More dumb questions on pipes...

I understand that the header, silicone tube ad pipe must be have no leaks.

Those straps that come with the macs header are enough to keep it leakproof?

Should I put some kind of gasket between the engine and the header? Asbestos, or what?

I figure I first gota run in the engine, before messing with the pipe.

Mike Starret reduces the blowdown in his .25 VF. I'd rather not. Any thoughts? The VF .40 runs bone stock on a pipe.

Glow plug?

Fuel, a blend of castor/ synth would be OK, at 20% oill and 10% nitro?

Time to laugh. Go on, my friendss, laugh you heart out...

Ion- now into pipes- muniz

>I understand that the header, silicone tube ad pipe must be
>have no leaks.
>
>Those straps that come with the macs header are enough to
>keep it leakproof?
>
>Should I put some kind of gasket between the engine and the
>header? Asbestos, or what?
>
>I figure I first gota run in the engine, before messing with
>the pipe.
>
>Mike Starret reduces the blowdown in his .25 VF. I'd rather
>not. Any thoughts? The VF .40 runs bone stock on a pipe.
>
>Glow plug?
>
>Fuel, a blend of castor/ synth would be OK, at 20% oill and
>10% nitro?
>
>Time to laugh. Go on, my friendss, laugh you heart out...
>
>Ion- now into pipes- muniz

Now, Ion, you are tempting me, again, with this laugh encouragement. Trouble is, I can't think of any good zingers to zap you with this time.

On the engine, I would stick with it stock unless you know someting others don't. Those ties (straps) are sufficient to keep the thing leak proof at that joint. Make sure you stock up on a bunch of them, however, so you can move things around. If you can, make your plane so you can remove the engine and pipe as one unit. That way when you must remove the engine, you don't have to cut so many ties and you don't have to find your setting again. You will measure from the center of the head (plug) to the mark on the baffle to get your pipe length. When you must cut something, cut the pipe. You want as much distance as possible from the open exhaust to keep from burning the pipe. Some people use a gasket between the engine and header, but we have had much problems with this. A little high temperature rtv might be OK, but any gasket is subject to blowing out. If it blows out, it leaks. If it leaks there will be a gap. If there is a gap the screws will come loose. If the screws come loose, the pipe will fall off. (Well, it worked that way for Matt anyway. Now you know why we don't use a gasket there.) Put a little something on the screws to make sure they don't come loose and you can probably forget about the gasket.

Hot glow plugs are good. You have some Brazilian plugs down there to play with. 20-22% oil in a 50-50 castor/synthetic ratio. Nitro will depend on set up, temperature, etc. With our set-up we start with 5%. If it gets warm (85-90 degrees) we might go to 7 1/2%. When it gets hot (95 or above) we might go to 10%. Others, with a different set-up, will start with 15%. A lot will depend on the venturi, number of head gaskets, etc. as well.

Personally, I would break it in on 5%, but others might give different advice. Put the pipe on and use it while you are doing the break-in. That way you can break it in at the same rpm and heat range that you will be running it at. Pipe length, rpm, prop used (diameter and pitch) are all a package along with fuel choice, venturi, and head shims. And that is without messing with the timing.

>>Time to laugh. Go on, my friendss, laugh you heart out...
>>
>>Ion- now into pipes- muniz
>
>Now, Ion, you are tempting me, again, with this laugh
>encouragement. Trouble is, I can't think of any good
>zingers to zap you with this time.

Len, as long as you don't tell anyone to not waste the beer on me, it's OK ...

BTW, Doug must have broken all records on flaming threads!!

>On the engine, I would stick with it stock unless you know
>someting others don't.

All I know is that Mike Starret raied his scneurle ports. As a disciple of you and Brett, I am NOT wiling to do that.

>Those ties (straps) are sufficient to keep the thing leak proof at that joint. Make sure you stock up on a bunch of them, however, so you can move things
>around.

>If you can, make your plane so you can remove the
>engine and pipe as one unit. That way when you must remove
>the engine, you don't have to cut so many ties and you don't
>have to find your setting again.

The design I'm building is just like that...

>You will measure from the
>center of the head (plug) to the mark on the baffle to get
>your pipe length. When you must cut something, cut the
>pipe.

I'm dumb, Len, but not That dumb...LOL

But I am to cut my pecious beautiful pipe???? Why not the header?

You want as much distance as possible from the open
>exhaust to keep from burning the pipe. Some people use a
>gasket between the engine and header, but we have had much
>problems with this. A little high temperature rtv might be
>OK, but any gasket is subject to blowing out. If it blows
>out, it leaks. If it leaks there will be a gap.

> If there
>is a gap the screws will come loose. If the screws come
>loose, the pipe will fall off. (Well, it worked that way
>for Matt anyway. Now you know why we don't use a gasket
>there.) Put a little something on the screws to make sure
>they don't come loose and you can probably forget about the
>gasket.

You mean that the header will not leak if apllied straight on the engine? How come we use sometning on the rear plate of engisnes?

>Hot glow plugs are good. You have some Brazilian plugs down
>there to play with. 20-22% oil in a 50-50 castor/synthetic
>ratio. Nitro will depend on set up, temperature, etc. With
>our set-up we start with 5%. If it gets warm (85-90
>degrees) we might go to 7 1/2%. When it gets hot (95 or
>above) we might go to 10%. Others, with a different set-up,
>will start with 15%. A lot will depend on the venturi,
>number of head gaskets, etc. as well.

I have ben happy with 13%, it gets to 110 degreees around here.

>Personally, I would break it in on 5%, but others might give
>different advice. Put the pipe on and use it while you are
>doing the break-in. That way you can break it in at the
>same rpm and heat range that you will be running it at.
>Pipe length, rpm, prop used (diameter and pitch) are all a
>package along with fuel choice, venturi, and head shims.
>And that is without messing with the timing.

OK, Len, you just sit tight and wait for the nxt dumb question

>>You will measure from the center of the head (plug) to
>>the mark on the baffle to get your pipe length. When
>>you must cut something, cut the pipe.
>
> I'm dumb, Len, but not That dumb...LOL
>
>But I am to cut my pecious beautiful pipe???? Why not the
>header?
>
>
>>You want as much distance as possible from the open
>>exhaust to keep from burning the pipe.

Your answer is right there. Ask Ted about this. The carbon pipe will fry if it gets too hot. On first glance it seems simple to cut the header. These are less expensive and one could even have several lengths of headers to get different pipe lengths. But if you cut the header, you will move the engine closer to the hot exhaust gasses coming out of the engine. The longer the distance these gasses have to travel, the more time they will have to cool. It may not be much, but it will be enough to keep from frying the pipe. If you cut the header and get the pipe too close to the exhaust outlet of the engine, you will find a new meaning to Genesis 3:19b (only in this case it is carbon).

>
>>>You will measure from the center of the head (plug) to
>>>the mark on the baffle to get your pipe length. When
>>>you must cut something, cut the pipe.
>>
>> I'm dumb, Len, but not That dumb...LOL
>>
>>But I am to cut my pecious beautiful pipe???? Why not the
>>header?
>>
>>
>>>You want as much distance as possible from the open
>>>exhaust to keep from burning the pipe.
>
>Your answer is right there. Ask Ted about this. The carbon
>pipe will fry if it gets too hot. On first glance it seems
>simple to cut the header. These are less expensive and one
>could even have several lengths of headers to get different
>pipe lengths. But if you cut the header, you will move the
>engine closer to the hot exhaust gasses coming out of the
>engine. The longer the distance these gasses have to
>travel, the more time they will have to cool. It may not be
>much, but it will be enough to keep from frying the pipe.
>If you cut the header and get the pipe too close to the
>exhaust outlet of the engine, you will find a new meaning to
>Genesis 3:19b (only in this case it is carbon).

You're right, Len... The header is metal, and it certainly disspates more heat then the carbon on the pipe, besides keeping thr "hot stuff" as far away from thr pipe as posible.

I don't want my precious little pipe to become ashes!!

I'll cut the pipe. litle by little, well understood...

One thing, Ion, there are formulas for cutting the pipe (which have to do with timing and rpm). I don't know what works best for the engine you have (desired rpm will depend on prop and other parts of the set up as well) but others may.

Just remember you have a range with which to work at any pipe setting (not much, but a little) and you can (and should) have a bit of a space between the header and the pipe. So it is possible to adjust a half inch or more in pipe length without additional cutting, and move it back and forth. Matt's first pipe was changed a lot as he experimented with settings and props.

>Should I put some kind of gasket between the engine and the
>header? Asbestos, or what?

ABSOLUTELY USE A GASKET!!! This is vitally important, because any tiny leak will make the engine run very inconsistently.

What comes with Randy motors is rubberized gasket material (used for water pump gaskets on cars, here anyway). This works for a while, but PW showed us a better way.

"Face off" the mating surfaces with 240 grit sandpaper taped to a piece of glass or some other hard and flat surfaces (stuff a paper towel in the exhaust to keep the grit out. I then go to a soapstone and oil to to get it perfectly flat. Clean it all up with acetone, and then put a very thin layer of silicone bathtub caulk on the engine side of the mating surface. Don't use latex bathtub caulk - use silicone. Make it thin, but make sure it's everywhere including around the bolt holes. Then bolt it all up nice and tight. If you can, wait overnight for it to completely set, but I have actually flown 10 minutes afterwards with no ill effects - it seems to cure up pretty quick when the header gets to 400 degrees! If you are worried, Paul uses 5 minute epoxy, which also works fine but gunks up the outside of the engine where it squeezes out.

Liquid gasket materials make for a perfect seal, and I have had no leaks at all since I started using this technique. I was using the "Ultra Copper" silicone automotive exhaust header sealer, but plain old silicone bathtub caulk can easily stand the temperatures of model engine headers (far cooler than a car).

Some setups are more sensitive to header leaks than others, but my experience with the 40VF was that even an almost undetectable leak will have very drastic effects on the run. Same with the pipe, particularly for leaks nears the front of the pipe.

I also build up a flange on the outside of the pipe to give the tie-wraps to have something to grab on to. I make a "ring" of 1/16 copepr tubing or 14 guage copper wire (like the ground wire in Romex house wiring) that fits perfectly around the outside of the pipe right at the front end. Then rough up the ouside if the pipe right at the front, and then J-B weld the ring to the pipe.

Rough up the header surface with 150 grit sandpaper to give it some grip, too. I use two tie-wraps on the header, and 2 on the pipe, to make absolutely sure.

If anyone is not currently using a gasket or sealer of some sort, it might be worth trying - it may cure some problems you didn't know you had.

pipes, they are pretty simple things, they have a hole at each end, and the holes are connected in the middle.....

I always say...there's no such thing as a dumbe question, as long as you don't profess to be an expert on the subject. Like thes guys that seem to think they know everything when they are answering someone elses question, but then ask the most basic questions themselves.

is this grogan guy joking?

>
>is this grogan guy joking?

I think we have a recycled Floyd. I was joshing with Ion, but...?

Oh, well, with Floyd gone, I guess there was a vacuum to be filled.

Floyd's gone?

floyd????ho's he???? probably another guy with a sense of humor. he probably got erased by Lenny boy. he probably knows that a pipe is a long hole,

what's the deal with these pipes.......aren't mufflers quiet enough for you?

>what's the deal with these pipes.......aren't mufflers quiet
>enough for you?

A muffler is a means of controlling the noise. (You tie one around your neck and pull it tight. Does a good job, but only if you pull it real tight. A little humor there for you.) A "tuned" pipe is a means of controlling the engine run. Guys flying speed will use one to boost the power--sort of a supercharging effect based on the speed of sound and the reflected wave and the rpm and...well, this isn't a science report. Guys flying stunt will use the pipe in various ways--to allow more useable power, to keep it from speeding up, to pick up power when needed--not all set their pipes in the same way or to do the same thing. And, to be honest, for some it is just a big muffler because they don't have it set right. But most current pipes, by my measurements, are actually noisier than good mufflers. In the US we do not have noise limitations. In the rest of the world, flying FAI, they do. So noise still must be a consideration.

Now Gieseke was using a pipe when he won the world championship. He buried it on the spot. Different type of pipe, however. That one used tobacco.

I took a look at a photo of Mike's setup.

He has some inches of silicone between the header and the pipe.

Billys "Perroquet" has the pipe VERY close to the exaust, but what the heck? He makes them...

I am building a special stand that will hold the engine and have a portion aft to support the pipe.

I'll start fidling with the distances auntill the engine is running at it's best.

Just one question: When breaking in the engine should I just hang the pi9pe on the engine, or should I start looking for the optimum distance?

>
>I'll start fidling with the distances untill the engine is
>running at it's best.

You won't really know what the optimum distance is on a test stand. This isn't like tuning a speed engine to get maximum power at a certain rpm.

>Just one question: When breaking in the engine should I just
>hang the pi9pe on the engine, or should I start looking for
>the optimum distance?
>
>Ion

Set it close to the distance you feel you will be running. Randy had a chart for setting the engine for ground and in air settings depending on rpm. This will vary with the timing of your engine as well. If the pipe is set too close you can burn up the insides of your engine. If it is too far away, well, it will be a long muffler.