How close can I mount an engine to the firewall without heat effects?
08-06-2006, 09:41 PM
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How close can I mount an engine to the firewall without heat effects?
Hello,
I'm currently working on a Graupner Extra 300S. The plane recommends an OS .60-.90 engine. I read reviews from a couple of people wished they put a .90 in instead of a .60, so I decided to go with a .90. Instead of putting an OS engine in, I opted for a .90 SuperTigre.
The mouting holes and/or overall dimensions for the OS .90 and the Super Tigre .90 must be different, because the plane manual recommends having the spinner backplate 2mm (.080") in front of the cowl. In order to do this with the Super Tigre .90, I had to modify the engine mount slightly, and it ends up putting the engine head cooling fins about 1/4" from the firewall.
My question is: Is this too close to the firewall? Will this cause the epoxy coating I put on the firewall to bubble/burn, or will it be okay?
I could move the engine forward a bit, so that there is more than 2mm clearance between the spinner backplate and the engine cowl, but then I'll start to run into problems with the carb intake interfering with the cowl.
I found a drawing of the overall size for the Super Tigre engine on their website, but cannot find the same for the OS engine.
Any thougths or suggestions?
Thanks,
Patrick
I'm currently working on a Graupner Extra 300S. The plane recommends an OS .60-.90 engine. I read reviews from a couple of people wished they put a .90 in instead of a .60, so I decided to go with a .90. Instead of putting an OS engine in, I opted for a .90 SuperTigre.
The mouting holes and/or overall dimensions for the OS .90 and the Super Tigre .90 must be different, because the plane manual recommends having the spinner backplate 2mm (.080") in front of the cowl. In order to do this with the Super Tigre .90, I had to modify the engine mount slightly, and it ends up putting the engine head cooling fins about 1/4" from the firewall.
My question is: Is this too close to the firewall? Will this cause the epoxy coating I put on the firewall to bubble/burn, or will it be okay?
I could move the engine forward a bit, so that there is more than 2mm clearance between the spinner backplate and the engine cowl, but then I'll start to run into problems with the carb intake interfering with the cowl.
I found a drawing of the overall size for the Super Tigre engine on their website, but cannot find the same for the OS engine.
Any thougths or suggestions?
Thanks,
Patrick
08-06-2006, 09:50 PM
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RE: How close can I mount an engine to the firewall without heat effects?
Shouldn't be a problem. Once the epoxy cures, I dont' think that your engine will put out enough heat to bother it. Make sure you have proper air exit volume, or you will have problems..
Also, it's common to have to cut out a little extra on a cowl for the carb on a two stroke--especially for a big one...
Also, it's common to have to cut out a little extra on a cowl for the carb on a two stroke--especially for a big one...
