properly broken in on a test stand. Very happy with engine performance and seems to be reliable.
10% nitro 18% oil Byron fuel and a 14X4 prop. Fox long glow plug.
Cowl is cut for both maximum entry/exit.

Looking for answers on what to do. I was told try an OS #8 glow plug or a cooler glow plug. Ideas appreciated.
I was also told to add baffles. Not familiar with this.
Any other ideas appreciated.

Regards,
Mike

RE: engine overheating help
 

I have the same motor and haven't had any overheating issues. The only thing I might suggest is to use a smaller diameter prop. This engine is made to scream and POSSIBLY the 14" prop is a bit large, even though the text might suggest otherwise. I run a 12x6 prop, maybe try something along that line to check for improvement. What kind of RPM's do you get with the cuurent prop?

RE: engine overheating help
 

You say your cowl is cut for maximum entry/exit. What is your exit amount compared to the entry?

RE: engine overheating help
 

baffles look something like this

RE: engine overheating help
 

I would try flying without the cowl. If it does not overheat then I suggest that you you extend the slot around the carb. upwards towards the cylinder head. You might also try internal baffles inside the cowl to force the airflow around the exhaust side of the cylinder and over the head fins.

You need to create airflow over the engine fins and this can be bit hit and miss. I think that large cut out on the rh side of the cowl [ looking from the rear] may be counter productive.

RE: engine overheating help
 

Going by the photos it seems the engine may be too close to the cowl at the back. Air flowing past both sides of the engine try to meet up but can't so it forms a stagnant area at the back of the engine. Depending on how much room there is at the back of the engine you can try fitting a wedge shaped piece to the firewall so the point ends very close to the fins. This will give air coming either side of the engine a chance to flow around the back but even then it really needs exit slots for the air to come out top and bottom of the cowl.

RE: engine overheating help
 

Trying a different glow plug is a good idea; I was running hot with an OS A3 (hot) plug and switched to an 8 (med), and definitely noticed a difference.

RE: engine overheating help
 

I agree, fly it without the cowl once. That might give you a quick answer. 10% Nitro isn't very high, you really shouldnt have this problem.

RE: engine overheating help
 

As the others have said, try flying without the cowl. From the pictures you posted it really looks like you are having an airflow problem around the head. If you take the cowl off I'm pretty sure you'll see an improvement. If you do then you can start adressing the airflow issues from there.

Ken

RE: engine overheating help
 

I think those pics are someone else's plane, there to show what 'baffles' or ducts look like. I don't see any pics posted by the OP, but I imagine they would be helpful.

RE: engine overheating help
 

Whether they are the pics of the plane or not doesn't matter, the advice is still the same. He needs to take the cowl off and fly the plane to see if the problem still exists. If so then he has an airflow problem, as I stated above.

Ken

RE: engine overheating help
 

I fly this engine all the time on different planes. Some with fairly enclosed/restricted cowls...


The prop you are using is your most likely problem.

Use a smaller higher pitch prop.

Get a temperature guage and measure the head temp just off the glow plug.

Run the engine at full throttle for 3 minutes on the ground and immediately measure the temp.

If it's over 340 degrees F, richen the engine settings until the engine stays around 310 or lower.

RE: engine overheating help
 

excellent idea. Before messing with baffles I think I'll try the OS 8 and a different prop.
thanks for everyone who responded. I'll let you know.

RE: engine overheating help
 

While a medium plug is fine, this engine likes "long" plugs so keep this in mind.

A Medium Fox long is good, etc.