After seeing all the threads for CAI and "ram" air systems, and seeing the cost of said systems, I took a good look at my 2012 GS stock air intake.

It seems that it would be pretty easy to fab up sides to the stock filter to seal around it, and cut the shroud to allow nothing but air flowing from the front of the car, pulling from in front of the radiator similar to the RamairSS. I doubt much good would come via a ram air effect, but getting away from engine compartment heat has to be good for an increase in performance, without the $400.00+ price tag.

Before I'm flamed for having a $65k car and going cheap, I just haven't see much, other than claims for gains, to justify that kind of money. I do want cooler air to go with my headers, and I understand the stock box on these cars flow all the air the engine needs.

If I thought for one moment, that I would gain 25hp for the money, on top of my headers and tune, I would go for it, but I haven't been convinced by what I've read.

Go....

 

What you are suggesting is what some of us here have done and for the same reason.

 

I did a search and about the only thing I found was some openings cut down by the filter, and a propped shroud.

Did you do one of these, or what I'm looking at, sealing the air box to pull from below? Were your results favorable?

Thanks for the reply.

 

Yes, I cut the shroud and attached an insert to the stock air box inserted into the whole and yes again I am happy.

 

Understand that hot air into the intake will cause timing retard to lose power.

When the car is moving fast enough, there is enough cool air going through the hood/engine bay to keep the air cool going into the engine threw the stock air cleaner, hence not timing pull to lose power.


Short of long drives in stand still traffic, or strip runs where you are sitting with the engine bay cooking, nothing is gained by going CAI.


So again, CAI does not increase stock power, but just holds that power amount if the engine bay gets too hot/hot air into the engine cause timing pull instead. During a dyno run where the hood is open and a fan drive air through the bay to keep it cool, stock or CAI will yield the same HP.

As for the downside of a CIA in a vet, the air is going to be pulled from so low in the car, that you can draw water into the intake to water hydro lock the engine instead. Also to point out, the less amount of air that is drawn through the radiator, the hotter that the engine may run (timing pull again).


So to sum it up, CAI is not a bad thing is thought out correctly (not to draw water into the intake, or divert air that should be going through the radiator into the engine bay around it instead), so long as it needed in the first place: where not enough air is going to be driven through the engine bay to keep it cool in the first place.

 

I opened up the shroud under the stock filter (nice clean rectangular cut) and I fitted some foaming material round it to create some channeling and sealing the top part and part of the side.
It works well imo... a$ dyno feels more responsive, I think I would go for a 102mm throttle body before some induction kit.

I was reading on some independent testing that TB would actually give about 10-12additional rwhp and if I decide to go Boost in the future it will complement ...that way I have not waisted 500bux in some intake with dubious performance gains.

 

[QUOTE=Dano523;1587554385]Understand that hot air into the intake will cause timing retard to lose power.

When the car is moving fast enough, there is enough cool air going through the hood/engine bay to keep the air cool going into the engine threw the stock air cleaner, hence not timing pull to lose power.


This is wishful thinking.

 

I've got a electronic manometer and elec thermometer boxed up somewhere. I think I am going to check the pressure relative to the area in front of the radiator vs the intake area at the intake while driving at different speeds. If I remember right, it will lock a max reading, so I can try different speeds. I'm curious to see if there is a increased pressure at the front of the radiator in addition to the temp difference that this area should show.

If I can find it, I'll do so measurements on pressure and temp and report back on here the results. Interesting to see what happens.

 

In case anyone is interested, I did a little scientific study this afternoon to satisfy my curiosity. I found my Dryer series 475 Mark III digital manometer and ran the tubes in my engine compartment. I had to have the manometer duct taped so I could read it through the windshield since it is old school like me, and doesn't log or save a max reading.

I ran two runs, same road, same time of day, no changes in weather. Car is a 2012 GS A6 with headers being the only perf mod.

I also used a digital thermo hygro that does save min and max. Readings are as follows:

Temperature study

Max temp at inlet to the radiator: 92.3 degrees F.
Max temp inside engine comp at filter inlet: 103.6 degrees F.
Difference of 11.3 deg F. Lower means a true CAI does some good.

Pressure study
Pressure increase across the board at radiator area vs stock filter inlet
30 mph : .50 inches water column
60 mph : 1.53 in. WC
80 mph : 1.78 in. WC
90 mph: 2.10 in. WC

Conclusion: not only is there a temp difference that is substantial with a true CAI that pulls air from in front of the radiator, but the additional pressure increase at higher speeds should help air flow. Of course, your engine is only going to pump air at the limits of its design, but it looks to me that it is worth it to design my own sealed CAI, but it might even justify buying a Vararam or RamairSS.

 

Thanks man. That's some very useful data.

 

Woodstoc, where these road course runs, or strip runs instead.

I ask since you gauge was only giving max difference for what looks like the total run, and if strip runs, then heat soak on the line could be a large contributing part of the math.

As for scope ramming air in at speeds, will agree that any positive pressure over atmospheric pressure alone into the air intake over what the heads can suck in on there own alone, will increase HP.

To Note, on the T/A's, although the scoop opening faced the windshield, the air pressure off the windshield back into the scope not only increased air pressure, but also helps to create a water separator as well. I state this since there is an air dam on the bottom of the Vet that could be used for the same effect (water separator to help prevent hydro lock).

FYI, IAT spark advance correction table that I have on from my own tune, showing about a degree of timing pull between the two extremes of 92.3 and 103.6.

 

Local road, (can't say exactly where, but it is long and straight and the lights are a fair distance apart, nice feeder road onto a tollway).

I thought that sitting at a stoplight may affect the results, so I didn't start the thermometer until I was immediately pulling out from a parking lot, on both runs, and running up an onramp. It is not 100% accurate, as I had to shut the hood, then jump in the car and take off down the feeder road, then of course pulled into another parking lot right off the tollway, no stoplights. Best I could do with my instrument limitations.

I would have thought +10 degrees would equal more than a degree in timing. I'm not worried about hydrolock, I don't drive through water deep enought to cause that. Casual rain would not go throught the grill, take a 90 degree turn up, and then all the way through to the engine. If it was pouring cats and dogs, I might pull over.

 

Forget spending money on a CAI I did it and gained nothing on my 2008 .I did put 2 bolts in front and held open the shrowd and got the same times and mph with the stock air filter as I have with the viraram.

 

Thanks for the input, that is about what I thought might be the case. I thought about fabbing up an enclosure for the stock filter, and opening up the shroud to get the cold air, might look into what you are talking about. Sounds easier.