: Pics of my Prototype CAI Velocity MAF housing before TIG welding

06-28-13, 10:34 AM
I'm putting this prototype together to test a theory of improved performance based on MAF placement in conjunction with a proper velocity stack and the use of materials with low thermal conductivity. Currently on my ATS I have a conventional CAI made from steel which places the MAF (with flow straighteners) in the middle of the intake track length. The cone filter is located just behind the fog light area.

Functionality wise this intake works pretty good. I definitely noticed an increase in power and response, but I think I can do better. Typically when air flows in a round cylinder it does not flow in a laminar (straight line) fashion. Air flows through a cylinder with twist or vortex. This is good because a vortex will increase the air's velocity essentially producing a ram air effect. The problem with this on the current CAI, is that the MAF sensor wants to see laminar airflow in order to register a proper reading. By placing the MAF in the middle of the cylinder, I will have to stop the vortex mid stream and loose the benefit.

Now I made this velocity stack MAF housing which I intend on locating in the area behind the fog light. By placing the MAF at the beginning of the intake with an integrated velocity stack (like the stock airbox), the MAF will see a uniform laminar airflow, register a more accurate reading, and the system will maintain the benefit of a vortex for the entire length of the tube. I am currently sourcing the plug and receptacle for the MAF harness so that I can extend it. I am also building a mandrel to produce the intake tube out of low thermal conductive 5 layer silicone. If it all works out, I will cast the MAF housing and become a forum sponsor. I'll keep you updated on the progress.






06-28-13, 11:01 AM
great info OP, I'd loved to see the whole shabang when you're done.

06-28-13, 01:02 PM
I agree - this is a serious effort. A few thoughts and/or questions that come to my mind:

1) I think it is a relatively safe assumption that with the ATS-V (and perhaps V-Sport) that functional grilles will become available for near the foglight to increase airflow. This obviously risks the intake of water from incoming rain, but a good design will minimize this and reduce risk of sucking in hot air. If those grilles become a "bolt in" part, that could be useful.

2) Changing diameter and length of the duct is going to tweak the velocity - in theory a velocity stack on the turbo would help but my hunch tells me that the stock turbo is honestly just too small to notice a huge difference - but have you managed to get any datalogging in to see what the impact is? Moreso, I don't know how sensitive the MAF is to that sort of thing - my LT1, for example, doesn't rightly care where the MAF is - but I've heard the LTG MAF is a little more sensitive. I haven't played with one on a flowbench though, so I can't say one way or another. I wonder if the current generation of GM MAF sensors has a family of diameters like the LT1/LS1/LS6 era where you could swap them around with minimal tuning impact (also see below).

3) If you're strongly considering having the MAF housing cast (or CNC'd) I'm curious if changing tubing diameter would have any advantage toward flow for those pushing the power up past 400hp - and a larger diameter intake might allow a velocity stack in the turbo or eventually a turbo with a larger compressor inlet - maybe a conversation with BNR/Trifecta to see what their tuning has exposed about the MAF already or if they know of any "functionally similar" sensors in the GM basket?

4) If you cannot source the connectors/plugs/harness for a MAF extension, drop me a line. I have contacts for those parts and can probably get a few sampled out, but it'd take a few weeks.

06-28-13, 01:28 PM
Placing the MAF at the beginning of the track where the air is still laminar effectively minimizes it's obstruction to airflow. The large bell mouth increases airflow transition into the tube by up to 20%. It also serves to minimizes turbulence and induce laminar airflow into the pipe.


Once you have to straighten vortexing air, so that it may flow over the MAF, the only way to minimize the obstruction is a larger cross section. I have made well over 400whp with turbo cars fitted with 3" inlet tubes.


BTW thanks for the offer. I have a contact that supplies GM. If that doesn't work out, I may hit you up.

06-28-13, 02:13 PM
True, moving the MAF is theoretically more ideal - but I can't help but wonder how much sensitivity the MAF and location have, especially after some people were having issues with their intakes. The days of "slap an intake on it" aren't as easy as they used to be!

I'd love to see what airflow increases your intake shows on the stock turbo, and then what a tune will do with it.

Only downside I see is the big gaping hole where the airbox used to be... Lol