Johansson´s Pocketbike

[racketmotorman]

Hi Anders
They're all seperate little bits of wood with tapered sides and fillets so they can be easily removed from the "sand" when casting .
Heres a pic of the backside of the diffuser pattern , with my bearing housing .
Cheers
John

[Fricke]

Hi Racket!

That looks interesting!
I have to agree with Anders, start a thread on the "thing"!

[Johansson]

O boy, you´ve put some work into those patterns. How accurate will the castings be when they are done do you think?

//Anders

[Johansson]

Anyway, next up on the project is to get the turbo spinning. First I need to take a few .001:s of the shaft to allow a certain degree of bearing movement. The guy who grinded it made it exactly 12 mm without testing if the bearings would fit, so a minor adjustment is needed. I will do it carefully with a wet grinding paper glued to a flat piece of metal, it would be a shame if I took too much since I don´t want to go through the whole process of buying a new shaft and sending it for grinding and balancing again.

It can take a while before the next progress report since I´ve got some other things to do while waiting for the last parts I´ve ordered to arrive, but hang tight y´all!

//Anders

[racketmotorman]

Hi Guys
Hopefully the castings will be fairly accurate .
The last time I got something cast , it came back with the imperfections of the pattern in the actual casting .
I'll keep you posted on how they turn out , it'll probably be a couple weeks at least before they come back from Melbourne (1500kms away) , I sent them to a friend who'll get them done for me , he'll be wanting a set for himself as well :-))
Cheers
John

[Johansson]

The shaft was grinded to the right shape today, I also finished the compressor wheel spacer which was a pain in the *ss to do because of the hole that must be 7.90 mm. The adjustable reamer I used kept getting stuck so I will have to check if came out right or if it is out of balance.

An odd thing I noticed was that the two 12mm SKF bearings differed quite a lot from each other, I used one of them when I grinded the shaft and got a perfect fit on both seats but when I tried the other bearing it got stuck just a few mm:s in. I found that a cheap chinese bearing was identical to the first bearing so I fitted that one instead. "Swedish quality bearings" - Bahh!

//Anders

[Johansson]

When I fitted the compressor spacer I found out that it was not accurate enough, so I made a new one today along with the spacer that should sit between the bearings inner races. I have borrowed a better camera for a few days so tomorrow I will take some more detailed pictures of the turbo.

I have also decided to make the fuel system slightly different from how I intended to do it earlier, I will skip the pressure adjustment on the idle system to save some space and build the main system a bit simpler and less bulky. I won´t try to explain how since it would only confuse anyone reading this, so I will let the camera do the talking when it is finished instead... ;-)

//Anders

[Johansson]

Finally! After borrowing my girlfriends camera I got some close-up pictures that looks good, here are a few pics of the shaft housing and the assembled turbine shaft.

//Anders

[Johansson]

Thanks for the kind words, it won´t take too long before we will se if it can live up the expectations...

Anyway, I have spent a couple of hours on assembling the main fuel system today. Here is a mock-up of it along with a picture of the almost finished nozzle couplings, the ball valve will act as the throttle so at idle all fuel is pumped back to the tank. When the valve closes the pressure in the system rises until it reaches 1.5 bar, then the safety valve opens and lets the fuel through to the nozzles. Closing the valve even further increases the fuel pressure and therefore fuel flow over the nozzles. I will do some testing of the system later to find out how much the valve must close to get max fuel pressure over the nozzles, and then fit an extended arm to it to mount the throttle wire on.

Tomorrow I will try to solder it together and make some other parts if I can find the time.

//Anders

[Johansson]

I washed the grease out of the bearings and tested the turbo with shop air today, and after a minor modification to the compressor spacer it spun freely without any play at all.

The shop air is a bit weak for this turbo if I intend to start it by blowing at the compressor wheel, so I am considering drilling and tapping a hole in the turbine housing so that the air will impinge on the tip of the turbine wheel. There is not enough room for the leaf blower when the engine is in place so a compressed air starter is the only way to go, perhaps a scuba tank and regulator is best since I´ve got both a tank and a 200 bar diving compressor for filling it...

Anyway, here is a quick movie of the turbo spun by hand.

//Anders

[Johansson]

I have been away for a week so nothing much has happened on the bike except that I have been shopping for parts and have reconsidered some ideas that I had before. I have nothing planned for the entire next week, so if everything goes well there won´t be much left to do on the bike at the end of the week.

A TOT-gauge have been bought along with a silicone hose for the compressor, I got the silicone hose for free from the local turbo-expert at TurboTech, 1000 thanks for that.

I am also in touch with a local airport trying to buy a barrel of kerosine, diesel would work as well but it would not smell right... ;-)

//Anders

[Johansson]

Today I have fitted an air impingement nozzle on the compressor housing, made connections on the combustor for the bleed air/P2 gauge and for measuring compressor outlet temp. I have also made the instrumentation board for the gauges and switches.

Unfortunately I have returned the borrowed camera, and I didn´t bother to take any blurry pictures of the parts with my own camera so pics will come later...

//Anders

[Johansson]

After some thinking I have decided to leave the impingement starter for now and do the first tests with the leaf-blower, that way I am assured that it at least get spinning fast enough and can focus on other things like lubrication and measuring idle rpm...

The bent-chinese project got in the way last week so I haven´t made much on the bike, but now I will try to get it ready for a quick start-up as soon as possible. After I have made a (hopefully) successful run it will be easier to make the remaining parts like weld together the fuel tank and fit a battery.

Sorry if I have done more talking than building lately, but life gets in the way of having fun sometimes...

//Anders

[Johansson]

The last two days I have been working on the exhaust pipe and assembled the engine and gauges in the frame. The over-all finish is a bit rough but I won´t bother to do anything about that before I know if the engine will run or not.

//Anders

[Mike Everman]

That's so cool! Don't cook your feet.