Fuel Tank: Size & Position
tank (Medium)

 SIZE: Do not use a tank that is too big if you plan to use muffler pressure because there will be a significant difference between mixture values at the beginning and end of the tank. The sizes below are about right and provide a fair bit of reserve. Somewhat smaller sizes can also be used if you are careful by not running too rich and/or limiting flight times, and/or not flying continually with full throttle. The best tank sizes therefore depend somewhat on personal tastes.

  • Saito 30, 40  6-8 oz
  • Saito 50, 56    8-12 oz
  • Saito  65, 72, 80, 82a, 91,100    14-18 oz
  • Saito 120, 150        18-20 oz
  • Saito 180          20 - 24oz
  • Saito 220         24 - 30 oz

At full throttle the Saito-180 uses a little under 2 oz per minute of fuel. Assuming one needs about 15 minutes of running time per flight, a 24 oz tank provides plenty of reserve because the engine is probably not normally operated continually at full throttle. However, most people don’t fly with continuous full throttle, so you can get by with a smaller tank say 18-20oz

Another factor is the needle setting. A richer mixture, will naturally use more fuel.

The Graupner tanks (sold by Hobby Lobby) are excellent but only available in larger sizes. However, in my opinion, the tubing and clunk hole diameter are a little too thin for the Saito-180

If you are paranoid about leaking tanks, you should consider coating the exterior stopper area with Goop. However don’t do this unless you are sure you will no

A Tank Tip:
Sometimes an engine will just not run right. In many cases the problem is the fuel system, viz tank, kinked fuel lines, clunk hole too small, junk in tank etc. To determine if you have an engine problem or fuel tank problem try this. Get another tank that you know is good and temporarily tape it to the side of the fuselage just behind the engine with the height of the carb level with the mid-level of the tank. Try using masking tape to attach the temporary tank. Now disconnect the old tank and connect up the temporary tank. Start the engine and see if  your problem goes away. The larger engines like the 150 and 180 are best with 1/8 ID fuel tubing; use a large diameter clunk hole and tubing on your test tank if you are checking a 150 or 180 engine.
    (...so what do you say about that idea ?  ......  “tanks a lot”)

t need to ever disassemble the tank.

 

 

 

 

 

 

TANK POSITION: Keep the center-line of the tank close to the level of the carb spray-bar (or a little lower), and also keep it as close as possible to the rear of the engine. With a properly located tank the engine will run fine with muffler pressure. If you use an appropriate fuel pump, or the Cline regulator, the tank position is not so important.

 

FUEL TUBING:   “Normal” or “Standard” size fuel tubing has 3/32 inside diameter; it will work OK for all Saito engines provided you have a conventional tank setup; ie the tank is just behind the engine. However, if you are using a larger engine (150 size or bigger) with a long length of fuel tubing (eg the tank back over the CG) make sure there is no restriction on fuel flow and I prefer “Large” size (1/8” ID) tubing for those larger engines when using longer fuel lines.  Also when using the larger engines make sure the hole in the clunk is not too small (ie it should be about 1/8 ID), and if you use a fuel filler valve it is better to use a large size one such as the large Dubro model. If you are using the Cline pressure pump system the tank pressure is quite large and the thin 3/32 ID tubing is adequate.

The symptom of insufficient fuel flow is evident at full throttle if you are unable to get a rich setting by fully opening the needle valve. There might be a number of reasons for constrictions so don’t assume it is only the tubing.

 

FUEL FILTER

Sullivan filters  are very good. The larger one  is well-suited for 120,150,180 engines.

Saito Filter   Saito fuel filter

 

Fuel_Consumption

How to Make a High-Flow Fuel Tank:
The Saito 180, and 220 engines need an unrestricted fuel flow. Regular size 3/32 tubing may not be adequate, particularly if the tank is back over the wing and the length of fuel tubing from tank to carb is quite long. First, get a Sullivan or Dubro tank of the appropriate size. Next buy a Sullivan “Super Klunk” (part No 396); this clunk is much heavier than the normal sizes and has a large hole for the fuel flow. Next get a Sullivan “Large Capacity Tank Stopper” (part No 479); this is a new stopper that fits both Sullivan and Dubro tanks and comes with a large 3/16” fuel feed. Assemble the tank and use 1/8” ID (or even better 5/32” ID) silicone tubing to connect up the clunk. Connect the tank to engine using 1/8” or 5/32” tubing. If you use 5/32” tubing from the tank to the engine you will find the tubing too big for the carb inlet nipple so you will have to use a step-down fitting (Sullivan part No 485) to convert from 5/32 to 1/8 just before the carb. Coating the outside of the tank stopper with Gunk will ensure the tank won’t ever leak. You can get 5/32” (4mm) line from Sullivan (Part No S221), and 1/8” ID tubing from Prather Products (Part No 7090).

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