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Post by turbojet atv on Jun 13, 2021 7:32:03 GMT -5
hi everyone, here’s a small update on what I’ve been doing to my engine. So I’ve welded all my caps to their rightful homes. I had to relocate my turbo forward more in my frame to fit it and my steering stem in its right location. I’m about to start drilling all the holes for the FT, injectors & making a home for the spark plug to live. I just want to run this by y’all to see if I got the math “correct” on the size and amount of holes for the ft. This part I’ve heard is the hardest part about making these engines. I do use a different turbo then most if not all of you so does it make a difference? ibb.co/yF0jjpZi feel like I almost hit the mark with what I calculated out but It’s a shot in the dark. -Cullen
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Post by racket on Jun 13, 2021 17:48:01 GMT -5
Hi Cullen Hold off drilling your holes until I have a good think on it . Your fuel injection will influence your Primary Zone holes , so more info on that please . Another issue is just how much air will be bled off , we'll need to design hole area for the remaining mass flow , so I'll need to do some rough calcs taking into account your turb stage sizing . www.garrettmotion.com/wp-content/uploads/2018/11/Turbine-Flow-GT55.jpg it looks like a Corrected Mass Flow of ~68 lbs/min , I'll assume a 3.5 PR across it with a TIT of 900C I'll get back to you :-) Cheers John
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Post by racket on Jun 13, 2021 18:44:01 GMT -5
Hi Cullen
You'll need to make your flametube holes for a 3.6" diameter inducer of ~10 sq inches area , this will better represent the ~2 lbs/sec flow going through the flametube at full bleed .
The Primary holes will be 3 sq ins , Secondary 2 sq ins and 5 sq ins Tertiary , the Primary holes will need to be fewer and larger so as to penetrate to the centre of your large dia flametube if a single spray nozzle is used , smaller and more numerous holes only work if Propane is used and is injected radially towards those numerous wall holes
Cheers John
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Post by turbojet atv on Jun 14, 2021 0:58:02 GMT -5
Hi John, The fuel injection side of things is the “complicated” side of it. I’m going to run 4 stainless steel spray nozzles through a special metering valve to control throttle functions. My fuel pump sounds a little over sized but better to over shoot it than to under size it. www.summitracing.com/parts/aei-11183The fuel pump flows 105gph/397lph @ 90psi. Here’s the metering valve. It’s 2 outputs, one for standard idle fictions and an output for high speed full throttle functions. There’s another metering valve with just one output but I thought having 2 will allow me to control fueling through all rpms. www.alkydigger.net/proddetail.php?prod=EN4025AAs for making the holes in the ft, I’ll wait to drill those until something can be worked out. -Cullen
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Post by wannabebuilderuk on Jun 14, 2021 2:44:54 GMT -5
Cullen,
You only really need one nozzle to save complicating things unless you're going for 4 to allow you to run 4 smaller nozzles to equal the flow of 1 large one?
As for the pump you need to have enough pressure to be above the engine pressure and have room to spare to spray at a decent pressure so automotive pumps usually work for the needle in a tube type setup (forgot the name someone please correct me) and for injector setups you want a much higher pressure which also gives better atomisation.
For that amount of money you could easily get a 12v hydraulic gear pump that can supply a couple hundred psi
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Post by racket on Jun 14, 2021 4:16:37 GMT -5
Hi Cullen
Way too much overkill with the fueling ...............our engines are simple "oil burners" , a single spraynozzle and a simple "dump valve" to control fuel flow , you're overcomplicating things .
With an airflow rate of ~2lbs/sec -120 lbs/min going through the flametube , you only need 120 -150 lbs of fuel per hour , 17-22 GPH , LOL, I use a cheap knockoff 044 pump at 1/10th the price of your one .
Cheers John
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Post by turbojet atv on Jun 14, 2021 5:28:31 GMT -5
Hi John,
I might’ve over killed it a lot with you saying that. I was thinking y’all run high psi (100ish or so) on the fuel delivery to the nozzle(s). Lol. I’m coming from a piston back ground. I’ve got a piston engine running 500+hp, turboed wtih methanol & efi w/ 8 225pph injectors. So my knowledge of something “simple” like this makes me think to “overdue” or “over complicate”. EFI applications are rough lol.
I’ll use a single variflow nozzle like you mentioned earlier John. The variflow nozzle sounds like I can adjust the flow pretty easily. The fuel pump I’ll rethink as well and get a lower flow pump that’s cheaper for one & is more suitable.
Drill through 12mm of stainless steel also persuaded me to use one injector and save the time drill multiple holes & breaking bits.
-Cullen
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Post by racket on Jun 14, 2021 16:50:23 GMT -5
Hi Cullen
LOL....Our engines have more in common with a home heating furnace than an auto engine , we need to leave most of our auto thinking behind us when starting to build a gas turbine
Cheers John
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Post by turbojet atv on Jun 15, 2021 11:56:49 GMT -5
Hi John, it definitely has very little if not nothing in common with a piston engine. The only thing they have in common is fuel & a spark lol. Here’s a look at some of the changes I had to make to the bike. ibb.co/VLzSrxkibb.co/CB0c0T8I ran out of room as soon as I introduced the steering stem to the equation so I decided to hang the turbo off the left hand side of the bike. I’ll contour balance the weight of that with the oil tank and a small ballast tank full of weights to even it all out. I’m fabricating the header going to the turbo as soon as it gets here and structural support to hold the turbo up. This is getting more exciting by the day. I’m eager to hear that 106 roar to life! -Cullen
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Post by racket on Jun 15, 2021 17:17:43 GMT -5
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Post by turbojet atv on Jun 16, 2021 8:09:01 GMT -5
Hi John, that’s one incredible looking bike you built. Definitely shows how much skill and craftsmanship you have to squeeze everything into a very small space and it work out perfectly.
Did you ever test its top speed capability? Looks like it made some impressive power as well.
-Cullen
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Post by racket on Jun 16, 2021 17:02:16 GMT -5
Hi Cullen 115 RWH on the dyno should have been more than enough for ~130 mph , but I only ever had it up to ~120 , there was no concessions made "streamlining??" , bits , including me , were hanging out everywhere . For top speeds , have a look at Anders build jetandturbineowners.proboards.com/thread/53/landspeed-bike-diy-gas-turbine , it was powered by a 98mm comp inducered engine he built , nearly 200mph . Cheers John
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Post by turbojet atv on Jun 17, 2021 19:05:54 GMT -5
Hi John.
That’s one sweet looking land speed bike. Looks awesome.
I’ve been looking mine over and was having a crazy thought. Why not just for shits and giggles duplicate what I’ve done and make a second 106mm performance engine? My atv would have two 107mm performance turbos feeding two combustion chambers. Double trouble is what I think yet I also see double the fun. Especially when I hit the throttle and activate that Honeywell starter with 100+ lbs of air.
See since I’m racing only, I can gear my ride to go 150+ in the 1/8 mile alone. Which is crazy for a engine with no pistons. It would roughly (on paper) do 200 In the 1/4 mile. If I’m lucky and what’s on paper reflects to reality but we all know that’s not the case.
I’m going crazy I think lol but I want to push the bar off what I can build and challenge my engineering mind to the absolute max.
-Cullen
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Post by racket on Jun 17, 2021 21:51:49 GMT -5
Hi Cullen
Remember the golden rule of gas turbines , the "holes" downstream must be big enough to VOLUNTARILY swallow whats produced upstream , we CANNOT force more through those "holes" as you can when using a piston engine where the pistons produce a higher pressure than what the compressor wheel turns out, ................you can run a higher exhaust manifold pressure than inlet manifold pressure on a turbo'ed IC engine but we can't .
If you try to force more through , your comp will go into surge and potentially wreck the engine ................and yes I have tried :-(.
LOL......if you want a "challenge" , feed your two lots of bleed air into a dedicated combustor then feed it through a "hot" turbine wheel.................heh heh , we'll be only too happy to push your mind to the max .
Cheers John
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slittlewing
Senior Member
Joined: November 2017
Posts: 458
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Post by slittlewing on Jun 18, 2021 4:03:18 GMT -5
Hi Cullen, I would advise getting your single turbo setup working perfectly first! You will soon find that you need to cram a whole load of other stuff in that frame.. batteries, oil tank, pump, cooler, fuel pump, fuel tank, instrumentation and controls etc! Do to a "twin" setup you will need to do some very tight packaging and even still probably lengthen or widen your chassis. Plus.. until you get your first engine running nicely, you wont know what modifications or improvements you need to make to any potential "sister engine" Cheers Scott
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