Glow plugs
 

We have finally got some good weather in New York;) I have been playing with my sonic and it goes ok no sound breaking runs though. I have an os .46 ax ported and polished with a mac 2 piece pipe. The engine has around 160 pounds of compression. I am using 15% nitro and a apc 8.8x9w prop. I am getting 16200 on the ground with it. My problem is that I can only get one flight before I blow the element out of the plug! I have tried an os A3, A8 and F. No its not lean. I do a run up every flight and it sounds perfect does anyone have any suggestions on a plug.

RE: Glow plugs
 

It may not be lean when you take off but may be going lean from foaming or towards the end of the flight when the fuel is low. Or maybe the pipe length?

RE: Glow plugs
 

What tank are you using C.?
If not a bubbless, maybe you should try one?
It sounded o.k. for most of the flight yesterday...but I thought it might have gotten a little lean toward the end of the flight?

RE: Glow plugs
 

When I tuned the pipe I went to the max RPM's and then cut back 1/2" and it came down 300 rpm. I am not running a bubbless maybe I will have to try one

RE: Glow plugs
 

K&B 1L

RE: Glow plugs
 

I will see if the hobby shop has some k&B1L tomorrow. Is that what you use in your speed planes?

RE: Glow plugs
 

K&B 1-L or K&B-HP plugs ---- somewhat easy to find.

As has been noted before, the primary reason glow plugs blow is a lean run.

The engine may run great on the ground, but when it gets in the air, and jumps on the pipe - it needs more fuel. You want to be sure to launch 600-700 rpm down from ground peak rpm.

Foam/bubbles will frequently be an issue when dealing with higher performance engines. The bubble tanks will help that situation, or simply re-check your existing tank, to make sure it is 100% isolated from the airframe with foam rubber. No part of the tank can touch the airframe.

Also..... the 9W is a little heavy for the engine, but if you have the pipe tuned for it ...... should work ok. Consider trying an 8.8x8.5

RE: Glow plugs
 

Nitro:

Jett has a 10 oz bubbbleless tank that works well and gives you enough fuel to fly a while, about 7-8 minutes with a 60LX. I need a few minutes to calm down and enjoy the flight, so is a good all-around tank. If by chance you have been using the Merlin plugs, I recently got a bad batch. They would only stay in for one start and run, then die. Was replacing a plug every run On Jett 35, 50 and 60, plus a Webra 55 every run. All had no problem when replaced with a OS 3-5 or 8, the only plugs I had left. Was first problem I have had with the Merlin plugs, one in the 35 was probably in there for a season of racing. (If it ant broke, don't fix it!!) ENJOY

RE: Glow plugs
 

I had a similar problem of blowing plugs every run. I eventually fixed the problem by installing a thicker head washer which would have slightly reduced the compression but seemed to make little difference to the power.
Maybe it is caused by poor quality plugs or running lean, but it might be worth ago.

RE: Glow plugs
 

Question to the guys who have more tuned pipe experience than I...
What about pipe volume? If you had a larger than usual (for a .46 ) pipe...like say, one for a 15cc engine on it...would that make it go lean due to the increased volume? Seems like it would make for inconsistant needle settings?

This is also the engine you have the nitrous on isn't it N-J?

RE: Glow plugs
 

I think he's still leaning out one the engine reaches speed flying because of no load.... I use cheap Tower plugs and love them...

RE: Glow plugs
 

yes this engine has the nos in it BUT I have not fired the nos yet in the air!!!! I am waiting untill I get the engine running good in the air.

RE: Glow plugs
 

So, if I understand correctly, you cut the pipe past the "tuned rpm"? If that is the case, then you are most likely just running it lean. Try running it up on the ground, keeping it so rich it doesn't stage on the pipe... then launch, and see if the engine pipes up once you get some speed. If it sounds happy once it's up to speed, then you were lean previously.

OS #8 plugs are very good plugs. They should have no problem with the rpm's you're running (unless you have monster compression, gobs of nitro or detonation)

For the record I should state that I almost exclucively use OS plugs in my heli's... for propped engines I use Rossi plugs, which only cost half of an OS, so I don't mind popping a plug a flight so much. The rossi's suck in heli's (starting and midrange troubles), but at full song in a propped engine, they work perfectly.

RE: Glow plugs
 

I didn't think you had run it with the nitrous yet...but I'm wondering why you are using a .91 sized pipe on a .46? Is it because you anticipate (sp?) a large increase in mass flow through the engine when you hit the bottle, and it will require that much larger a pipe?

My thinking is that the 15cc size pipe is causing it to go lean...(I could be wrong?)

RE: Glow plugs
 

How do you know what pipe he has and he's got Nitrous Oxide on it????? Am I missing posts?

RE: Glow plugs
 

They are both in NY!

RE: Glow plugs
 

:D We're both in the same club...and we were both at the field last Saturday.
We are going to have some "unofficial" style club races this year...one way or another...
My Sonic isn't quite finished (almost ) but I did finally get a chance to test run one of my K&B 6.5's...(FIRE )

I got 18,300 with an APC 8X8 with 15% Powermaster, on a 60 degree day, but I blew a couple of (used ) O.S. #8's during testing. (got a pump on it, and getting it and the carb adjusted, I got it leaned right out a few times and...pffftt :eek:)
I figured 18,300 w/ a "Newton muffler" and a well used piston/sleeve with virtually no pinch ain't none too bad, huh?

RE: Glow plugs
 

Proptop I got a new pipe from tommy boy yesterday. I hope to be at the field around noon or a little later. Yes I ran a bigger pipe becouse when I hit the NOS I did not want too much back pressure.

RE: Glow plugs
 

Did you get a smaller pipe? Hope it works...don't know if I'm gonna be able to make it out there tomorrow?

Just thinking about something...if you used a .45/7.5cc sized pipe with the nitrous...
If the regular sized pipe for a 7.5 cc engine would cause increased backpressure at the higher r.p.m. caused by the N two O hit, that should cause an increase in tank pressure, and richen the mixture, which should be just what you want when using something like nitrous?

Getting all the bugs worked out might take some time, but if you can get it to work, that will be really cool :D

You might need an in-flight adjustable needle valve assembly like a lot of the D.F. set-ups use?