Exhaust

[Duck Rogers]

Please continue this thread.......I still have a FULL bag of popcorn left

Well please enlighten us Mr Rogers on how to get this done.

Hey, I didn't say anything! Just enjoying the thread...

Gotta top up my Coke now......

[Chunky]

I had an enhaust made by Jeremy Pinkus .....

Have you got contact detail?

Massimo - Pls share the details with us if you find someone.

It was a few years ago but i am sure I could find his number. I got hold of him through the motorcycle racing guys. He is very well known for 2 stroke exhaust systems. I actually watched the process how he makes the expansion chamber. Takes two pieces of stainless plate, welds them together and then 'pumps' air in between the plates and the exhaust just 'pops' out.

It made a huge difference on the 462 so I am sure on 582's it will be even better.

[John Boucher]

Practical 2-Stroke Aircraft Engines

The engines we use for flying do not have a true expansion chamber but rather a semi-expansion chamber and muffler combination. You can imagine what happens when the positive pulse arrives at the piston a bit too early or too late. The benefits of a tuned exhaust in enhancing the retention of the fuel charge are not fully realized. When it's just right, however, it will push some or most of the fresh fuel charge that has started to exit the exhaust port right back into the cylinder just before the exhaust port closes.

The exhaust side is semi-tuned since we use a muffler and not a true expansion chamber. The most highly tuned 2-strokes will have an individual exhaust pipe and expansion chamber for each cylinder, and the resulting increase in horsepower output will be dramatic, but only in a narrow band. This is not good for a wide power band like we need on aircraft engines. Also, the noise would be unacceptable for use in local flying.

The exhaust manifold on our 2-strokes almost always joins into a Y on the 2 cylinder models, and this creates a further problem. The pulse will travel down the pipe, but when it returns it will try to go back up both pipes in the Y. At certain RPM ranges it will be causing more harm than good relative to conservation of the fuel charge.

Rotax spent a lot of time and trouble in designing the exhaust system for their engines. While it's not a pure tuned exhaust such as used in racing, it is nevertheless tuned, and the shape and distance from the exhaust port to where the elbow enters the muffler chamber is very important.

If you play with fire... ya burn your fingers! Popcorn burnt sir Duck... fetch another bottle of voggies, coke & eish!

[Duck Rogers]

Practical 2-Stroke Aircraft Engines

The engines we use for flying do not have a true expansion chamber but rather a semi-expansion chamber and muffler combination. You can imagine what happens when the positive pulse arrives at the piston a bit too early or too late. The benefits of a tuned exhaust in enhancing the retention of the fuel charge are not fully realized. When it's just right, however, it will push some or most of the fresh fuel charge that has started to exit the exhaust port right back into the cylinder just before the exhaust port closes.

The exhaust side is semi-tuned since we use a muffler and not a true expansion chamber. The most highly tuned 2-strokes will have an individual exhaust pipe and expansion chamber for each cylinder, and the resulting increase in horsepower output will be dramatic, but only in a narrow band. This is not good for a wide power band like we need on aircraft engines. Also, the noise would be unacceptable for use in local flying.

The exhaust manifold on our 2-strokes almost always joins into a Y on the 2 cylinder models, and this creates a further problem. The pulse will travel down the pipe, but when it returns it will try to go back up both pipes in the Y. At certain RPM ranges it will be causing more harm than good relative to conservation of the fuel charge.

Rotax spent a lot of time and trouble in designing the exhaust system for their engines. While it's not a pure tuned exhaust such as used in racing, it is nevertheless tuned, and the shape and distance from the exhaust port to where the elbow enters the muffler chamber is very important.

If you play with fire... ya burn your fingers! Popcorn burnt sir Duck... fetch another bottle of voggies, coke & eish!

Now you see why I said this was a popcorn and coke thread?
Got any left Bad Nav?

[Duck Rogers]

Massimo, seems like no-one will come to the aerrie to take measurements but almost any exhaust shop can do the bending and welding bit.
Go buy a length of 40mm pvc pipe at the hardware (the kind used for your kitchen basin waste). Cut it in approx. the lengths required and use a hair dryer or heat gun to soften it up where you want it to bend. (be careful, it goes rather soft very quickly if heat is applied too long in one spot) Have a wet rag handy (did I mention it has to be wet?) Once you have the bend you want, apply the wet rag directly to the hot bend to set it in position.
Make your own mock-up set of pipes this way and then take the whole lot to an exhaust shop to have the real thing made up

ps, who do I make the invoice out to?

[Chunky]

The exhaust manifold on our 2-strokes almost always joins into a Y on the 2 cylinder models, and this creates a further problem. The pulse will travel down the pipe, but when it returns it will try to go back up both pipes in the Y. At certain RPM ranges it will be causing more harm than good relative to conservation of the fuel charge.

Very True, but if its done right you should have 2 seprate expansion chambers.

There are always pro's and cons to any engine mod. I needed extra power and the easiest way to do it was to change the exhaust. I had a Jet ski that essentially had a Rotax 618 engine. On an aircraft it is rev limited to 6500 (+-) had new exhausts fitted by the same guy. It ran for over 600 hours (mst of the time at 13500 RPM) as it was used for racing. Never blew the engine up. Not once.

Had an M3 that was fitted with Nitrous oxide. I purposly tried to blow the engine up as I wanted to have another engine mod done to it. Drove it for nearly 30 min on the Rev Limiter at 250 kmh and used 11 kg's of Nitrous. That Car is still going fine today and has over 120000 km on it.

Rotax engines are so restricted by their exhaust system to comply with Eropean Noise standards. A582 will have no problem delivering 85 hp continuosly all day if it has oil and enough cooling.

[Massimo]

Massimo, seems like no-one will come to the aerrie to take measurements but almost any exhaust shop can do the bending and welding bit.
Go buy a length of 40mm pvc pipe at the hardware (the kind used for your kitchen basin waste). Cut it in approx. the lengths required and use a hair dryer or heat gun to soften it up where you want it to bend. (be careful, it goes rather soft very quickly if heat is applied too long in one spot) Have a wet rag handy (did I mention it has to be wet?) Once you have the bend you want, apply the wet rag directly to the hot bend to set it in position.
Make your own mock-up set of pipes this way and then take the whole lot to an exhaust shop to have the real thing made up

ps, who do I make the invoice out to?

Ah now thats better Duckie, you see sharing is caring, thanks. Well i have done this with aliminium tubing but im not 100% satisfied with the results so i will re-do it with the piping which im sure will work much better.

In the mean time i have got a silencer made up buy one of the "proffessional" companies and its fits very nicely but im not at all happy with their service and attitude so im not going back to them for the branches, but thats another long popcorn and coke story. I have arranged with another company to come out to site and do it on saturday but i will try duckies method tonight and if the results are good ill get it made up off site.

[Massimo]

Well Duckie i tried your method and i think it worked ok, but once the guys got to site the end product looked nothing like my moulds. So in my very "limited" experience i can only say the best way is to get the engine to pro's or pro's to the engine. Now i have an exhaust! To see some pics go to my thread under projects.

[Gaylord Focker]

Call a PLUMBER 0800 up the pipe

[Tailspin]

Call a PLUMBER 0800 up the pipe

Gaylord

You Offering some services here

[Boet]

You are scratching where it does not itch. Stop F.ing around and buy a new system from Rotax if you need one for your engine. On the long run your modification will cost you a lot of money, if not your life.

[Massimo]

You are scratching where it does not itch. Stop F.ing around and buy a new system from Rotax if you need one for your engine. On the long run your modification will cost you a lot of money, if not your life.

Well if Rotax had a system for my aerie i would have bought it. Would have made my life much easier. But all they want to do is sell me doughnouts and pipes to make a system so then