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Some years ago there was a person selling flexible tuned pipes for Cox engines. They were a Kevlar sleeve impregnated with high temperature silicone. The part that slid over the cylinder was a brass ring. Can't find it now, but somewhere I have one. The mold was probably turned on a lathe, Once cured the flexible pipe would slide off the mold. Alternatively the mold could have a removable insert that would allow easy removal.

Was sold as a "tuned muffler" iirc.

Pond Skipper

Update - I have sourced 1/2A pipes for $55 ea.

New PROFI Rambler .8cc tuned pipes

ALBERTO CABALLERO, FLA / USA
Ebay contact; speeddomingoe

combatpigg

My Feedback: (3)

There you go...!
Good find..!

Pond Skipper

Yes whew.... cheaper than having to get them made or buy direct as shipping is rough.

MJD

My Feedback: (1)

Much better plan. I had already asked Alberto for a quote for comparison but he hasn't written back yet. That's where I got all my Profis.

The two piece pipes are way lighter too. Mine weighs about 11 grams.

Might need a bit of header unless you plan to run everything at a bazillion rpm.. of course.

Pond Skipper

If using a .049 pipe on a .061 a APC 4.5 x 4 on 10% nitro should be around 35k propping up will slow down the exhaust cycle through the smaller pipe volume its what I must do to park the pipe as shown in the comparison pic no mods.

Pond Skipper

.8cc vs 1cc may force a jump up to a 4.75 x 4.


[TABLE]
[TR]
[TD][/TD]
[TD] [/TD]
[TD]4.2x4[/TD]
[/TR]
[TR]
[TD][/TD]
[TD] [/TD]
[TD]4.4x4[/TD]
[/TR]
[TR]
[TD][/TD]
[TD] [/TD]
[TD]4.5x3.5[/TD]
[/TR]
[TR]
[TD][/TD]
[TD] [/TD]
[TD]4.5x4[/TD]
[/TR]
[TR]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD][/TD]
[TD] [/TD]
[TD]4.6x3[/TD]
[/TR]
[TR]
[TD][/TD]
[TD] [/TD]
[TD]4.75x4[/TD]
[/TR]
[/TABLE]

Cross Check

Hi MJD,

Sweet ! It is worth repacing the soft screws !?
That 'resonant' sound, reminds me...

I put that pipe on the aft end of a K/B .20 Sportster muffler.
No 'tach' data, but it did liven up the performance of a simple cross-flow engine.

Wherever 'the length' was set, from idle to full throttle response, was amazing.
Seemed like the pipe was sucking more than the carb would allow...
Perhaps not more 'top end', but, performance was enhanced allot.

Goo diverting, and friggin cool 'resonant' sound...

There is more to 'pipes' , than max RPMs....

Just saying,

Take care,
Have fun,
Dave'crosscheck'Fallowfield
Maac 6437
Unabashed Combat Team

MJD

My Feedback: (1)

I found 6 cap screws that fit in a loose bin of screws.. much better!

Took out a shim, and will fire up again this weekend. And I made a bench prop for the Profi speed.. need to hear that too.

Pond Skipper

Ok Alberto has me a happy camper with two new pipes to work with one for the CS Speed engine and the other for whatever engine I want woot!

Pipe fits the CS as expected.
Looks like the 1/2A Skorch was born for pipe strapped to its back

Pond Skipper

Very well made pipes and light I read 11.3g
I will have to do some messing around if with a Cox engine it has to be non SPI -
I plan to fabricate to a Cox engine (for the fun of it) I have 1 excellent option for a fast retro fit.
Out of 6 dune buggy mufflers 2 have no breather hole, 1 has a small hole the other 3 have large breather holes opposite of the exhaust tube. The dune buggy muffler unlike the other examples shown is a snug non breathing fit around the two ports and may have a chance at reasonable use.

So with two good ones on hand I can remove the collar on the pipe and make it adjustable to find the best length to get max possible rpm as is. I will then run it for the pipe sound, goo control, looks and cause I finally get to with ye ol Skorch.

combatpigg

My Feedback: (3)

That's a very cool looking power plant you got there...!

MJD

My Feedback: (1)

Planning to run it at 35,000 rpm?

Pond Skipper

I have some metric aluminum tube to extend the existing header section of the pipe for both engines it matches the inside perfect to keep the super sonic section constant where it counts.

Do plan to try the pipe as is on the CS engine and attempt to prop to suit the pipe the engine its rated up to 40k - but yes want to run around 33-35k
I have already cut one of the pipes to test with the TD if need be can use the remaining coupler shown on the CS engine to set up for a
extended header.

For the TD I think about 3" additional header section would be a reasonable start. I will try some props and see what it takes to step up onto the pipe then go
from there to tune for the APC 4.5 x 4 would be ideal for the Skorch / 23k to 25k would be great the plane is fast at 24k with that prop.

For comparison the Profi .049 pipe then MACS .10 - .15 then the OS 20 to 25 pipe.

Cross Check

Hi MJD,

I'm between Alliston and Orangeville ~1PM Wed.
I'll drop off my OD 'Runtley' for the Utcam 2.5cc. (I'm pretty sure it will fit)
Designed for a .15/360sq.in/15%thk pylon racing event.
You will have a Laugh !
All I will say is, it has a '4-bolt' wingmount, that has survived 'really abusing to failure' an ASPuke .32 !

Back to this really cool pipe thread...

I'll bet a soldered brass one would be more than 11g...

Take care,
Have fun,
Dave'crosscheck'Fallowfield
Maac 6437
Unabashed Combat Team

aspeed

Just looking at some metal spinning videos. This one is stretched pretty far. It may work better than starting with tubing. www.youtube.com/watch?v=bXu_16eZKnw

Pond Skipper

Nice I wonder how soft the aluminum is to pull that off although with the process it must compress the molecules to make stronger by nature.
You could do in two parts and thread it up in the like the Profi.

I took a non SPI TD RC .051 piston / cylinder set and with the buggy exhaust pipe I have about 1" additional header worth trying as is and then go from there.
Nice tight seal no leaks the dirty part is I went from a round header to a square section not ideal but it's a start and its a straight shot to the cylinder big plus I will fabricate something cleaner. The plan is to cut down the square exhaust tube to the hilt and drill tap two hold down grub screws to fix a round tube adapter with enough length to use with a silicone coupler. The Tarno RC carb may handle more forced draw from the pipe than the Cox RC carb so will give it a twirl.

Pond Skipper

19.3k with a 7x3 same .074 on page 1 with a improved header.

https://www.youtube.com/watch?v=lrOTQv1YUIE

aspeed

I think the 1100 series of aluminum are the best/softest, but 5052, 3003 and even 6061 seem to be used as well. I would guess that the threading would be difficult, as it would be quite thin at the bulge, and a mandrel would need to be made up too. So you got 2000 rpm more from the new header on the .074? Was that the same CS pipe, or the Profi one, and what was the unpiped rpm? Maybe some extra homework. I am pretty busy lately, new house, and the weather is not nice lately for playing outside.

Pond Skipper

Alan the two .074 vids posted on this thread are not mine just and example of someone's efforts with a 1/2A pipe. I hope you are enjoying the new house!

aspeed

Well we have to paint the basement tomorrow, and then I can bring my model stuff over. The best part is I can go down in the back yard and go over a breakwall, and there is a big lake (Erie) to play with some boats I have collected. A few float planes too. Have to build a shop/garage still. Busy summer with very little flying, I am afraid.

Pond Skipper

Sounds like a great opportunity to be your wife's hero
When hobby time does happen you will be just that much more enthusiastic to enjoy your stash of boats and planes.

Pond Skipper

Holy sheep shank the Lil pipe that could..

APC 4.5 x 4Tonight I tested with crank case pressure it was running rich on purpose reading 18,760 at full throttle after about 5 seconds it jumped up on the pipe
and accelerated an additional 3,260 rpm.
This engine is being broke in as it is a rare .050 / cylinder non SPI so being gentle just wanted to see / hear the pipe work.

The pressure built up fast and the pipe blew off after 20 seconds or so - only had 1 zip tie on the pipe side.
I have ordered a 7mm ID silicone coupler long enough to get a solid grip on the pipe will need two zip ties.
The pipe coupler will be from a 1/10th scale silicone exhaust deflector for cars small as they come at 7mm ID
I will cut the long end off and rough up the pipe some for better grip.
One thing I noticed it idled very well not very low 9,070 rpm but steady.

aspeed

Is that header totally blocking off the front exh port? If it isn't being used for exh, it may as well be used for a bypass. Maybe something to try on an old cylinder. There are no shortages of old Cox cylinders.

Pond Skipper

As luck would have it when the cylinder is tighten down one port faces the pipe. The Cox car exhaust pipe fits so snug around the cylinder there is hardly any volume.
I have two that have no front breather hole in that muffler 1 of two on hand the rest out of my hoard of 6 have the front hole my guess to help with SPI engines.
Now have 4 zip ties holding the lot together and a rear stinger isolated silicone holder to keep the pipe from migrating in the air - tight enough fit to suppress the pipe
from unscrewing at the aluminum ring. The black silicone coupler is for 1/10th scale cars local hobby shop had one on hand. 7mm on one end and stepped to 9mm.
I have one on order that is 7mm all the way thru.