Andrew Clink

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Eurovan TDI Conversion: Intake and Exhaust

21 December 2015

This part requires some creativity and fabrication, depending on your goals. There's also a ton of different ways to do it. If you want stainless exhaust, you have to make that happen. If it needs to be mandrel bent (and the downpipe really does) you have to make that happen. Is 2" Ok? Do you want 3" back? Need a catalytic converter? Where should the intercooler go? Et cetera.

Airbox and Turbo Inlet Pipe

While the thing is huge, I opted to retain the factory airbox. There is already mounting available from the factory and it's in a convenient location with regard to the turbo. If it's able to reasonably support five cylinders at 5000 rpm (7500 g/min) it will be comparable a 1.9l four-cylinder at 3500 RPM (~8000 g/min at 15psi boost). Plus I get to keep the cool over-engineered airfilter change handle.

To construct the turbo inlet pipe I purchased three silicone elbow hoses and cut them all to fit. The mass air flow sensor outer diameter is approximately 70.0mm or 2.75". The turbo inlet for a VNT-15 compressor housing is 45mm or 1.75".

The 2.75" bend runs from the airbox to the MAF, then the 45° runs over the engine mount to a very short piece of 2" OD exhaust tubing. Connected to that is the final 90° bend into the turbo. Be cautious using normal hose clamps on silicone piping— it has a low shear resistance and may be damaged by the holes for the teeth in the band. 

It's also worth mentioning that the hose closest to the turbo inlet is fairly tight between the engine mount and the firewall soundproofing. Because there's relatively soft steel inside at this point, I stepped on it to oval it out a bit. This ends up creating a sort of pancake pipe that has pretty decent clearance. Overall I'm pretty pleased.

2.75" 90° elbow 4" Leg length eBay
2.75" to 2" 45° reducer 4" Leg Length eBay
2" to 1.75" 90° elbow   eBay