userscott
Junior Member
Joined: March 2019
Posts: 96
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Post by userscott on Mar 11, 2019 20:33:00 GMT -5
Hi guys, New member - Scott from Manchester (UK). I'm about to start building a HX55W jet to mount on a go kart that runs on railway tracks. I've built 11 rail karts before with various traction systems (electric, petrol, hybrid etc) and it's amazing how little horsepower you need due to the lack of resistance in the rails/wheels, so I thought I'd see what would happen with something more interesting..! I chose the HX55 as I had a spare complete unit for parts and I'd also found a lovely looking one in good nick on eBay, with a 19 cm exhaust housing and 67 mm inducer. I have rollers, TIG, lathe, mill etc at home so will hopefully be fabricating my flame tube from laser cut stainless but I'm sure this will end in tears... I'm hoping to run on kerosene with gas for starting but I'm not sure whether to just run on gas full time - I'm still reading all the many build threads on here and trying to get my head around the status quo on this! Currently looking for oil pumps (12v) that would be suitable for this turbo - I need 30 psi minimum and 58 psi at full chat so that puts the Marco stuff out I think? Even the UP3 would only just make 30 pounds. Again I'm keeping on reading this board to see what others use... To give you an idea of what a kart looks like - here is one of my favourites - this one routinely runs at around 50 mph and is a workhorse! For this project I will be utilising a scrap chassis from a previous project. It's quite long, has good strong brakes and has no mechanical drive whatsoever as it was powered with a road kart rear axle and rubber wheels, so it's going to make an ideal chassis. The seat and other bits and pieces were what I found scouring the workshop so I hope to reuse some of the aluminium tanks and bits and pieces... Look forwards to updating you all! Scott
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Post by racket on Mar 11, 2019 21:50:16 GMT -5
Hi Scott
Wecome to the Group :-)
An interestng build you're planning.
With a 67mm inducer you'll need to go to kero , generally theres a cutoff point ~50 mm comp inducer for running on propane , the fuel burn rates simply creates problems .
Have a look aroun the various builds for some ideas.
Cheers John
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userscott
Junior Member
Joined: March 2019
Posts: 96
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Post by userscott on Mar 13, 2019 16:49:27 GMT -5
Thanks for your response John! I have now factored in kero into my plans - I'm very comfortable with rigging up the fuel system and have a few ideas so I'll gladly incorporate that into the design. I've just read your PDF so I'm feeling very confident now..
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Post by Johansson on Mar 13, 2019 17:07:16 GMT -5
Hi Scott! A very interesting and unique project you are doing, I bet you can get some good speeds out of a rail driven jetcart. Keep us updated! Cheers! /Anders
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userscott
Junior Member
Joined: March 2019
Posts: 96
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Post by userscott on Mar 13, 2019 19:10:30 GMT -5
Hi Scott! A very interesting and unique project you are doing, I bet you can get some good speeds out of a rail driven jetcart. Keep us updated! Cheers! /Anders Thanks Anders! Rail is the secret for madness with these things I reckon. It's been done before (Scrapheap Challenge S10E07) but not with the effort or consideration that I make to reduce rolling resistance nor to manage the wheel profile accordingly. The aluminium loco in my original post has a BHP figure just barely in the double figures but will easily hit 50 mph without breaking a sweat - it was originally geared to a figure far higher than this (and achieved it) but was adjusted for safety reasons - the wheelbase is too short for those speeds! So I do have some expectations of what something like the HX55 may achieve in a rail application, given I don't make a pigs ear of it..... I shall keep you updated with my progress - I've requested the mods move this thread to the build threads section.. Cheers Scott
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Post by Johansson on Mar 14, 2019 0:15:26 GMT -5
Hi Scott,
The thrust available from a HX55 turbo could later be harnessed through a secondary turbine wheel and made into horsepower, even the most basic power turbine stage would give you more HP than you could ever want for a rail cart.
In one of the Gas Turbine Builders Association newsletters years ago there was a man who built a small locomotive with a motor driven fan that fed a combustor and the gasses ran a turbine wheel coupled to the wheels, very inefficient but it worked well enough to propel the locomotive with him on top.
Here is a video of another gas turbine train, with only jet thrust from the same engine the train would never have moved from the spot.
Cheers! /Anders
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Post by racket on Mar 14, 2019 16:23:53 GMT -5
Yep Anders , a nice second stage Allison C20 wheel would be ideal ...........50-60 HP
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userscott
Junior Member
Joined: March 2019
Posts: 96
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Post by userscott on Mar 17, 2019 18:17:11 GMT -5
I think for now I'll just get it built up as a conventional unit and nailed into the chassis. I'll lay it out in such a way that a second stage can be added at some point. I got one of the Volvo S80 (ZF) power steering pumps for my oil pump now, and so I'll get on with that shortly. I'm just drafting up the last of the flanges and cones in CAD then it's time to fire up the lasers. I think I still have some questions: - I have struggled with getting to the bottom of the exhaust outlet diameter. My current drawings are for a tube which replicates the exducer diameter with a straight pipe, with a nozzle at the end which reduces the diameter by 30%. What is the science behind this - and how long should the exhaust (jet pipe be)? - I want to build the engine with a 90 degree bend between the combustion chamber and the turbo, so my jet pipe is in the same alignment as the combustion chamber (albeit opposite sides of the turbo!). This is as per the drawings on the Yahoo group that I think you did Racket, on the first page (The abbreviations page with the stage numbers). Is there anything I need to worry about with this? - When entering the pipe out of the compressor into the Combustion Chamber, my understanding is it should enter the CC at right angles, and on the center line of the tube, and closer to the turbo flange end rather than the end with the fuel injectors. Is this correct? I've read and read and read everything but don't want to make a schoolboy error... I have included temperature senders on the majority of my build to match the 5 locations shown on the diagram in the abbreviations page on the PDFs so I'm hoping I can use this data to tune my engine design... Lastly, could we get this thread moved to the build threads section?
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Post by racket on Mar 17, 2019 19:16:23 GMT -5
Hi Scott
Yep , jetpipe ID the same as the scroll's exducer shroud dia so theres no step, and the jetpipe at least a couple of "diameters " long , as for the jet nozzle sizing that will depend on a number of variables , but I wouldn't be too concerned about it just yet , get the engine running first without a nozzle , it'll start easier and run cooler minimising potential first spoolup disasters ;-)
If you must have a 90 degree bend between combustor and scroll keep it as large a diameter as possible to prevent "restriction" caused by the turning of the flow , better with a straight in approach .
Your third point is correct .
Cheers John
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userscott
Junior Member
Joined: March 2019
Posts: 96
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Post by userscott on Mar 17, 2019 20:07:53 GMT -5
John, Thanks for your prompt response. All crystal clear. I'm just about to order some cut stainless. My 67 mm inducer has lead me to a 134 mm ID Flame Tube with and I've left a 20 mm gap, resulting in an ID of 178 mm in my outer housing. My length is 403 mm. Hopefully that is correct..! Cheers Scott
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Post by racket on Mar 17, 2019 20:43:07 GMT -5
Hi Scott
The clearance gap could be reduced a tad to 15 mm if it makes finding a suitable outer can easier , have you looke at the "7 inch" fire extinguishers for the outer can ??
Cheers John
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userscott
Junior Member
Joined: March 2019
Posts: 96
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Post by userscott on Mar 17, 2019 20:54:29 GMT -5
Hi John, I have indeed I think I'd rather just laser and roll something. It would be a lot less work I think.. I will just chuck it on the order for the end caps and I can laser out the inlet on the side whilst I'm there to save getting my hands dirty! Daft question, what size do people generally run the liquid fuel lines at (Kero)? My first guess was 15 mm (for ease of getting ball valves etc for shut off) but having looked at the price of the tube for making rigid fuel lines out of... wow!..!
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Post by racket on Mar 17, 2019 22:16:27 GMT -5
Hi Scott
You only need 3/16" OD steel brake line for your fuel line , 1/4" OD is all I use on my 12/118 engine .
Cheers John
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userscott
Junior Member
Joined: March 2019
Posts: 96
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Post by userscott on Mar 18, 2019 15:38:03 GMT -5
Thanks for the advice John. I've gone for 1/4" OD as it's far simpler to package it and today have purchased all of the required fittings etc. It should be quite neat. I want the engine to be removable with relative ease so my plans at the moment are based around all my sensors/senders, the oil flow and return, and the fuel all being engineered into a junction around 12" from the CC and Turbo where I can package in various quick releases etc. At this point my fuel and oil lines will switch from rigid steel to braided - I'll use conventional Goodridge stainless braided for most of it from here. I think it's easier that way and I have tons of AN10 threaded oil stuff knocking about. I've found one of these in my boxes of old race car bits - new and unused... www.glencoeltd.co.uk/walbro-gsl392-fuel-pump-pump-only/ but I can't help but feel it will be somewhat overpowered. It was a spare for a 750 hp V8 and my recollection was it was only suitable for injection systems. Sadly I think it might be no use to this project - what's the general view on this?
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Post by enginewhisperer on Mar 18, 2019 17:56:10 GMT -5
That pump should work ok for an evaporator type setup. It looks to be an equivalent for the Bosch 044 which is a popular pump, and the Walbro pumps are usually pretty good in my experience.
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