Aluminum has a very short fatigue life. Oil lines under pressure can become very rigid, and try to move about with some force. They apply unhappy forces onto the fittings of oil coolers and coolant radiators. Such devices must always be mounted softly.

Movement in any direction must be allowed. Mounts are lined with foam strips. Air supplies end with foam

seals. You should be able to grab a cooler and move it some in any direction with the engine at take off power. Note that coolers also become quite heavy when filled with liquid. Such coolers respond to lower frequency vibrations as their weight increases. Also they respond to the 4th harmonic of any primary frequency.

 

Although it is tempting to use aluminum from a box store (6061-0) use it only for patterns. I once used a piece for a timing pointer on the dyno and it fell off after about 10 minutes. Two pieces still bolted to the engine. Pointer on the floor. Use 2024-T3 for the real thing. Remember that pressurized hoses try to go

to dead straight when under pressure. Use big sweeping bends or formed 90 hose ends with straight runs of hose where possible. Where you see a cooler mounted rigidly over a hole in a panel, you should also see the hoses clamped close by to the same panel. So hoses and cooler move together.

 

Consult any hose book on mounting rules.

 

For work above 8,000 RPM I use RedLine racing synthetic 2 cycle oil. 128:1 or one ounce per gallon. No oil related failures since 1980.

 

Been there, broke that.

 

Lynn E. Hanover