jamiep
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Posts: 102
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Post by jamiep on Aug 26, 2011 11:07:49 GMT -5
www.youtube.com/watch?v=ToOG9nolGuAHere is testing from the other night. I may move the spark plug as suggested. I also have a PWM motor controller coming to fine tune AB fuel pump. Might also go down a jet size to make a finer stream of fuel. Jamie
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Post by ernie wrenn on Aug 26, 2011 11:12:07 GMT -5
Congrats.... Looks like a happy face!
ernie
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Post by Johansson on Aug 26, 2011 13:54:27 GMT -5
Your afterburner flame pattern behaves just like mine on my first jetcart afterburner, a lazy yellow flame that flutters. Mine flamed out as soon as I increased the turbine revs above 50%.
The reason for this was that I used a too weak fuel pump, once I changed to a Bosch EFI pump (standard pump in any european fuel injected car) I got a rock steady bluish flame and it ran better and better the higher the turbine revs climbed. I believe that the injector diameter was around 1-1.5mm.
Another reason might be the very large jet nozzle diameter, is it larger than the turbine exducer diameter?
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jamiep
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Joined: November 2010
Posts: 102
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Post by jamiep on May 24, 2012 10:55:40 GMT -5
I took some time to work on other projects but am back to the turbine again...
looking to add a free power turbine to see if I can get some shaft power for a kart. Would love to see others setups that have done this. Thinking about using a large turbocharger hot section for the free power...
jamie
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Post by racket on May 24, 2012 17:37:34 GMT -5
Hi Jamie
Good to hear you're thinking shaft horsepower :-)..............theres a build thread of my 2 shaft kart in the DIY section
Cheers
John
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jamiep
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Posts: 102
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Post by jamiep on May 25, 2012 14:34:27 GMT -5
I looked around and didn't see it...you have a link?
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Post by racket on May 25, 2012 17:27:55 GMT -5
Hi Jamie
It was at the bottom of the second page, but now at the top of the DIY Page :-)
Cheers
John
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jamiep
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Post by jamiep on Oct 25, 2013 16:36:26 GMT -5
I am finally getting around to thinking about building the freepower section of my jet to actually do some work with the shaft power.
Question - have you used or considered using an air starter/pneumatic turbine starter (the kind used as onboard starters for jets) for the freepower section? seems easy to mate up and make some work. Thoughts?
jamie
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Post by racket on Oct 25, 2013 18:41:13 GMT -5
Hi Jamie
It is possible to use a turbine starter , but the turbine wheel will need to be "hot rated", so that rules out air starters , the cartridge starters have been used, but with limited success due to their flow restriction, to modest sized gas producers .............but theres still a lot of work required to get them to cope with what we want them to do .
Sometimes its just easier to start from scratch and build whats required .
Cheers
John
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jamiep
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Posts: 102
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Post by jamiep on Oct 25, 2013 20:53:31 GMT -5
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Post by racket on Oct 26, 2013 0:10:31 GMT -5
Hi Jamie
I wouldn't touch any of those Ebay items if I was you ...........
The first one has too much BS in the ad , the owner was a Member on DIY Site many years ago and we went through the process of trying to get that kart going at that time .
The second one is only a glorified "leaf blower"
The third one is compressed air only , its not "hot rated" .
You'd be far better off trying to get a VT/ST 50 turbo hot section and modify it to fit a kart sprocket in place of the compressor wheel.
Cheers
John
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jamiep
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Post by jamiep on Oct 26, 2013 10:26:32 GMT -5
ok...the second two I understand about the hot rated. But on the first one (cartridge starter), the turbine wheel and scroll and gearbox seem like they are way better than anything I could homebrew... what are the issues you see in that one? seems like it could handle more airflow than a VT/ST 50.. and it comes with the gearbox. ??
jamie
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Post by Johansson on Oct 26, 2013 13:55:02 GMT -5
Take my word for it and follow Johns advice, you´ll spend more time and money trying to get one of those to work than what it would take to make your own freepower section that actually would fit your gas generator.
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jamiep
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Post by jamiep on Oct 26, 2013 16:29:33 GMT -5
I just want to understand why the turbine wheel scroll and gearbox from the cartridge starter wouldn't work... If i build something myself, it seems like that is exactly what I would build. ? need some education on that one.
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Post by racket on Oct 26, 2013 17:30:40 GMT -5
Hi Jamie
OK , a bit more explanation :-)
The cartridge starter works on either the hot and very high pressure combustion products ( 2,000 F - 1,200 psi ) or moderately high pressure "cold" air , possibly 30 -45 psi, .....the high temp/press gases are feed via a few De Lavel CD nozzles onto the impulse bladed turb wheel at very high velocities, at one would assume near ambiant pressure , the cold air will be travelling a lot slower but still ~supersonic from the NGV stator , cold air is a lot denser than any gas producer efflux that you are likely to feed into that same NGV , you'll also only have a max of ~10 psi feed pressure , again lowering the density and most importantly the mass flow that the NGV can "process" ............hence the relatively low power output possible if using the starter in its original configuration .
The starter is meant to "plug in" so theres a need for radial support for the output shaft in a karting scenario .
The 15:1 internal gear ratio would mean a max output rpm of potentially only ~2,000 rpm when we take into account the "reduced" turbine rpm from the lowish gas velocities from the lowish pressures being fed into the starter and the impulse blading that produces "best" power at half gas velocity for its blades .
At a 2,000 rpm output there would need to be a roughly 1 :1 chain "redux" on the kart , but due to the high gearing ratio within the starter ,the output torque will be beyond karting chain capacity , so heavier duty sprockets and chain required.
I could probably find a few more things to comment on, but you should be getting the drift of what I'm saying by now.
The reason I made my 2 shaft kart was to demonstrate the easiest way to make horsepower from one of our DIY engines to power a kart , no gearbox just simple and relatively inexpensive karting sprockets and chain.
It wasn't built to produce the fastest kart , I was "dumping" 40% of the gases out of a jet nozzle because I was using an undersized but readily available turbocharger turbine for the freepower wheel , and the turbine rpm was limited by the chains max rpm/loadings to ~20,000 rpm , or roughly half its potential rpm with the gas pressures available, but a freepower turbine will produce 80% of its potential power at 50% rpm, so not a great loss of power for a big reduction in rpm .
If you want to, and have the machining capabilities to make the necessary changes to the cartridge starter, then use one, but I wouldn't for the simple reason its a lot of work for a limited horsepower output with the original turb wheel and NGV parts , you'd have less work if you found a "scrap" ST/VT50 turbo with an intact turbine wheel , possible one with a wrecked comp wheel , but with the largest available turbine scroll A/R (I won't go into why you need that large scroll) , and machine the centre housing to take a couple of ball races, shaft should be 0.750 inches dia , so "off the shelf" bearing OK , then make a suitable mount for the kart sprocket in place of the comp wheel, and you'll be making horsepower with minimal effort and cost .
Hope this helps :-)
Cheers
John
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