Posts: 3498
Joined: 7/3/2003 From: New Richmond,
WI, USA Status: offline
quote:
ORIGINAL: Not24
Yes, definitely. Just as you have shown in your diagram. It made a big difference in the 1.08, and I feel it will help the 2300. I think the carb is adjustable enough to work well, maybe even better than the 7D. I'll be putting the tank back behind the wing tube again to help with the cg shift. The plane requires a trim change in flight with the tank in the nose.
One question. Which line do you use to fill the tank? I would guess the best one would be #6.
Yes, #6. I think it will work. Most say that the pump will not work with the 2300, but I bet the bypass system will. Keep us posted.
Posts: 999
Joined: 12/7/2002 From: Gloucester,
VA, USA Status: offline
Got her running tonight on the pump. I tried two configurations. One is the bypass, and the other is direct. Amazingly, it seems to behave exactly like the OS 1.08 in both configurations with one exception. There is not enough fuel flow with the bypass to go rich on the high needle. This is similar to how it runs without the pump and the open muffler.
Let me talk about the direct system first. With the pump as lean as it will go, I could richen and lean the high needle, and the low needle, but the midrange is excessively rich. That's the way the 1.08 runs. Definitely not flyable. I saw a peak of 8000 with the 18-8, and an idle of 1400 all day long. Just don't add power quickly, because it'll load up really bad, and never clears in the midrange.
The Bypass system works really well, but still needs one little tweak. The pump is set to full RICH, the high needle won't allow for slobbery rich, but will allow for finding peak and backing off a few hundred revs. The low needle acts just as it does without the pump. Idle is good, good as any I have seen, and will run forever at 2000 rpm. It will load up slightly if you do let it idle for a long time, but it is manageable with smooth throttle inputs. 15-30 seconds of idling won't load it up enough to be bothersome, and it definitely won't quit. The good thing about this setup is that the engine runs perfect from 3000 to 8000 rpm with NO BAD HABITS. Transition is perfect, and spool up is what I would call very good for such a heavy prop. Noticeably better than without the pump. It gets right on up to peak rpm within 1 second. Also, I can run the engine to 5000 and raise the nose to vertical and it won't lean out. Overall, a very flyable setup that is easy to tune. The pump is not even part of the tuning equation. Set it to full and forget it. I might also add that I did stretch the spring to 2X original length.
The only thing to play with now is to install a needle valve in the return line between the engine and the check valve. This will allow me to increase the pressure at the needle valve, making it possible to get it to go rich. It should also allow me to lean the low needle a little more, making for long idles with no hiccup on acceleration. This restriction was also required on the 1.08 to make the mid range rich enough. So, for all of those who still think the carb on the 2300 is not worthy, I say, so far it hasn't proven that to me.
The real test is in the flying. I'll report on that in a few days.
Posts: 3498
Joined: 7/3/2003 From: New Richmond,
WI, USA Status: offline
Nice test stand.
Keep us posted on the needle valve in the bypass. I have thought about doing it(needle valve in bypass), but never have had to yet. It will be interesting to see how your low and mid react to more pump pressure at low rpm even with it leaned out.
Not sure if you are going to do this, but when you do your install in the plane make sure you get your "T" as close as you can to your needle valve.
Have you tried a cooler glow plug than the type "F"? You are running 10% with some castor correct?
Posts: 999
Joined: 12/7/2002 From: Gloucester,
VA, USA Status: offline
quote:
ORIGINAL: STG
Nice test stand. Keep us posted on the needle valve in the bypass. I have thought about doing it(needle valve in bypass), but never have had to yet.
I'll just borrow one from the 1.08 for testing. The wheel collar is a little too chinsy for that purpose, but it does work.
By the way, I like flying with the 18-8 much better than the 18-6. It pulls more like a four stroke and doesn't sound like it's screaming all the time. 8000 rpm is very respectable. Initially, I only saw 7300 on that prop. I also have a 16-10 three blade to try someday.
Posts: 1512
Joined: 9/4/2002 From: Bruce,
MS, USA Status: offline
Not24, theres one thing I must say and that is you are one determined 2300 owner. That set up looks like a man in the recovery room after surgery. Keep up the good work and keep us posted.
Posts: 999
Joined: 12/7/2002 From: Gloucester,
VA, USA Status: offline
Thanks, but it's really not that complicated. I made the stand in about an hour, and the plumbing is really simple. Two T's and a check valve, plus the pump. A picture is worth a thousand words. Can't wait to fly again!
Posts: 978
Joined: 9/21/2004 From: STOCKHOLM Akersberga, SWEDEN Status: offline
quote:
ORIGINAL: Not24
Thanks, but it's really not that complicated. I made the stand in about an hour, and the plumbing is really simple. Two T's and a check valve, plus the pump. A picture is worth a thousand words. Can't wait to fly again!
Not 24, Nice work Keep us informed about the running habits with the T and the check valve.
Posts: 999
Joined: 12/7/2002 From: Gloucester,
VA, USA Status: offline
I borrowed the needle valve off the 1.08 and installed it in the bypass line. It was extremely difficult to get the engine to start, and tuning was a nightmare. That needle controls the fuel pressure, so if you move it, it screws up both the other needles, making tuning extremely exaserbating. I'm going to pass on the needle in the bypass line and go back to the setup in the pictures. To get the high end to richen up, I have two remaining options. I can drill out the fuel nipple on the carb to allow a higher flow rate, and I can add some backpressure by pinching the muffler closed a little. Without having a pressurized tank, I don't know if the muffler actually has anything to do with fuel draw anymore, so I will enlarge the fuel nipple first.
Posts: 3498
Joined: 7/3/2003 From: New Richmond,
WI, USA Status: offline
quote:
ORIGINAL: Not24
I borrowed the needle valve off the 1.08 and installed it in the bypass line. It was extremely difficult to get the engine to start, and tuning was a nightmare. That needle controls the fuel pressure, so if you move it, it screws up both the other needles, making tuning extremely exaserbating. I'm going to pass on the needle in the bypass line and go back to the setup in the pictures. To get the high end to richen up, I have two remaining options. I can drill out the fuel nipple on the carb to allow a higher flow rate, and I can add some backpressure by pinching the muffler closed a little. Without having a pressurized tank, I don't know if the muffler actually has anything to do with fuel draw anymore, so I will enlarge the fuel nipple first.
quote:
The pump is set to full RICH, the high needle won't allow for slobbery rich, but will allow for finding peak and backing off a few hundred revs.
Why do you need your high speed to get richer than that if you are not trying to break in the motor anymore? Thanks for the info.
Have you tried to run your "T" closer to your needle valve? Have you tried a cooler glow plug?
Posts: 3498
Joined: 7/3/2003 From: New Richmond,
WI, USA Status: offline
quote:
ORIGINAL: Not24
quote:
ORIGINAL: STG
Have you tried to run your "T" closer to your needle valve? Have you tried a cooler glow plug?
Thanks for all your testing and reporting.
I was thinking about trying that too, with the T being very close to the needle next time. I really can't see why it would matter, but I'll try it.
I'm having good success with the F plug. I have some a3's when it dies.
I was really disappointed in the way it ran tonight. I suppose you could tweak it in, but it would take many tanks of fuel to do it. Not worth it!
Moving the T closer to the the needle valve is just lessening the distance gravity can work against the correct fuel setting. I don't think it will change much on the bench, but in the air it might some -- especially since you have established that the pump is not over supplying the motor with fuel at higher needle settings(very open high speed needle). -------------------- Have you seen this on glow plugs? As you know the A3 and TYPE F are very hot. Have you tried a cooler plug with the bypass(like a #8)? It may help you get a richer high speed and more power and economy.
I know everywhere you read the "F" plug is supposed to be the plug for the ST2300, but a lot of that has come from pattern fliers who mount the motors inverted, and with the glow plug straight down a hot F plug(that can stay lit as fuel pools on the plug at low settings) may be the only thing that could stop a flame out. The pattern fliers usually are running very low nitro levels(and thus hotter plug needed)
"Too cold a plug will cause loss of power and or poor throttling. TOO HOT A PLUG will also cause loss of power and or poor throttling..."
"FINE TUNE THE MIXTURE at maximum power. This not only increases the power further and improves the throttling but it can also increase the MILES PER GALLON BY UP TO 40%!"
I used to think that a hotter plug would help throttling in the bottom and mid range, but according to some sources if the plug is hotter than optimum then the needles need to be set richer to compensate. The richer mixture retards the timing to stop pre-detonation. And this richer setting actually can hurt throttling and more.
Ignition timing is 'automatic': At higher rpm, the plug becomes hitter and, appropriately, fires the fuel/air charge earlier; at reduced rpm, the filament becames cooler and ignition is retarded.
Posts: 999
Joined: 12/7/2002 From: Gloucester,
VA, USA Status: offline
Thanks for the links on glow plugs. I will get a new #8 and an A5. That should cover the whole heat range. Speaking of heat, it's too cold out there now to run that beast. It needs to be above 50 to keep me from freezing my hand off.
It will be interesting to see the different peak rpm's with the different glow plugs. I never paid that much attention to heat range before. Thanks for bringing it up.
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RE: My 2300 only likes one prop - 
Keep us informed about the running habits with the T and the check valve.