Highwayman Air Scoop

Preliminary testing of adding a scoop to the side of the engine showed a drop in temperature. Which makes sense, the faster you go the more air gets pushed over the cylinder head.

At some time in the 80's someone had the same idea but it may have just been for looks

To test it properly a test jig with air speed measuring device was made up in the cowl... it is yet to be put into practice...

Update (13/02/2010) - gave the test jig a quick whirl on the Lab Rat

Another issue that has reared it's head is that because the Vespa has no scoop, the actual efficiency of the air cooling will drop the faster you go because the fan is trying to suck air in as it flys by. The faster the air going by the harder it is to suck. So there will be less cooling at ~105 km/hr than at 36 km/hr with the fan spinning at ~6,000 rpm.

I would not be surprised if an air scoop could increase cooling efficiency by as much as 100%. This is because it would both fix the problem above and then ram additional air in as well. I am going to measure a few things with the simple device above and if it proves my theory, then I will hire a professional airspeed logger.

Update (15/01/2012)

An issue has been raised on what temperature is optimal for a Vespa engine, if the engine is keep too cool then it will not run optimally. The cylinder and head are obviously built to run at a specific temperature where the heat expands the metal to just the right proportions. The highwayman scoop may need to be designed to automatically control temperature, maybe blocking the flywheel fan intake when the engine is cold (to aid in getting to optimal temp quickly) and then openning up and then scooping depending on temperature.

The above will require some mechatronics.