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How to build your own Jet Engine

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Step 9: Plumbing the fuel and oil systems

Now that you have the flame tube drilled, open the combustor housing and insert it between the rings until it snugs down into the back against the exhaust cap. Replace the injector side cap and tighten the bolts. I like to use hex head cap bolts just for the look of them, but the convenience is also nice as you dont have to fidle with a regular wrench.

Now you will need to get some fuel to the system, and some oil to the bearings. This part is not as complicated as it may first seem. For the fuel side you will need a pump capable of high pressure and a flow of at least 20 gallons per hour. For the oil side of things you will need a pump capable of at least 50 psi pressure with a flow of about 2-3 gallons per minute. Fortunately, the same type of pump can be used for both. My suggestion is the Shurflo pump model number 8000-643-236. Other alternatives are power steering pumps, furnace pumps, and automotive fuel pumps. The best price I have found on the Shurflo is from http://www.dultmeier.com and is currently $77 US. Do not skimp out and buy the other Shurflo pumps which look the same but are cheaper. The valves and seals in the pumps will not work with petroleum based products and I can not guarantee that you will have much luck with them.

I have provided a diagram for the fuel system, and the oil system for the turbo will work the same way. If your pump does not have a bypass return directly on it (the Shurflow does not, but some furnace pumps do) then you can omit the pump bypass as it is only there to catch blowby from the pump itself.

The idea of the plumbing systems is to regulate pressure with a bypass valve setup. The pumps will always have a full flow with this method, and any unused fluid will be returned to its holding tank. By going this route, you will avoid back pressure on the pump and the pumps will last longer too. The system will work equally well for fuel and oil systems. For the oil system you will need to have a filter and an oil cooler, both of which would go in line after the pump, but before the bypass valve.

For an oil cooler, I suggest B&M transission coolers. Oil filters can be the regular screw on type by using a remote oil filter mount. Make sure that all lines running to the turbo are made of "hard line" such as copper tubing with compression fittings. Flexible line such as rubber can blow off and end in disaster. Oil or fuel hitting a hot turbine housing will burst into flame very quickly. Also of note is the pressure involved in these pump systems. Rubber hose will soften with heat, and the high pressures from the pumps will cause the lines to rupture and slip off of fittings. Be safe and use hard lines. It is just as inexpensive as flexible lines. YOU HAVE BEEN WARNED OF THE DANGERS, SO I ACCEPT NO LIABILITY FOR YOU UNWILLINGNESS TO FOLLOW INSTRUCTIONS!

When plumbing the oil lines to the turbo, make sure that your oil inlet is on the top of the turbo, and the drain is at the bottom. The inlet is usually the smaller of the two openings. If you are using a water cooled turbo it is not neccesary to use the water jacket at all, and nothing need be hooked to these ports. It will only be useful if you would like to supply a flow of water for cooling the turbo upon shutdown.

Tanks for fuel can be any size, and oil tanks should be capable of holding at least one gallon. Do not place the pick up lines near the return lines in tanks, or the aeration caused by the returning fluids will casue air bubbles to get in the pick up lines and the pumps will cavitate and lose pressure!

For fuel injectors, I recomend HAGO nozzles from McMaster Carr http://www.mcmaster.com Look on page 1939 of the online catalog for the water misting nozzles in stainless steel. An engine of this size will need a flow of approximately 14 gallons per hour at full bore.

For my oil system I use Castrol fully synthetic 5w20 right now. A fully synthetic oil with a low viscosity is a must. The fully synthetic will have a much higher flash point and be less likely to ignite, and the low viscosity will help the turbine to get started rotating easier.

For more information about calculating fuel requirements and such, I suggest you join a user group such as the Yahoo Forums "DIYgasturbines" user group. There is a wealth of information there, and I am a regular member.

Ahh, you will need a source of ignition! Since there are numerous ways to get a spark from a sparkplug I will not even try to go too in depth. I leave it to you to search the internet for a nice high voltage circuit to get a spark, or you can cheap out and wire an automotive flasher relay to a coil and get a rather slow, but usable spark out of your plug.

For the power to all of the 12 volt systems, I like to use 12 volt 7 or 12 amp hour sealed gel cell batteries such as are used in burglar alarms and battery back ups. They are small, light, and well suited to the task, plus they fit easily on a jet kart or other small vehicle.

Ok, so you've made it this far. All you need now is a stand on which to mount your engine. You can see the test stand I made in other pictures here and get an idea of how to make one for yourself. Do you have your leaf blower ready? Ok, lets get it started!
 
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jveta1723 years ago
will propane be efficient and poweful? how powerful of a combustion does it have compared to avgas o jet-a? i dont want to spend money on unnecessary things, propane is cheaper and requies no pump.
It's about a powerful as gasoline. You can use it in any carbureted gasoline powered engine with little to no ill effects on power and fuel efficiency. The only reason you can't use it in a fuel injected engine is because of the electric pump which can't pump a gas (I know what you're thinking, "But my propane is filled into the bottle as a gas!" This is true, but it immediately turns vapor when it hits atmospheric pressure and is there by unpumpable.) And that guy above is wrong; Propane works in such a way that you can almost get a constant 100 psi out of a bottle at right around 72 F providing that the bottle isn't almost empty. To me this sounds like plenty of pressure.
just use propane. PROBLEM SOLVED
how does the "bypass from pump" bit work... what is its purpose. Surely when the valve is closed you would want all fuel going to the injectors. would the bypass not jsut allow fuel back into the tank?
bigford7054 years ago
what kind of valve is that in the diagram?( needle valve or bypass valve).
1956GMC4 years ago
instead of using a standard plug could I run a glow plug?
what is the fuel you wat to use
no you have to use a igniter
sillypig4 years ago
i have an e book you can purchace for £2 that explanes it all
iq_abyss6 years ago
Dose the spark plug need to be pulsing, why not use a glow plug?
it needs a spark to ignite the fuel primery propane to heat the it up to over 100 dc
Can I run diesel for this unit. Kerosene is very exspensive.
yes you can but you have to use a evaporator in it