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Post by racket on Sept 10, 2014 21:50:23 GMT -5
Hi Mitch
Hopefully below the secondary holes , between them and the large tertiary holes if possible .
Cheers
John
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mitch
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Joined: August 2014
Posts: 285 
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Post by mitch on Sept 11, 2014 22:54:58 GMT -5
Well, I went to run it today... Dropped the entire engine off the stand it was on. Luckily nothing seems to be broken, but I spilled all of the oil out of the oil tank, got pissed, and smashed the oil tank with a sledge hammer (the welds were awful and it leaked like a sieve, so it had to go anyway, what better way to get rid of something than with a sledge hammer?).
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mitch
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Joined: August 2014
Posts: 285
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Post by mitch on Sept 18, 2014 10:29:34 GMT -5
What kind of oil temps are common in a turbojet of this size? I plan to use a cooling fan with my oil cooler, in hopes of keeping temps below 140 degrees, as that is the max temp my pump can work with.
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Post by racket on Sept 18, 2014 16:19:35 GMT -5
Hi Mitch
There can be up to an ~80 degree F rise in oil temperature going through a turbo .
The oil cooler is generally placed between oilpump and turbo so the pump would be seeing the hotter oil , but if you have a decent sized oil tank capacity and you don't run the engine for extended time periods its possible to get away without an oil cooler .
Cheers
John
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mitch
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Joined: August 2014
Posts: 285
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Post by mitch on Sept 18, 2014 22:37:03 GMT -5
My current oil cooler is positioned after the tank and filter, but before the pump. It is a smaller transmission cooler, and I was thinking about mounting some fans on it to increase cooling, but im not sure if a couple pc fans will be enough to make a difference. The new oil tank I am working on also has a higher capacity than my last, so that should help to increase run time.
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Post by racket on Sept 19, 2014 0:37:35 GMT -5
Hi Mitch
Be careful about the pump cavitating if theres any restriction in the cooler and filter , generally better to have the pump force oil through filters and coolers .
Cheers
John
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mitch
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Joined: August 2014
Posts: 285
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Post by mitch on Sept 21, 2014 17:09:31 GMT -5
When I last ran the engine, the vacuum side of the oil system (before the pump's inlet side) (which uses soft 3/8" vinyl line) was caving in. This only happens when the oil gets hot. I know it's not cavitation, because the oil is not flashing or vaporizing (which from my understanding is what happens in cavitation from the increase in vacuum) but I am wondering if it is sort of a precursor to cavitation.
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Post by racket on Sept 21, 2014 17:25:41 GMT -5
Hi Mitch
Suction lines need to be metal or strong hydraulic type flexible hose , a sucked in plastic tube will mean no oil to the turbo :-(
Cheers
John
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mitch
Senior Member
Joined: August 2014
Posts: 285
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Post by mitch on Sept 29, 2014 11:08:45 GMT -5
Next thing on my mind is making an ECU for the engine, probably considering going with an arduino mega, since I have a little experience with arduinos. It will monitor boost pressure, oil pressure and temperature, and EGT. Will probably have it cut fuel if it sees a drop in oil pressure or temperature go above a set point, or if it sees boost pressure spike. Most likely will just run my fuel pump through a relay instead of the switch its on now, and just have the arduino control it through the relay.
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Post by racket on Sept 29, 2014 15:53:49 GMT -5
Hi Mitch
Yep , some safety devices are always a good idea , things happen, and often faster than we realise :-(
Cheers
John
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mitch
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Joined: August 2014
Posts: 285
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Post by mitch on Oct 19, 2014 21:47:17 GMT -5
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Post by racket on Oct 19, 2014 23:05:50 GMT -5
Hi Mitch
Good one, congratulations :-)
Please have metal lube supply tubing near the turbine scroll , ............ radiant heat from the scroll can seriously degrade anything else , .............a burst lube line near the hot scroll and you'll have a fire ball :-(
Cheers
John
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mitch
Senior Member
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Posts: 285
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Post by mitch on Oct 19, 2014 23:12:58 GMT -5
The vinyl line you see entering the bearing core is just a bypass line, the oil feed line that feeds the turbo's bearings is steel. But that is a good idea! Also, check out this from another angle. At first, the turbine is red because I closed the fuel bypass valve too far, spiking liquid fuel levels above what they should be. What I don't understand though, is why the turbine wheel stops glowing, then starts to glow again, then stops. This all took place with the fuel at the same constant pressure. www.youtube.com/watch?v=ShsP1m3MFqk |
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Post by racket on Oct 20, 2014 1:21:19 GMT -5
Hi Mitch
The change in temperatures could have caused by the engine being at too low an idle , try and maintain at least 5psi P2 for a safe stable idle with minimal temperatures .
Is the variable nozzle fixed in position or free to move , its movement will change the temperatures depending on the airflow rate
Cheers
John
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mitch
Senior Member
Joined: August 2014
Posts: 285
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Post by mitch on Oct 21, 2014 12:06:32 GMT -5
the variable nozzle is fixed in position. I have the solenoid hooked up to 9v, so I can move the vanes slightly with the flip of a switch, however in the second run (viewing the turbine side) I did not power the actuator, so the vanes were fixed. My flametube is still not quite opened up enough to match jetspecs, so before my next run i will add the few remaining dilution holes to hopefully allow the engine to "breathe" better, and lower turbine inlet temperatures.
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