B250
DESIGN: SynchroLite ~
Engine - Cooling
Additional Fins:
Sketch:
Notes:
Consider putting 1/8" thick aluminum plate between engine head exhaust port and exhaust pipe. This plate would be used to remove heat from cylinder head and to direct airflow past cylinder head. Would this plate and gasket(s) cause a problem?
Would this aluminum plate melt, as would an aluminum exhaust at around 800 degrees F?
Would it be possible and would it be a good idea to have the first part of the exhaust pipe from the engines be made of a material with high thermal conductivity and have fins on it, similar to the engines aluminum cylinder and head. There was a note in one of the books that said that cooling the exhaust might effect the tuning. Maybe it could be tuned for this.
Idea: Have a 1/4" aluminum flange bolted between the exhaust port and the exhaust pipe that has a large OD and fins on this large OD. This idea might not work if a gasket must go between engine and this flange. Could a portion of the deflector be made out of aluminum and welded here also?
Idea: Locate a fan with outer ring shroud inline with v-belt. The fan would be spring-loaded to push the outside diameter of the shroud up against the v-belt. It will be axially inline with the exhaust side of the cylinder and head. The friction will drive the fan.
Engines are cooled slightly by downwash of rotors. Shaping of body and power-train may improve this.
January 10, 2000 - John U writes - Also, your engines must be fan cooled or they will fry.
Hirth cooling on 2703 blows air into exhaust side and out the carb. side.
Additional Thoughts:
Could the device consist of 5 or 6 thin sheets of aluminum, approximately 6" x 8" in size? In the middle of each sheet there are 3 holes, which have the same diameter and position as those in the exhaust flange. The only difference is that the large hole is slightly oversize to accommodate a non-heat-transferring ring. A non-heat-transferring gasket is located between this device and the exhaust flange. The primary metal to metal contact, for heat withdrawal is between the engine and this device and the exhaust gas nor the exhaust pipe will transfer heat to this device.
Once sandwiched in place, the thin sheets can be appropriately spread apart to act as cooling fins and any excess sheet metal can be removed with shears.
This should help remove some of the heat from the hottest part of the engine.
Concern:
Can sufficient heat be transferred from sheet to sheet or must the sheets be fused together in the area where they are sandwiched between the engine and the exhaust flange?
Additional Thought:
What about putting a ceramic coating on the inside of an aluminum exhaust. The ceramic will stop the heat from getting to the aluminum. If the aluminum exhaust flange is directly coupled to the engines port then the aluminum pipe (possible finned) may help remove some of the heat from the engine, near the exhaust port.
Notes:
The Zanzottera already comes equipped with cooling fan and shroud.
Sources:
Coating:
http://www.swaintech.com/twostroke.html
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Last Revised: January 15, 2005