| Nick had posted a couple weeks back about the modification to the compressor housings that are needed to fit the V2 inlet pipes and some concerns were brought up regarding the machining of the taper to the compressor inducer. When I originally machined the housing I only cut the taper enough to match the i.d. of the new flange to the existing taper within the housing as shown below: 
A few people asked about cutting the taper so that it runs back closer to the compressor inducer blades. Now that we have completed the first batch of inlet pipe kits, yesterday I revisited this and re-machined the housings to achieve this request. Here is the final product: 
In all honesty the differences are a bit of "splitting hairs" but undoubtedly will improve flow to some degree. FWIW: When you are considering the flow of air through a duct and seek to avoid turbulent flow, you need be far more concerned with divergence rather than convergence... i.e. Does it taper to a wider diameter or a narrower diameter. When flowing through a divergent duct (one that opens to a wider diameter) you have to consider flow seperation - this is what occurs when the flow of air along the walls of the duct "seperates" from the wall. There is a very thin layer of air at the surface of the walls of a duct that "sticks" and doesn't really move. If you try and expand the gases out to a larger area too quickly it will generate a vortex of air at the boundary layer that rotates perpendicular to the flow. These vortexes, or boundary layer seperation, create drag on the air and reduce flow. This is the primary reason for Greg Dupree's (SpecialtyZ) development of the tapered turbo discharge pipes. However, the compressor housing is a different animal. The flow is convergent as it passes from the turbo inlet pipe into the compressor wheel. The cross section is reducing and in this situation flow seperation will not occur. The primary focus in this case is to consider the increase in air velocity as it funnels into a narrower cross section. The faster the flow of air, the more sensitive its flow properties are to sharp corners. By tapering this convergence in the compressor housing inlet at a lesser angle such that the convergence meets at or very close to the leading edges of the compressor inducer blades, any turbulence that would have been created by the step being placed further upstream will be eliminated. Once the air enters the compressor wheel its flow is entirely controlled by the wheel itself. We have many sets of comp housings that were sent in to us for modification for the V2 pipes which we will be addressing through the course of today and tomorrow. We have a rather wide variation of housings from stock, HKS2530s, GT2860R and RS versions. I will post back with pictures of these housings once they have been modified later today.
Enthusiasts soon understand each other. --W. Irving.
Are you an enthusiast? If you are out to describe the truth, leave elegance to the
tailor.
Albert Einstein
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Update on comp housing mods for V2 inlet pipe systems >> - 
