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Post by racket on Feb 26, 2016 16:40:35 GMT -5
Hi Anders
Thanks for the video :-)
All the best for tomorrow , hope the weather stays good .
Cheers John
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Post by Johansson on Feb 27, 2016 12:27:08 GMT -5
We had trouble all day with loss of oil pressure, we will have to redesign the whole oil system with a better designed oil tank, a 12V oil pump instead of the unstable 4-stroke pump and all oil lines redirected so there cannot be any air trapped in the system.
The jet kick is in one piece and Olov ran 139.2km/h which is way better than we have done before so we are satisfied!
Cheers! /Anders
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Post by racket on Feb 28, 2016 16:29:11 GMT -5
Hi Anders
Bummer about the oil :-(
Yep , I'd go electrics rather than IC engine for driving pumps , the IC engine on the first turbine bike gave me lotsa problems with the fuel system as the IC engine never maintained consistent rpm whereas an electric pumps rpm won't jump around .
139.2 kph isn't a bad speed, Olov should be very pleased ,..............how was the kick's handling at speed ??
Cheers John
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Post by Johansson on Mar 2, 2016 1:44:02 GMT -5
Hi John,
It is a pretty strange problem actually, when we run the engine stationary the oil pressure is stable but as soon as the kick starts moving forwards the problems start. Here is a short helmet cam video from one of the runs where you can see the oil pressure gauge on the right, it drops suddenly from 6bar to 3.5bar where the pressure safety switch cuts the fuel pumps.
We will fit an electrical pump and build a new oil tank for next year, so hopefully the problem will disappear. The tank is placed in front of the turbochargers now but we´ll find a place for it further back so the oil won´t back up the turbo drain lines when the kick is accelerating.
With the tank design we have now the drain lines ends up below the oil level in the tank so any P2 air that has passed into the shaft tunnel will blow directly into the oil making it froth like crazy, that can very well be contributing to the loss of oil pressure.
The kick is handling very well, he says that there is no tendencies of instabilities at all at speed so that is great. It doesen´t matter how powerful the engine is if the driver can´t keep it on the track.
Cheers! /Anders
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Post by racket on Mar 2, 2016 16:05:54 GMT -5
Hi Anders
Yep , the oil pressure is restored as soon as the P2 pressures drop , gotta have that oil entering the tank above the oil level so that the entrained air can easily be disposed of .
An oil tank with a deairator plate for the drain oil to spill onto should fix the problem .
Oil tanks preferably need to have a fair bit of "vertical" space , rather than a shallow flat design, ideally like a karting fuel tank that copes easily with cornering forces as well as hard accel/decell forces without air getting in the fuel offtake
With my turb bike it had a long tank with a taller section at the oil return/drain end for the deairator plate as well as a couple of baffles along the tank to cope with any surging problems , by having the oil takeoff from the rear of the tank there was no supply problems under hard acceleration .
Nice to know the handling is good , one less thing to have to think about whilst hanging on .
Cheers John
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Post by Deleted on Mar 3, 2016 14:33:23 GMT -5
Something like this John
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Post by racket on Mar 3, 2016 16:03:51 GMT -5
Hi Andy
Yep , thats the ideal arrangement , its a bit difficult to fit into our builds unless we use a scavenge pump , with gravity drainage and "vertical" build height restrictions we need to compress it down a bit to a less ideal form , the aircraft ones like in your image need lotsa airspace inside due to the very low ambient air pressures the aircraft can operate in , we can get away with less "frothing" space at our altitudes.
Another help with a "shallow" tank is to have a horizontal baffle just above the oil outlet position to prevent a "vortex" developing , once in the past I used an automotive sump filter , positioned close to the bottom of the oil tank to spread the "suction" over a larger area to prevent the vortex and air entering the suction line to the pump .
If we have the possibility to use a tall tank its best, but if not , then we need to add extra features to a shallow tank to prevent/lessen problems arising .
Cheers John
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Post by Johansson on Mar 4, 2016 16:38:16 GMT -5
Hi Anders Yep , the oil pressure is restored as soon as the P2 pressures drop , gotta have that oil entering the tank above the oil level so that the entrained air can easily be disposed of . An oil tank with a deairator plate for the drain oil to spill onto should fix the problem . Oil tanks preferably need to have a fair bit of "vertical" space , rather than a shallow flat design, ideally like a karting fuel tank that copes easily with cornering forces as well as hard accel/decell forces without air getting in the fuel offtake With my turb bike it had a long tank with a taller section at the oil return/drain end for the deairator plate as well as a couple of baffles along the tank to cope with any surging problems , by having the oil takeoff from the rear of the tank there was no supply problems under hard acceleration . Nice to know the handling is good , one less thing to have to think about whilst hanging on . Cheers John Hi John, We built the entire jet kick in four months so there weren´t really much time to think things through or go that extra mile with the tank design, we just found a helium tank that fit the frame and welded fittings to it. With the new placement of the tank further back we will have much more room for separating the return lines and suction line, internal baffles will be made and a deairiator plate will be added to give the oil some time to rest. Handling and engine performance is perfect, so with a more solid oil system we will hopefully make havoc with the inofficial jet kick record next year! Cheers! /Anders
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Post by Johansson on Sept 15, 2016 15:58:58 GMT -5
Time to get the twinturbo jetkick running again! We´ve decided to rebuild the oil system as a dry sump system to get rid of the problems we´ve had with the gravity drain, the oil level is so close to the bearings so the blowby P2 air froths the oil in the tank until the pump start sucking air and loses the pressure. At least that is the theory why we keep losing oil pressure when we reach 100km/h, at half throttle the kick runs all the way to the finish line which can be explained with the fact that there is less air leaking past the shaft seals. The oil tank is by necessity placed in front of the turbochargers so the G forces throws the oil up the drain lines into the turbos. Not good. The idea now is to use the original oil tank as a dry sump where a pump pumps all of the drain oil up into the new oil tank welded to the back of the fuel tank, a long and narrow oil tank prevents sloshing around and the oil gets plenty of time to lose any air trapped in it before being recirculated. The oil will get plenty of cooling from the fuel on the other side of the aluminum tank wall. This is how far I got last night, I need to make a handful of 1/2" weld bungs for the oil line connections before I do anything else. Olov is going to modify the 4-stroke engine powered oil pump so it accepts a second and slightly larger oil pump that will move the drain oil up into the main tank. Cheers! /Anders
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Post by Johansson on Sept 22, 2016 15:49:08 GMT -5
The plan today was to finish the oil tank job and get the kick back to Olov so he can do the rest, but things don´t always work out the way you want... I have made four 1/2" weld bungs for the tank, the one at the bottom is oil out to the pump, the three on top are return oil from the regulator, return oil from the dry sump pump and the dry sump tank ventilation. With the holes drilled and everything cleaned up and ready for welding the TIG welder decided to throw in the towel, it lights up like it should but doesen´t react to anything. Time to call it a night then and hope it has repaired itself by tomorrow... On a side note I have bought myself a race van! A Fiat Ducato Maxi which will house both the bike and all stuff needed for a race weekend, a pair of stacked beds and a propane fueled kitchen if I build everything smart enough. Very nice to have everything with me in one vehicle instead of having to drag a trailer behind the family car and have a friend tow a caravan so we have somewhere to sleep. Cheers! /Anders
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Post by racket on Sept 22, 2016 23:47:06 GMT -5
Hi Anders
Tank is looking good , bummer about the TIG :-(
Yep , a van is the way to go , everything out of the weather .
Cheers John
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Post by Johansson on Sept 23, 2016 13:25:30 GMT -5
Believe it or not but the TIG started working today after a couple of tries, I have no idea what happened but after blowing some dust out of it and disconnecting the tig torch it started right up and kept running after I hooked the torch back in.
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Post by Johansson on Sept 24, 2016 15:01:06 GMT -5
With the TIG welder working I could finish the oil tank job today. I welded the connections and, after a thorough cleaning, welded the lid in place. Now I will take the jet kick back to Olov so he can make a new set of tank mounts, fit the new twin oil pump to the 4-stroke motor and connect everything with new hoses. Cheers! /Anders
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Post by racket on Sept 24, 2016 19:22:21 GMT -5
Hi Anders
There shouldn't be any problems with that nice tall tank :-)
Cheers John
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Post by Johansson on Sept 24, 2016 23:45:20 GMT -5
I hope not, it will hold 8 liters of oil and still have plenty of space left for frothing oil. It will be very interesting to test this out on the first ice on the lake (if the snow won´t come first and ruin our race track), Olov has made numerous passes that ended in a flameout so he can tell instantly if it behaves differently now.
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