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Post by smithy1 on Apr 21, 2019 4:21:34 GMT -5
Could one also pre heat the diesel somehow to aid atomization/evaporation? I know diesel turns to vapour at/over 100 degrees celcius and auto ignition is around 210 degrees celcius so could (this may sound silly) run it through the wet jacked turbine housing then into the combustion chamber through a nozzle? I'm assuming this wouldn't work because the temperature would get above the 210 degrees celcius and the whole thing would go pop? 🤔 Does it depend on fuel pressure too..?? My engine is running near 750+psi at the nozzle at max flow. Smithy.
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Post by smithy1 on Apr 2, 2019 17:52:08 GMT -5
Oil tank..?? Are you feeding the bearings with straight oil...?? This can be a bad thing as these bearings will tend to "skid" in the races instead of rolling, even when the preload is correct. They only need a fine "mist" type lube at the front compressor bearing, the pressure differential behind the comp wheel causes this mist to travel back through the shaft tunnel and it is then burnt out the back....a total loss system.
I've found the Kamps method of balancing is only just "adequate" and usually results in a figure of ~70-80mg-in, on a good day.....Not really good enough for constant high rpm running. It really needs to be under 20mg-in to keep the bearings happy.
Smithy.
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Post by smithy1 on Apr 1, 2019 4:16:19 GMT -5
Hi Smithy Im using 608 size bearings, I've found the angular contact ones online they all seem to be about $150 each. when you say the standard ones will fail, do you mean completely destroyed and damage something else or just get worn out quickly? Cheers Adam Hi Adam, Normal 608 sized caged steel bearings aren't rated for the temps, rpms and loads you're submitting them to....they just can't handle it....basically they're not designed for it, the heat and rpm is what kills them, and yes, it's certainly possible for a failed turbine bearing to destroy the whole engine....there's an extremely high amount of energy in a turbine spinning at 125k rpm....I've seen them blow up and essentially turn the entire engine into a door stop. The proper silicone-nitride ball, angular contact bearings are indeed expensive but they're designed to handle the heat, rpm and axial loads. Also, how are you balaning the rotor..?? Unless they're very well balanced, even the correct bearings won't last long. Hydrostatic bushes like a normal journal type, oil pressure fed turbo can handle quite a high amount of imbalance compared to a bearing mounted shaft. Smithy.
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Post by smithy1 on Mar 31, 2019 18:56:25 GMT -5
What size are your bearings..?? You can easily buy full compliment angular contact bearings for these turbines, they're not cheap though.....I have several sets. Most common for this size turbine are the 608 size (SiNi balls).... 8mm ID x 22mm OD x 7mm width. Caged bearings and/or ones with steel balls are just not suitable and will fail quickly.
As John mentions, angular contact bearings need to be "loaded" from the inside or you'll destroy them in no time. Mist lube of 5% fuel-oil mix has proven to be the best....I have an 18kg thrust turbine with well over 70 hours run time on the same bearings.....and they're still ok.
An axial preload of approx 3-4kg will see them work fine and last well if the rotor is balanced under ~5mg-in.
Smithy.
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Post by smithy1 on Mar 31, 2019 18:50:32 GMT -5
Some of the better EFI pumps will see you out of trouble. You need to remember the pump needs to produce enough pressure and flow above the P2 pressure, or you'll struggle to get good atomization.
Smithy.
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Post by smithy1 on Mar 28, 2019 19:37:29 GMT -5
Possibly too much restriction in the exhaust, the turbine can only swallow so much air and is possibly a bit small/tight for the compressor....she was running a tad warm judging by the glow of the turbine inlet....if he runs it without the tail pipe, it may fare a bit better....there's a lot of losses down the length of that pipe methinks.
Smithy.
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Post by smithy1 on Mar 28, 2019 19:18:04 GMT -5
What John said, a normal EFI pump is fine for vaporizer type setups, but if you go to a single injector, you'll probably need higher pressures to get decent atomization.
I have an aircraft fuel injector in my machine and it requires well in excess of 500psi at full noise. The pump I have is quite capable of well over 3000psi..😮
Smithy.
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Post by smithy1 on Mar 28, 2019 19:10:49 GMT -5
Ah , electronics .............not my thing :-( Likewise.....I much prefer manual/mechanical things I can physically change and adjust myself. Smithy .
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Post by smithy1 on Mar 28, 2019 19:09:20 GMT -5
Geeze, that chassis/frame looks suspiciously similar to the old 6041 beast John...different brakes but similar nonetheless. Smithy. Lol you can have it if you like Pass...😁😁 Smithy.
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Post by smithy1 on Mar 27, 2019 22:40:50 GMT -5
Geeze, that chassis/frame looks suspiciously similar to the old 6041 beast John...different brakes but similar nonetheless.
Smithy.
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Post by smithy1 on Dec 12, 2018 20:28:31 GMT -5
So a possible transient imbalance could cause this methinks.??....I wonder what force it takes to bend the shaft enough for the impeller to hit the housing..??
Smithy.
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Post by smithy1 on Dec 9, 2018 18:26:39 GMT -5
Yep, we always lubed the threads and the nut contact face on the C20 and C30 comp nuts during assembly, it's in the latest RR manual.
Anders, I wonder if there's a "transient imbalance" which may have had the comp wheel touching the inlet housing at certain rpms and then causing the nut to loosen. We often noticed a balance issue at certain RPM algorithms on the balance machines. Some of the manufacturers mention to not run constantly at certain rpm's....and to either stay under or go right through to a higher rpm.
Doesn't take much for the shaft to "bend" enough to cause grief.
Smithy.
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Post by smithy1 on Dec 6, 2018 20:23:21 GMT -5
A wastegated turbo isn't usually much good to us....and it's very small at just 43mm.
Smithy.
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Post by smithy1 on Dec 4, 2018 0:43:14 GMT -5
Anders, like the others I suspect aeration of the oil....my 6041 keeps very good oil pressure of around 75psi ~5.1bar.... until it starts to warm up to 85C, then it drops to about 55-60psi or 3.7~4bar, I still think this is plenty for our purposes though. I've not seen less than 55psi on the beast....it uses a gravity drain into the tank via an "anti-aeration" plate...perfectly made by John....still the same as the day he made it.
The oil system is one of the few things I haven't changed from John's original design....it just works and works well.
Smithy.
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Post by smithy1 on Dec 2, 2018 3:04:50 GMT -5
It can be done and once setup is virtually trouble free. I'm running a combustion chamber which is a modified Rolls-Royce C20B unit, modified of course due to vastly different pressure ratios between the C20 and the GT6041.... I made it to suit the GT6041 turbo....also running a single modified "dual stage" C20B injector....but it runs well over 500psi to try and get good atomisation, she's a bit fluffy at idle when cold but once the "innards" are warmed up, she's good and smooth. I have a high pressure fuel pump, also from a C20B which is easily capable of over 3000psi....works very well indeed.
Cheers, Smithy.
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