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SHIFT_FASTER
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I took the JWT Pop Charger out last week and put the stock airbox back in. If what I posted about the computer compensating for the intake is true, I would probably see a drop in performance at first, then a gradual increase. Keep in mind that so far, this is still a "seat of the pants" test, and I, like everyone else (who isn't deaf) is subject to the placebo effect.

This isn't quite what I noticed though. It seems the stock airbox has a bit more torque when lower than 4000 RPMs, and the JWT has more torque above 4000 RPMs. The stock airbox is smoother. I don't really notice any particular RPMs where there is a lot more power, where-as with the JWT, there were obvious points with more power. With the JWT, there was seemingly more power at ~3000 RPM and ~5000 RPM, with a noticeable jump at 4000 RPM - which is also where the intake system opens up and lets more air in, also drastically increasing the sound of the JWT (placebo effect?)

I did notice though that the power seems to be increasing after the drop I noticed when I first put the stock airbox back in. This could just be me getting used to the difference though. Something to me that indicates some degree of truth to the computer "dialing back" the power increase, is that the JWT seemed much louder the first day or two I had it installed. Once again, this could be just because I got used to it.

I'm still going to do a test (when time permits) of logging the timing advance in addition to other variables, in an attempt to see a difference between the two intakes, caused by the computer adjusting for them. I also have the possibility of doing a 1/4 mile or 1/8 mile drag run with timeslip, so that might show something too.
 

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Hmmm..... It's so hard to determine what's real and what's perceived. I thought the Murano was slow when I first got it, then I realised the lack of shift shock and the engine RPM being independant of speed were both creating this illusion.

I'm really looking forward to seeing what you determine!

I would expect an increase in torque as I've always seen that with an increase in the intake length. (But I forget why, so if anyone can remind me, that would be great! I suspect it has to do with more mass of the air behind the air being sucked into the intake port, but my memory's rusty on this one...)
 

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Discussion Starter #3
jaak said:
I would expect an increase in torque as I've always seen that with an increase in the intake length. (But I forget why, so if anyone can remind me, that would be great! I suspect it has to do with more mass of the air behind the air being sucked into the intake port, but my memory's rusty on this one...)
That sounds about right. But part of it may be the tuning. When the intake valves close, the air in the intake slams against them, then a wave travels back out the intake. It then bounces off the air filter or some other "obstruction", and moves back toward the valves. If the intake length is "tuned" to the particular RPM you're at, then you get the air reaching the intake valves as they open again, and end up with more air in the cylinder.
 

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Hey Tyler, I just pulled off the front part of the air box as an experiment and noticed two things...

1) Immediately, it tended to chirp the tires more than it has in ages. This seemed to go away after a couple of minutes, but I haven't done an extended test. This could also be the tires warming up.

2) It sounds pretty nice when the computer lets it open wide...:D I can understand the attraction of the replacements, as far as the sound goes.

Maybe you'd like to throw that into the performance comparison mix... It's the cheapest mod I know!
 

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SHIFT_FASTER
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Discussion Starter #5
jaak said:
Hey Tyler, I just pulled off the front part of the air box as an experiment and noticed two things...

1) Immediately, it tended to chirp the tires more than it has in ages. This seemed to go away after a couple of minutes, but I haven't done an extended test. This could also be the tires warming up.

2) It sounds pretty nice when the computer lets it open wide...:D I can understand the attraction of the replacements, as far as the sound goes.

Maybe you'd like to throw that into the performance comparison mix... It's the cheapest mod I know!
The thing is, I like the idea that those parts help pressurize the area around the filter once you get up a bit in speed. But really, it's letting more air in, albeit warmer air.
 

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Someone needs to come out with an air duct(8) replacement to allow more cold air in. The inlet is ratter small, should be the full width of the unit.
 

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Yeah, exactly what I was thinking, last night as I was looking at it.

They make it so wide, but half of it's blocked off. I wonder if it's a tough mod, to open it up?
 

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Tyler_Canada said:


The thing is, I like the idea that those parts help pressurize the area around the filter once you get up a bit in speed. But really, it's letting more air in, albeit warmer air.
Well, the interesting thing is it looks like the air has to go through the grille and then up under the hood through where the latch is. While it looks good in concept, there's a gasket along the hood edge, that prevents the air from going directly into the intake from under the hood.

So, I wonder just how good it is... Now if it was opened the full width and then the hood gasket cut out in front of it.... Then maybe it would make a difference.

As it is, I wonder how much pressure at speed, there really is.

However, it is in front of the rad, and it's design is good at keeping anything with mass out. e.g. water, dirt...
 

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Discussion Starter #9
jaak said:


Well, the interesting thing is it looks like the air has to go through the grille and then up under the hood through where the latch is. While it looks good in concept, there's a gasket along the hood edge, that prevents the air from going directly into the intake from under the hood.

So, I wonder just how good it is... Now if it was opened the full width and then the hood gasket cut out in front of it.... Then maybe it would make a difference.

As it is, I wonder how much pressure at speed, there really is.

However, it is in front of the rad, and it's design is good at keeping anything with mass out. e.g. water, dirt...
After you remove the "scoop" part of the intake, is there any opening between the hood and the grill? Thinking from the pop charger perspective, maybe I should remove these parts. The scoop does go into a rather narrow tube before opening up at the airbox.
 

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I saw one once ( a wider air duct inlet) offered for an FX. But can't seem to locate the vendor again. It may have been th folks who kinda offer an exhaust for the Mo out of NY. Paddock?


jaak said:
Yeah, exactly what I was thinking, last night as I was looking at it.

They make it so wide, but half of it's blocked off. I wonder if it's a tough mod, to open it up?
 
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