new 37SZ-H Problem
04-21-2008, 05:35 PM
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new 37SZ-H Problem
I have about 2 gallons of rich's Brew 25% Nitro Heli fuel through this motor, break in was with 10%. I have switched to Cool Power 30% Heli fuel, and am having problems with going through glow plugs, and overheating within a few minutes of mid throttle run, I am still learning so no full throttle. She will start to lose power, back off on throtle, regains power, till load is placed. I have it running pretty rich, blowing lots of smoke, and lots of oil on Helicopter. This is in a Thunder tiger Raptor 30v2. 1 glow per 5 minutes run, and engine has always been run rich.
04-22-2008, 09:32 AM
#2
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RE: new 37SZ-H Problem
The symptoms you mention sound a lot like overheating. That can be caused by too much nitro for the compression. You may need to add an additional cylinder head gasket to lower the compression a bit. That's because higher-nitro fuels need the lower compression to prevent detonation. The detonation causes overheating, which then causes the power loss. You can have a rich mixture and still get detonation.
You also may need a colder plug.
Heli engines are also prone to overheating because they are run at high RPM levels and can have erratic cooling. You need to make absolutely sure that the engine is getting enough cooling air as well.
The give-away to the difficulty is the fact that the engine is readily 'eating' glow plugs, and that it's losing power very quickly after you get into the mid-to-high throttle areas. If the engine won't run at full throttle, then something's severely wrong, and likely not the engine, itself. If it ran well on 10% nitro fuel, the engine's fine. You now need to get it tuned for the high-nitro fuel.
You also may need a colder plug.
Heli engines are also prone to overheating because they are run at high RPM levels and can have erratic cooling. You need to make absolutely sure that the engine is getting enough cooling air as well.
The give-away to the difficulty is the fact that the engine is readily 'eating' glow plugs, and that it's losing power very quickly after you get into the mid-to-high throttle areas. If the engine won't run at full throttle, then something's severely wrong, and likely not the engine, itself. If it ran well on 10% nitro fuel, the engine's fine. You now need to get it tuned for the high-nitro fuel.
04-22-2008, 05:34 PM
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RE: new 37SZ-H Problem
Found the issue, I pulled the motor, and found I was getting blow by, out of the head. the bolts had worked loose, so completely went through it, cleanned, oiled, tested. Running great. Never had a case of my OS aircraft engines ever backing thoose bolts loose.
04-23-2008, 10:00 AM
#4
My Feedback: (11)
RE: new 37SZ-H Problem
Cylinder head bolts working loose is an indication of overheating. When the engine overheats, the aluminum expands and stretches the bolts a little bit. When the engine cools, the aluminum shrinks back slightly-smaller. The bolts don't, but stay a bit stretched. This makes things loose. If you have to tighten after every few engine runs, you have a heat problem.
