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Post by racket on Mar 1, 2015 20:37:46 GMT -5
Hi Miuge
Be careful about machining the boss at the turbine hub where the piston ring fits , its not very thick at times where the friction welding of shaft to turb wheel is , I'd be inclined to leave the boss as close to standard as possible.
Cheers John
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miuge
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Joined: March 2014
Posts: 199
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Post by miuge on Mar 2, 2015 2:02:01 GMT -5
Hi John, Yes I try to keep it as close to standard as possible, I believe if we won't machine it deeper than the piston ring groove it won't decrease it's durability. If you got any other ideas, let me know
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Post by racket on Mar 4, 2015 19:44:06 GMT -5
Hi Miuge
Yep , that should be OK
Cheers John
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miuge
Veteran Member
Joined: March 2014
Posts: 199
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Post by miuge on Mar 26, 2017 16:36:13 GMT -5
Hi all, No updates here yet, just some borrowed parts for other past projects but now I've got them all back New powerturbine shaft isn't yet machined, but again I've been thinking of upgrading the bike before making any assembly. First I really would like to get better acceleration, top speed isn't that important with that frame and wheels combination. As seen from the S500 comp map, an intact turbo would work somewhat efficiently up to 60krpm and probably withstands even higher rpm temporary. Currently the freepower wheel would turn less than 20krpm at the speed of 150kph, which isn't much I think. John mentioned earlier in this topic that freepower would produce 80% of it's power at half of it's rpm. So maybe double or even triple the rpm?? I think I'd have a solution for reduction gear -Miuge
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Post by racket on Mar 26, 2017 21:35:41 GMT -5
Hi Miuge Yep , freepowers have a very fat dyno chart postimg.cc/image/4g1ghuvct/ You'll probably find your freepower will only spin to a max of ~40,000 before the gas speeds can't keep up with the blades , so if your current max is 20,000 then there won't be a lot more power available , though a gearing change will certainly improve acceleration , a 2:1 gearbox ratio is all thats probably needed ............but your chain will suffer due to the greater torque going through it especially when near stall . Cheers John
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miuge
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Joined: March 2014
Posts: 199
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Post by miuge on Mar 27, 2017 10:42:49 GMT -5
Hi John, Yes I remember that chart. I still think it wouldn't see past 100kph speeds too often so freepower would just spin rather low rpms I have a pair of gears ratio around 3.5:1, then I'd need a secondary gear (sprocket/chain) ratio around 5.5:1 to double the current freepower rpm. That could be achieved using a regular chain.
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Post by racket on Mar 27, 2017 15:45:09 GMT -5
Hi Miuge
Yep , they'd do the job .
Karting chain has its limitations , good for high rpm but it soon stretches if the torque is high .
Cheers John
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