hsukaria

no bent rod. I will ask the original owner where he emailed. I'm guessing that is what the said, that prior hydraulic lock caused early damage that failed later. Not sure if that is what happened with the original owner.

unless somebody gives/sells me a used crankshaft cheap, I will use this engine for spare parts.

the pope

Not gonna believe what happened today . You guessed it broken crank pin . The engine was running too rich , so I leaned it out till it was just running smoother and 1/2 way through the flight , bingo . Never had a hydro lock or a heavy landing . I was ready to have their back but Im not so sure now . Seems that you have a happy engine if its running too rich to have decent throttle range but lean it out to where it should be and watch out . I was putting up with the rough running as I normally fly full throttle with this thing so its not really a prob but today I thought I would do something about it and did I ever . Not sure what my next step will be other than whacking on a OS 55 on the plane for a while . Maybe turning it into a glow might be an option . This is just my experience today . Sometimes its better to stay in bed . Cheers from the crying pope

hsukaria

Your engine copy-catted my engine. Sorry about that. I was actually running it just rich off peak as you would expect to do when an engine is broken-in when the crankpin gave way. Did you get a good look at the crankpin and conrod bushing? Mine doesn't show signs of any stress except a clean break off the crank.

the pope

Hi there husky , no need to be sorry it gives me a chance to try another engine out of the cupboard ! Had a quick look at the field and it looks like a clean break as well . Haven't had the engine apart other than the backplate but will check the rod and liner today and report back.I wonder why there doing this , maybe it has a bit too much compression . If I fix mine which I probably will one day I might add another head shim or maybe trying to turn it to glow. Maybe that's the reason they go kaput , they should have designed the Gasser from the ground up . Who knows ? Not this little black duck . Cheers the pope

Charley

My Feedback: (2)

Sorry to hear that, Pope. I guess I ought to look at the crankpin on mine. Maybe I ought to put a Fox .50 that I have mothballed on the Escapade & put the GX-40 back on the test stand.

CR

the pope

Hi there C -man , how's yours running ? Is it sloppy rich or clean and crisp ? Mine has had about 3 litres through it . Cheers

Sport_Pilot

I think you mean a pumped carb? Both have gas carbs. Old 30's engines had a gas carb that was just a venture and a spraybar. My lawnmower has a gas carb with float that would be totally unsuitable for a flying model.

Charley

My Feedback: (2)

Mine still won't run clean, even with 3 shims in it, it sounds like it's detonating. See my Post #1293.

Here's the latest from Dmitry:

Hi Charles,

It is impossible to pinpoint the problem via email as there are so many variables. Address this issue in the forum. We have sold many of these engines and end users might give you a good suggestion.

Regards,

Dmitry

So NV has thrown in the towel.

CR

hsukaria

Think about it Charley, once you get over the detonation problem and run long enough to get past the break-in period, the crankpin will break off and you will end up with a paper-weight. Something to look forward to.

I installed a JBA 56 in the Escapade and will fly that for a while. The baseline engine for the Escapade has been the Super Tigre G51 and it flies great with that. I have tried the following engines on the Escapade:
1. OS 55AX - insane power for that plane
2. Super Tigre G51 - excellent power
3. Irvine 40 ABC with tuned muffler - very good to excellent power
4. JBA 56 - excellent power and will get better as it breaks in more
5. NV Engines GX-40 - almost as much power as the Super Tigre G51 if it had lasted long enough to undergo full break-in
6. Norvel AX-40 - decent power, good as a second trainer.

The Escapade has been my engine flight testing platform. I still have a Fox 45 and a small-case Fox 40 to test on it. Who knows what other engines I might get my hands on and test it on the Escapade. The NV GX-40 is only one of the many engines to test and now that it broke, I will move on.

Like I said before, if I can guarantee that the crankpin won't break again and if all I need is to purchase a crank and not also a conrod and circlips, I would do it. But until the issue is resolved, there is no sense in putting any more money or time into it.

aspeed

Sorry about your losses ;-( If the crankpin has a hole in it, you could indicate it on a mill and press a hardened dowel pin in. If there is no hole, you can kind of guess. Only a few bucks, and only time. It is a hobby. If three washers are in and it sounds like detonation, maybe it is still overcompressed, but a diesel has kind of an odd sound when undercompressed, and maybe that is it? It would be harder on the rod if it is the wrong decision.

Charley

My Feedback: (2)

I suppose you're writing to two different people, one of whom is me, so I'll comment. If you're a machinist with a machine shop at your disposal such a repair as you advocate might be effected economically. How long a pressed in pin would last is another question, moot at this point. Maybe hsukaria ought to send you his crank. Are you up for giving it a try?

For my part, I'll run My GX-40 some more & see what happens. Things can't get worse. It's already paper weight.

aspeed

I could give it a go, but am in the middle of a long move, and if a house sells, the machines may be out of commission for a number of months, and winter will come for sure. I have not dug any holes for the new shop yet, so that is going to slow things. It seems like no one is able to do any construction work around here. They all seem to have moved out west to the oilfields for work. I wonder if there is a hole in the crank where the pin was. It is easier to drill through and locate from this. Shipping from this country would likely be at least $15 too. Maybe each way, so a new crank may be the best anyway, or get someone local. It is not really hard to do, just a .001" interference press fit. I have only done one Picco .67 so far, and never tested it. I believe some motors are done that way, and it is acceptable. I think at least one FAI speed guy did it that way, and they rev up pretty high. If there is enough meat to drill out and have some material left, it may be fine. If a lot of the web is removed for counterbalance, then a new crank may be needed.

the pope

Just pulled mine to bits . To change to glow with the Aus $ compared to the US $ and the parts I would get Its gonna probably be pushing $100 Aus . with shipping included . Not willing to part with that at this stage but next week things may change . Cheers

aspeed

At least you had yours for almost 2 years. It could have busted on the first run. Ya, shipping really ruins things. There was supposed to be a Hobby King depot in Canada according to rumors. The Canada Post ruined that idea. Apparently it is trying to be self supportive now, with no government help. China supports the shipping and gets all the business now.

hsukaria

I guess I could check around locally for a machine shop to put a pin into it. It is a hollow crankpin. If I plan on keeping it gas, it would have to be pinned as you describe since a new stock crank might break the same way.

dkwflight

Hi

I just read through the complete thread and I have read about others who have tried running various glow engines on a gas mix.
I believe the key is getting the compression right.
I have a GMS 2000 120 size engine I bought to run a giant scale stick a few years ago.
It has only a few hours on it . Compression is still good.

I am considering giving gas a try. This engine originally came set up for FAI fuel, no nitro.
The instructions said to install the extra gasket to run nitro. It seemed to run fine on 10% glow fuel. Just not quite enough power to suit me.

Can any one suggest how much compression to go for.
I have been thinking I would try what I have and see. If it seemed to need more I can trim the head on my lathe

DaOldGuy

Just got caught up reading since my last post, interesting turn of events indeed.
Last I heard from Dmitry was he sent me the Glow head bit to convert to glow. He then followed up with an email stating that I should add a shim, on board glow igniter and it will run the gas mix just fine according to the engineers. We have always joked this motor may run better with an on-board glow as it was. Dmitry still has not shipped the shim to me as of yet.

Charley

My Feedback: (2)

I've run glow engines on gas but always with spark ignition. My experience was that I got a bit less RPM on gas & they ran hotter. I've read that some folks add glow fuel to gas & get that to run on a glow plug. Never tried it myself.

CR

Charley

My Feedback: (2)

Dmitri told me that he was in sales, not a tech. I couldn't get out of him how to contact a tech directly. The last suggestion he gave me was that I should try lower octane gas! Where he got that I don't know. Maybe he talked to a tech and the guy decided to have some fun with us.

Just for grins I took out the extra shims I had in the engine (2) and tried it again with the octane booster in the fuel. It conked out after about a minute & a half with the glow battery connected. Gonna try a different gas.

CR

Sport_Pilot

If you run very high octane gas in an engine built with low octane then you will have less power and a slower flame burn which would retard the ignition slightly. The latter could cause the engine to run hotter. But not usually enough to notice unless you are using 120+ octane.

DaOldGuy

Agreed... Dmitry is a Rep and not the tech. This was the last reply I got from him for using the Glow insert and gas. It very well could be all in fun. He shipped me the glow head bit but I have not gotten the promised glow head gasket as of yet.

Hi Ron,

Since you have a standard glow head now, here is what you can do now:

1. Install a standard glow plug
2. Install an additional glow head gasket (two total).
3. Install an on-board glow plug driver ignitor 0.8-1 apm/h.

With this set up, you can use gas without problem. Our tech guy is sure about it.

Regards,

Dmitry

hsukaria

just want to make sure, by "glow head gasket", they mean the metal head shims, not the gasket that is unique to the GX?

DaOldGuy

I asked the same question, he replied
"One copper gasket is installed. I can ship you another one. Same gas is fine."

hsukaria

ok, so it is the glow engine copper head shims.

AndyW

My Feedback: (1)

Octane is generally misunderstood, sometimes. Octane levels refers to an engine that WILL NOT ignite its charge under compression alone. With spark ignition, this is what you want. You don't want the mixture to ignite under compression alone, but ONLY when provoked with a spark.

High Octane fuels aren't more powerful inherently. High octane fuels are NECESSARY when you have set up an engine with very high compression. That's actually where more power is extracted from the fuel.

If you have a high compression engine and use a low octane fuel, the charge will pre-ignite,, that is, too early, before the spark plug goes off. So you need a high octane fuel to prevent this. A high octane fuel RESISTS ignition by compression alone.

Reducing the compression ratio, (adding gaskets) is the same as using a lower octane gas. In both cases, the mixture won't ignite too soon.

The opposite of octane is cetane. Diesel engines need a high cetane fuel,, fuel that WANTS to ignite due to compression alone.

Methanol fueled glow engines walk a fine line between the two. The glow is always present and initiates ignition when the compression is just right.

Here, https://www.youtube.com/watch?v=_pN6-rgXEFk I have a Norvel .15 rigged up with my own invention, a glow head where you can adjust the compression WHILE the engine is running. The intent was to experiment with various blends of nitro and oil without having to constantly adjust for compression ratio with shims. Higher nitro lowers the octane rating of glow fuel, yet delivers more power. I does so at lower compression ratios, allows for easier starting and better throttling. The latter being my passion, this is why the VCR (variable compression ratio) head was invented.

However, I see that the device could be quite useful in exploring the use of gasoline as well. Here, https://www.youtube.com/watch?v=nRj_JEOXc54 I used the engine to see if an ignition hot spot would benefit use with diesel fuel. As posted, it didn't do much for diesel operation.

Unfortunately, some lung problems have left me with a doctor who forbids me from running engines for the time being. I've been told that I have the lungs of a two pack a day smoker, ( I've never smoked). I guess that sweet smell of nitro exhaust has caught up with me. I'll see if I can use a charcoal, filter mask for future work.