Rotax 503 - Exhaust design/manufacture

[Le Pou]

The Flying Flea I am building is tractor propelled and I would like to modify the exhaust layout so that I can fit the expansion box behind the engine. i.e. between the engine and the firewall. This will require replacing the cone shaped pipe attached to the expansion box with one of a different shape. The present one curls back on itself whereas I would need one with a right angle bend in it.
1.Can anyone advise me on the design criteria for this tube?
2.Can anyone refer me to someone who could make up this mod? (Preferably in the Jo'burg area.)

Thanks
Le Pou

[Tailspin]

The Flying Flea I am building is tractor propelled and I would like to modify the exhaust layout so that I can fit the expansion box behind the engine. i.e. between the engine and the firewall. This will require replacing the cone shaped pipe attached to the expansion box with one of a different shape. The present one curls back on itself whereas I would need one with a right angle bend in it.
1.Can anyone advise me on the design criteria for this tube?
2.Can anyone refer me to someone who could make up this mod? (Preferably in the Jo'burg area.)

Thanks
Le Pou

Hi Roy

Speak to Duck Rogers "Gerrie" on the Forum.

[Le Pou]

Hi Gavin,

Thanks for the info. With some more playing around I have found that I can get what I want simply by cutting the expansion tube in the middle of the 180 degree bend and then rotating the one piece relative to the other by 90 degrees and welding it in this position. I will also have to reposition the anchors for the springs on the 2 movable joints. BUT then I will have a very elegant exhaust sytem which will fit neatly behind the engine, between the engine and the firewall! So I guess I can say problem solved without having to make major design mods.

Roy

[Tailspin]

[Aerosan]

Guys

Just remember that this is a tuned system. Distances should be kept the same as it could have some nasty effects Duckie will know what to do.

Cheers

Sanna

[Le Pou]

Hi Sanna,
Yes, my original question was a call fo help on exhaust design for the 503 as I thought I would have to make up a new expansion tube. However, with luck on my side for a change, I found that I could get the configuration I needed with simply cutting the expansion tube on the bend, rotating one piece through 90 degrees and then welding the 2 pieces together again. Thus neither the length nor the volume of the tube is changed, so hopefully I won't have a problem. Let these not be "famous last words"!!

Thanks for your comments,
Roy

[bryan]

PLEASE post some photos of your build on the forum. It is always good to see something different being built. Do give some specs and costing. Sounds like a good project.
Regards
Bryan Erasmus.

[Le Pou]

Will do. In the meantime have a look at:

http://www.fraseraerotechnologycompany.com/

Regards,
Roy

[Boet]

Roy, whatever you do with the expansion chamber, do NOT make it any longer or shorter. It is a "tuned pipe" and tampering with it can have a negative effect on the performance of your 2 stroke engine.

[Le Pou]

Thanks, Boet, I wont tamper with the tuned pipe other than to cut it through on the bend, turn one piece through 90 degrees and weld it up again.
Regards - Roy