RCMagic
06-06-2005, 04:02 PM
Tuning your Nitro or Gas engine takes patience!
STEP #1: Begin by setting your engines mixture at the manufacturers spec. (check it, don't guess). This is usually 3-1/2 turns out on the Needle and 1 turn out on the air screw. If anything run your engine to RICH! It will run but "blubber" or sound "muddy" this is a good SAFE starting point. (TERMS: "out" means counter clockwise).
PRECAUTION #1: If it runs LEAN it could seize at high RPM! Remember, if you lean out (turn the screw in, or clockwise) the air screw you must go richer (turn out, counter clockwise) the needle screw! If you don't you are leaning the entire engine which can damage or seize the engine!
STEP #2: Start the engine. Your engine should gain RPM nicely with a QUICK grab (less than 1 second) of the throttle (at the radio) and return to idle smoothly and quickly. If it sounds OK (crisp & snappy), get it in the water. No more adjustments can be made until water cooling has stabilized the engine's operating temperature as the boat is run. The heat generated from the engine will start changing the performance and require mixture adjustment of the carburetor (EVERY TIME you run the boat!). Nitro engines will require more adjustments more often than Gas engines like the Zenoah.
PRECAUTION #2: Running of the boat out of the water for more than about 30 seconds can damage or seize the engine!
STEP #3: Now carefully, bring the boat back to you (at the shore) and adjust the engine for better top end RPM. Remember the peak RPM only counts if the boat is in the water. So make the adjustment and send the boat back out for another pass. Repeat this process until you feel your engine is achieving it's peak RPM and check the boats engine temp often. You should be able to touch the engines head for a second. If it is scalding hot, Richen it back up!!!
PRECAUTION #3: Running an engine LEAN is THE quickest way to destroy an engine!
If it dies: typically the engine is to lean (rich engines do not normally just stop running). Note the throttle position when the engine dies. This determines if you adjust the Idle (low end), Air Screw (middle) or Needle (top end).
If it is "muddy": typically this means the engine is too rich. If the engine is pretty "snappy" off of idle then lean the Needle (or top end clockwise) a few clicks at a time. If the throttle response is muddy all the way through, then turn the air screw clockwise ONE click at a time. This adjustment is very sensitive! This leans the bottom and top end at the same time.
If it smokes: It's running hot and maybe to lean. Richen it up (needle counter clockwise) until it starts to run a little muddy again. Once muddy go
If you make ANY of the following changes to your boat, richen the mixture and start from the beginning to make sure the engine is not run to lean.
Things that change the tuning:
1) Prop pitch (richen top end to start)
2) Pipe length and type (affects the top end the most)
3) Nitro level (usually requires changes to air screw and needle)
4) Temperature (warmer air more fuel) more info
5) Humidity
6) Altitude (less air means less fuel is required)
7) Chips or Scratches in the bottom of the Hull (creates more drag)
1) Starting a Nitro Engine:
Hold your finger over the exhaust for 2 or 3 seconds when first starting the engine. This works for electric or pull starters. Then apply glow starter to the plug and crank it over... it'll fire right up! This pressurizes the tank, forcing fuel into the carb.
See the tuning section of this site for detailed information on setting the correct mixture on your engine.
2) Polishing a Prop:
Sharpen the curved edges and only polish the "keyed" side of the prop. Leave the back side (the back side is the side shown below closest to the nut) in the factory cast or "sand blasted" looking finish. This will help to push or throw the water. NOTE: Beryllium Copper Props are top quality racing props and require finish work before use. Click here for more detailed information on how to properly prepare your metal prop
3) Exhaust exits: If the exhaust exit from your boat is to low (close to the water), a simple splash of water can kill the engine! Be sure to route the exit well above the splash level on your hull. If your exhaust tip is a piece of tubing, you can also try cutting a 45 degree angle on the tip. This will not allow a splash of water to completely close off the exhaust flow.
4) Fuel Oil %: Be sure the fuel you use contains 16 or more % OIL (lubricant) or you'll damage the engine. The higher the % of Nitro the less oil.
5) Fuel Nitro %: It is always a good idea to start at 20% Nitro fuel in your engine and work your way up if you need more power. 20% is very reliable in a boat and less temperamental. 30% to 60% makes more power but requires many more adjustments and can damage your engine if the mixture and engines temperature are not closely monitored.
6) NiMh Batteries: Charge Nickel Metal batteries at half the amperage you'd charge a NiCad battery. This means 3 amps or less for a normal 6 cell battery pack (3000mhA "stick" packs) and 1 amp for smaller AA sized batteries.
7) Motor to Shaft: Do not use rigid couplings from the motor shaft to the prop drive shaft it will rob your boat of power and speed! Always use a flex or U-Joint style coupling. This assures non binding free play if there is any flex or mis-alignment.
8) Break in your Glow Plugs: The idea is to temper the tiny coil by heat and cooling 4 times. Take new glow plugs and ignite them with your glow starter for 10 seconds and then let cool. They'll last a lot longer and save you money.
9) Center of Gravity: Keep the weight in your boat as low as possible. Start with the obvious heavy items like the battery and get them on the "floor" or lowest point in the hull. Try to keep the same general balance when relocating things.
10) Stay Organized: Get a fishing tackle box and fill it with spare parts. This will assure you can play all day long!
11) Fuel Line: Smooth all edges that may wear on the inside or outside of the tubing. Also leave a loop of about 1 foot in the line to the carb. and the line from the pipe to the tank. This will keep more fuel in the line and the engines performance more consistent.
12) Paint Colors: Try painting your boat Yellow or White, they are the MOST noticeable colors on the water.
13) Seal the Hull: ABS plastic hulls are light weight and easier to build but require sealing. Do this before you test the boat! Nitro fuel will attack and eat any part of a unsealed R/C boat. Sand the hull lightly with 320G sand paper, wipe clean and prime the hull inside and out with special "Nitro tough" paint from your local hobby store. Then spray on the color of your choice! Be sure to do this outdoors. The stuff that makes the paint tough is pretty toxic until it dries.
14) Rudders and Turn Fins: The parts in the water should have a very sharp leading edge and a flat back edge. This way the water does not try to "steer" the surface as it passes by! Get all the surfaces smooth (or polished) if at all possible.
15) Surface Drive Set Up: Line up the prop centerline with the lowest surface of the boats hull. Anything lower is considered to be "submerged."
16) Radio Check 1: Before you leave the house, turn on the boat and radio to confirm everything is charged and working properly. This will save you the drive to the lake if things don't work! Be sure to turn it all back OFF.
17) Radio Check 2: Once at the lake, always check your frequency before you start your boat! You can do this a couple of ways: 1) turn on your receiver in the boat and see if your servos start "glitching". 2) If you are at a R/C pond officially check out the frequency. If you can never get a clear frequency, change the frequency crystal in the Receiver (RX) and in the Transmitter (TX). Just be sure to get frequencies that match your radios band of 75Mhz or 27Mhz.
18) Get a friend: It is a big help to have a friend help you start your boat the first few times (the kids always want to help too).
19) Build a boat stand: Build a nice boat stand from standard PVC plumbing pipe. This entire stand cost only $10 and properly supports the boat without scratching the paint! Note: cool Lexan prop guard and storage shelve under the boat.
20) Boat Recovery: Here is the best to recover a stuck boat. Get a solid rubber ball (I recommend medium size) from your local pet store. Run a piece of fishing line through it. Once attached to the fishing line, use a fishing rod and reel to cast the ball out and pull the stuck or stalled R/C boat back in to shore.
21) Build a travel case: Use any standard storage bin(s) from your local store to safely transport and store your boat. It's cheap, will not leak water or fuel and I don't like the nitro fuel smell in my car on the way to and from the lake!
(taken from Fun RC Boats)
STEP #1: Begin by setting your engines mixture at the manufacturers spec. (check it, don't guess). This is usually 3-1/2 turns out on the Needle and 1 turn out on the air screw. If anything run your engine to RICH! It will run but "blubber" or sound "muddy" this is a good SAFE starting point. (TERMS: "out" means counter clockwise).
PRECAUTION #1: If it runs LEAN it could seize at high RPM! Remember, if you lean out (turn the screw in, or clockwise) the air screw you must go richer (turn out, counter clockwise) the needle screw! If you don't you are leaning the entire engine which can damage or seize the engine!
STEP #2: Start the engine. Your engine should gain RPM nicely with a QUICK grab (less than 1 second) of the throttle (at the radio) and return to idle smoothly and quickly. If it sounds OK (crisp & snappy), get it in the water. No more adjustments can be made until water cooling has stabilized the engine's operating temperature as the boat is run. The heat generated from the engine will start changing the performance and require mixture adjustment of the carburetor (EVERY TIME you run the boat!). Nitro engines will require more adjustments more often than Gas engines like the Zenoah.
PRECAUTION #2: Running of the boat out of the water for more than about 30 seconds can damage or seize the engine!
STEP #3: Now carefully, bring the boat back to you (at the shore) and adjust the engine for better top end RPM. Remember the peak RPM only counts if the boat is in the water. So make the adjustment and send the boat back out for another pass. Repeat this process until you feel your engine is achieving it's peak RPM and check the boats engine temp often. You should be able to touch the engines head for a second. If it is scalding hot, Richen it back up!!!
PRECAUTION #3: Running an engine LEAN is THE quickest way to destroy an engine!
If it dies: typically the engine is to lean (rich engines do not normally just stop running). Note the throttle position when the engine dies. This determines if you adjust the Idle (low end), Air Screw (middle) or Needle (top end).
If it is "muddy": typically this means the engine is too rich. If the engine is pretty "snappy" off of idle then lean the Needle (or top end clockwise) a few clicks at a time. If the throttle response is muddy all the way through, then turn the air screw clockwise ONE click at a time. This adjustment is very sensitive! This leans the bottom and top end at the same time.
If it smokes: It's running hot and maybe to lean. Richen it up (needle counter clockwise) until it starts to run a little muddy again. Once muddy go
If you make ANY of the following changes to your boat, richen the mixture and start from the beginning to make sure the engine is not run to lean.
Things that change the tuning:
1) Prop pitch (richen top end to start)
2) Pipe length and type (affects the top end the most)
3) Nitro level (usually requires changes to air screw and needle)
4) Temperature (warmer air more fuel) more info
5) Humidity
6) Altitude (less air means less fuel is required)
7) Chips or Scratches in the bottom of the Hull (creates more drag)
1) Starting a Nitro Engine:
Hold your finger over the exhaust for 2 or 3 seconds when first starting the engine. This works for electric or pull starters. Then apply glow starter to the plug and crank it over... it'll fire right up! This pressurizes the tank, forcing fuel into the carb.
See the tuning section of this site for detailed information on setting the correct mixture on your engine.
2) Polishing a Prop:
Sharpen the curved edges and only polish the "keyed" side of the prop. Leave the back side (the back side is the side shown below closest to the nut) in the factory cast or "sand blasted" looking finish. This will help to push or throw the water. NOTE: Beryllium Copper Props are top quality racing props and require finish work before use. Click here for more detailed information on how to properly prepare your metal prop
3) Exhaust exits: If the exhaust exit from your boat is to low (close to the water), a simple splash of water can kill the engine! Be sure to route the exit well above the splash level on your hull. If your exhaust tip is a piece of tubing, you can also try cutting a 45 degree angle on the tip. This will not allow a splash of water to completely close off the exhaust flow.
4) Fuel Oil %: Be sure the fuel you use contains 16 or more % OIL (lubricant) or you'll damage the engine. The higher the % of Nitro the less oil.
5) Fuel Nitro %: It is always a good idea to start at 20% Nitro fuel in your engine and work your way up if you need more power. 20% is very reliable in a boat and less temperamental. 30% to 60% makes more power but requires many more adjustments and can damage your engine if the mixture and engines temperature are not closely monitored.
6) NiMh Batteries: Charge Nickel Metal batteries at half the amperage you'd charge a NiCad battery. This means 3 amps or less for a normal 6 cell battery pack (3000mhA "stick" packs) and 1 amp for smaller AA sized batteries.
7) Motor to Shaft: Do not use rigid couplings from the motor shaft to the prop drive shaft it will rob your boat of power and speed! Always use a flex or U-Joint style coupling. This assures non binding free play if there is any flex or mis-alignment.
8) Break in your Glow Plugs: The idea is to temper the tiny coil by heat and cooling 4 times. Take new glow plugs and ignite them with your glow starter for 10 seconds and then let cool. They'll last a lot longer and save you money.
9) Center of Gravity: Keep the weight in your boat as low as possible. Start with the obvious heavy items like the battery and get them on the "floor" or lowest point in the hull. Try to keep the same general balance when relocating things.
10) Stay Organized: Get a fishing tackle box and fill it with spare parts. This will assure you can play all day long!
11) Fuel Line: Smooth all edges that may wear on the inside or outside of the tubing. Also leave a loop of about 1 foot in the line to the carb. and the line from the pipe to the tank. This will keep more fuel in the line and the engines performance more consistent.
12) Paint Colors: Try painting your boat Yellow or White, they are the MOST noticeable colors on the water.
13) Seal the Hull: ABS plastic hulls are light weight and easier to build but require sealing. Do this before you test the boat! Nitro fuel will attack and eat any part of a unsealed R/C boat. Sand the hull lightly with 320G sand paper, wipe clean and prime the hull inside and out with special "Nitro tough" paint from your local hobby store. Then spray on the color of your choice! Be sure to do this outdoors. The stuff that makes the paint tough is pretty toxic until it dries.
14) Rudders and Turn Fins: The parts in the water should have a very sharp leading edge and a flat back edge. This way the water does not try to "steer" the surface as it passes by! Get all the surfaces smooth (or polished) if at all possible.
15) Surface Drive Set Up: Line up the prop centerline with the lowest surface of the boats hull. Anything lower is considered to be "submerged."
16) Radio Check 1: Before you leave the house, turn on the boat and radio to confirm everything is charged and working properly. This will save you the drive to the lake if things don't work! Be sure to turn it all back OFF.
17) Radio Check 2: Once at the lake, always check your frequency before you start your boat! You can do this a couple of ways: 1) turn on your receiver in the boat and see if your servos start "glitching". 2) If you are at a R/C pond officially check out the frequency. If you can never get a clear frequency, change the frequency crystal in the Receiver (RX) and in the Transmitter (TX). Just be sure to get frequencies that match your radios band of 75Mhz or 27Mhz.
18) Get a friend: It is a big help to have a friend help you start your boat the first few times (the kids always want to help too).
19) Build a boat stand: Build a nice boat stand from standard PVC plumbing pipe. This entire stand cost only $10 and properly supports the boat without scratching the paint! Note: cool Lexan prop guard and storage shelve under the boat.
20) Boat Recovery: Here is the best to recover a stuck boat. Get a solid rubber ball (I recommend medium size) from your local pet store. Run a piece of fishing line through it. Once attached to the fishing line, use a fishing rod and reel to cast the ball out and pull the stuck or stalled R/C boat back in to shore.
21) Build a travel case: Use any standard storage bin(s) from your local store to safely transport and store your boat. It's cheap, will not leak water or fuel and I don't like the nitro fuel smell in my car on the way to and from the lake!
(taken from Fun RC Boats)