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Post by racket on Mar 4, 2015 19:13:49 GMT -5
Hi Guys Yep , I'll go for a scavenge pump unable to handle the "frothy" volume , I had a similar problem with the scavenge pump originally fitted to the TV84 bike's gearbox , OK when stationary but not when the gearbox was spinning fast , the gearbox eventually filled with oil and was forced from the gearbox breather and over the bike and my nice riding boots eventually leaving a long trail down the road . I replaced the single "rubber vane" pump with a pair of automotive oil pumps (Datsun I think), spinning faster as well, ....... I also added a large diameter return line from the gearbox breather to the oil tank in case the pair of pumps still weren't large enough to handle the flow and the gearbox filled with froth , it could then be forced back to the tank without problems . Scavenge capacity could need to be up to 4-8 times supply capacity . I mentioned in an email a while back about the possibility of fitting a lightly loaded "blowoff" valve in the scavenge line between motor and pump which would "lift" and allow "froth" to bypass the scavenge pump and be forced back to the oiltank by any pressure buildup in the shaft tunnel . Once the "pressurisation" ceased , the scavenge pump would resume the entire scavenge duty and prevent oil leakage by providing , hopefully, a slight vacuum in the shaft tunnel . Mmmmm , heres another thought , ..........Anders, is the scavenge line able to cope with any "vacuum " without collapsing when flowing hot oil , I'm thinking of the possibility that the line is being sucked shut ? Another thought , you were only able to fit a single piston ring at the comp end with the design you used , to fit both rings I needed to install a small stainless steel "bush" into the diffuser housing wall that projected into the oil slinger for the ring to seat in . But I think the blowoff bypass will fix all your problems, if you can "lift" the valve by simply blowing through it, then it will always lift at any P2 above idle , your "static" pressure behind the comp at the seal will be roughly half the P2 pressure and probably a similar pressure at the turb seal, though I'm not certain about that. After shut down, with the lube pump still running, the scavenge pump will "vacuum" oil from the shaft tunnel and probably suck air through the seals preventing any fires in the turbine wheel region from oil dribbles that I experience without a scavenge pump . Cheers John
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Post by racket on Mar 4, 2015 19:27:16 GMT -5
Hi Smithy
Yep , you need to keep adding fuel until those TOTs are at 750 C at your design max rpm/P2 , this is the design TOT and should be producing a 900C TIT , no point going to a higher temp as the turb scroll's mass flow will be reduced due to choking .
Once at 750 C for the TOT , any further increase in A/B fuel flow will need a jet nozzle area increase to keep/restore the 750 C .............yep , slow and steady increases until a thrust of ~190 lbs is reached , ..............heh heh , you might need to make up a means to measure thrust , ..................perhaps a set of bathroom scales that the kart can push against , have the kart on a slight downslope so that the rolling resistance is overcome , start with maybe 20 lbs of load on the scales before firing her up .
More video please :-)
Cheers John
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Post by smithy1 on Mar 4, 2015 19:39:59 GMT -5
Thanks John,
I'll take this little discussion back to the proper spot so we don't clog up Ander's thread..
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Post by racket on Mar 4, 2015 19:44:33 GMT -5
OK
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Post by Johansson on Mar 5, 2015 4:56:49 GMT -5
Hi Guys Yep , I'll go for a scavenge pump unable to handle the "frothy" volume , I had a similar problem with the scavenge pump originally fitted to the TV84 bike's gearbox , OK when stationary but not when the gearbox was spinning fast , the gearbox eventually filled with oil and was forced from the gearbox breather and over the bike and my nice riding boots eventually leaving a long trail down the road . I replaced the single "rubber vane" pump with a pair of automotive oil pumps (Datsun I think), spinning faster as well, ....... I also added a large diameter return line from the gearbox breather to the oil tank in case the pair of pumps still weren't large enough to handle the flow and the gearbox filled with froth , it could then be forced back to the tank without problems . Scavenge capacity could need to be up to 4-8 times supply capacity . I mentioned in an email a while back about the possibility of fitting a lightly loaded "blowoff" valve in the scavenge line between motor and pump which would "lift" and allow "froth" to bypass the scavenge pump and be forced back to the oiltank by any pressure buildup in the shaft tunnel . Once the "pressurisation" ceased , the scavenge pump would resume the entire scavenge duty and prevent oil leakage by providing , hopefully, a slight vacuum in the shaft tunnel . Mmmmm , heres another thought , ..........Anders, is the scavenge line able to cope with any "vacuum " without collapsing when flowing hot oil , I'm thinking of the possibility that the line is being sucked shut ? Another thought , you were only able to fit a single piston ring at the comp end with the design you used , to fit both rings I needed to install a small stainless steel "bush" into the diffuser housing wall that projected into the oil slinger for the ring to seat in . But I think the blowoff bypass will fix all your problems, if you can "lift" the valve by simply blowing through it, then it will always lift at any P2 above idle , your "static" pressure behind the comp at the seal will be roughly half the P2 pressure and probably a similar pressure at the turb seal, though I'm not certain about that. After shut down, with the lube pump still running, the scavenge pump will "vacuum" oil from the shaft tunnel and probably suck air through the seals preventing any fires in the turbine wheel region from oil dribbles that I experience without a scavenge pump . Cheers John I´ll make a bypass valve for each scavenge pump then, not much work and I don´t have to take the engine apart to do it. The suction lines are steel braided AN hoses so I think that they are sturdy enough to avoid collapsing. I have actually modified the diffuser housing with a stainless insert bush so I am running two piston ring seals now, I can run 6 bar oil pressure cold without a single drop of oil coming through there. Is there anyone here that has experience with inductive tachometers that can read the revs by counting compressor blades passing by? I really don´t want to use the LED tacho since it upsets the airflow by being positioned in front of the compressor, and the white paint gets dirty/thrown off the blades now and then. The RC turbines use a small probe in the compressor housing 0.25mm from the inducer blades, if I could make something similar I would have a bullet proof tacho that isn´t in the way for the air and cannot work its way loose and wreck the engine. Cheers! /Anders
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Post by Johansson on Mar 5, 2015 5:14:54 GMT -5
A short summary of the weekend, sorry for the language. Cheers! /Anders
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Joined: January 1970
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Post by Deleted on Mar 5, 2015 10:15:45 GMT -5
Hi Anders I have one of these for the free power section, uk.rs-online.com/web/p/counters/4927319/don't know if its frequency is high enough for the engine, but it does have a function to calculate pulses and divide , you can also use it to set switch points with a relay out put. Mine ties into the fuel and cuts the fuel if the free power gets above a set point, dropping power off, programming them is a pain though you then need a none ferrous hall effect or Inductive Proximity Sensor like this uk.rs-online.com/web/p/precision-position-switches/2037004/not sure which you would need, but I hope it gives you some ideal
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Post by Johansson on Mar 5, 2015 14:16:15 GMT -5
Thanks for the hints Andy, hopefully some helpful soul steps up and tells me exactly what I need and how to hook it up. I suck at this stuff...
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Deleted
Joined: January 1970
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Post by Deleted on Mar 5, 2015 14:42:32 GMT -5
Thanks for the hints Andy, hopefully some helpful soul steps up and tells me exactly what I need and how to hook it up. I suck at this stuff... Not my strongest part electronics etc, I can manage to put an ignition box together with out blowing my self up, oh I meant to mention for your viper I have a bth that works just about, but would be happy to make you one of the ones that the guys and I worked out for the cost of the parts, Chris K is perhaps best person to help you
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Post by enginewhisperer on Mar 5, 2015 16:50:11 GMT -5
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Post by smithy1 on Mar 5, 2015 20:03:46 GMT -5
Anders, For your rpm...Andy mentioned "Hall effect" sensors work well....most of the small RC type turbines use a Hall effect sensor for their RPM reading. What they do is fit a small neodymium magnet in the comp nut and the Hall effect sensor can be mounted outside the aluminum comp housing, I have a sensor here if you wish to experiment with it, I can shoot it to you in the post. I think you can use an Arduino controlled LCD for your readout, just a matter of making it work. With your setup, you can get small round neo magnets which are polarized on the sides of the magnet instead of top and bottom, you can then machine a small rebate in the underside of the nut to accept the magnet and you should be good to go, it's best if the comp nut is made of aluminum though. I'm attempting to do this myself somehow, the only problem is the 6041 comp is all one piece... Cheers, Smithy.
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Post by Johansson on Mar 5, 2015 23:52:28 GMT -5
Thanks for the hints Andy, hopefully some helpful soul steps up and tells me exactly what I need and how to hook it up. I suck at this stuff... Not my strongest part electronics etc, I can manage to put an ignition box together with out blowing my self up, oh I meant to mention for your viper I have a bth that works just about, but would be happy to make you one of the ones that the guys and I worked out for the cost of the parts, Chris K is perhaps best person to help you Hi Andy, I think I have figured out the Viper ignition actually, a 24Vdc/230Vac truck converter and a neon transformer should do the trick. The ignition lead I bought on Ebay fits the engine so I only have to fit the transformer lead to the end of it. Thanks anyway! That is exactly what I need! I would be very interested in finding out the parts number for the sensor since it probably is 1/10 of the cost to buy from an electronic supplier without the fancy mount and cable connection. Where can that interface be found? Anders, For your rpm...Andy mentioned "Hall effect" sensors work well....most of the small RC type turbines use a Hall effect sensor for their RPM reading. What they do is fit a small neodymium magnet in the comp nut and the Hall effect sensor can be mounted outside the aluminum comp housing, I have a sensor here if you wish to experiment with it, I can shoot it to you in the post. I think you can use an Arduino controlled LCD for your readout, just a matter of making it work. With your setup, you can get small round neo magnets which are polarized on the sides of the magnet instead of top and bottom, you can then machine a small rebate in the underside of the nut to accept the magnet and you should be good to go, it's best if the comp nut is made of aluminum though. I'm attempting to do this myself somehow, the only problem is the 6041 comp is all one piece... Cheers, Smithy. Hi Smithy, The tacho fitted to my AMT Pegasus turbine now is a Hall type with an aluminum spinner nut, the old one was a cylindrical rod that was sitting flush with the compressor wheel blade profile. I would prefer the latter since I won´t have to do any modifications to the rotating parts of the engine, and such a sensor is exactly what Enginewhisperer posted above. I have an Auber ASL-62 tachometer fitted to the bike for reading the front sprocket revs, it says it can use proximity sensors so perhaps I can connect one of those sensors directly into the tacho? Cheers! /Anders
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Post by enginewhisperer on Mar 6, 2015 0:04:28 GMT -5
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Post by enginewhisperer on Mar 6, 2015 0:15:04 GMT -5
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Post by Johansson on Mar 6, 2015 0:15:38 GMT -5
Wow, that SBT kit looks sweet! Data logger, EGT, pressure and revs, exactly what I need! If it can be programmed for metrical instead of imperial units I am very tempted to buy one and fit to the bike. Many thanks for the link!
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