[robhersch]

I have found that only Volant offers an alternative to the OEM GM SRX intake system. It seems a bit pricey - although it appears to be a total replacement air intake system which Volant claims to add HP, torque, better mileage, and does not void any warranties - instead of just a replacement air filter unit; and I ask myself if the results are worth the cost?? But, I have yet to find any others, ie K&N or Fram Air Hog type units for the SRX N*.
I offer the following N*air passage data: My 1999 Concours N* has ~ 7.5x10x 1.125 filter (~75 sqin); 1999 Sevilles & newer N* use ~6.375x8.75x1.125 (~55 sqin); 2005 SRX N* uses ~6x9x1.125 (~54 sqin). (Assuming comparable "fin or fold" filter surface area, I would guess that the SRX N* needs ~ 80 sqin to be at least as efficient as my Concours N* which gets ~20% better mileage than my SRX N*; both currently have OEM air filters).
Since both my 1999 Concours @6000 rpm and my 2005 SRX @6500 rpm have nearly identical manifold air intakes ~1.91 in dia with ~11.46 sqin area; what is the required manifold air flow to optimize either efficiency or performance; and are the parameters different??? Is turbulent air flow desired or required?? Does either filter surface area support or affect air flow?? Is less restrictive air flow and/ or filter efficiency an answer???
One reasonable (?) solution to improved fuel mileage appears to be a filter "mounting frame" for the SRX box that would accept the 1999 Concours Fram Air Hog or comparable air filter.
Anyone have any other ideas??
Incidental data: 1999 (w/4spd auto) drive ratios: 3.71/2.84; 2005 SRX (w/5 spd auto) ratios: 3.23/2.42; both vehicles typically driven under similar speeds & conditions.
robhersch

 

[robhersch]

Thanks to GW for the reference; it seems that the test (if/when completed) is for CTS, but may also provide some insight for the N*. I have been considering trying a 1999 Concours air box in my SRX (see above). Any one have comments on this?? Questions are: 1) can the 1999 box be properly connected to the cold air input tube of the SRX??, 2) where should the air flow sensor be located since the locations are different in the two boxes, 3) will the increase from ~54 to ~75 sq in area be of any value?? I believe that both K&N and Fram-Air-Hog filters are readily available (??) for the 1999 Concours.

 

[robhersch]

An update/clarification to my 10/10/05 note above:
Assuming "comparable fin surface area" was WRONG!!; my SRX V8 air filter has 20 folds @ ~4"x1" + 20 folds @ ~4.5"x1" = (80+90)*2 sides =~340 sq in;
my Concours air filter has 71 folds @ 7.375"x1" = ~523*2 sides =~ 1046 sq in;
so instead of a 75:55 ratio more air, the Concours has a 1046:340 ratio more air filter surface than my SRX N* V8 !!
Q?? How/ what effect does this have on the intake air monitoring devices??

 

[robhersch]

To hhsrx & gw & john D,
The CTS "great air intake challenge" has some dyno test graphs that seem to show significant (??) (ie, greater than +5% torque for Volant vs stock) out to ~ 3750 rpm (for the 3.6 CTS), but does this carry over to the 4.6 SRX N*?? or does it imply that one might expect an even greater effect for the N*??
I did remove & inspect my N* stock system; found the intake "snorkle" to be smaller and est it to be more restrictive than the tube from filter box to manifold. Don't believe that a less restrictive Volant could hurt unless the air intake sensor misleads the computer controlling engine parameters.

 

[robhersch]

To John D & hhsrx --
Thanks for the info. I concluded that the 99 Concours air box (~ 75 sq") approach will not fit my Cad-SRX-V8 without significant jerry-rigging, that the Cad-XLR N* uses 2 filters the size of 2000 & newer N*V8 (~ 2 x 55 sq"), and that Volant seems to be the only real after-market option. David at premiertrucks shipped a Volant to me the next day after my phone order. I find the Volant "intake tube" is a bit larger in dia and less restrictive than stock and the cone filter (~ 75+ sq ") has about the same surface area as my 99 Concours filter. My general thought on "intake performance" is that the "manifold design" after the throttle body taken together with cylinder intake timing holds the key to air flow inertia and "intake efficiency" and that the air intake before the throttle body should not be restricted; I believe similarly that exhaust headers and pipes design/ length affect the "exhaust efficiency" and exhaust flow inertia. I have not yet installed the Volant, but plan to do so in a few days. One TBD unknown is the effect of the mass air flow sensor (the Volant uses the stock unit) on the power train computer. I will try to keep good records for "before and after" SRX comparisons under my "typical city and periodic freeway" driving conditions (NOT WOT & NOT JUST 0-60 PERFORMANCE) and I have no plans to experiment with the stock exhaust system.

 

[robhersch]

FYI - Update of my experience on OEM vs CAI on mileage: 2005 N*V8 SRX RWD with tow pkg, no hitch: same driver, same load, mileage calculated from indicated odometer miles and actual premium fuel pumped in:
1) Jan 05-Nov 05 - first 7k miles with oem air filter: hiway 3 RT LA-Las Vegas = 21.294 mpg; average = 14.007 mpg
2) Dec 05-Dec 06 - 2nd 7k miles with Volant CAI: hiway 3 RT LA-Las Vegas = 21.529 mpg; average = 13.987 mpg
NOTE: hiway speeds probably a bit higher on 2nd 7k miles just due to human nature. Hope this helps on decisions.