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Gelbster · 12-11-2016, 03:47 PM

The stock "airbox" is a problem.
A CAI system allows you to remove the huge complicated box.This hack is reversible because if you have to break up the stock plastic box to remove it, you can always get a used one and refit it.(good luck with that !)
The new CAI is easy to remove and allow easy access to the 4,5,6 -Bank 2 side of the engine to work on injectors and the fuel pressure regulator. Frankly the stock airbox is almost impossible to remove without drastic moves.
In theory you can lower the engine (a long way !) and loosen the inlet manifold & other things to do this but it is a very difficult job - see Pelican for details.There is a reason you will find many people just hack it to pieces or worse.
Much easier to just remove an aftermarket CAI to gain easy access.
The problem is most CAI systems fit a filter in the engine bay and then put a marginally effective bit of bent metal around the filter and claim all the intake air is coming in through the stock side vent on the Boxster. They probably produce higher intake temperatures than stock.So how to design an effective,compact CAI ?
A clever(?) alternative is to use the hollow between the inner and outer fender wall as a plenum and filter housing. Then there is just couplings and a flexible hose in the engine bay.Easy access and cold air achieved?
Compared to the very small opening in the stock snorkel, this system has a much enlarged Intake area.The trapezoidal side vent is around 25 to30+ sq.in. The snorkel is maybe 5" !Of course the 30 number is reduced by the ppi of the filter but so is the stock system. W/o the snorkel, the effective diameter is 3" - the same as the stock Intake for the TB - so 9 sq.in. So if the porosity of my filters when new is over than 50 % -they are not restrictive compared to stock and they should not produce any more pressure drop.
The tricks are:
1. careful selection & placement of the new foam filter, porosity and thickness in the side vent.Yes, the filter goes in the side vent tunnel.
2. Make a plate to cover the trapezoid on the inner fender.Fit a 4"MAF adapter+ a 4 to 3" 90 deg elbow.
3. Finding all the hardware inexpensively and w/o using Made in China junk that has 2 month delivery times.
If it works, I'll even wrap it in gold, heat reflective foil - very seasonal!
If you plan on fitting Ben's plenum mod and a larger TB, probably use a 4" Intake in place of the 3" ?
Anyone done this ? I ask because if it was such a good idea and it worked, many would have done it already. It is so obvious that Ben would have made one for sale by now?

12-11-2016, 03:47 PM	#19
Gelbster Registered User Join Date: May 2014 Location: S.California Posts: 2,027	CAI - a different reason to fit one The stock "airbox" is a problem. A CAI system allows you to remove the huge complicated box.This hack is reversible because if you have to break up the stock plastic box to remove it, you can always get a used one and refit it.(good luck with that !) The new CAI is easy to remove and allow easy access to the 4,5,6 -Bank 2 side of the engine to work on injectors and the fuel pressure regulator. Frankly the stock airbox is almost impossible to remove without drastic moves. In theory you can lower the engine (a long way !) and loosen the inlet manifold & other things to do this but it is a very difficult job - see Pelican for details.There is a reason you will find many people just hack it to pieces or worse. Much easier to just remove an aftermarket CAI to gain easy access. The problem is most CAI systems fit a filter in the engine bay and then put a marginally effective bit of bent metal around the filter and claim all the intake air is coming in through the stock side vent on the Boxster. They probably produce higher intake temperatures than stock.So how to design an effective,compact CAI ? A clever(?) alternative is to use the hollow between the inner and outer fender wall as a plenum and filter housing. Then there is just couplings and a flexible hose in the engine bay.Easy access and cold air achieved? Compared to the very small opening in the stock snorkel, this system has a much enlarged Intake area.The trapezoidal side vent is around 25 to30+ sq.in. The snorkel is maybe 5" !Of course the 30 number is reduced by the ppi of the filter but so is the stock system. W/o the snorkel, the effective diameter is 3" - the same as the stock Intake for the TB - so 9 sq.in. So if the porosity of my filters when new is over than 50 % -they are not restrictive compared to stock and they should not produce any more pressure drop. The tricks are: 1. careful selection & placement of the new foam filter, porosity and thickness in the side vent.Yes, the filter goes in the side vent tunnel. 2. Make a plate to cover the trapezoid on the inner fender.Fit a 4"MAF adapter+ a 4 to 3" 90 deg elbow. 3. Finding all the hardware inexpensively and w/o using Made in China junk that has 2 month delivery times. If it works, I'll even wrap it in gold, heat reflective foil - very seasonal! If you plan on fitting Ben's plenum mod and a larger TB, probably use a 4" Intake in place of the 3" ? Anyone done this ? I ask because if it was such a good idea and it worked, many would have done it already. It is so obvious that Ben would have made one for sale by now? Last edited by Gelbster; 12-29-2016 at 12:57 PM.