4-stroke carbon pipe design Q's

[BUDDYonRC at aol.com]

In a message dated 5/23/2005 10:00:28 AM Central Daylight Time,  
patterndude at comcast.net writes:

 
I've gotten a lot of recomendations to add a carbon lightweight 4-stroke  
pipe to our lineup so I'm starting to look at a 4 stroke pipe design.  I  have 
some questions:
1. What are the proper pipe inlet diameters that you desire on  pipes
2. Worst reasonable case: how close is the pipe to the exhaust port
3. What max temperature at the inlet do you suspect (I'll be doing  detailed 
research on this but want your opinion).
4. Is it possible to tune a 4 stroke at all, or is the muffling the only  
goal?  If tuning is possible, how does this work?
--Lance

 
--
District 6 AVP  
www.aeroslave.com



Lance
Inlet o.d. 5/8"( See my note on this below.)
outlet o.d 7/16"
Some dim's that I use
1. Center of exhaust port to end of header 4"
2. Teflon tube distance from end of header to inlet of muffler 6" (Shorter  
Teflon tubes may result in Teflon tube or header failure, the Teflon tube  
becomes very flexible when heated this relieves the forces on the header.) Tube  
used by most is 3/4" od x 5/8" id. Shorter tubes are definitely a problem and  
cause header failure, It is also very important to let the system warm up 
after  start to allow the Teflon to become flexible, If you don't you will 
experience  tube and header failures.
3. Distance from inlet of muffler to the muffler including the pipe  section 
and inlet cone 4"
4. Muffler tube length less inlet and outlet cones and tubes about  16"
5. Outlet cone and tube 3"
6. O.D. of muffler 1-1/2"  ( I have no idea where the baffles are  located or 
what they look like) 
The system is just a muffler, not a tuned pipe.
Temperatures of the exhaust are fairly hot running high nitro fuel in a  
properly tuned engine the temperature will get to +/- 400 deg. on a  unturned 
engine running lower nitro temp can exceed the Teflon tube limit and  cause 
failure of the tube.
In your design I suggest a slightly larger inlet tube Say 11/16"o.d. with  an 
aluminum tube insert molded in. Others without it have a high failure rate.  
this will require that the Teflon tube be expanded with heat to install. Some 
of  the ones I have have a 3/4"o.d. inlet that makes it very difficult and 
almost  impossible to expand and install the Teflon tube.
Last but not least keep it light. If you want them to sell they must  be 
lighter than aluminum versions 
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