How to... Fit a coldside airfilter kit--NB (MK2.5)

Here’s a little project that been in the planning stages for a long time now and finally got round to trying it out – a ‘cold side’ air filter set-up.

Ever since father Christmas got me a Scangauge, the air inlet temperatures even in cold weather were rather alarming to say the least, up to 50deg.C at times in traffic, but no more than say 10deg.C outside!

This is the oft reported issue with the standard aftermarket air filter fitting, unless you can stretch to a Jackson Racing Cold air intake or Monsterflow with heat shield, etc. And so a cold side air filter location has always piqued my curiosity, that and the advantage of a greatly reduced intake tract.

The arrangement I came up with uses a 65mm, 67.5degree sharp bend, black PVC, sourced from B&Q, and to be found in their guttering section.

This uses the stock mass air flow sensor and air inlet temp sensor wiring as is, i.e not cut or extended, but requires the loom protection and tape to be ‘adapted’ to allow the sensor wires to be returned back to the cold side of the engine bay.

The mounts were a pain to get right, what with the odd mounting angle involved, but basically attach to the 2no. mounts on the mass air flow sensor, and bolt back to two different fixing positions on the inlet manifold and throttle body. The rest just clamps together with rubber gaskets and jubilee clips

A slight problem was also had by the expansion bottle tube which is unfortunately not quite long enough to move out of the way of the filter. The route of the tube can be adjusted by taking it out of the left hand side radiator bracket and positioning over the top of the radiator header. It still lays across the air filter so I have added some plastic cable wraps to stop any rubbing or wear.

Possibly some improved throttle response but maybe imagined, more induction noise (good), but most of all, much cooler running (very good) – bring on the summer I say!