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Post by turbojet atv on Jun 18, 2021 7:41:53 GMT -5
Hi Scott,
The idea for making a sister engine came up as a “bright idea” recently when I was looking over my chassis. There is a whole lot more to cram and squeeze into this small space that’s for sure. A lot of what I need is custom fabricated but that only helps a small bit with what space I have left.
The idea to extend my frame has come up but I figured I wouldn’t have to do so at this point in time. It would help haha that’s for sure.
I do want to build a sister engine and place it right next to the original engine in this frame and make it a twin engine but you’re right. Wait until all the bugs are worked out with one and then transition it to the other.
-Cullen.
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slittlewing
Senior Member
Joined: November 2017
Posts: 458
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Post by slittlewing on Jun 18, 2021 13:41:05 GMT -5
Sounds good Cullen, one thing you may be able to do is try your best to package all the ancillaries etc away from the “opposite side” to your engine (I.e. at the very front of the chassis or tail) if you want to add a second engine later. That way you don’t have to move everything and Re-plumb all the systems!!
Cheers Scott
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Post by turbojet atv on Jun 20, 2021 7:04:21 GMT -5
Hi guys, so I’m over here drawing the designs for all the complicated parts for my engine and trying to imagine them working. Imagining one thing and reality are two different things haha so sounds good on paper but not in reality.
Since I have to bleed air off from the engine, I’m trying to find a way to power my transmission (that turbine starter) & not kill the engine. One thing I drew was a linkage connected to my bypass valve & a throttle cable. Throttle increases opening the small bypass valve and letting more air go to the trans & creating more power. That linkage is also connected to the fuel valve so fuel pressure can increase with the throttle.
Or honestly have a separate throttle body that is specifically for the transmission only and have a linkage going to the bypass valve (that’s vented to the exhaust like a wastegate) & fuel valve.
Honestly coming up with how that will work and how the flame tube will be set up are the hardest things on this engine. But it’s not impossible, only a big pain in the rear lol.
-Cullen
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Post by wannabebuilderuk on Jun 20, 2021 9:37:56 GMT -5
Hi Cullen,
I'm not too familiar with a setup like this but I'd think that you'd be fine running the splitter valve biased towards the combustion chamber at idle and as you spool it up then start to open more towards the air starter.
The starter should be able to take a constant small flow through it which means you'll need the brakes to be on to not move (think of it like an automatic car where you start to roll when you release the brakes and then move to the throttle to speed up) and once you increase the throttle you'll want to bleed more air off however you'll have to do some testing to find what the ideal percentage going combustion chamber/starter is and it should be possible to setup a linkage between the valve and throttle.
I'm sure John or someone more experienced will be along to provide better solution but that's what I think would work.
Ben
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Post by racket on Jun 20, 2021 16:58:14 GMT -5
It'll depend on the shape of your compressor and turbine maps , but not having either will mean trial and error testing .
My gut feeling is that you'll need the bleed at least partially open during start , you might find that a fixed opening is satisfactory , lotsa unknowns , you'll need to be very careful during that first spoolup
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Post by turbojet atv on Jun 21, 2021 1:46:35 GMT -5
Thanks Ben & John.
I’m going to trial and error that process to see what the engine likes best. I’m going to test this experimental engine out with both ways of air bleeding. I’ll try a fixed opening and then try a linkage butterfly method next. Surely one of those will hit the bullseye.
I’m taking a lot of caution when I go to start the engine for its first time. The first time around I’ll see how the turbo and flame tube get along with each other. I will most likely have to add or make some holes bigger until the engine is happy happy.
I feel it’s not safe to wing the flame tube design but I’m going to start making some progress with it and work with it until I hit the mark. I’m going to start with 50-75 holes over the whole thing with 1/4”, 3/8” & 3/4” holes.
This is a highly experimental part of it but I might as well trial and error it.
-Cullen
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Post by racket on Jun 21, 2021 4:13:00 GMT -5
Hi Cullen
RE, my email of week ago ...............
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 21, 2021 4:40:43 GMT -5
Thanks John,
I don’t think I read that correctly the first time around but I got a hold of it this time. I’ll redo the math and try it again with those numbers to get the right measurements.
-Cullen
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Post by turbojet atv on Jun 21, 2021 7:45:34 GMT -5
Hey John, I found where I kept messing up my math. The formula I found was from a guy running propane in his engine but it’s all good now. I redid the math with fewer holes to work with my single spray nozzle & got more decent results out of it. Let me see/know if this will work? I’m hoping this shows up as a pick and not a link. But anyways, does this look more accurate for a engine my size or more holes to restrict a little air flow. By all means if that works right there I’ll work with the fueling and add pressure or another injector to work with what I have right there. -Cullen.
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Post by racket on Jun 21, 2021 17:09:18 GMT -5
Hi Cullen
Not enough holes , I'd go for 10 holes in each row , 10X 5/8" dia for Primary , 10X 1/2" Secondary and 10X 3/4" for Tertiary
Cheers John
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Post by turbojet atv on Jun 21, 2021 19:09:12 GMT -5
Thanks John.
I will start testing the engine out here shortly after I get those holes drilled. I’ve got everything else ordered and will start testing in the next month or so. Progress pics to come!
-Cullen
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Post by turbojet atv on Jun 22, 2021 16:29:47 GMT -5
Drilling stainless never gets old lol I love it with my whole heart. I got version 1 of my flame tube made today. More versions are surely to come as the original gets modified to fit the engines need. This doesn’t look bad for a starting point, thank you John for helping me get this part started. The header going to the turbo comes in soon and I’ll get the charge pipe ordered here shortly so I can finish the structure of the engine. After that it’s just getting a spark plug & injector put in & some cosmetics to complete it. -Cullen
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Post by turbojet atv on Jun 23, 2021 17:20:11 GMT -5
So this is just a general question for the people that have direct injection and not a evap system.
How do the injectors mount in your engine? Is the injector body threaded or have a section that is threaded?
I’m still planning to use one variflow injector. Maybe y’all can help with what size injector I need as I’m not sure exactly what to use.
Kero or diesel is my fuel choice. I read gas, methanol & nitro aren’t a recommended fuel because they’re very volatile fuels (I use VP M1 methanol in a boosted piston engine).
-Cullen
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Post by racket on Jun 23, 2021 18:00:25 GMT -5
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ausjet
Veteran Member
Joined: May 2013
Posts: 133
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Post by ausjet on Jun 24, 2021 0:12:08 GMT -5
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