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All Forums >> Glow Engines, Gas Engines, Fuel & Mfg Support Forums >> RC Fuels >> Fuel tank location and distance from engine?
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Fuel tank location and distance from engine? - 5/23/2003 6:28:22 PM   
WA8INZ


 

Posts: 45
Joined: 12/27/2002
From: Hazel Green, AZ,
Status: offline 		I'm scratch building an airboat but want to place the fuel tank in the hull about 7 inchess below the carb, how far will an OS.91 4 stroke pull up the fuel?.

Bill
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Fuel tank location and distance from engine? - 5/23/2003 10:39:25 PM   
JWN



Posts: 4858
Joined: 3/26/2002
From: Florence, TX, USA
Status: offline 		7" below the carb? Not a chance unless you install either a Perry micro-oscillating pump or a Cline regulator.

John

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Fuel tank location and distance from engine? - 6/4/2003 4:47:45 AM   
Spaceclam



Posts: 4640
Joined: 4/13/2003
From: chatsworth, CA, USA
Status: offline 		i got a .91 four stroke with a crankcase-pressure pump allowing it to pump fuel nomatter how slow it goes. i broke it in pulling it about 5 feet strait out of a gallon. that is how well that works. however, as long as your fuel tank is 7 inches above the hull aswell, you won't have a problem

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Fuel tank location and distance from engine? - 6/4/2003 4:53:04 AM   
JWN



Posts: 4858
Joined: 3/26/2002
From: Florence, TX, USA
Status: offline 		How did you handle venting the crank on your .91? The only 4-strokes designed to not vent are YS's. All others will eventually fill the crank with oil and cause running problems.

John

< Message edited by JWN-RCU -- Jun 4 2003 12:00AM >

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Fuel tank location and distance from engine? - 6/4/2003 7:22:04 AM   
Spaceclam



Posts: 4640
Joined: 4/13/2003
From: chatsworth, CA, USA
Status: offline 		it does have a crankcase vent, which turns back into the carburator. to be honest, the pump came factory installed. it is the os .91 surpass III with pump. it runs for about $325. but, the crankcase vent is hole is much smaller than the displacement under the piston, so the pump works really well.

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Fuel tank location and distance from engine? - 6/4/2003 8:13:43 PM   
JWN



Posts: 4858
Joined: 3/26/2002
From: Florence, TX, USA
Status: offline 		Ah yes, I forgot about the pumped OS engines. I was afraid you hooked up a Perry pump to the crank vent and called it good.

John

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Fuel tank location and distance from engine? - 6/4/2003 8:33:02 PM   
Spaceclam



Posts: 4640
Joined: 4/13/2003
From: chatsworth, CA, USA
Status: offline 		no. but those pumped engines are great. however, i am surprised that the 1.20 is pumped but the 1.60 FLAT TWIN isn't. nor is the 3.0 flat twin. as a matter of fact, i don't think their flat fours or their radials have them either.

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Fuel tank location and distance from engine? - 6/4/2003 8:38:14 PM   
JWN



Posts: 4858
Joined: 3/26/2002
From: Florence, TX, USA
Status: offline 		I believe the .91 and 1.20 are more geared towards performance whereas the other engines you mentioned are aimed at sport/scale fliers who don't try to get every last bit out of their engines.

John

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Fuel tank location and distance from engine? - 6/13/2003 9:16:07 AM   
canadianjosh


 

Posts: 253
Joined: 3/2/2003
From: victoria, BC, CANADA
Status: offline 		I have built an airboat and this is a big problem, my boat is a twin engine rig powered by two OS .40 FX's, so i am running two 8oz tanks, now that gives it about 18 mins runtime, so i could go with smaller tanks, but i had them so i used them. The engines, tanks, servos for throttle and servos for rudders are all up in the nacelles, as well as the battery and receiver. If you build a hull with a large enough beam then you won't run into any tippy problems. 7 inches is a long way to draw fuel vertically. i don;t know the specific weight of fuel, but i think it is pretty close to that of water, So if you are using 1/8" id line, times 2.54 to get it into mm, divide by two and square, then multiply by pi, then divide 1 by that number to get length in mm of tubing that will take 1cc of fuel. this equals 13.33mm of tubing equals one cc. so 7 inches is 17.78mm which is 177.8mm
so 177.8 divided by 13.33 equals about 13.3338 cc
that equals 13.3 grams of fuel. to draw up which may not sound like a lot but it is. You could try using a perry pump i don't know how much they will pump up though.

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Fuel tank location and distance from engine? - 6/13/2003 10:15:15 AM   
Spaceclam



Posts: 4640
Joined: 4/13/2003
From: chatsworth, CA, USA
Status: offline 		i think you just fried my brain

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Fuel tank location and distance from engine? - 6/13/2003 9:26:23 PM   
JWN



Posts: 4858
Joined: 3/26/2002
From: Florence, TX, USA
Status: offline 		Any of the Perry pumps will handle 7" draw distance without any issues.

John

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Fuel tank location and distance from engine? - 6/24/2003 9:47:33 AM   
matt walch


 

Posts: 3
Joined: 7/8/2002
From: cement city, MI, USA
Status: offline 		My dad and I both built a dumas swamp buggy about fifteen years ago. I built mine to specs. and it runs great with an O.S. 15. He went overboard and raised the motor mount, put a K&B .40 with a perry pump and carb on it and put the tank down in the boat. The darn thing never did run right Here is the amazing part though. Last summer I stuck my .46fx on it and it ran like a top - sucked the fuel a good 6-7 inches up with medium fuel line. The problem was that the boat thought it was a sub. I attached a peice of metal off the back of the boat on an angle. It kept it on top of the water with a nice spray too. What we won't do to make a bad design work!

< Message edited by matt walch -- Jun 24 2003 1:12PM >

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