TampaRC

What is this engine responding to (with muffler attached)? Can you tell me what you are using for top performance:
Prop: 5 or 6" ? What brand?
How much nitro?
Doug Galbreath 1/2a Conversion Head? Nelson plug?
Head shims?
Remove intake screen?

Looking for best performance on a plane like a 20 oz mach none.

aspeed

I always use one head shim, unless it is hitting the head. All the nitro you have is good. For just speed, a 4 or even 5" pitch is good. Maybe a 5-4, or the electric APC 4.75 - 4.75 and wear a face shield. I just ran up an .06 c/l one the other day with a reduced hole in the carb, it just didn't run with the .200" hole. The 4 & 1/4 - 4 APC was up around 26,000 rpm. with no muffler, the .049 was around 24,000. I think the .109" hole I used would be about equal to the RC carb. This was 10% no muffler on the older .06, not the Big Mig. I just use whatever plug is around, as long as it is not a 1/4 - 32 conversion plug, they all seem similar except the old Babe Bee low compression plugs. The Norvel, TD, or Merlin ones seem about the same as the one I think is the Galbreath head. (it just came on a motor I picked up at a swap meet so it is just a guess) Get out your tach, and experiment to really know. It is hard to get speed #s on an rc, but I would think about 20 to 25,000 rpm on the ground would be what you should aim for. Any higher and you may need parts. Having said all that, my Ace simple 400 keeps me thinking fast with just a 5.5 - 4" black Windsor prop on it, likely revving slower than 20,000. It is at my limit of flying ability right now, yours will likely be higher. As far as the screen, Just blowing through it, it seemed to restrict the air more than the .200" venturi hole, but less than the .109" but I took it off just in case.

Mr Cox

I use only 10% nitro and have 20% all castor in the fuel. To me these engines needs to rev around +20000rpm on the ground to be happy. Here are some numbers for the .061RC, pre-revlite version with the stock muffler:

Graupner 6x3; 18200rpm
APC 6x3; 19000rpm
Cox 5x4 (narrow blade) 20500rpm
APC 4.7x4; 22000rpm
APC 5x3; 23500rpm

I have a 10oz "Yellow Jacket" that's a blast to fly on the 5x4 cox prop. The actual speed is not that high I think, it is just that these small planes very quickly become tiny in the air...


"Yellow Jacket", here with a Cox .05RC

combatpigg

My Feedback: (3)

A screaming .061 Norvel in a 20 oz Mach None is like having a 9,000 rpm capable 302 Z/28 engine in a '55 Chevy BelAir.
It will have more BARK than BITE.

Pond Skipper

I think these specs are for an old skewl MachNada
Wing Span - 40 in
Length - 30 in
All Up Weight - 22 oz
Engine - Cox TeeDee .049
3 or 4 channel (Rudder Optional)

combatpigg

My Feedback: (3)

If you want a screaming AME .061, keep the prop load to a 5 x 3 or a 4.2 x 4 and use 25% oil. Adjust the compression and nitro to suit your tolerance for changing blown glow plugs. If the engine tends to quit "lean" half way into the tank, then lap / polish the crank with a mixture of oil and powdered sink cleanser.
If you want to take the performance higher, you can do so with a Dremel and some educated hogging of the parts but the life expectancy of the engine goes down the tubes.
For the price of 3 used up, worn out AMEs, you could still be running a hotter Cyclon .049 - .061 for many more flights if not years to come..

aspeed

Or a Fora, or a Norvel .074 for that plane. You could cut the wing shorter too? Cyclons and Foras have no throttle or muffler. Kind of field unfriendly.

combatpigg

My Feedback: (3)

You don't need to be too clever to fit a muffler over a Cyclon or a Fora, and if you need a throttle then this is the wrong thread topic for that.

DeviousDave

Profi's are the way to go on a budget these days, I've got two guys trying to buy my Cyclons from me right now for FF and I hate to sell them to them because they need them to compete but I don't think there is an importer after Alexander went MIA with those guy's deposits on the JAK .09's.

Either that, or have Doug Galbreath do up your Picco.

aspeed

This pic is for illustration/discussion only for CP's benefit.

Pond Skipper

ASpeed can you flip that Norvel over

aspeed

It isn't attached. Just to give someone ideas. It would need a new header with a better mounting system, and more importantly a good seal to work as a pipe. It wouldn't hurt to raise the exh. port a bit..... I thought it looked cool though, and it could work. Our field needs a muffler and a means of shutting off the motor. I have flown a control line plane there, I guess I could ditch it to shut it off LOL.

combatpigg

My Feedback: (3)

A fuel line pinch-off [or flood-off] works every time...better than closing the throttle on some engines with carbs.

aspeed

I am afraid to put the Fora on an rc plane, my Norvel .06 gets away on me for the first 30 seconds or so of each flight. I would have to go with a backwards 6-2" prop running rich, and gradually working my way up to full speed. I think I will just put it on a little C/L combat, with a muffler like that one in the pic. Originally, I wanted it for a speed plane, but have given up on looking for a parking lot to fly in. Last place was going to call the cops. Just like when I was a kid. A throttle will not fit in the venturi without gluing it or something crazy. Should have got one of the other Russian ones with the straight out exhaust and a regular venturi.

combatpigg

My Feedback: (3)

I built a fairly large delta to help get used to my first FORA .049 and used a 5x3 black rubber Cox prop. It still seemed pretty fast, but some of the "illusion of speed" comes from the sound effects. If they are balanced properly and set up with very limited elevon travel, they practically fly themselves.

combatpigg

My Feedback: (3)

One "sreaming mod" that AMEs really respond to is to open up the forward boost port passageway for better flow.
The crank counterweight and the piston skirt block flow up into the passageway. Bring the piston to BDC to see the interference that I'm talking about.
If the piston skirt is notched, this helps. The notch can extend up to the lower edge of the wrist pin boss.
The crankshaft counterweight can also have a notch ground, [shaped like a ramp] to help guide the crankcase vapor up into the forward boost passageway. This mod greatly improves flow, plus it lightens the piston.

aspeed

Jeez, now I have to open up a motor to have a look, get a control rpm, do each mod separately, check each mod... do ten motors...

aspeed

Just remembered I have this on favourites. Kind of relates to the original post as well as CP's thoughts. http://www.toadsrc.com/engines.htm

klord125

Combat my friend used to race a 55 in D/Gas with the little 302. It was a multi national record holder in the late 60's early 70's. I think the quickest it ran was high 10's.. But your right it screamed shifting at 9,000 rpm's.. Although that pic it had a 283 bored .060 to a 301. They changed to 302's