|
Post by racket on Nov 9, 2015 22:09:11 GMT -5
Hi Smithy
LOL, you noticed the bolt head , yep , it was out of the GS750 engine that I cut the gearbox off early in the TV84 turbine bike development ~20 years ago , I eventually only used the frame , scrapping the gearbox and replacing it with that great heavyweight cast iron electric motor job.
Interestingly , making this pump up was a lot more complicated than I first thought it would be , much easier to direct mount the Subaru pump to the front of the electric motor like yours .
Cheers John
|
|
|
Post by smithy1 on Nov 10, 2015 14:38:39 GMT -5
Hi Smithy Interestingly , making this pump up was a lot more complicated than I first thought it would be , much easier to direct mount the Subaru pump to the front of the electric motor like yours . Cheers John LOL...Simple is good....pump and 36v leccy motor on the "Black Beast" are still working well, 65-70psi cold, 55-60psi warm, am very happy with that....running 10W40 "Penrite" semi-synthetic atm....no problems with the lube system at all, doesn't even puff smoke on shutdown either...which is nice. Oil is still nice and clean. Cheers, Smithy.
|
|
|
Post by racket on Nov 10, 2015 15:55:14 GMT -5
Hi Smithy
Good to hear she's still chugging along :-)
I'll be interested to see how the pressures and flows are with this new pump , it might spin a bit faster than your one as its a 24 V motor rather than 36 V , hopefully the drop to 12V will "halve" the rpm to ~1250 for a flow of ~12 lpm .
I'm not sure what the actual relief valve setting is , but it sounds like your warm oil reading is probably it , the higher cold oil reading could be caused by the relief valve being "overloaded" with too much flow and causing that extra 10 psi of pressure .
I'll probably be using the same 5W-40 oil thats in the oil tank from when I was testing the 10/98 engine .
Cheers John
|
|
|
Post by smithy1 on Nov 10, 2015 20:05:02 GMT -5
You shouldn't have any dramas with oil pressure using the 24v motor and what looks like a 1:1 chain drive....the relief valve can be modified to allow higher by-pass flow if required....but for our purposes it will be fine. The old Subaru pump is ideal for the application.
If needed I could drive the 36v motor using a 6 cell Li-Po battery (~22.2v nominal) to get the pressure/flow up...but it's not required...if I do see oil pressure problems I suspect it's probably going to be a turbo bearing wear issue rather than a pump issue.
Keep up the good work...!
Cheers, Smithy.
|
|
Chuks
Senior Member
Joined: August 2015
Posts: 498
|
Post by Chuks on Nov 11, 2015 12:25:49 GMT -5
nice work Racket
|
|
Chuks
Senior Member
Joined: August 2015
Posts: 498
|
Post by Chuks on Nov 11, 2015 12:29:22 GMT -5
a got a question i wanna ask, forgive me if its off.... why do you do clipping on a turbine blade? is it necessary? will it still work if you dont do it?
|
|
|
Post by racket on Nov 11, 2015 15:53:03 GMT -5
Hi
With turbine stages either the nozzle/NGV can run choked and restrict/control compressor flow, and/or the turbine wheels exducer can run choked and restrict/control comp flow, this will only happen if the turbine stage is "undersized" for the compressor flow .
By clipping the exducer we effectively increase its flow area , but we also reduce its power producing capability due to the reduction in gas deflection as the new exducer angle is always at a more axial angle .
Generally speaking , most turbocharger turbine exducers have too tight an angle when used as a gas turbine gas producer , the angle is more appropriate for a turbocharger , where they're trying to extract the maximum power from the wheel with the minimum backpressure on the IC engine , but we have a different set of requirements , we want lotsa pressure downstream of the turbine wheel in contrast to an IC exhaust where minimal exhaust system pressure is preferred.
A lot of "performance" turbos have "undersized" turbine stages as they are designed to be used with a wastegate to regulate flow through the turb stage , these turbos don't generally make very good gas turbines as the comp is wanting to flow more air than the turbine stage can swallow , the result is a compressor wheel flowing close to the surge line at poor efficiency and/or actually going into surge , but with "radical" clipping of the turb's exducer they could make good gas turbine engines if fitted with the largest available turb scroll A/R .
So to answer your question , ..........most times the standard turb wheel shape will work if its exducer area is 20% greater than the comps inducer area, if its not , then clipping should be considered as a possible way of bringing the comp and turb stage flows into balance .
Years ago when I was doing the development work on my Garrett TV84 engine I experienced some "strange" performance data , the engine simply wasn't behaving as the theory said it should when I started swapping scroll housings , the problem was eventually tracked down to the turbine wheel being of marginal size , the exducer was choking , comp inducer was 3.5", turb exducer 3.8" , so ~17% greater turb exducer area , this was also exacerbated by me running high temperatures through the turb stage to maximise power output .
Clipping the turb exducer cured the problem and the engine started performing as the books said it should , I ended up having to use the smallest available scroll housing( 1.23 A/R) to keep comp flow under control , all of the larger housing A/Rs caused the engine to "temp out" at ever decreasing P2s the larger the scroll housing A/R used ( 1.39 , 1.60 and 1.84 A/Rs)
The TV84 turb exducer was clipped back 0.5" axially at the tip and 0.25" at the exducer blades root, a very severe clipping resulting in a wheel looking similar to the one for this 12/118 engine .
In hindsight I probably could of got the engine working with the standard turb wheel by running a more modest T I T and/or fitting the smallest A/R scroll rather than starting with the largest and working my way down .
Clipping to increase exducer flow area between the blades is only necessary if the exducer area isn't 20% bigger than the comp inducer area .
Hope this helps :-)
Cheers John
|
|
Chuks
Senior Member
Joined: August 2015
Posts: 498
|
Post by Chuks on Nov 12, 2015 10:41:25 GMT -5
thanks John, i never knew its gonna result to choking, i was thinking it will will help to make use of every energy to produce more trust and high speed
|
|
Chuks
Senior Member
Joined: August 2015
Posts: 498
|
Post by Chuks on Nov 12, 2015 10:44:33 GMT -5
this forum is just gonna make me know more than i should before i will start schooling abroad..... thanks a lot
|
|
|
Post by turbochris on Nov 12, 2015 14:46:08 GMT -5
you can tune that pump with different size sprockets, i had a couple of belt and gear driven pumps and it came in handy to make them run really efficient.
|
|
|
Post by racket on Nov 12, 2015 16:50:58 GMT -5
Hi Chris Its currently got a 1:1 ratio which seems about right thankfully . Some data from the testing .............. Electric motor is 24 V 500W at 2500 rated rpm with a rated 27 Amps capability, currently run on 12 Volts through a 20 Amp fuse. Oil used is 5W-40 full synthetic at ambient temp ~20 deg C At 65-70 psi with the output valve from pump closed resulting in recirculation through the pumps internal relief valve the motor/pump ran at 1180 rpm , but working hard by the noise it was making . At 60 psi it flowed a measured 6 litres per minute ( LPM ) , still some recirculation through relief valve as rpm at 1156 rpm At 50 psi it flowed a measured 10 LPM at 1195 rpm At 0-5psi with the throttling valve fully open it flowed >12 LPM at 1365 rpm The actual battery charge changed a bit over the differing tests so some variables with rpm , but it appears that at pressure producing flows the rpm are up ~1200 rpm with a healthy 50 psi of pressure and 10 LPM available . I ran the pump at 60 psi for 15 minutes , the 5 litres of oil started to warm up a bit , possibly a 15 deg C rise , the motor barely changed temp .............she'll do With a 400 mm long piece of 5/16" OD copper pipe in place at the pump outlet to simulate the plumbing within the engine it required 40 psi at the pump outlet to force 10 LPM through the pipe . With only 20 psi available , the rest being dumped back to tank, it flowed 6 LPM . I feel I'll need at least 3/8" OD pipework within the engine to minimise pressure drop and maximise pressure at the bearings . Cheers John
|
|
|
Post by smithy1 on Nov 12, 2015 19:19:13 GMT -5
John...that setup should work nicely....all those numbers look good.
At it's rated @24v and 27amps she'll be working pretty hard...648watts..!
At 65-70psi with the outlet closed ....and you say she sounds like she's working hard, 12v and less than 20amps....it's only running ~240watts maximum...so she can't be working that hard..! ;-)
I'd be using the largest dia pipe you can fit in there... just to be safe..!
Cheers, Smithy.
|
|
|
Post by racket on Nov 12, 2015 20:21:56 GMT -5
Hi Smithy
Yep , I'm trying to squeeze in 1/2" OD copper pipe, just might be doable , the main inlet hole in the shaft tunnel is 10mm diameter, which then has a couple of 5mm holes going to the bearings.
At 50 psi she's just purring along , so probably this is "hot oil" sorta flow/pressure , basically what you have with the GT6041.
All looking good :-)
Cheers John
|
|
|
Post by smithy1 on Nov 12, 2015 20:53:11 GMT -5
Yep....I'm seeing ~55-60psi warm....oil temp never seems to rise above 60-65C since fitting the cooler system..I will be running the "Beast" again this coming Sunday so I'll try to take a bit of notice this time..! I always forget to look at all the gauges when she's running, I mostly just look at the EGT, if that's OK I tend not to worry too much, I should definitely be looking at the oil pressure more often though...
Cheers, Smithy.
|
|
|
Post by racket on Nov 13, 2015 0:01:48 GMT -5
Hi Smithy
Can you remember if your pump has a stronger relief valve spring ??
I might think about getting a bit more relief valve pressure in this one .
Enjoy the show :-)
LOL, I hope you're gunna get some video ;-)
Cheers John
|
|