Our simple recommendations for intake sizing are a single 75mm diameter up to 210 BHP, 100mm diameter is ok to around 280Bhp, 127.5mm to 152mm recommended for 280 BHP+ or multiples of smaller diameter inlet pipes giving the same or larger open surface areas. As a rule of thumb, bigger air box volumes and inlet diameters are better so that the engine is under atmospheric conditions, and tuned lengths are then just controlled by the inlet runners. Think carefully about the position of your fuel rail (on fuel injection systems), if it overhangs the trumpet mounting face, you will need a fuel rail spacer type back plate or use our air box trumpet grommets and brackets to have the air box sit and seal around the trumpets instead.Ĭonsider the type of filter you want, if you want a filter inside the air box then consider a Silverstone or Zolder 112 (so long as you have 78mm - 112mm of depth from the mounting face), or use any of our air boxes with filters or filter boxes or for lower horsepower outputs internal foam trumpet socks singles or pairs.ĭecide on the inlet diameter you wish to use. If you want to use a single throttle body on the air box for N/A or forced induction then be sure to select a plenum rather than an air box. If you are using throttle bodies on a normally aspirated engine then pick an air box from our vast range based primarily on your fitting constraints, try and fit in the largest air box volume you can, allow for some engine movement.

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