: SRX N*V8 Intakes



robhersch
10-10-05, 02:50 PM
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

inline6
10-10-05, 04:24 PM
Our SRX is a V6 but the arrangement should be similar. You could go with pvc from the intake to where the current air box is and replace the box with a K&N or equal cone filter. You would probably want to construct some sort of heat shield so only cool air was used.

The stock air filter element is the worst part of the car next to the cheap sunvisors. We went with the Volant due to the much larger filter surface area than stock, the enclosed box to assure only cool intake air like the factory unit, no noise increase and it does not cause any codes to be thrown. We did it at ~2K miles so I cannot definitely say any gains were from the intake or just the car getting broken in.

gottawonder
10-11-05, 07:47 AM
Search "volant" in the caddy forum and you'll find a thread (outside the SRX forum) where some guys are getting ready to do a dyno test with stock vs. Volant vs. a small shop box... it's taken them a few weeks to get all the parts lined up but they're about ready to go. I think the header is 'The great air intake challenge'

GW

robhersch
10-15-05, 10:34 PM
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
10-19-05, 06:44 PM
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??

john d
10-20-05, 12:40 AM
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??

How does the fresh air intake snorkle openings compare?

hhsrx
10-24-05, 04:17 PM
before you spend your money remember that what increases HP decreases torque. it is the low end torque that gives you the perception of speed with accelleration. If you decrease the resistance to airflow and change the intake length and volume you may detrimentally decrease real world performance and perceived performance. The numbers that are given on dyno testing are derived at WOT and most of us do not drive that way. I had a conversation with Steve Dinan while riding in one of his cars. I was ready to drop 1-2 K on mods giving me 28 HP when asked if that would give me a perceptable change in accelertion his answer was no.

robhersch
10-24-05, 06:22 PM
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.

john d
10-24-05, 08:20 PM
to robhersch-
Do you think removing the filter and box for a few timed runs 0 - to whatever against identical 0 - to "same" whatever's with the filter and box connected be a reliable test for evaluating K&N types of aftermarked intake filters? Thanks for the intake snorkle info.

hhsrx
10-26-05, 06:41 PM
having been down this path before i have never felt a difference in performance before other than with a supercharger. when looking at the most restrictive point ask what diameter is the throttle body and mass airmeter. Another point is that GM spend alot more money than the intake manufacturer on drivability testing under all realworld road conditions and load conditions. i doubt the dyno used is as complex as that used on F1 cars that can vary load dynamically at differing throttle positions. Without going into the math and calculation of maximum airflow and airlow velocity the logic that minimal resistance leads to maximal acceleration is wrong. Basically as the engine revs build if airflow is too slow the motor must suck air into the cyclinder. When the intake is slightly more "restictive" the inertia of the airmoving through the intake fills the cylinder a matched rate. This was explained to me by a BMW engineer. The same hold true with exhaust. I once had a race car that lost @10% of its power on dyno when we shortened the tailpipe. restoreing the length returned the power. Lookat old honda F1 car pics and the oddly long exhaust. The tuning of the intake and exhaust are more important than decreasing diameters and peak WOT wide open throttle numbers are not as important as the area under the curves ie peaky curves yield slower accelleration than slightly lower power figures but wide flat curves. Hope this helps

robhersch
11-02-05, 06:47 AM
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
03-05-07, 02:28 AM
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.

PERK
03-05-07, 04:30 PM
1/2 price Volant CAI..for /04 SRX N* $150 , slightly used but looks like new in the box...did not find any appreciable difference in MPG or HP so will let someone else give it a go...please fax 425-337-1503 for photo and shipping details...Perk