the Wasp

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guys, note that I had to edit, my Pipe is a "Quiet pipe,, NOT a Muffled Pipe..

Guys, I bought an unused "Quiet" Tuned Pipe for $30 with an unused .60 size Header, not sure what brand, but I think I was told it's a Macks, and, also I'm not 100% sure but I think it is a .50 size Pipe ??,

so IF it is a .50 size I'm just wondering how well you guys think it would work on my OS 61FX on 20% Nitro,

dimensions;

>Diameter is a tiny bit under 1&1/2 inches,
>over-all Length, end to end is right-at 15 inches,
>Stinger is about 1&1/8 long from where the Rear Cone Taper ends,
>from the tip of the Front Tube to the point the Front Cone starts to taper is about 1&5/8 long,
>Front Cone is about 4&1/8 inches long,
>Rear Cone is about 1&9/16 inches long,
>the Header IS a 60 size Header and it has not been cut,, also note it did come with a .50 Header, I bought in a privet sale..

I am not a racer, just a sport flyer that wants to go faster, so with that I still want a usable Power Band to keep my plane enjoyable to fly..

my plane is the Great Planes ShoeString, (61 inch span), over all, acceleration and top speed it flies great with an APC 11x8 (RPM is 12,200 with a SlimLine Pitts on 20% Nitro) and I would like to keep using an APC 11 inch diameter prop, and a pitch of 7 or 8,,

got questions, I will answer them,

I hope I am not asking for too much LOL

thanks big time guys !!

Jim

aspeed

Since no one is answering you, I would say to just give it a try and compare readings to an open exhaust. Pitch is always your friend for speed, and cut down the prop till it gets on the pipe in the air. If it is already on the pipe with your desired prop on the ground, then maybe shorten the pipe as a last resort. You can probably still get on the Macs website, although the owner has unfortunately passed on. Someone else will likely chime in?

Pylonracr

First, the pipe you describe is not a quiet pipe, it is an unmuffled pipe. It will be loud. I make carbon fiber pipes, and I am holding a couple in my hand to measure for comparison. It sounds like you have a 40 sized pipe. The diameter at the waist gives it away. Your measurement of the "rear cone", which is the convergence cone by the way, of 1 9/16 confuses me, I would expect 2 1/2 or so. It will be too small for your FX61. You can try it and see what it does. Start with a tuned length of 17", that is from the piston face to the center of the convergence cone down the middle of the header when it turns.

I think you would be better off with a red tuned muffler fron Dub Jett. I use them on 2 FX61 engines, and they add about 1000 rpm.

Scott

MJD

My Feedback: (1)

+1 on the Jett muffler.. more tractable and less temperamental setup. If you set the pipe length and prop combination up properly, pipes are good fun. If you have the system out of whack.. they'll boost your misery but little else.

Hey check this out - close enough to what you`re asking about: https://www.youtube.com/watch?v=fmIVi9G5_EE

Pylonracr

Hey Mike, did we actually agree on something or are you just hanging on my coattails????

Scott

the Wasp

My Feedback: (1)

thank you for your replies !!
but after reading I see I forgot to add the length of the center Tube section (don't hit me guys LOL)

the center Tube section is 6 inches long

anyway, my pipe looks just like the one at the top of the page in my Macs link, but then again it also looks like a Macs Heli Pipe in my 2nd link,

AirO pipe,
http://www.macspro.com/tunedpipes.asp

heli pipe,
http://www.macspro.com/HeloSys.asp

to add, as I said my pipe's over all length is just a tiny bit (maybe 1/16) short of 15 inches long, and I do not see a Mac pipe in his site that is 15 inches long, I am wondering mine is another brand, or the guy I bought it from could have cut the pipe shorter, but If he did he did a very good job

I re measured the Rear cone in a different way, and I will have to say it's closer to be 1&3/4" long

also note in Mac's site, it shows the Muffled pipe at the bottom of the AirO page, but in that photo it doesn't show the "Can" over the Rear cone (I have seen those before), so that is what confused me (muffled or quiet),,

the pipe I have has an Inside tube that runs from the front Tube to about 1/2 inch before where the Rear cone started to taper smaller (I measured it, I used a small OD wire bent at the tip),, I feel it's a Quiet pipe

I will have to test it, but it will be another month before I can, but when I do I will first test it with the Stock OS muffler to get a base reading

to add, I have had Tuned pipe on my bikes in my old dirt bike days, and Cone pipe on my 45 and 90 size Boats, so I know the basics of them

thanks again guys !!!

Jim

the Wasp

My Feedback: (1)

quote; "I think you would be better off with a red tuned muffler fron Dub Jett. I use them on 2 FX61 engines, and they add about 1000 rpm"

that sounds good to me, and I know that Red muffler

Jim

the Wasp

My Feedback: (1)

here we go, it looks like this pipe in the video

https://youtu.be/kGaBFtc94fw?t=64

Jim

Pylonracr

I stand corrected. If the waist of the pipe is 6" long it is a muffled pipe. That would also explain the short convergence cone since it is the end of the muffler section and not a tuned portion of the pipe.. I am still certain that it is a 40 sized pipe.

MJD

My Feedback: (1)

It was an accident, let's not let that happen again.. . These forums are too tame without arguments.

I'm thinking of all the tuned pipe posts that go pretty much the same way each time, and the reduced fuss factor. Mind you, if I already had the pipe setup and had to mail order the tuned muffler, I'd probably be going at the pipe system to make it work.

Jim it's not a nightmare to set up a pipe system, don't let us scare you. A methodical approach with the fundamentals in mind will get you there. Your prop choices and rpm goals are fine, there is not a whole lot more to it than to start longer than needed and trim 1/4" increments until rpm stops climbing as per the usual instructions posted here and there. The biggest cause of headaches I've seen on RCU is pipe systems too short often coupled with the user being convinced the problem is something else.

MJD

My Feedback: (1)

Found this via Googling "OS61 tuned pipe".



ORIGINAL: dave_anderson

I may end up using my OS .61 FX for a ballistic ship. Anyone have a good tuned pipe setup they can suggest for that engine? Header length would be a help also.

Thanks,

Dave MACs has everything you need.... (don't get the pre-tuned system)

Header will depend on the aircraft (header reach length). Just buy the one sized for the OS61 with the reach you need for your aircraft installation.
http://www.macspro.com/headers_side.asp

Pipe ---- I prefer the regular MACS 1260 muffled pipe.
Performance is good, shorter, lighter, and it costs a bit less expensive than the quiet pipe 1060.
http://www.macspro.com/tunedpipes.asp
(And actually, the 8.5cc works well too)

If you have an concerns about sound/noise or some obnoxious 94db club sound limit, you will need the quiet pipe. Your choice.

Length: I would start off with 13.75" (measured from glow plug, along the center line of the header, to the weld/fat part of the pipe). This should be a bit long. With an APC 11x7 or 11x8, you will eventually get down closer to 13.5 - 13.2". Cut the header as needed to achieve the length. (of note, you want no more than 1/8" gap between the header and pipe where it joins at the coupler). And, its obvious .... it is easier to cut the header than to un-cut it. Start longer if in doubt.

Your target here is to get to 14,000 rpm on the 11x7 APC (to start with).

Important - do not even dream of testing/tuning the pipe install on the plane. Be sure to do any tuning on a test stand.

aspeed

Those muffled pipes, the ones with the straight tubing section, should really be measured for effective length from the inside cone. It is likely an inch or two less than the overall length. It is really a pipe with a muffler behind, but the inside pipe is the one doing the real job. Oh, and Macs likely won't be selling pipes any more, as the owner died, unless someone else takes/took it over.

MJD

My Feedback: (1)

It should be easy enough to measure centerline from the plug center to the first major diameter - fat part - as Bob (Jett online tech support and knows his stuff) describes it here.

F4 Phantom blue angles

No, your not asking to much. That is how how you learn. I had a YS 61 with a mac tuned pipe and it screamed. The reason for a tuned pipe is: you need to get a pipe that is made for specifically for the engine your using because it allows for so much exaust to be released,and so much pressure to be built up for that perticular engine which creates an equilibrium between engine and exaust giving you maximum performance of your engine. Mac tuned pipes are expencive,but good quality.

the Wasp

My Feedback: (1)

well like I said I had T-pipes on my boats, so I have adjusted Header lengths before, the real reason I asked was because I knew mine was smaller pipe than a true 60 size pipe, <that's why I asked "if I was asking for too much" from this pipe,

back when I had boats starting in the lat 80s the big thing was to put over size pipes on smaller engines, like a 60 size pipe on a 45, and a 90 pipe on a 60/67

Jim

MJD

My Feedback: (1)

In the case of a sport timed engine like the FX, as noted in that cut and paste, bigger isn't always better - there is only so much mixture you can cram back into the engine with it's current exhaust timing.

Pylonracr

I must admit I am kind of curious as to how well that pipe will work on that engine. I have never run that small of a pipe before.

Please post your results when you test it against the stock muffler.

Scott

MJD

My Feedback: (1)

An interesting comparison would also be open exhaust rpm against the piped rpm. i.e. does it just gain back the loss or is ther emore?

Pylonracr

Mike, will you please quit agreeing with me!! Please refer back to post #10...............

Scott

MJD

My Feedback: (1)

You're right. Have I gone all soft and compliant and full of the milk of human kindness all of a sudden? I'll call the doctor..

the Wasp

My Feedback: (1)

well poop don't stop does it LOL,,

note that my engine is mounted on it's side on the ShoeString, so the Exhaust Port is pointing straight down, well I finely got the engine mounted, and I found the Header is not deep enough to get my T-Pipe on the plane without dragging the Stinger in the grass, and surely it will hit the ground on a hard landing,

I looked and looked on-line but I can not find a Header that has a right angle coming off the engine so it will come out the side of the cowl and then have a 2nd right angle (or curve) to point straight back down the side of the plane,

you can see in my photo below what I have, notice the Right Angle (Boxed) Mounting Flange on the Pitts muffler,,,

I have a friend that is a very good welder, if I cut the tube off the Header's Flange, and cut the tube off the Pitts my friend will weld the Header tube to the Pitts's Flange,,

surly it will work, but my question is>> will that "Box Type" Flange produce a loss in power ??

thanks guys, you have been really great..

BTW, I know why they are called a "Pitts" muffler LOL

Jim

F4 Phantom blue angles

Your absolutly right,If you alter your pipe any way,you will have defeated the purpose of your pipe in the first place

aspeed

Maybe you could fill the header up with sand or ice, and bend it with some kind of fixture. I have been thinking of trying to make up some headers myself, as nothing is ever just the way you need it. There are different lengths of headers available, or at least there was until the Macs guy passed away. Some are even shaped like a question mark.

Pond Skipper

http://www.ebay.com/itm/OLD-HEADER-L...3D272621197736

You could clean up a used one.

the Wasp

My Feedback: (1)

​Pond Skipper,, the headers in your link are 4 stroke headers, I have a 2 stroke

Jim