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Post by Johansson on Nov 27, 2017 3:13:02 GMT -5
Before doing anything drastic I will move the pressure sensor to the pump outlet and run the pump with the oil line routed back to the tank, this way I can see if the oil system is causing any back pressure that makes the pump work harder than necessary.
R&D, it never ends..đ
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Post by Johansson on Nov 27, 2017 0:21:10 GMT -5
Hi Anders Perhaps the new cabling has allowed the pump to spin faster creating more flow which can't pass through the engine so is being heated by the pumping process . Have you done any flow testing to check just what the pump is actually doing ?? You are pulling a lotta Amps on the pump , twice what I do . You might need to send the bypassed oil back through a cooler to the tank to provide some cooling. Cheers John Hi John, Yeah, something is surely going on in the oil system. I can´t remember that the oil has heated up this fast before so the extra power to the pump must have created a new kind of problem. One cause might be the AN6 oil lines and oil regulator restricting the oil flow to the engine, I have the oil pressure sensor just next to the engine so with cold oil the pump might be struggling hard to get the pressure up to 4-5bar at the engine end of the oil system. A fix for this would be to fit larger oil lines and make a new and beefier regulator, I talked with Olov yesterday about PWM controlling the oil pump with some automatic system that keeps the pump running at a constant oil pressure but it is just another thing that might cause problems so I think I will stick to the manual ball and spring regulator. Cheers! /Anders |
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Post by Johansson on Nov 26, 2017 17:53:17 GMT -5
Hi Anders, Â Will the JU-02 be making an appearance at speed weekend? Regards Dan I don't think so, it is too much work to bring everything and we will have our hands full with the iceliner stuff. |
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Post by Johansson on Nov 26, 2017 17:51:39 GMT -5
Or use a oil cooler,there are some neat small heat exchangers out there,such where you can Run fuel through it as cooling medium! Cool projekt Anders! Hmm, perhaps one of those coolers would work. They are really small so I might be able to fit one to the bike, thanks for the idea Stoffe! |
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Post by Johansson on Nov 26, 2017 16:48:25 GMT -5
One thing I need to do before next run is to try another type of oil, now I use 0w30 and once the oil starts to heat up the low viscosity makes the oil pressure drop. Nothing like before when the battery voltage was crap but still, I ran the engine for a total of almost 10 minutes today and at the end the oil lines were so hot I couldn´t touch them for long.
This is more of a problem now than at a race since a run takes like a minute or two tops, but I would still like some more margin.
I will get me some 5w50 synthetic oil and see if the higher viscosity when hot keeps the oil pressure more stable, an easy fix if that is the case. If the oil temp won´t have time to drop enough at a race I can simply empty the tank and fill it up with cold oil, then keep switching back and forth as the drained oil has cooled off.
Cheers!
/Anders
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Post by Johansson on Nov 26, 2017 16:37:04 GMT -5
Thanks!  Yeah the temps are really encouraging, especially since there is some reason to the temp readings after years of strange temp variations on JU-01. Now it is just a smooth temp rise that follows the P2 both up and down, I am so glad that the JU-02 engine is behaving well so far. I have never heard an engine that sounds this angry at idle revs, at 0.5bar P2 it is really roaring despite the cold 500-ish exhaust temps. When I passed 2 bar I got a bit nervous standing right in front of the engine, I really need to get the digital scale sorted out so I can get a thrust reading out of it next time! Cheers! /Anders |
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Post by Johansson on Nov 26, 2017 16:31:22 GMT -5
Hi Anders Always good to see them spinning around , it looks like you produced a fair few rpm Cheers John Yup, and no wobbly wheels making grinding noices. |
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Post by Johansson on Nov 26, 2017 11:42:04 GMT -5
Will do just that John, I am finishing a cup of coffee and then it is off to Olovs place to start working on the chassis. I assembled the turbofan so we can mock up a mount for it tonight, when it was put together I couldn´t resist spinning it up with the leafblower. No vibrations at all could be felt and both wheels ran true so this is looking promising. Cheers! /Anders |
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Post by Johansson on Nov 26, 2017 9:39:48 GMT -5
Hi guys! I test ran the engine today with the new battery, the oil pressure is much more stable now although the prolonged test heated up the oil until the pressure started to fall down to 3kg. I ran the engine up to 3bar P2 where the engine was really screaming, my trusty foam plugs was nowhere near enough hearing protection so I need to use my artillery ear muffs on top of them next time. You can see the flag starting to wave from the air flow when I throttle past 2 bar, and the shed doors started to close from the jet stream passing by. Exhaust temps were in the high 650°C region at 3bar P2, perfect since the temps will go up a bit when I push the engine toward 4 bar later. When I shut the engine down a compressor rub can be heard, I will investigate it when I disassemble the engine later. Shaft play feels ok and nothing is rubbing now so hopefully is isn´t anything serious. Cheers! /Anders |
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Post by Johansson on Nov 24, 2017 17:55:23 GMT -5
WTF have you done Olov?? We were supposed to just bring a pile of crap to the race, drink beer and talk about how fast we will go next year!  |
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Post by Johansson on Nov 24, 2017 1:42:35 GMT -5
Nice one John!
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Post by Johansson on Nov 23, 2017 17:19:41 GMT -5
Hi Anders, If your transition is a diffuser and it must also be a slip fit, you may be able to use any leakage (IE bleed) to your advantage to increase chamber pressure and reduce length.  I am not sure I understand that picture, what is the bleed air for? Anyway, the reason for the slip joint is to free the fan cover from any kind of directional stress so I think a simple heat proof gasket of sort inside a slip joint will do.  I welded up the exhaust manifold tonight, I know I said that I would make a better looking manifold but after giving it some thought I decided to stick with this one for now. It is difficult to make a proper one with the space limitations and since we hope to have the ice yacht ready to run for Speed Weekend (a long shot but might be doable) this one will have to do.  My biggest concern is that since we start one gas producer at a time the first one might blow exhaust gasses up into the second one making it difficult to start, but if that is the case we just have to figure out a way to start them both at the same time. Cheers! /Anders |
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Post by Johansson on Nov 22, 2017 13:11:49 GMT -5
I charged the battery over night and took it out to the workshop after dinner, just for fun I compared the weights of the new battery and my old Deka Dominator. I am lowering the bike weight by 6kg by doing this battery change, great!  So, I hooked the battery up and started the pumps. The first thing that happened was that the 30A fuse for the oil pump blew after like 5 seconds, this indicates that the battery is giving more juice to the pump than before. I replaced the fuse holder with a length of 6mm2 wire and tried it again with better luck. The + cable gets just noticeably "warm" but nothing that I need to worry about. Might add a larger fuse later.  Anyway the oil pressure is rock solid, nothing like before when the pressure started to drop after a dozen seconds or so. Success! Cheers! /Anders |
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Post by Johansson on Nov 21, 2017 16:55:28 GMT -5
I will do a 5 minute oil pump test and see if the oil pressure remains stable, if so I will consider this a smashing success! |
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Post by Johansson on Nov 21, 2017 15:59:27 GMT -5
Finally the new LiFe battery has arrived! I am charging it over night and hopefully I will find time to hook it up to the bike and test run the pumps tomorrow, I have high expectations for this!  Cheers! /Anders |
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