CH3NO2
Senior Member
Joined: March 2017
Posts: 455 
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Post by CH3NO2 on Apr 24, 2019 14:36:05 GMT -5
Hi Anders,
Will the bike go on the dyno when its all finished?
Tony
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Post by Johansson on Apr 24, 2019 15:15:56 GMT -5
I havent thought about it, but if there is a dyno owner around here that will accept the bike then it would be fun.
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Post by Johansson on Apr 26, 2019 11:21:24 GMT -5
Lots of progress made on the bike during the last couple of days, I think I finally have found the best (or maybe least bad?) way to route all of the oil and fuel lines and today I bought the last couple of AN4 angled fittings. I have also started to wire up the bike again, not a very big job since I can reuse most of the stuff I had last year. Once I am satisfied with everything and have proved it on the track I will spend a winter on rebuilding all of the wiring and control systems into a neat and compact unit since what I have now is a Frankensteinish mess that has grown and mutated badly over the years.   Last but not least I removed the gearbox this morning and have welded up the interstage duct along with adding a fitting for the exhaust temp sensor, it didn´t distort anything from the welding so the slip joint is still in good shape.  I have decided to send the power turbine wheel along with the primary gearbox shaft to Turbotech for balancing, it hasn´t been done before and I don´t want to run the bike again before I know that it is balanced correctly. While waiting for it to get back I will do a proper check of the gearbox bearings and gears for signs of wear. Cheers! /Anders |
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Post by racket on Apr 26, 2019 16:56:59 GMT -5
Hi Anders
Interstage looking very nice :-)
It'll be interesting to see how the Allison NGV performs , its certainly got plenty of excess "theoretical" flow so interstage temps should be lowish .
Cheers
John
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Post by Johansson on Apr 27, 2019 1:29:43 GMT -5
Hi Anders Interstage looking very nice :-) It'll be interesting to see how the Allison NGV performs , its certainly got plenty of excess "theoretical" flow so interstage temps should be lowish . Cheers John Hi John, I would like to keep temps and revs on the moderate side to begin with, still plenty of power to go faster than last time and I can modify the engine over time to reach design temps and revs. Cheers! /Anders |
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Deleted
Joined: January 1970
Posts: 0
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Post by Deleted on Apr 28, 2019 5:13:19 GMT -5
Looking good.... so looking forward to seeing it fired up again |
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Post by Johansson on May 3, 2019 9:32:48 GMT -5
I opened up the gearbox yesterday and found that the bearing closest to the pinion gear had a slight rattle that didn´t go away despite being washed through in kero.  It is a 6305 hybrid ceramic bearing rated 18kRPM in oil, so I have run it a fair bit faster than I should. Funny thing is that the second bearing is exactly the same kind and it seems to have survived just fine. Might be the combination of side loads from the gears and the revs that took its toll. I have emailed Boca Bearings to hear what they can suggest, one thing that comes to my mind is to gear the bike a bit taller so I peak around 20-25.000rpm instead of 30.000+rpm like now.  That was the "bad" news, the good news is that the gear mesh looks really good, no difference in the wear pattern now compared to after the first run when I forgot to fill the gearbox with oil...  I took the turbine wheel and pinion shaft to my balancer today and hope that he will have time to balance it in the near future, I have lots of work to do wiring up the bike etc so I won´t be sitting idle. Cheers! /Anders |
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Post by racket on May 3, 2019 20:18:36 GMT -5
Hi Anders
What sort of lube supply to the pinion bearing ??
Is there any preload ??
Cheers
John
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Post by Johansson on May 4, 2019 12:10:18 GMT -5
Hi Anders What sort of lube supply to the pinion bearing ?? Is there any preload ?? Cheers John Hi John, There is a 1mm oil jet pointing into the ball bearing, no preload since the pinion gear will apply an axial force as soon as it starts turning, so I figured that preload wasnt needed forcthe bearing. There is a chance that the bearing damage was caused by the disassembly, I had to press the bearing off the shaft by pushing on the outer race so the balls might very well have been damaged by this. If I reduce the power turbine max revs to 20.000rpm to better match the bearing max rpm rating, how much power will I lose by this? Cheers! /Anders |
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Post by racket on May 4, 2019 17:33:27 GMT -5
Hi Anders
Does there appear to be any heat marks on the bearing groove ??
My SKF manual has a Reference speed of 24,000 and a Limiting speed of 16,000 f0r that sized deep groove bearing , but that speed doesn't account for oil jet lube which should penetrate the bearing unlike a static oil bath.
Is the gas pressure on the wheel balancing the gear thrust or adding to it ??
The SiN balls will damage the steel raceway without being damaged themselves , I had some horrible bearing damage with FM-1 when playing with hybrid bearings , but the balls came through OK , it might pay to disassemble the bearing to have a look inside .
At 20,000 rpm you'll probably only lose 10% power , a freepower will turn out 80% power at 50% rpm , its a very FAT power curve :-)
Cheers
John
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Post by Johansson on May 5, 2019 1:54:18 GMT -5
Hi John, I cannot see any damage or heat signs at all in the races, it looks just like new. If I rotate it slowly one turn I feel like 1000 tiny "clicks" so something is surely wrong. The bearing closest to the turbine wheel is slightly brownish from oil deposits burned into the bearing from heat soak but it feels perfectly in order. The gas pressure on the turbine wheel counteracts the gear thrust. It might just have been disassembly or some crap that has gotten into it sometime during its lifetime, since the freepower turbine hasn´t been balanced before vibrations might also have contributed to the damage. I´ll wait and hear what the tech guys at Boca Bearings have to say, and most likely order one more of the same. I will see what kind of gearing I can fit to the bike, I think I´ll find the smallest available rear sprocket to get the freepower revs down a bit. If I can get it to peak out at <25.000rpm I think I am doing the gearbox a big favour. Cheers! /Anders |
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Deleted
Joined: January 1970
Posts: 0
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Post by Deleted on May 5, 2019 2:20:23 GMT -5
Hi John, I cannot see any damage or heat signs at all in the races, it looks just like new. If I rotate it slowly one turn I feel like 1000 tiny "clicks" so something is surely wrong. The bearing closest to the turbine wheel is slightly brownish from oil deposits burned into the bearing from heat soak but it feels perfectly in order. The gas pressure on the turbine wheel counteracts the gear thrust. It might just have been disassembly or some crap that has gotten into it sometime during its lifetime, since the freepower turbine hasn´t been balanced before vibrations might also have contributed to the damage. I´ll wait and hear what the tech guys at Boca Bearings have to say, and most likely order one more of the same. I will see what kind of gearing I can fit to the bike, I think I´ll find the smallest available rear sprocket to get the freepower revs down a bit. If I can get it to peak out at <25.000rpm I think I am doing the gearbox a big favour. Cheers! /Anders Hi Anders there are not a lot of bearings than can cope with the temp and speeds we need will be good to hear what the bearing guys think Could you get me a photo of your setup behind the fan looking at the bearing (hot side) I have nearly completed my gearbox and the Hot side design was the last thing to tackle as a temporary setup Im going to use a rubber oil seal (which will fail) but have already started to make a piston ring type setup which will replace the rubber seal in time cheers Chris |
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Post by Johansson on May 5, 2019 23:34:27 GMT -5
Hi Chris, I´ll get you a couple of photos tonight unless it completely falls out of my mind. Anyways, there is a thick steel washer between the turbine wheel and first bearing, it is locked in place with a grub screw and a piston ring seal on the turbine shaft hub seals against its inner bore. I get a little bit of oil leakage past the seal into the engine exhaust but nothing that matters, it just smokes a little after engine shutdown when the oil pump is still running. No bearing preload springs in my design, I was a bit restricted in what I could do since I used an existing industrial gearbox and modified it for this use. Cheers! /Anders |
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Post by Johansson on May 7, 2019 14:29:36 GMT -5
Hi Chris, With the turbine shaft off for balancing this is all I have to show, the shaft tunnel with the oil jet.  Cheers! /Anders |
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Post by Johansson on May 16, 2019 13:17:38 GMT -5
New ceramic bearing is shipped from US of A, the balancer has started working on the power turbine and a smaller 41 teeth rear sprocket has arrived in the mail. Before I have the gearbox put back together there is little I can do since I have to fit the gearbox before I can do the final assembly of the bike, so I´ll spend my time getting a boxcar built for a kids race in the village this summer and attend a couple of big IPSC matches. Cheers! /Anders |
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