Johansson´s Pocketbike

[Fricke]

Why can´t You slide the rear bearing from the compressor side? It´s done every day on all sorts of shafts!

The Sophia j-450 & J-850 engines uses turbocharger turbines, it works for them...

And there is no problems with balance, the spacer will not affect the balance that much.

Or do as they did on the Phoenix 30.3 engine.

//F

[Johansson]

Why can´t You slide the rear bearing from the compressor side? It´s done every day on all sorts of shafts!

You must have misunderstood me, I meant that I must slide both bearings from the compressor side. Bahh, we can settle this in the language of the brave and beautiful (swedish) over PM instead.

The Sophia j-450 & J-850 engines uses turbocharger turbines, it works for them...

The Sophia engine looks good, I will see if I can find more info on it.

//Anders

[Fricke]

Ok...

It´s easier... ;)

[racketmotorman]

Hi Anders
You'll need the tube between the bearings , it can be balanced as a seperate unit before installing on the balanced shafting .
Because it will be situated near to the centre of rotation any small inbalance in the tube won't affect things as badly as it would if of large dia .
This is how I intend doing it :-))
Cheers
John

[Johansson]

Here is a rough drawing of how the turbo will be assembled, it is drawn to scale so you can see that the engine will be quite compact. There are no oil/air entry holes drawn yet, but the entry hole will be between the bearings and the two larger exit holes will be outside the bearings. Everything will be made in steel. (I won´t start with the weightsaving yet, first I have to get her running!)

Fricke came up with a clever idea of how to get the oil into the bleed tube, simply make a tank for the oil and pressurize it with bleed air to get an oil supply that only works when the engine is running. Brilliant since I would probably forget to turn on/off an oil pump, now I won´t have to worry as long as the oil nozzle don´t get clogged up by dirt.

The preload will be a wave washer which will be set at the right pressure by schims.

//Anders

[Fricke]

Looking good... ;)

And for the oilsystem... Don´t forget to mount a levelswitch, that cuts the fuel when the oil runs out... ;)

[Johansson]

John: I am finally convinced that I need a tube, earlier I just pictured me a turbine shaking itself to pieces. As long as I make the tube and spacer carefully and brotsch (don´t know the english word for it, you use it after drilling to get exactly the right diameter) the holes there shouldn´t be any problems with the balance...

Fricke: I would have to monitor the oil level often, perhaps a switch is needed so I won´t run it dry. But that is a later problem...

//Anders

[Fricke]

Are you not worried about oiling on startup? I know the ball bearings are much more tolerant of oiling conditions than the hyrdrodynamic ones in most turbochargers, but are they friendly enough to get to idle without overheating?

I’m jumping in here =)

There should be no problem... The micro jets are using the same principle, oil & air mist. The bearings will have some thin oil film on them from the previous run.

I have a old turbocharger with ball bearings and it have been run with out oil at the start a few times, and this turbo was made in the middle 60ties... No exotic materials...

//Fredrik

(Disregard my sign. =))

[Johansson]

The project is getting closer and closer to the actual building part, almost all parts are bought or ordered, the bearing drawings are mostly finished (the final adjustments to the parts will be done while building) and a new plasma cutter is bought which will be very handy since it can cut up to 12mm thick steel, so it will be easy to cut sheet stainless and make flanges for the engine.

I could have stressed it and probably been halfway through the project by now, but since I learn something almost everyday from books and the web it is best to advance slowly...

The engine will be manually controlled, no electronics that can mess up everything. I want it to be something like this:

By holding a push button down the ignition module turns on and a solenoid opens to let compressed air from a tank through to a nozzle on the compressor housing, the turbine starts to rev up and when the rev is high enough I flip the idle fuel switch which starts the idle pump. The spray nozzle coupled to the pump flows enough fuel to keep the engine idling, so when the engine is running the air button is released which closes the solenoid and shuts down the ignition. The air hose is deattatched from the bike and everything is set for driving.

When the engine is running at idle the throttle, which is coupled to the main fuel valve, is opened so the main fuel pump injects fuel through several syringe needles into the hooked vapourizor tubes. The idle pump is always running to prevent flame-outs if the throttle is closed quickly.

The compressor discharge pressure pressurizes the oil tank for the bearings, so the higher the revs/P2 the more fuel and bleed air is flowing through the bearings to prevent them to overheat.

A generator is coupled to the power turbine so the battery can be charged simply by having the engine at idle (possibly high idle) with the rear wheel lifted, this way the only thing needed to start and run the engine is a tube with compressed air.

Simple! *smile*

//Anders

[Johansson]

Finally! Today was a busy day for me, I´ve worked all day on the lathe and have got much done on the turbo assembly. If things keep going well tomorrow I will post a pic on what it looks like half-done.

//Anders

[Johansson]

Here are some pics of what I´ve done this weekend, I will try to spend a couple of hours in the workshop tomorrow too.

//Anders

[Fricke]

Looking good...

Are You going to weld the flanges to the center parts?

[Johansson]

Yup, the flanges are 3mm thicker than they should be so if they bend from the welding it won´t matter, I can just make them plane on the lathe. (damn language, I haven´t learned the technical part of english yet. You get the point anyway...)

Tomorrow I will try to finish the plates and start making the bearing tunnel, I have some time next weekend so with a bit of luck I can get most of the machining done by next Saturday.

//Anders

[Fricke]

Make sure to bevel the edges on the flange and center piece, so the weld penetrates deep in to the steel... And weld short legths opposite each other all the time...

So in a few weeks there will be a nice center piece!

Good luck!

//F

PS: This is how I vision You and Your bike! - see attachment! ;)

[Johansson]

Nice... *LOL*

//Anders