flianbrian

A buddy gave me this header he had no use for, that fits my ST.61, and I thought I might try a tuned pipe (e.g. Macs), something I've not tried before.

Is there a limit to the manifold length between header and pipe?
Can the manifold be just silicone tubing or should I use a metal pipe (it would have to have a couple bends)?

I have plans for an older pattern plane that show as an example, an OS 61 rear exhaust with a manifold about 7" long with about a 2-3/4" drop to the tuned pipe.

Can I do something like this?

Here's the header:


Thanks!
flianbrian

ChuckAuger

My Feedback: (12)

I used to have the ST "double bend" pipe that went with that header. That's all it was, a piece of aluminum tubing bent in a lazy "S" kinda shape.

I was looking for it a while back and couldn't find it. I'm sure an electrician could use some conduit benders on an old tent pole to make one. That's what I would do if you can't get the correct one-piece header to fit your engine (a better set up IMHO, but you have the one in the pic)

DarZeelon

Flianbrian,

In a tuned exhaust system, the system length is most critical.

This header is VERY short. Only if you use a long pipe system, to bring the total length up, would you be able to use large enough props for good thrust.

The length includes all the inches in straight and S-bend sections.

This header also has the bolt going through it (restricts flow) and is a very snug fit to the fuselage, requiring a very thin aircraft.

flianbrian

I'm aware of this, hence part of my questioning. I hope someone can give me some "ballpark" numbers to play with. Perhaps someone who's done a pipe with a .61.

Doesn't REQUIRE a thin aircraft, but certainly ALLOWS one!

Do you recall it's diameter? I suppose that's another consideration.

I think I've seen this header (Macs?) somewhere, but it is for "bolt-through" cases. Mine's an older one where the bolts go into the case from the muffler side but not through it.

Thanks guys,
flian'

ChuckAuger

My Feedback: (12)

Brian..just going from memory (I looked for the tube again after your post) I'd guess the piece was about 5" OAL, it would be a little longer if stretched out. The diameter was a little larger than most pipe headers, maybe 3/4" ID instead of 3/4" OD...might have been metric. I wouldn't worry about exact diameter, as long as it mates up pretty good to your manifold it should work fine.

RaceCity

Just as a "for what it's worth"....

The header shown by the original poster appears to be a TOP FLITE unit...made to be used with a Pitts Style (in cowl) muffler...NOT a tuned pipe. Seems to me that TF offered these originally for use in several of their Gold Edition scale kits.

It is FAR too short for a pipe.

'Race

DarZeelon

Flian,

The i/d of the silicone coupling for .35-.90 engines, is 5/8", meaning the i/d of the header and the pipe should be the same, allowing for some stretching.

If the exhaust goes straight back from the exhaust stack, as this header dictates, the firewall must be only a little wider than the cylinder head (about 40-45mm), or an extensive cutout must be augured out of it, as well as out of the fuselage behind it, to allow for exhaust piping passage.

Call it what you like, but to me this plane's nose must be quite narrow to allow this.

The bolts that come with this header do bolt into the crankcase.
There are some longer headers, in which the bolts do the same, but only hold the header flange to the exhaust stack.

The header you have looks like it is intended, for some type of C/L speed event, not for large R/C models, and low RPM props.

flianbrian

Race City
Yes this is the TopFlite header made for in-cowl installations in some of their kits (Tower cat p.237), and they sell a "can' muffler, that's supposed to be bolted to the firewall behind the engine. Of course it's too short as a pipe. I'm asking about adding a pipe/extension/manifold/whatever, to go to the tuned pipe.

DarZeelon
This header is for STs .61 - .75.
This engine would be mounted inverted, or nearly so and there is clearance under the firewall to route a pipe. An extension of the cowl, underneath the firewall and fuse hides the manifold before it exits under the fuse to the bottom-mounted tuned pipe. No firewall butchering needed, and fuse width doesn't enter the equation. I hope this is more clear.

flian'

RaceCity

Flian....

I think you'd be better served if you got a Macs header to suit your particular model. They're not too expensive either.

You COULD use the header you have, but you are going to wind up with a Rube Goldberg contraption...

Check out the Macs Products website.

Good Luck!

'race