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Tuned pipe for OS 61FX

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Old 09-22-2008, 12:54 AM
  #1
DwightMann
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Default Tuned pipe for OS 61FX

I am looking for a tuned pipe to fit a O.S. 61FX. I see two choices, MACS and O.S.
The MACS manufacture p/n 1973 - pre tuned for $91.99
OS manufacture p/n 72101230 and 72101120 $42.99 and $154.99 = $197.98
Is there $100 more performance?
I have found no claims for either.
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Old 09-22-2008, 05:28 AM
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Default RE: Tuned pipe for OS 61FX

A couple of opinions:

I'm not too sure that pipe (# 72101120) is actually the right pipe for for a 61FX...That particular pipe is designed specifically for the Hanno Special engine...

I've recently had three brand new Macs headers crack while running engines on my test stand...Mac's is using thin wall .035 aluminum tubing while OS uses much thicker .065 tubing...The thin wall tubing is very nice from a weight standpoint but I'm finding it just doesn't hold up very well...Maybe I just happened to get three bad headers in a row?? Maybe the side exhaust headers hold up better?? I'd recommend the OS header as they are very nice from a quality standpoint..

I'm not sure I really agree with the whole "pre-tuned" thing...Maybe call it "close enough" or "in the ballpark" or something like that?? I think you still really need to "tune" your exhaust for the particular prop, fuel and atmospheric conditions your running in...

In short..I'd get the Mac's 10cc quiet pipe and an OS header ...

Just my opinions...Have Fun..

Chuck

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Old 09-22-2008, 08:22 AM
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Default RE: Tuned pipe for OS 61FX

The mac's #1060 10cc Quiet Pipe is a good choice for the FX. Graves has them for $52.99 which is the lowest price I've found:

http://www.gravesrc.com/MAC_S_MUFFLE..._p/mac1060.htm

I bought my 10cc long stroke quiet pipe from them and the service was very good.

David
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Old 09-22-2008, 09:52 AM
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Default RE: Tuned pipe for OS 61FX

the 2 guys that i knew would have the info! just wasn't any need to tell the original poster who would know as you guys came around soon enough.

david
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Old 09-22-2008, 02:52 PM
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Default RE: Tuned pipe for OS 61FX

What I have seen in using them in CLPA is just what Atlanta 60 has said.
Whenever a question about an engine/pipe set-up is asked the answer is, "I used a So and So pipe at 18 1/4" on my Super Lion 61 with a BollEather suchxandxsuch prop turning 10,100 static with Fartblast 15 percent."

Pre-tuned would only be "close enough" I would think. Fuel, prop, weather model weight and drag would all factor to the right length for the pipe. I take those MACS header length charts as a starting point.

Pipes can restrict the speed of the engine too, so it can be used as a brake downhill. There are a lot of variables to using the tuned pipe.

Chris...
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Old 09-22-2008, 05:41 PM
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Default RE: Tuned pipe for OS 61FX

Atlanta 60
The info that I found for that pipe indicates that it is for the 61 FX. That might mean that it will "work" or it could mean it was designed for that engine specifically.
The fact about wall thickness is VERY helpful, and probally explains the price difference. Is the Hanno pipe more than a name and color upgrade?
I am not looking to turn this into a rocket, I just want an extra boost. And my plane stays cleaner with the exhaust farther back
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Old 09-22-2008, 07:29 PM
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Default RE: Tuned pipe for OS 61FX

Here is a thread with a little more information:
http://www.rcuniverse.com/forum/m_7306311/tm.htm

Huh...I dunno...Maybe it will work?? My reservations are the Hanno pipe is designed for a Long Stroke engine...It's a good bit longer between the divergent cone and the first baffle than both the Hatori 650 or 700...The Hatori 650 & 700 are 10cc long chamber pipes that were very popular for the YS long stroke and standard OS RF/SF LS engines back in the day...

The Hanno pipe was suppose to be specifically designed for the Hanno engine...The Hanno engine has some different porting than the standard OS RF...I assume the extra length of the pipe has something to do with it...

A quote from Tower Hobbies tech notes:

"This is the tuned pipe that is designed for the O.S. .61 RF Hanno special engine. This pipe should not be used with the regular .61RF. "

Link:
http://www3.towerhobbies.com/cgi-bin...?&I=LXCC49&P=7

Like I say I've never tried it...I don't claim to be a super expert on tuned pipe theory either...I'm just learning...

I did try and run a YS 60 short stroke engine on a Hatori 650 long stroke pipe...The results were not good...Noises that I'd associate with detonation, rattling and overheating were some of the symptoms I experienced running a short stroke motor on a long stroke pipe...I'll personally never do that again...

Just my experience...

Chuck
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Old 09-23-2008, 11:00 AM
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Default RE: Tuned pipe for OS 61FX

The pipe for the O.S. Max .61 RF Hanno engine is designed to work properly at about 9,600 RPM. With the O.S. Max .61 FX engine, you'll want a pipe that operates at about 12,500 RPM, depending upon how you prop the engine, but the .61 FX "likes" RPM. The Hanno pipe would be considerably longer than a different pipe. Even a pipe for the O.S. Max .61 SF/RF engine would be different because those engines would run best at about 11,500-11,900 RPM.

1,000 RPM can make for significant differences in the pipe.
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Old 09-23-2008, 12:52 PM
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Default RE: Tuned pipe for OS 61FX

Bax!! Just the guy I was hoping would chime in here!!

Thanks for the explination...

I still have lots of learning to do...

Chuck
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Old 09-24-2008, 02:50 PM
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Default RE: Tuned pipe for OS 61FX

An option if you want to eliminate guess work and go with something different...

Bolt on a jett-stream muffler .... use an 11x7 or 11x7.5 prop, and enjoy the ride.

Its not going to exit the exhaust way aft (as per one of your posts) but it will give you the performance.

And for those wondering .... the muffler/engine combination is SPA legal

(photos for illustration - that is a Magnum 91 on the F-18, and an OS91 on the su-27 .... but you get the idea)

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Old 09-29-2008, 02:58 PM
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Default RE: Tuned pipe for OS 61FX

for those who havent dealt with macs products before, they have excellent service, if your header cracks send it back for repair, they are very good and have fast turn around. one thing i see flyers doing to headers is bending them to fit their aircraft , this is fine but the header has been tempered and you will induce a crack if you bend without annealing first, the material macs uses is 6061 t6 tubing, its annealed then bent and brazed, polished then re tempered. FYI
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Old 09-29-2008, 04:08 PM
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Default RE: Tuned pipe for OS 61FX


Quote:
ORIGINAL: lfinney

for those who havent dealt with macs products before, they have excellent service, if your header cracks send it back for repair, they are very good and have fast turn around. one thing i see flyers doing to headers is bending them to fit their aircraft , this is fine but the header has been tempered and you will induce a crack if you bend without annealing first, the material macs uses is 6061 t6 tubing, its annealed then bent and brazed, polished then re tempered. FYI
No bending...I only cut the headers and added a flexible joint...They were VERY Brittle kinda like they may have missed the re-heat treating process?? One of them basically "shattered" after only moments of run time...It was really pretty funny...

I may give them a call and see what they have to say...I'm normally not the type to call customer service...I'm more likely to just toss it, write it off to experience and go find something better...

Problem is these days Mac's is just about the only game in town.. [:@]

I've been meaning to check out Karl Mullers stuff...I thinking when it comes time to mount this stuff in an airplane it will probably have a Muller header..

Have Fun..

Chuck
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