G37 OEM Airbox mod

[PG37]

Hi all, my first post here. During test drives looking for my G37 I came across a G35 that had an injen installed and it sounded incredible! I'm looking to replicate that on my G37. I've noticed that mid throttle/mid rpm my G37 sounds awesome with a nice low frequency sound to the exhaust/engine note, but at full throttle the rasp really comes through and you lose some of that nice low frequency sound. From past experience with VTEC's I know that a conical intake really comes to life at those high rpm's, but is really barely noticeable at low rpm's and not at full throttle.

After doing some research I've noticed that the factory airbox is more than enough at stock power levels and is actually quite well designed (even though it doesn't have a velocity stack built in).

I'm wondering if anyone has done or has considered either enlarging the intake hole on the factory airbox or cutting off the whole front of the factory airbox to help get some of that sound. Doing some of my own "sound" tests I've noticed that just there is additional low frequency sound even just removing the the air filter and opening up that slot. (my test involved me removing the airbox and basically using my mouth to create a low frequency sound through the air intake, not running the car without a filter, just FYI)

The theory seems sound, but I figured I wasn't the first person to think of doing this, so I'd rather see if anyone else tried it already to see what their experience was. It seems like it would be good to keep the factory air filter/maf housing intact, and it seems like the intake would still mostly be shielded from heat.


Modified by PG37 at 8:32 AM 2/20/2009

[pfarmer]

Hi all, my first post here. During test drives looking for my G37 I came across a G35 that had an injen installed and it sounded incredible! I'm looking to replicate that on my G37. I've noticed that mid throttle/mid rpm my G37 sounds awesome with a nice low frequency sound to the exhaust/engine note, but at full throttle the rasp really comes through and you lose some of that nice low frequency sound. From past experience with VTEC's I know that a conical intake really comes to life at those high rpm's, but is really barely noticeable at low rpm's and not at full throttle.

If simply going for the sound I would hang a speaker ot the bottom of the car and play sounds based on throttle position.

Perry

[audtatious]

You can try a GAB mod (ghetto air box). Similar to this:

http://www.nicoclub.com/articles.php?id=157750

[PG37]

If simply going for the sound I would hang a speaker ot the bottom of the car and play sounds based on throttle position.

Perry

Hmmm.... not that helpful. It may seem weird to you that I am only asking about sound, but I'm sure you agree the VQ engine emits some beautiful sounds. I have already read numerous posts and blogs stating that the most you can hope for on a VQ engine is that an aftermarket air intake doesn't cause power loss due to heat soak. I don't plan on heavily modding the car at this point, so I was thinking of ways to open up the intake tract without screweing with the air/fuel ratios.

[PG37]

You can try a GAB mod (ghetto air box). Similar to this:

http://www.nicoclub.com/articles.php?id=157750

That's not bad, at least for sound testing purposes. I suppose if it helps the sound I could then decide to cut out the front portion of my box.

If I knew a Stillen or Pop-Charger wouldn't get heat soaked and lose power I would just buy one of those, but at this point I don't have a lot of faith in their ability to make solid power gains when the engine gets hot.

[TeflonG35]

Yeah....Don't use a hanger on a g37....Just throwing that out there. It's bad enough My fan is hooked to a switch. Lol. It's good for when I'm at the track though. I can have the car off, The hood up and the fan on.

[PG37]

Yeah....Don't use a hanger on a g37....Just throwing that out there. It's bad enough My fan is hooked to a switch. Lol. It's good for when I'm at the track though. I can have the car off, The hood up and the fan on.

Yeah, I was looking at the filter and it doesn't seem to lend itself well to this, even for testing. I wouldn't want to lose the seal on the filter even for 5 seconds. I'd rather just cut a hole in the box and buy a new one for $90 if it turns out sucking. Sucking in a bad way that is. I just can't imagine why it would have any negative side effects to hack off the front of it. The factory intake track to the MAF would still be intact, as a matter of fact everything after the air filter element would still be factory. It would just open up the air filter from being a little 4" hole to being something like 8 or 10". I don't think those little dinky resonators that are hanging off of our intake pipes by the throttle body are really reducing the sound that much...

[audtatious]

I ran without the filter while drag racing and it had an awesome sound without the filter and the panel holder blocking the intakes.

[pfarmer]

Hmmm.... not that helpful. It may seem weird to you that I am only asking about sound, but I'm sure you agree the VQ engine emits some beautiful sounds. I have already read numerous posts and blogs stating that the most you can hope for on a VQ engine is that an aftermarket air intake doesn't cause power loss due to heat soak. I don't plan on heavily modding the car at this point, so I was thinking of ways to open up the intake tract without screweing with the air/fuel ratios.

Basically I was sort of poking fun at those that go for just 'sound'. I find that my 08 35 xs can blow the doors off of nearly any of the noise makers I encounter with the big pipes hanging three feet off their rear bumpers.

Also a lot of those that go for sound will actually see a decrease in performance, if no where else then in the places where most of their driving is actually done.

I like how mine sounds now (in fact one reason I purchased it), but I would not be against a little extra performance and if a beautiful sound came with it great. On the other hand if I got a 100 hp boost and a decrease in sound, I would probably go with that sound of power as well.

One article on a special type of hybrid for example illustrates this point. Consider a car with a 100 hp engine that could take the car to 100 mph. Now doesn't sound like much performance does it (but does cover most driving situations)?

However consider that while driving normally this engine is far more than enough to keep the car rolling and charges a super capacitor at the same time (no banks of heavy batteries). When you stomp on the gas, this discharges through a 300 hp electric motor and you now have a top speed in the same general area as what we have now. The negative is that what goes up has to come down.

Now before we make judgements and state, well there are a lot of gas powered 400 hp vehicles, keep in mind that an electric motor typically starts out with maximum torque. The byproduct here is that if the gas engine is not topped out at this point that the noise level may go down (except for the wind rushing rapidly by).

I'll probably never own one of these 'special hybrids', but the concept fascinates me and like I stated above, if you can add lots of performance and you get better sound, so be it, if you actually get a decrease in sound, well now the 'Sound of Silence' could be very nice indeed.

Perry

[PG37]

I've never changed the exhaust on any my cars and I probably never will. This car in particular came from the factory with a beautiful exhaust note. I've heard some custom setups that sound amazing, but at what cost? I, like you, don't like the loud fart can cars, or the raspy test pipe exhaust notes that I hear all the time, and I also make fun of them. The thing I have always liked about the exhaust note is that the amount of noise coming out is throttle dependent. If you are driving around at partial throttle as usual, then you would never know a car has an air intake, but floor it and run it up to 7500 rpm and it emits a beautiful sound (well some cars do).

As for the power loss in the mid range, this would only come if you changed the diameter of the piping or changed the intake air temps. The whole point of me wanting to use the OEM airbox is that it would actually not be changing anything once the air hits the filter. The OEM filters are usually designed to smooth out the air as it approaches the MAF. Keeping the stock setup would keep this at factory settings.

[PG37]

wow. not a very high post rate in here... I haven't checked this in a long time and I'm still on the first page.

[audtatious]

Not as many G37 owners posting. The older G35's have lowered in cost to the point that more people are getting them who could not initially afford them which means more '35 owners.

[PG37]

In other words people were smart and waited until the price dropped below 28k, unlike me who will spend 20K in depreciation alone in 39 months. I'm depressed now, time to got driving to cheer up.

[audtatious]

Probably. The G35 prices dropped more when the '37 came out.

FWIW, the Stillen intake system seems to be rating pretty well. I've seen some dyno's that look promising.