Airbox & cold air feed- Octobber 2009 on

The Mojo has always run with sock filters, simply because the inlet trumpets are pretty close to the underside of the engine cover, and they seemed the only real option. However, socks never seem particularly well regarded as a filter solution, so as mine starting showing signs of deterioration, I was keen to find an alternative solution. Also aware that it can get pretty warm in the engine bay, incorporating some kind of air feed from one of the inlets in front of the rear wheels seemed like a good idea.

After lots of background reading into airbox design and tuning I have settled on a solution including a fabricated aluminium airbox with a 76mm feed to a cone filter located inside the rear right wing, in front of the rear wheel.

The cone filter will require some protection from the potentially significant quantities of water thrown up by the rear right wheel, so at the same time I plan to fabricate an inner wheel arch. This will serve an additional purpose, that of keeping water off the alternator belt, which quite often slips with nasty shriek when driving in the wet.

I remembered seeing a Marlin 5exi at the Donington show a few years ago with inner arches made from Correx, the corrugated plastic material used by Estate Agents for their For Sale signs. After some digging around I found a local(ish) supplier, www.theplasticshop.co.uk. A quick email confirmed that they would be able to supply me with a single sheet (their normal price was £45 for five 2.4m x 1.2m sheets), or maybe even some offcuts if I got lucky. I therefore made up some cardboard templates of the required shapes before paying them a visit. They proved to be a very friendly place, and pulled out a rather larger offcut than expected, at about 2.0m x 1.2m, and only asked for £5! Bargain! The only problem was fitting into the tintop, but eventually it formed a rather tasteful black headlining running right over my head...! Here is the offending item giving the Mojo a little weather protection:

My parts accumulation has also included a 76mm cone filter bought at the Stafford show for £10:

A plastic connector to join the airbox to the feed pipe (found in the scrap bins at work!):

And a (now redundant!) 500mm length of 76mm pipe from Ruari Coles' TVR:

Update:

Next job was to start making the inner arch from the Correx. This was made up from 2 separate sections. The Correx proved to be very easy to work with, cutting very easily with a stanley knife. The largest piece was fixed to the side of the chassis by zip ties. In order to avoid bending the sheet (it tends to crease quite easily) I had to remove the shock unit but this was still an easy job. The second section runs between this piece and the fibreglass wheel arch, and proved more tricky to secure at the outer edge - the return lip is very close to the tyres so couldn't be used. I am therefore still considering my options, bonding it in place being one of them, but I can't do this until the rest of the cold air feed is sorted... Hence, the second piece of Correx is yet to be fitted... More news as it happens!