hosedup
Junior Member
Joined: October 2019
Posts: 68
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Post by hosedup on Dec 15, 2019 17:39:51 GMT -5
OOPS ..............sorry about the confusion , its just you had the updated flametube design with the question , use the updated design , the upper holes will help cool the cap before entering the combustion phase . Sounds good, thank you. Another question but this time about EGT. In a different thread I asked about instrumentation and it was suggested that I needed at least 1000 deg C range. How much higher? I am considering using a type K thermocouple and they are good to 1260 C. Is that high enough? Plan is to put it right in the gas stream after the exducer. If that doesn't go high enough, my next thought is an after market EGT sensor.
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BFTO
Veteran Member
Joined: February 2016
Posts: 128
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Post by BFTO on Dec 15, 2019 17:46:04 GMT -5
1000 deg probes is enough for EGT, if you see 1000deg EGT your turbine isn't happy
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Post by racket on Dec 15, 2019 18:56:14 GMT -5
Yep , K type is plenty , you really only want to see ~650 deg C - 1200 F coming out of the turbine wheel at full power if you want safety and are in the least bit concerned about the "heritage" of the turbo and the materials used in the wheel , if its a new "reputable brand" turbo with a verifiable Inco wheel (or better) then higher temps of ~750 C- 1400F can be used as a TOT in the jetpipe , but at this stage of your development keep below 650 C , though you might see a bit higher during spoolup , but rpm are low and the wheel material takes time to heat up , so as long as your spoolups are less than ~20-30 seconds even an 800C TOT isn't going to be a problem .
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hosedup
Junior Member
Joined: October 2019
Posts: 68
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Post by hosedup on Dec 21, 2019 20:08:13 GMT -5
Here's another newb question, how about startup procedure?
I figure for startup: -start up oil pump, confirm pressure and flow -couple startup air blower to inducer -once turbine is as fast as its going to go, turn on ignition and slowly add fuel until it lights -once lit allow engine stabilize, flame moves into flame tube -slowly remove startup air, add fuel if needed to maintain sustain
For shut down, I'm thinking: -slowly reduce fuel until at idle, let idle for a couple min -while turning off fuel supply, connect startup air -leave air connected until turbo housing and/or TOT is below 300F (maybe 200F?) -remove air, allow oil to circulate for a few min -shut down oil supply
Couple related question: Anything special I need to watch out for on initial startup? How hard can I push it? My thought was to find out the design boost pressure from OE application and not exceed that. Is there a safe way to do a quick shut down if for example oil pressure is lost due to leak or power failure?
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Post by turboron on Dec 21, 2019 21:06:21 GMT -5
hosed, I find it helpful to watch the pressure gage on the Outer Combustion Chamber (the pressure vessel) as the engine spools up. ON my DIY I turn off my start blower when the gage gets to 10 psi. You would remove the leaf blower at that point. Acceleration can be rapid so be gentle with the throttle(fuel valve) until you get a feel for the sound and acceleration.
Thanks, Ron
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Post by racket on Dec 21, 2019 22:01:42 GMT -5
Its advisable to have a pressure switch on the oil supply line to deactivate the fuel pump if oil pressure drops below a set psi , mine is set for 45 psi with normal start oil pressure of 70psi which slowly drops as the oil heats up.
I once accidently deactivated the oilpump switch on my 2 shaft kart whilst the engine was running and powering the kart, thankfully the pressure switch shutdown the engine and no damage done, its a must have bit of safety equipment , it gives great peace of mind .
For initial spoolup , your temperatures are the most important thing to be concerned about especially if theres a spoolup problem resulting in a hung start and temperatures spiking , don't let them get over 800C during the spoolup, and if you follow Rons advice and keep the starter engaged until you have a healthy P2 pressure on the gauge, at which time the temps should have dropped to ~500C- 900F ...........don't prolong your spoolups beyond ~20 seconds, if it hasn't started producing several psi of P2 by that time better to cut the fuel and investigate .
As for cooldown temps with the blower, 300 C- 500F would be adequate as the continued oil flow will take out the remaining heat from the bearings, no need to cool the engine completely .
Cheers John
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hosedup
Junior Member
Joined: October 2019
Posts: 68
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Post by hosedup on Dec 22, 2019 17:05:07 GMT -5
So for future reference, this will be the thread that I post stuff to.
Currently I do not have a low oil pressure switch, nor do I have an electrically controllable valve to kill the fuel. I am currently working on getting a switch and ill wire it to a klaxon and red strobe until I get an electric valve for fuel.
My oil processor, known as the Lubinator (but I may rename it Nigel) is based on a carbonator unit used for making carbonated water for a soda machine. It has a relief valve set for ~75 PSI and a regulator set for ~40 PSI but is adjustable from 10 to 75. My plan is to start up and run with 50 PSI and if the P3 pressure starts to approach 30 (I don't see how it could), bump the pressure oil pressure up so it is always at least 20 PSI greater.
As for oil, I was thinking of using rotella 15W-40 since it is what is generally called for on the engine this turbo came off.
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Post by racket on Dec 22, 2019 18:05:55 GMT -5
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hosedup
Junior Member
Joined: October 2019
Posts: 68
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Post by hosedup on Dec 22, 2019 19:19:16 GMT -5
15W-40 should be OK , is it full synthetic?? If it needs to be then yes, thats what ill get. Im working on fuel valves right now.
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hosedup
Junior Member
Joined: October 2019
Posts: 68
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Post by hosedup on Dec 30, 2019 21:19:25 GMT -5
Currently videos are being edited and may be a little while before being posted.
Well, it runs, sort of. When the air source is applied, fuel turned on and spark active, it will spool up but as soon as the start air is removed, it will flame out. (likely surging) We tried slowly or abruptly removing the air and adding fuel and it would flame out. Sometimes it would make big boom and restart followed by flame out. When the engine would light, the blow hose was being sucked onto the inducer. The fuel nozzle radial holes are lined up with the second row of primary holes.
After thinking about it and verifying measurements, found a likely smoking gun. Original plan called for: Primary holes: First row, 8x 0.25in (6.35mm), 0.5in offset from top Second row, 8x 0.34in (0.34mm), 2.0in offset from top Jetspecs recommendation: 1.1 sq in Actual area for both rows: 1.12 sq in 1.7% oversize (likely fine)
Secondary holes: 15x 0.25in (6.35mm), 6.5in offset from top Jetspecs recommendation: 0.74 sq in Actual area: 0.73 sq in 0.5% oversize (likely fine)
Tertiary holes: 16x 0.375in (9.5mm), 11.0in offset from top Jetspecs recommendation: 1.8 sq in Actual area: 1.77 sq in 3.54% undersize (ok?)
Well, it turns out that the second row of primary holes were accidentally drilled to 0.375 (9.5mm) as opposed to 0.34 (8.6mm). If my numbers are correct, this means that:
Primary: Jetspecs recommendation: 1.1 sq in Actual area for both rows: 1.28 sq in 16.1% oversize
Secondary and Tertiary were cut correctly.
So here is what I am thinking. Option A: Plug the first row of primary holes and leave the second row, 8x 0.375in (9.5mm), 2.0in offset from top as they are. Add an additional 0.125in hole between each 0.375in hole. (It would alternate 0.375 (9.5mm) and 0.125 (3.2mm) all the way around)
Option B: Plug all holes and redrill new holes, 29x 0.219in (5.5mm). If I did this, I am thinking of moving the offset to 1 inch from the top as opposed to 2in. This configuration would give 1.092 sq in, which comes out to 0.6% undersize.
Sorry for the big dump of information, wanted to make sure everything was covered. Once the videos are uploaded, Ill post links. There will be 2 videos, one showing several attempts and the second is the control panel showing all instruments. This video was shot during the very last run attempt. Instruments are as follows:
Control panel First row, P2 (psi), P3 (psi), TOT (deg F) Second row, switches for stuff, future oil temp
Oil unit Output regulated pressure (psi), oil pump raw pressure (psi)
Notes on oil unit: It was a carbonator that was heavily modified. Oil path is, tank, pump, radiator, filter, accumulator, then splits to 2 paths. One to a relief valve set for 80 psi then back to tank. The second is process loop and goes to to a regulator set for 30 psi, flows through another radiator, then to the turbo itself and then drains back to tank.
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mrcoffee
New Member
Joined: November 2019
Posts: 7
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Post by mrcoffee on Dec 30, 2019 22:13:48 GMT -5
Hey All. Just got the videos uploaded to Youtube. (I told Hosed not to post yet, but what can you do.) At any rate, Here is a 20 min video of the first test fire session. It has some noise correction, and a few small edits: (Edit - Gained the Audio up a bit and reuploaded - May be an hour or two before you can see it (23:30 EST-US)
youtu.be/1k-oBPjI-RMThis second video is a short clip of the gauges Hosed took during the firing session (during the last fire "Attempt" if you will - You can see him holding his cell phone at the gauges.) www.youtube.com/watch?v=-z_GZxTUjcoTemperature is in Farenheit. We are changing this to Celsius tomorrow, so it'll be easier to follow in all future posts/videos. This video was actually taken yesterday, just a quick clip showing the most important light on the machine:
At any rate, it seems that some flame tube corrections are in order. It's nice to have the granularity of this new control system though. As well as a proper oil system. -Rhys P.S: Also, Hosed has transposed his numbers again. Both sets of Primary hole numbers are the same, he meant to correct that in an Edit, but didn't get around to it and is now in bed.
We are currently at 1.28 In^2 for primary where Jetspecs wants 1.1. (suspected too much primary)
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Post by racket on Dec 31, 2019 16:15:59 GMT -5
Hi Rhys
Don't change the flametube , propane is an extremely forgiving fuel that will burn over a wide A/F range so some minor variation in holes percentages shouldn't cause a problem .
Having watched your video the first thing I'd recommend is checking the fuel supply , does your propane cylinder have any "safety" device which cuts supply if theres a large fuel takeoff ??
Secondly the starter blower , it needs to be kept sealed against the comp housing until you have at least 5 psi coming from the comp , preferably 7 psi , it should be hard to "unstick" .
Thirdly , the engine is making the right spoolup sounds before suddenly cutting out , this sounds more like a fueling issue , I'm a bit concerned about the fuel delivery tube , large volume tubing isn't always a good choice .
Finally , propane is heavier than air so "sinks" in the flametube and doesn't make for reliable ignition with a endcap mounted sparkplug , a sidewall position is better with a "vertical" combustor.
Could you post some more pics of the engine , inlet, exhaust etc as there coud be something else that needs attention ..............ah, almost forgot, your oil drain should always slope downwards , no dips otherwise oil can be forced out of your seals on shutdown
Cheers John
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Post by turboron on Dec 31, 2019 18:21:15 GMT -5
Rhys, as John says, the Barbie size propane tanks have an overflow protection safety shutdown which causes problems in getting fuel to the engine. It is to shut off if there is too much flow in the line such as would be caused by a hole in the line. I use a floor leveler tank. Its safety seems to be more forving than the 20 pound Barbie size valve. You have to go to a big 100 pound tank to eliminate the valve completely.
Thanks, Ron
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hosedup
Junior Member
Joined: October 2019
Posts: 68
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Post by hosedup on Jan 1, 2020 15:16:04 GMT -5
Hi Rhys Don't change the flametube , propane is an extremely forgiving fuel that will burn over a wide A/F range so some minor variation in holes percentages shouldn't cause a problem . Having watched your video the first thing I'd recommend is checking the fuel supply , does your propane cylinder have any "safety" device which cuts supply if theres a large fuel takeoff ?? Secondly the starter blower , it needs to be kept sealed against the comp housing until you have at least 5 psi coming from the comp , preferably 7 psi , it should be hard to "unstick" . Thirdly , the engine is making the right spoolup sounds before suddenly cutting out , this sounds more like a fueling issue , I'm a bit concerned about the fuel delivery tube , large volume tubing isn't always a good choice . Finally , propane is heavier than air so "sinks" in the flametube and doesn't make for reliable ignition with a endcap mounted sparkplug , a sidewall position is better with a "vertical" combustor. Could you post some more pics of the engine , inlet, exhaust etc as there coud be something else that needs attention ..............ah, almost forgot, your oil drain should always slope downwards , no dips otherwise oil can be forced out of your seals on shutdown Cheers John Racket, Ron, Well, heres what happened. Before seeing your message about not changing the flame tube, we changed the flame tube. All existing primary holes closed, replaced with 29x 0.219 in (5.5mm) diameter offset 1 inch (25mm) from the top of the flame tube. No other changes made and its like a completely different engine. It starts and idles and comes up to power. We did have problems with the P2 90 pipe flying off but thats due to a less than stellar design. Its about to be updated. One thing we've noticed is that its hard to get 5 psi P3 with the air starter attached, we usually get around 3 or 4 but the hose is sucked on tight. As for propane tank, we usually have them in slightly warm water to keep pressure up. In the pics below, we did not submerge it because it was a quick test. I do not think we have run into issues with a flow limiter on the tanks. If this becomes a problem, Ill either acquire a 100 pound tank or run 2 tanks in tandem. The oil return does have a dip in it. It is on the list of things to be fixed. During operation, we can see the constant oil drooling and every once and a while a bubble of a small amount of smoke comes through. Nowhere near the amount of smoke as out last build. FYI, for the foreseeable future, we do not plan on using liquid fuel. Flame tube after modification: Pics of build:
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Post by turboron on Jan 1, 2020 16:44:23 GMT -5
hosed, the triangular shaped valve handle on the propane tank means it has the overflow safety valve. The 100 pound tank and older 20 tanks without the overflow safety valve have a outside water faucet type handle. Open the tank valve very slowly initially to fill the line before opening the ball valve. Do you use a needle valve at the turbine to control fuel? If so you want it to be closed before you slowly open the ball valve.
Thanks, Ron
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