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Post by enginewhisperer on Feb 4, 2024 23:15:02 GMT -5
these stresses seem much worse than I'd have guessed.
How does it compare to things like car engine flywheels or auto transmission flex plates? They're often ~300mm diameter and ~2mm thick with a starter ring gear on the outside - which is often pressed on! Most of them don't need to handle 10krpm, but they often do 8-9krpm, and practically everything does well over 4000rpm.
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Post by enginewhisperer on Feb 1, 2024 19:43:23 GMT -5
I have been looking for something similar, hoping to put a turboshaft setup into a motorcycle too.
I actually have a Detroit DD15 freepower turbine unit but it has been sitting in storage in the USA for a few years. I need to work out how to ship it to Aus for a reasonable price! They are very heavy though, and it's probably not easy to make it much lighter.
I have a few Segway gearboxes, which are around 24:1 reduction and have very high quality gears in them. For my purposes I'm thinking I'll convert one to single stage (the second stage is 5.35:1), to bring my 40+krpm turbine speed down to something that will work with a chain drive to the rear wheel. I'll try to get an extra large rear sprocket for at least a 4:1 reduction on the chain.
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Post by enginewhisperer on Dec 13, 2023 14:36:32 GMT -5
if you can get away with a 50mm shaft, you can get 50mm hollow gokart axles in various wall thicknesses.
Otherwise, it should be possible to buy precision ground solid shaft. I have used it up to 40mm diameter and it's very accurate for perfect bearing fits, etc.
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Post by enginewhisperer on Sept 24, 2023 22:53:32 GMT -5
that's certainly not ideal!
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Post by enginewhisperer on Jul 17, 2023 21:04:33 GMT -5
I think it's the first time I've seen John jump at the afterburner ignition!
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Post by enginewhisperer on Jul 16, 2023 23:27:11 GMT -5
that's quite a lot of power!
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Post by enginewhisperer on Mar 15, 2023 16:46:06 GMT -5
that's probably true about the Leaf motor, but the inverter is the really difficult and expensive part - so you're generally limited by the inverter you have. You can't necessarily swap different ones between motors either - and some of them are built into the motor assembly like the Tesla ones.
The ebay turbos are definitely better than they used to be, but don't expect them to handle high temps or rpm. Probably good for a freepower more than a gas producer if you can get one big enough - but large scrap truck turbos are also pretty cheap usually. A turbo compound power turbine like the one on a Detroit DD15 could be a nice option for the generator. I bought one a few years ago but haven't managed to get it home to play with yet.
The turbo models are usually some sort of rough approximation of old Garrett models, and often doesn't mean much. Generally the T number was the overall frame size of the turbo, which usually set the turbine housing flange and the turbine inducer diameter. GT models are the high performance version, usually with ball bearings. Later they went to names like GT3071, which is a ball bearing T3 frame turbo with a 71mm compressor wheel. Just to confuse it further, brands like HKS had their own specifications of Garrett models and used similar naming conventions that mean different things - eg. a GT2835 is basically the same as the Garrett GT3071 (roughly translates to a GT28 turbine side and GT35 compressor) There are also two variants of the Garrett GT3071, with T2 or T3 turbine housings, and different turbines - to confuse things even more!
The ebay turbos can be loosely based on any of these variables so you pretty much just have to go by the wheel measurements, assuming they are published!
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Post by enginewhisperer on Mar 14, 2023 19:32:21 GMT -5
you could definitely put together a decent turbo based gas producer engine for $1000 or so with some good parts hunting.
From then on you can add a freepower turbine and potentially a generator to it for not much money - especially if you can find a big scrap turbo with a damaged compressor side.
The EV drive train stuff gets expensive very quickly. If you can do your own CAN bus hacking and work out how to interface various OEM bits together it's not too bad if you're in the USA where parts from damaged cars are cheap.
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Post by enginewhisperer on Mar 13, 2023 14:14:36 GMT -5
yeah the 60hp is probably the main drive motor's output.
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Post by enginewhisperer on Mar 12, 2023 16:08:35 GMT -5
yeah the RX7 is just an example of the same thing being done. A turbo based engine can be done to replace the model turboprop. It'll just be much larger and heavier (but can also require a lot less maintenance!)
Any electric motor is also a generator (or alternator). Something that runs at high rpm like a large RC brushless inrunner motor is a possible option, especially if you do it without a reduction gearbox. Rectifying the 3 phase AC output with a simple diode bridge is not super efficient, so you need to oversize the generator or run active rectification (a motor controller), which is expensive.
For racing you may be better off using the turbine to drive the wheels with the electric motor as a power boost - but with a small battery you'll probably only get a lap or so out of it. It's very hard to get useful regen braking energy on the race track (braking times are too short and the system can't handle the high currents needed for decent braking performance)
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Post by enginewhisperer on Mar 12, 2023 4:11:07 GMT -5
Here's one with a more "off the shelf" model turboprop engine driving the generator: www.youtube.com/watch?v=tCxW9I-IfdwA parallel hybrid using the main motor to charge the batteries would work, but then you have the worst possible gearbox requirements for your turbine engine. If you can use a high rpm generator you can get away with a much simpler gear reduction - but you'll have more complex electronics and control systems to sort out.
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Post by enginewhisperer on Feb 5, 2023 4:37:47 GMT -5
I seem to recall it was a Camry starter?
I may have a similar one in the shed.
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Post by enginewhisperer on Jan 31, 2023 19:37:11 GMT -5
yeah that is not the most convenient shape!
If you measure the total length of the edge you can find the equivalent diameter round tube and then probably squash / hammer it into shape pretty well.
I've done some irregular shaped turbo outlet dump pipes this way before with good success.
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Post by enginewhisperer on Jan 29, 2023 6:20:25 GMT -5
yep, 106mm comp inducer and 113mm turbine exducer!
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Post by enginewhisperer on Jan 28, 2023 6:11:21 GMT -5
very cool! It's similar in size, weight, and materials to the CAT GT6041 I have
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