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Post by racket on Jan 11, 2019 16:30:09 GMT -5
Hi Ron
LOL...........yep , lotsa assumptions with our engines , all we can hope for is that they're ballpark as you said ..............I think Aaron will be pretty happy with the outcome :-)
Cheers John
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Post by azwood on Jan 12, 2019 3:59:24 GMT -5
Hi Ron LOL...........yep , lotsa assumptions with our engines , all we can hope for is that they're ballpark as you said ..............I think Aaron will be pretty happy with the outcome :-) Cheers John Yep a go kart with 65 odd horsepower and heaps of torque is going to be fast enough to get me a stupid grin on my face and do the happy dance
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Post by azwood on Jan 12, 2019 4:04:28 GMT -5
I have a clutch and drive gear (two to one ratio) from a r6 to go in and bring the final to 5.7/1 with a lot of rotating mass and a clutch she should take off like a rocket greatfor drag racing.
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Post by turboron on Jan 12, 2019 7:00:10 GMT -5
Aaron, very dangerous to unload the power turbine when it is under power. It will spin to destruction in a few seconds. I mention this concern since you have a clutch in the system it must stay engaged at all times. Perhaps it should be locked up so it can not be accidently disengaged. Free turbines develop their maximum torque when they are at rest by a 2/1 factor. The drop drops off as the speed (rpm) comes up.
Thanks, Ron
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Post by azwood on Jan 12, 2019 18:07:40 GMT -5
Aaron, very dangerous to unload the power turbine when it is under power. It will spin to destruction in a few seconds. I mention this concern since you have a clutch in the system it must stay engaged at all times. Perhaps it should be locked up so it can not be accidently disengaged. Free turbines develop their maximum torque when they are at rest by a 2/1 factor. The drop drops off as the speed (rpm) comes up. Thanks, Ron OK I havent put it on yet maybe I wont then I see your point.
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Post by azwood on Jan 18, 2019 8:23:19 GMT -5
Got some morerys oil conditioner viscosity stabiliser I thought might help with my slightpressure drop when the oil heats up.the only concern is it says not suitable for silver bearings I thought turbos ran brass or bronze ones
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Post by turboron on Jan 18, 2019 11:13:00 GMT -5
Aaron, I assume that silver bearings refers to babbited bearings. My understanding is that all turbochargers with hydrodynamic (not ball or roller) bearings have brass bushings.
Thanks, Ron
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Post by azwood on Jan 18, 2019 20:12:32 GMT -5
Aaron, I assume that silver bearings refers to babbited bearings. My understanding is that all turbochargers with hydrodynamic (not ball or roller) bearings have brass bushings. Thanks, Ron That was my understanding too I guess the stabiliser will be ok.
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Post by azwood on Jan 20, 2019 2:45:17 GMT -5
Been playing round with the oil pump I always thought it had more in it.turns out blocking off the the relief valve helped a lot I now have a solid 65psi rather than 45psi so that’s nice I also added the oil stableiser I’m now prettyhappy with the setup to work well for long runs
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Post by azwood on Jan 20, 2019 17:59:15 GMT -5
One other reason I'm chasing more pressure is I'll loose a bit from running the drive.
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Post by turboron on Jan 26, 2019 9:52:16 GMT -5
Aaron, hope you are making progress with your power turbine. I found a book section I copied from somewhere in my files yesterday. The author calculates an area ratio between the IGV and the rotor exducer for a turbocharger. He found the ratio of the IGV throat area to the impeller exducer throat area (An/Ar) are to be 0.6. Since we know that the flow must choke(reach sonic velocity) in one throat or the other it would be interesting to see what this ratio is on your power turbine. I remember John saying that his first DIY on the bike was actually choking in the rotor exducer.
Thanks, Ron
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CH3NO2
Senior Member
Joined: March 2017
Posts: 455
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Post by CH3NO2 on Jan 26, 2019 10:54:02 GMT -5
Hi Ron,
Wouldn't a An/Ar of 0.6 just about guarantee choke at the IGV throat?
Tony
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Post by turboron on Jan 26, 2019 11:09:26 GMT -5
Tony, yes I think an An/Ar of 0.6 would be great. It would insure, I think, choking in the IGV which I think is preferred. However, Aaron's An/Ar is an unknown at this time. Hopefully, he can determine his throat areas and compute this ratio before he finalizes his design.
Thanks, Ron
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Post by racket on Jan 26, 2019 18:43:36 GMT -5
Hi Ron
With our freepower units theres generally not sufficient total pressure available to choke anything , the best I could get from my TV84 engine was ~12 psit ( 26.7 psi absolute) in the interstage, roughly only an ~1.8 :1 PR across the entire freepower stage .
With the Allison 250 their freepower stages have "interesting??" areas with the NGV having only marginally smaller throat areas than the following wheels exit flow throat areas.
Its a diffent case with our "turbo" gas producers though , its possible to swap around the pressure drops to better suit the wheel/NGV physical sizes which aren't always whats optimal .
I'm looking forward to seeing how the change in exducer flow area with the new G Trim turb wheel work out in my 12/118 engine .
Cheers John.
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Post by azwood on Jan 27, 2019 0:32:58 GMT -5
Still building away got the outer scroll all done.working on the diff and chain drive now have 520 pitch Sprocket's
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