So I got bored and installed Stillens intake the other day. Note that I also covered most of the Stillen airbox with heat reflective tape.

Initial impressions: It's kind of a PITA to install and the instructions suck. The sound at WOT is really impressive. Butt dyno really didn't notice any significant change in power.

The data: Here's a simple comparison of the before and after numbers from my Blitz R-VIT. This comparison is not particularly scientific and is only based on observations in my G. Your results may vary.

Stock airbox w/ K&N filter-

Max recorded MAF voltage: 4.44v
Average temp while cruising: 8-12 degrees above ambient temp.
Average temp after WOT run to 60 mph: 10 degrees above ambient.


Stillen's airbox-

Max recorded MAF voltage: 4.48v
Average temp while cruising: 9-11 degrees above ambient temp. (Seemed much more stable)
Average temp after WOT run to 60 mph: 8 degrees above ambient.

Conclusion: The Stillen appears to give a very slight temperature and flow advantage as perceived by the ECU. The sound is almost worth the price of admission. If you're not in it for the sound I'd probably skip this particular mod and stick with the stock airbox w/ K&N filter.

Note: at idle the intake temperature seems to rise much slower than the stock airbox did. Unfortunately I didn't take any baseline measurements with the stock airbox to compare this too.

 

Nice review. To add, I didn't notice any sound different until I put in the ztube. I got a sedan so maybe it's just more quiet.

 

jawjaw,

The coupe and sedan intake air cleaner case and air duct are the same. So, unless you have other mods, the intake sound should be the same.


roneski,

Here's a picture of my modified Stillen CAI and one of it in operation on a cool morning.

Two weeks ago we did another test of my setup against another. The ambient was 74F...the competition was 108F, my IAT = 82F. Test speeds varied from 75mph to double nickel plus. We also did idle tests. Nothing really that much different from the original tests we posted a while back.


DaveO

 

Are you running a different cone filter? I think that mine has the big metal disk that has the Stillen stamp on the front. If so where did you get it? I wouldn't mind giving it a try to see if the results change any.

I'm not sure about where the ECU takes the intake temp at. I figure that it must be further down the line which would explain the slight differences in our results. I of course am assuming that the Techtom is using it's own sensor.

 

I can't help but wonder if the slight temp. improvements were more a result of the reflective heat tape than the Stillen box itself. What's your gut-feeling on this?

 

I agree with that. In my opinion there isn't any appreciable difference between the temperature transfer characteristics of the Stillen and oem airbox.

 

I'm currently using the JWT Popcharger air filter. I like the Stillen heat enclosue and the JWT open end filter design. The velocity rings are the same.

The IAT Sensor is located in/with the Mass Air Flow sensor. The same place on both of our cars and all (?) other G35s . The TechTom reads the same points from the same senor outout signal that the ECM "sees". Mass Air Flow is displayed in volts, the intake air temp in degrees F.

The reason for my original post was to support your findings. Yes, your's are somewhat different, but that's to be expected. Our test results were posted on G35Driver a long time ago.


DaveO

 

I removed the power duct and have a Z tube and removed the catch can below the airbox and got a 4.94 or 4.95 reading once. I thing DAVEO has pointed out in the past that hotter air gets into the tube with the power duct off so the results may be offset.

 

I'm seeing 4.90s with Power Duct removed/Z-pipe. I've also logged 10 degrees higher intake temps at a stop in warm weather. Once rolling, I've measured no real change between the cover off or stock.

 

I also have a H-line on my under-hood that helps keep hot air from coming into that area which has a cut out in the liner to snug fit over the box and the rubber seal. I can't test it as I cant take it off but I'd bet it helps some in keeping the hotter air away from box. The liner it self probably contributes to heat soak as it reflects everything (heat/sound) back down into the engine compartment.