Turbine series hybrid car

[racket]

That sounds a wise course to follow :-)

This hobby can get expensive very quickly if an engine fails

[enginewhisperer]

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.

[thestankinator]

That sounds like about my guesstimates. I attached my (very rough) cost estimates below. Some of the numbers should be revised because I was pricing electronics for Tesla Model 3 parts, but I read somewhere that the LEAF motor is capable of a lot more power than Nissan allows through their inverter so I figured I'd use that instead (also the batteries are a lot easier to package, though it'd be possible with probably not that much more work to mix and match motor/batteries). I am in the US, and I could probably get some lower-priced parts with enough junkyard hunting, but I don't think it's wise to plan a project of this magnitude around that.

That also implicitly answers another question I'd been meaning to ask - can I just use the turbine section of another (larger) turbocharger as my freepower section? It seemed like the answer should be yes but I'm guessing it's less efficient than custom designs or purpose built freepower wheels.

I'm rather intrigued by the cheap Ebay turbochargers - I've been eyeing the ones labeled GT45 (tangent: I haven't been able to figure out what that designation means - is it a standard turbo size or a model number that they're all clones of?) as they're cheap and easy to replace should I blow one up, they're decently large and have the larger turbine exducer relative to their compressor inducers, and I see a few other members have successfully used them for this purpose. If as I read in another post I should be able to get about 1hp for every pound of static thrust, according to jetspecs I should expect it'd be capable of around 45hp, which would probably be ideal after accounting for transmission losses. That'd make a hell of a go kart powerplant. Then to pair with it, IIRC the recommendation is a freepower unit with an exducer twice the area of the gas producer's exducer, so a diameter of 77.5mm * sqrt(2) = 110mm. Does that all sound about right?  Alternatively, if I want to go the other way and use a GT45 turbine as a freepower unit with a smaller gas producer as a proof-of-concept, it'd be best to match it with a turbo of 77.5mm/sqrt(2) = 55mm?

[enginewhisperer]

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!

[racket]

My 2 shaft kart

jetandturbineowners.proboards.com/thread/40/2-shaft-turbine-kart-build

used a larger turbo turbine wheel for the freepower , they work OK :-)

[thestankinator]

Perhaps I should have been clearer - I've seen your kart design, but I noticed you fabricated your own scroll for it. Was that necessary for a reason other than that you got the wheel without a scroll or wanted to minimize weight (i.e. could you have just used the entire turbine section of the turbo it came from)? It seems like a lot of work for a part that could just be an off-the-shelf thing.

[racket]

There were a couple of reasons why I fabricated the scroll , #1 I needed to keep weight down , #2 I didn't know where to get a very large scroll A/R for that wheel .

Because my RPM were limited by the karting chain's max rpm limit of ~20,000 I needed to get the maximum mass flow through the wheel hence the large A/R so that gas entry was vertical rather than tangential at the turb inducer at the "lowish" 20,000 rpm limit .

There was sufficient pressure/temperature energy exiting the gas producer to feed that freepower at 40,000 rpm and produce a lot more power but the chain was the limiting factor in the design , the freepower wheel was considerably undersized for the gas producer hence the need to "dump" a large proportion of its flow out through a jet nozzle , the nozzling size maintained the right gas producer temperatures, that freepower could have been fed by a turbo with a 70mm inducer rather than the 88 mm one I used .

The same gas producer turbo had previously produced 115 HP in my turbine bike with a full sized freepower running at its max rpm through a gearbox

Cheers
John