Stage 1 air intake tubes now available.
#101
03-11-2014, 03:53 PM
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Don,
The Jaguar engineers added cambers to tune the sound of the motor, trying to make it sound a certain way without effect performance too much. Back when the X350 came out the were targeting the car toward people who wanted a quiet fast car. The quite part being more important than the performance. With N/A the engine has to breath with atmospheric pressure only so tuning of the intake length, diameter, camber volumes, ect all effect the performance. But with a S/C motor, the less restriction the motor has to breath the better performance.
Its the same with exhaust systems. An N/A motor needs to have well tuned exhaust to manage the air flow. But turbo motors just want to get the exhaust out as quick and easy as possible, for the most part.
The Jaguar engineers added cambers to tune the sound of the motor, trying to make it sound a certain way without effect performance too much. Back when the X350 came out the were targeting the car toward people who wanted a quiet fast car. The quite part being more important than the performance. With N/A the engine has to breath with atmospheric pressure only so tuning of the intake length, diameter, camber volumes, ect all effect the performance. But with a S/C motor, the less restriction the motor has to breath the better performance.
Its the same with exhaust systems. An N/A motor needs to have well tuned exhaust to manage the air flow. But turbo motors just want to get the exhaust out as quick and easy as possible, for the most part.
I'm definitely going to do some more research. There is so much conflicting information available it's sometimes difficult to get beyond assumption and wild guesses to get the full story. We all assume an engine with freer air flow will perform better. That's what makes the design of the XJR intake pipe so curious.
My late father designed water and fuel pumps for an OEM that served the Big Three and some of the Japanese manufacturers, so I grew up around fluid dynamics (my grandfather worked at NASA, so even though I'm not an engineer, it's in my genes). Dad was always surprised at how little real understanding there was among engineers who were designing systems for cars and trucks that were manufactured in huge numbers. He had to write his own computer programs to compensate for manufacturing variations that no engineer at Ford, GM, Chrysler or Toyota could explain.
The stock XJR intake does not look like the result of guesswork or simple sound tuning. Has there been anything published by Jaguar that states that the design objective was limited to keeping the engine quiet, or is this just a generally accepted assumption?
Cheers,
Don
#102
03-11-2014, 05:55 PM
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Okay,
To answer my own question, I checked my copy of the Jaguar Service Training Course NP04, 2004 Model Year, New XJ Technical Introduction manual.
Page 5-15 does state that intake noise at lower speeds and rpms was a concern addressed in the design of the air intake, and it is at least implied that NVH concerns took precedence over ultimate performance.
This is my first attempt to post an image, so hopefully this will work:
Aren't you glad I asked all these questions? I've produced actual Jaguar documentation that would appear to support the benefits of caldoofy's intake!
Now I have to start saving my pennies!
Cheers,
Don
To answer my own question, I checked my copy of the Jaguar Service Training Course NP04, 2004 Model Year, New XJ Technical Introduction manual.
Page 5-15 does state that intake noise at lower speeds and rpms was a concern addressed in the design of the air intake, and it is at least implied that NVH concerns took precedence over ultimate performance.
This is my first attempt to post an image, so hopefully this will work:
Aren't you glad I asked all these questions? I've produced actual Jaguar documentation that would appear to support the benefits of caldoofy's intake!
Now I have to start saving my pennies!
Cheers,
Don
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#103
03-11-2014, 07:17 PM
Don,
Glad you found the info I was searching for and posted it! It follows that the info you have supplied falls in line with general consensus and dyno charts already posted by other members showing that a modest increase in power is achieved when increasing efficiency of this air intake.
As previously stated in a previous reply noise, vibration and harshness (nvh) is of paramount importance to premium brands and can actually take priority over outright performance, the profile of initial purchasers of these vehicles would suggest that having a car as quiet as possible is a very desirable trait.
Interesting to note the comments regarding the air box flap which was recently confirmed by cambo at a rolling road session loosing , if memory serves, around 12 hp when his failed shut and did not open on WOT! So in that instance the engineers designed in a feature that if failed could reduce power output!
I guess the moral is to ensure that equal time is put into researching both sides of an issue and also search on the forum for posts relating to that issue, then you are in a better position to query .
Forced induction engines will always behave differently to naturally aspirated.
Best regards,
John
Glad you found the info I was searching for and posted it! It follows that the info you have supplied falls in line with general consensus and dyno charts already posted by other members showing that a modest increase in power is achieved when increasing efficiency of this air intake.
As previously stated in a previous reply noise, vibration and harshness (nvh) is of paramount importance to premium brands and can actually take priority over outright performance, the profile of initial purchasers of these vehicles would suggest that having a car as quiet as possible is a very desirable trait.
Interesting to note the comments regarding the air box flap which was recently confirmed by cambo at a rolling road session loosing , if memory serves, around 12 hp when his failed shut and did not open on WOT! So in that instance the engineers designed in a feature that if failed could reduce power output!
I guess the moral is to ensure that equal time is put into researching both sides of an issue and also search on the forum for posts relating to that issue, then you are in a better position to query .
Forced induction engines will always behave differently to naturally aspirated.
Best regards,
John
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Don B (03-11-2014)
#104
03-11-2014, 08:57 PM
Interesting to note the comments regarding the air box flap which was recently confirmed by cambo at a rolling road session loosing , if memory serves, around 12 hp when his failed shut and did not open on WOT! So in that instance the engineers designed in a feature that if failed could reduce power output!
#105
03-11-2014, 10:55 PM
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Yes, and believe me you could feel the difference with the flap jammed shut! More info in the thread here https://www.jaguarforums.com/forum/x...25/#post870950
Very interesting that you actually experienced the power decline when the flap failed to open, and that this phenomenon was actually documented in the Jagaur new model introduction training manual for service techs. Usually we owner-mechanics have to discover those things on our own.
Cheers,
Don
#106
04-15-2014, 10:41 PM
Veteran Member
On Twin Helix/Roots type superchargers any restriction before the supercharger will reduce performance. It' not a compressor but an air mover. Twin screws compress. I'm just getting into the jaguar xjr performance mod scene with my 2004 xjr however I have a ton of experience with both m90/m112 blowers in ford applications as well as twin screw applications. I'm an engineer by trade but have fun with cars as a hobby. Most all OEM air intakes compromise performance a tad (or a lot) for reduction in noise. Its not rocket science that this intake will make power (as well as increase noise) Being I'm new and all...I guess I have a few questions pertaining to the air intake. Have different sized tubing been experimented with on the 2004 xjr? I guess you will be limited by the restriction of the cast inlet piece (which I cant seem to find a photo of off the car or dimensions) I'm really interested however to know what the stage II kit will be as Id be pretty interested in that for sure. Just some FYI. When I was playing with the little m90 on fords 3.8 v6 the factory air intake, SC inlet, TB and MAF were all restrictive on a stock motor. For a long time it was thought that a 3.5" intake, 85mm MAF and 85MM TB with enlarged SC inlet was enough. Well more performance was extracted enlarging SC inlet yet further, adding a 95MM MAF with a 4" air intake along with a slot type MAF within the 4" tube with highly modified engines or twin screw retrofits.....THATS WITH AN M90 and a v6! I have so many question but don't want to highjack the thread. Anyway for anyone questioning this intake...It is going to work, and appears to be a quality piece as many have said. Look forward to the stage 2!
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#107
05-09-2014, 02:20 PM
Junior Member
I own an '06 XJR and am interested in changing out to your intake system. My friend Mike (aka Mike in Tennessee) purchased and installed this and it works and looks great. I am prepared to use this reply to order the Stage 1 intake tube in black. What would the cost be at present and I can pay through PayPal. Thanks Jim (halstead1948)
#109
05-29-2014, 04:28 PM
#115
09-12-2014, 11:02 PM
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#117
10-08-2014, 07:39 PM
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#119
11-22-2014, 10:43 PM
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caldoofy (11-23-2014)
#120
11-22-2014, 11:51 PM
Veteran Member
Well I dynoed my 2004 xjr stock and it produced 312 at the rear wheels. I now have this intake and the mina gallery filter with heat sheild and a custom cold air intake using the stock scoop. I can tell you the car feels much faster however I am dynoing it again next weekend. Im then installing a tune and an SC pulley and re-dynoing again. Interested to see the results. Any restriction before the SC inlet will reduce performance. That factory air box has got to be a restriction not to mention the inlet myself
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caldoofy (11-23-2014)
