combatpigg

My Feedback: (3)

It isn't an apples to apples comparison unless all planes in question are identically built ME 163s. At some point 150 rpm difference isn't even worth 1 mph. Your friends' plane is faster because he is running a hot engine on a cleaner airframe than the other ones in question.

mtntopgeo

My Feedback: (12)

Well, I didn't want to start modifying anything on this engine, 'cause I felt that I was gonna put it back on the 'bay. But, curiosity about that goofy muffler got the best of me, so I got out the Dremmel & a carbide burr, & cleaned out that muffler. Also drilled out the outlet to .228". Results are attached. Not as much increase as I had hoped for. Made runs with & without exhaust pressure to the fuel tank, & there is still quite a bit of difference needed in the needle setting. Appears that there is still a fair amt of back-pressure in the muffler. Still need to use the heat gun to spin this thing over. If the piston/cyl fit ever gets "normal" I'll tare the engine down to polish the crank a little. Really don't have a lot of hope though. ...................... George K.

Japanman

GCB: Yeah. My feeling too about stuffing the case. I think I would need to fill the donut, make a new backplate/modifiy it and lower the cylinder/make new rod to make a worthwhile gain. Thats a lot of work when I have very littlle time for much at the moment.
I am much more confident that taking the step out of the case that blocks the exhaust port will do something, and its a 5min mod.
MTNTOPGEO:
Nice work with the muffler.
I may get a chance to run my engine tommorrow. If so, I`ll see if I can take out the step in the case and get numbers for both runs.

Stefan

Japanman

It`s raining here, so i ran the engine as the family potato digg was called off. I only had a short plug so the compression was a long way off what it could be, but I thought for running the engine in it would not be a bad thing.
I am using a bit bigger venturi size (6mm vs 4.8mm) as I had a carb of an O.S25 that I`ve fitted. It really draws well with this- 1and3/4 turns on the main needle but then thats with muffler pressure and that muffler would seem to slow it down a bit.
the only prop I had that looked like a good one for it was a MAS 7x3. I have a APC 7x3 too, but thought the MAS might load it up a bit more and be about right for running in.

I was running with the muffler at at first I got 17.4K
Next I took out the step in the case that blocks the exhaust port and got 20.1K and it sounded and needled better.
I think with a bit more compression and a better muffler situation it might really get up and go.
mtntopgeo: it would seem to be worthwhile trying. I have no Idea what you`ll get on a bigger prop, but I`d imagine it ain`t gonna hurt. Do you have numbers for running your Enya11 with the APC or MAS 7x3? I`d be interested in a comparison.

Stefan





I am going to

mtntopgeo

My Feedback: (12)

Very nice increase in performance with the exhaust port clean-up. I'll have to look into that once (if) this engine of mine loosens up. 8 more OZs of fuel through it, & still too tight to turn over without using a heat gun. After seeing the innards of that muffler, I'm surprised that the engine would be capable of running 17K(+) even with nothing more than a flywheel mounted on it. With your port clean-up, and a good muffler, maybe there is still hope for some good 8x4 numbers. .................. Sorry, got no numbers for the CX 11 with a 7x3. I started big (on prop size), & went smaller until i got some reasonable #s. ................... George K.

Falco250

I have just broken in a Norvel AME .15 BB C/L using about 250 manual flips and pre-oiling, essentially as per instructions,
and without using any hair dryer. My first 100 hand flips were done with a light sewing machine oil which was insuficient.
The next 150 flips were done with some heavier Sturmey-Archer cycle gear oil and that brought the interference
low enough when fliped briskly to allow starting the engine. After going erractically through some 4oz of 30% Cool Power Race
(Pink) fuel cut down to 15% with 99.9% pure methyl alcohol and 20% synthetic/castrol oil, the engine was practically without
compression while hot and then still binding when cooled down. The needle valve was initially set at 4 turns counter-clockwise
and gradually reduced to 3t; but engine response to needle valve changes was very slow at first, but then would gradually
peter out.

So after pre-oiling overnight with the gear oil, the interference was reduced enough to permit a second power session
which ran consistently and uninterrupted through 2oz of the same fuel mix. The needle valve was initially set at 3 turns
and gradually reduced to 2.5t and then increased to 2.75t which gave the best sound. Engine response to needle valve
changes was more pronounced. and there was no cutting-out. There was till some compression while hot,
and good compression with minimal interference (when turned slowly) after cooling.

Ahter experimenting a bit I found that having the center-line of the fully filled fuel tank in line with the ventury fuel spray bar
made for easier starting. I also rotated the engine 90deg with the muffler at the bottom to allow for automatic fuel drainage
when flooding the engine.

I have now pre-oiled again using 10W30 car engine oil and have very good compression, with brisk flips and no interference;
I will use this oil for all future pre-oiling. So I expect my next power run to be essentially as per normal operation starting
at 3t and gradually reducing to 2.75t.

So far I am satisfied with this engine, although initially while brand new it had quite noticeable interference and even felt gritty
when hand turned.

Japanman

Falco, I don`t think you need to do any pre-oiling anymore. I would think that from now the oil in the fuel is what you want on the cylinder bore. Castor oil and mineral oils are not compatible (they react to form gums from what I have read) and you might run into problems long term if you keep re-applying mineral oil.

Any tached numbers for your engine?

Stefan

Falco250

The Norvel break-in procedure specified castor or lightweight motor oil; hence my use of 10W30 motor oil.
I think the castor oil will gradually gum up by itself as it ages since it is a bio-degradable plant bi-product.
I only pre-oil to reduce the interference or roughness in turning during the break-in stage, to facilitate
hand starting. I don't intend to pre-oil after normal operation. Unfortunately I don't have a tach on hand yet.

I was just trying to reassure anyone else that might have been worried or frustrated by the Norvel break-in
process. My experience so far is that pre-oiling overnight with motor oil allows for smooth and quick
hand starting during break-in without requiring any preheating of the engine.

gcb

All my NORVEL engines except the .25 were purchased from NORVEL before SIG got involved. I think the techs at SIG invented the pre-soaking and flipping process because so many were coming through very tight.

One thing I noticed on mine was that when new, I encountered much more resistance if turning them over slowly than if flipping smartly.

Out of habit, I would oil mine after checking the insides for contamination. I don't remember ever giving them a bunch of hand flips (unless on the break-in bench). Most started easily and were broken-in well enough to fly after a couple of tankfulls of fuel.

For the .049-.061 engines, I got a couple of "Start Ups" so I could use the tank and spring for the others. Sometimes I could not use the spring because at that time not all came with the little hole drilled in the mounting lug.

Of course for the .15's I used a normal break-in stand and tank setup.

George

Japanman

yesterday I took the norvel 15 out to the riverside whe I can let her rip with out worrying about noise, and put a few more tanks through it.
I made a new head button to take turbo plugs, and to up the compression a bit.
I am using some 10% fuel I mixed up with an extra 5% castor added.
I also ground the baffles out of the muffler but left the exit hole the same.
When I measured the muffler and calculated what it should resonate at, It worked out to about 22-24K so I thought I`d leave the outlet alone just for now, though it does seem a bit small.

I am still running in, so I was running rich quite rich, but I got 22,500rpms and the needle was a broad as Texas. The rpms did not vary almost at all within 1/2 a turn of the needle- this made me think the muffler is working as a pipe (bang on the middle of the range I calculated) so I`m pretty keen to try some bigger props and see how it pulls them. I was at a model shop the on saturday to get some new turbo plugs, but forgot to get a prop.
Crap, the price of O.S turbo plugs has gone through the roof! earlier this year I got some for 500yen (about $4.30US) and now they are 760yen! Someone mentioned about OPS turbo plugs and I think I`m gonna have to investigate that soon and get 20 or something before the price goes up any more.

J.M

Falco250

I got several hot turbo plugs on eBay from this seller:

http://cgi.ebay.ca/Novarossi-C5TC-Ho...QQcmdZViewItem

He was honest and reliable.

Japanman

Well, I had a chance to pick up a 8x4 prop to try-
With an O.S no8 plug and the orgional head button with 0.5mm shaved off to increase the compression, I was getting 13,800 and with the turbo plug I got 14,200.
I don`t think either of these numbers are really ones to crow about, but that was with 10% nitro fuel, and the claimed performance for this prop is 13,500- though I would be mighty surprised if had got there on anything less than 120% nitro fuel with the case blocking the exhaust port as it was.

Yep. Get yourself an unobtainium piston, run 120% nitro and most engines`ll run great

J.M

gcb

Guys,
Bear in mind that the NORVEL instructions recommend 80% methanol and 20% castor for normal running (25% castor for break-in). They also suggest adding an extra head shim for each 5% nitro added, up to a maximum of 35% nitro.

Remember that for any set port timing, varying the prop, nitro, plug heat range, and head shims is used to vary the combustion timing. Perhaps some have not varied these enough for maximum.

Japanman, by lowering the cylinder timing ports, my GUESS is that it may reach maximum on a different sized prop. For example, it may swing bigger props now, etc. Did you add shims to compensate for lowering the head or might the higher RPM be partly from higher compression?

All interesting stuff.

George

gcb

JM

Since you have machining facilities you might try some different squish band and combustion chamber shapes. I like that idea of using a turbo plug!

Good luck.

George

Japanman

I didn`t actually change any of the port timings- the crankcase deck where the cylinder flange bolts to is untouched, but I did remove about 1.5mm of material from the top of the exhaust port opening that is cast into the case. Essentially the engine is stock, just its "better" stock.

My feeling is the engine has fallen off its power peak- It seemed a lot happier rpm wise with the smaller prop. I suspect this prop cut to 7x4 might work well, though I`ll save that till it`s in a plane.
It does haul this prop without complaint though, and the extra weight of the prop makes hand starting easy- prime, and everytime a coconut

S

combatpigg

My Feedback: (3)

The best $2 speed prop for just about every sport .15 I've ever run is the 7x5. If you can find a old 7x5 Revup or TopFlite pylon prop, make a mold of it! For general sport flying it is hard to beat a 8x4 or 8x3 with some .15s. The 7x3 will give you neither good speed or the best climbing power, this prop is better suited for .10s. If you want to move up in price for a speed prop, then try the APC $3.95 competition series [like the 6.5x6] or try Eliminator Props, he has a nice variety. As you well know, the smaller the engine, the more "spot on" you have to be for matching the prop to the application.

gcb

JM,

Apologies. I misread and thought you had milled the crankcase deck to drop the cylinder down.

I use an 8x4 on mine. But then, I don't need max power. If I need more power, I just use a bigger engine.

George

iskandar taib

My Feedback: (5)

Actually, I remember seeing instructions about this a long time before SIG started selling Norvels. This was for the Bigmig .061. They were darned tight to begin with. The old pre-Revlite ones were even worse. But come to think of it, I've never done it. Just persevered until they started (using the spring starter - it took a while) and then a few tanks later they were OK. Now I have a pair of .15s, I think I'll give it a try. Lots of castor oil on hand.

I had some head buttons made for my Foras - I plan to drill and tap them for turbo plugs and 1/4-32 plugs (because I bought a truckload of O'Donnell plugs when Tower was getting rid of them a month ago). Maybe I'll do the same with the Norvel.

Iskandar