Custom Induction System

It Must Be Sealed

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or any worthwhile improvement in the design of Kermit’s induction system, the new pipework must be sealed. This means no water drainage holes, no leaky pipework, it must be air tight.

This is one consideration I have when assessing the standard airbox and induction design. It’s not an especially bad design - don’t always believe the standard “it’s very restrictive” approach - but it is deliberately leaky. This is so that any water present in the air filter has the opportunity of escaping via the drainage holes.

The standard airbox and induction system also encompasses the crankcase breather pipework. At the time of writing, I have still not established what and how I will deal with this problem using the customised induction set up. The evaporated air should be sent back through the engine so that the fumes are burnt, but the concept of a sealed induction system presents some difficulties in this respect!

However, setting aside this issue for the time being, the good news is that I’ve finally established a gameplan for Kermit’s custom induction system. Kermit’s customised induction system will probably use the Pipercross Twister cone filter. The reason for this is not because of Pipercross’ claims that the air twisting design improves performance, but is because the air filter includes an integrated heat shield. Unfortunately, this filter element is especially expensive - it’s close to £90.

The air filter will be connected to the throttle body by a SAMCO elbow, probably finished in red to match the strut brace. The other end will be attached to the intake system, which I’m probably going to incorporate behind the upper front grill. I may mount the intake a little bit lower, subject to space and inclination, but rather than use a simple round intake it is my intention to use a duct of some description. This will not be the last word in aerodynamic sophistication by any stretch of the imagination, but will be designed to have half a stab at funnelling air into the induction system when driving along the motorway. There are aerodynamic considerations, which I discuss below.

I am going to deliberately mount the twister air filter with a nose down attitude so that water drains away from the engine when stationary.

Alternatives

As an alternative, given that the Twister is so damn expensive, I may well look to source a open ended air filter and fabricate my own sealed heat shield.

I have yet to determine what I’m going to do about the crankcase breather unit. I may have to incorporate an alternative filter element of some description.

Aerodynamic Considerations

There are some important considerations with regard to designing an intake system.