684i B4 / TS / QS Engine Manual
more infos: www.3w-modellmotoren.com
It is strictly prohibited:
To mount the engine directly onto spacers for the following reasons:
a. If the spacers are too long and/or not stiff enough the engine could vibrate leading
to the crankshaft starting to twist, further leading to the crank case being destroyed.
b. If spacers are used to adjust the side and/or down thrust and this spacing no longer
provides an even plane (i.e., a flat and level surface) the crank case will be distorted,
leading to the crankshaft starting to twist, further leading to the crank case being
destroyed.
To mount the engine directly onto a large (wide) former or firewall for the following reason:
a. If the cylinder(s) is/are too close to this wide former or firewall, the floating air cannot
pass freely over and then away from the cylinder(s). Cavitating hot air can/will overheat
the engine.
Engine Cooling
A proper cooling system is vital for any engine. An air cooled engine requires an appropriately
sized air intake. Also to keep this air cooling process working the incoming air must be exhausted.
Further, the exhaust air outlet should be four times (4X) the size of the cool air intake.
Example:
•
10 square inches of air intake area would require
•
40 square inches of exhaust air outlet area
It is up to you to insure that the air flows freely to, over, and away from, the hot cylinder(s) and
muffler(s). Please refer to Engine Installation for motor box considerations, and to the following
tips on baffling.
Baffling
Deflecting of the air (baffling) to and over the cylinder(s) is highly recommended for engine cooling.
The idea is to get all of the cool air that is coming through the air intake opening(s) to hit the middle
of the cylinder(s) directly, and then be forced over the cylinder(s), creating turbulent air moving
