2009-2013 Cadillac CTS-V Performance Mods Discussion, Airaid before and after Dyno results in Cadillac CTS-V Series Forum - 2009-2013; Alright so I am new the CTS-V forum but I have been on the STS-V one for a few years ...
Alright so I am new the CTS-V forum but I have been on the STS-V one for a few years now and we went through the same 'he said' 'she said' arguing over HP numbers from just doing intake work that seems to pop up on every forum. Some people say that just changing the intake can offer big gains (5-10%) and others say that it is just a simple pressure differential relationship (restriction amount) so the only real benefit is a clean filter vs. a dirty one and if you can truly increase the cross sectional area of the intake. Both can be true depending on the car and the actual answer is very complicated.
I do CFD (computational fluid dynamics) analysis for my company and when it comes to mass flow rate through a pipe there are a variety of factors that have an influence on the overall effciency (pressure, boundary layer formation, Re number, vorticity, resonance, cross sectional pressure distribution, etc). The specific application and conditions determine whether these factors are negligible or not and since we are NOT dealing with a smooth single pipe in the stock intake design I can firmly state that without doing the flow analysis or bench testing it is impossible to approximate the efficiency of the stock intake by simply defining its' pressure restriction. I do find it interesting that the ZL1 camaro which is making almost 30 more hp features a 'dual-inlet' airbox design to remove the need for any resonator plumbing in the intake. I recognize that the ZL1 also has a different exhaust and the power steering is electric which help as well...but I can't help but think that the GM engineers changed the whole intake design for a reason.
All that aside, I can run CFD analysis to show the efficiency of the stock intake system at delivering air to the throttle body compared to any other aftermarket design and estimate the improvements in mass flow if there are any. Does anyone know if existing CAD models are available for the stock design (some companies will upload CAD models which are available to the public but I haven't found any for the LSA)? Or if any of the aftermarkey companies are willing to provide their CAD models? I can run the analysis relatively quickly but getting accurate measurements on the plumbing/airbox is the difficult part.
Your intake system is always going to be most influenced by the 'choke' point in the plumbing....whether that be tb or intake pipe or filter or intake manifold. However, that said, the velocity and pressure profile distribution across the cross sectional area of the throttle body will determine whether that is our choke point on a v with an intake. I don't know how uniform the flow is going into our tb so I can't really answer that question. In aerodynamic terms it comes down to how dirty or clean the airflow is at this location. I'll do some example cfd runs this weekend and post some pics to try to explain.
Wow, there is a lot to air flow I didn't know but very interesting. I would like to see air flow bench tests for every CAI on the market for our cars. I settled on the New Era because of the ram air part of it. Made more HP then the air raid for my car anyways.