| Quite a bit of really good info found this morning at the flowbench and some additional calculated information regarding flow demands of the inlet system. First off, here are the flow results for the stock turbo inlet pipes vs. the parts that were built yesterday. OEMID = OEM Inlet Driver
OEMIP = OEM Inlet Passenger
ASHID = AshSPEC Inlet Driver
ASHIP = AshSPEC Inlet Passenger
The results were a little better than I expected but pretty close. 8.3% improvement on the driver inlet and a 15% impovement on the passenger side. What I'm happiest with is the consistency between our two inlet pipes at only 3.2% difference compared to the stock at 9.1%. The passenger side turbo has to work that much harder just to make the same boost pressure! :-O I also took the opportunity to flowtest the entire OEM inlet system from the filter pipes to the turbo inlet flange as seen below. The turbo inlet pipes are just one part of the induction system and the results show that replacing just the turbo inlets wont get you all the way to better flow. Flowtest results of the COMPLETE inlet system:
 
Additionally, the stock accordion pipes flowed 391.8CFM. I am sure this can be improved upon with mandrel bent 2.5" tubing, however, the real question is how much more of a benefit will it be to go to a 3" accordion replacement as well as 3" for the filter pipes that run underneath the headlamps.
Ive also taken the opportunity to put together a CFM flow chart for the turbo feed system relative to engine RPM and boost pressure. As I mentioned yesterday, there is significantly more air volume moving through the inlet pipes than through the charge pipes when boosting. This chart below shows the relationship between these points:
The lowest blue plot shows the engine CFM dependent on the engine RPM. This is pretty much a fixed figure regardless of what boost pressure you are running since the engine itself controls the volumetric flow of air. Volumetric efficiency not included in this of course, but this plot gives us a good ballpark metric to compare to. The other three plots are showing what the volume of flow must be through the inlet pipes in order to supply the engine with a given mass of air, which is dependent on the boost pressure and RPM. Looking back at the OEM inlet pipe total system flow numbers, 301.6 + 282.9 = 584.5CFM total for both sides. At 1bar of boost pressure you're already at 1psi of pressure drop in the OEM inlet pipes around 5500RPM. At 18psi this pressure drop is occuring by ~4800RPM and even earlier at higher boost pressures. At 29psi of boost pressure you will have several psi of pressure drop through the OEM inlet pipes in the higher revs. Just looking at these calculated figures and seeing how limited the stock inlet pipe system is as a whole shows there is a lot of room for improvement. In fact, even going to a full 2.5" inlet pipe system (this is from the filter to the turbo inlet only) isn't going to provide the kind of volume while minimizing losses through pressure drop. Our new inlet pipes have a total combined flow of 796CFM. It would be great to shoot for a 750CFM total flow at 1psi pressure drop but I dont think this will happen using 2.5" accordion replacements and the OEM piping underneath the headlamps to the filters. So, were going to make up our own 2.5" accordion replacements in the next few days as well as replacements for the tubes underneath the headlamps and see what kind of flow numbers we can achieve. I'll also make up a set of 3" accordion replacements as well as some 3" mock-ups for the tubes underneath the headlamps to compare the flow and see if it will be worthwhile to increase the tubing diameters for these parts.
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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Flowtest Results for Turbo Inlet System >>>> - 
