You can hear a decent amount of intake noise with a GAB. Not like an open filter but definitely an improvement over stock. You can hear how it sounds on my car:

http://www.youtube.com/watch?v=xh00y41HwxY

 

that's not bad! im running right now with the snorkus(?) from the grille off. gave a little bit more sound.

here's how my contour sounded with a cut airbox:

you need some volume, the mic isnt very good in this old camera

http://www.youtube.com/watch?v=K3Bt1flGHC8

 

Yeah, I had a GAB'd airbox for 2 years and loved it. I just recently moved to a JWT setup and I love it even more! But GAB is the best bang for your buck, there's no doubt about that.

 

very true. def a good *free!!* stepping stone to a full sri or cai.

 

Fluid dynamics it is! A jet engine has intake, compression, power and exhaust as well....it the same process different procedure.....but air and fuel is being used cause they're both internal combustion engine but of different types!!!! The higher the air velocity thru airfilter/bellmouth the more power! Wish I had a Ram Air designed hood and a nice heatshielded intake, it would really scream! But I'm just being informative, it's your car and your choice, I'm happy with my $100 setup and I've tried many different setups....

Injen


SRI #1


Hybrid SRI

 

What looks like a "bellmouth" on the smaller AEM filter actually isn't. I own both a 6" AEM filter with a velocity stack, and a regular 3" AEM filter.

That bellmouth shape that's molded to the 3" filter is only on the outside for appearance. Inside, there's nothing but sharp corners.

This is the purpose of a velocity stack:



The VS allows for a more even, smooth flow of air into the engine. In other words, it decreases turbulent air flow, which could create pockets of stalled air, (and potentially vacuums) within the filter housing, which would in turn, destabilize the air flow of the entire intake/filter setup.

 

The venturi effect makes use of the laws of fluid dynamics. For gases in motion, the amount of flow is constant at the inlet and outlet. This means the cross sectional area of the inlet/outlet determines flow velocity. Bernoulli’s equation tells us that the total pressure must remain the same at the inlet and outlet. However, the equations of continuity tell us that the dynamic pressure increases with air velocity. Therefore:

Ps1+Pd1= Pt =Ps2+Pd2

Ps = Static pressure
Pd = Dynamic pressure
Pt = Total pressure
(1 and 2 denote the entrance and exit of the pipe)

The equation of continuity also tells us that the dynamic pressure increases with air velocity.

Dynamic pressure = ½ (p) V2
P = air density (constant)
V = Velocity.

This means that static pressure must go up when flow velocities drop and cross sectional area is larger. This seems counter intuitive, but here lies the fun of fluid dynamics. Basically said; the larger entrance to smaller exit of the venturi stack takes full advantage of this principle to increase the velocity of the intake charge, as well as smoothing the airflow along the way.

 

nicely said, and completely correct. it just seems like all that smoothing of the air is in vain when it slams to a halt at the intake valves. in (slow air moving) car engines, its not how fast, its how much. it honestly doesn't care. and without a compressor the motor is gonna have no problem sucking in the tiny amount of air it needs, whether its smoothed for the first few inches (as the intake tract tears it up immediately) or all jumbled for those first few inches. its just seems futile to me.

make one of these to go after the intake valve, ill buy 6


cmax, i like that hybrid. isn't there a way we can delete that last resonator?

 

Physics FTW?

Or fluid thermodynamics?

Either way, I'm looking forward to studying this stuff.

 

Something has to be there for the breather on the rocker cover, or you blow oil all over the place

 

If anyone's looking to pinch pennies and buy a cheap, cheap SRI kit, here:

http://www.cosmoracing.com/productin...d=232&pid=1368

It has everything you need. Although I will say this: I bought the CosmoRacing CAI about two years ago, and while the kit worked, the filter it came with was junk, and the couplers seem to be made of some kind of weak silicone and will eventually need replacing.

I converted my kit into a custom SRI setup, and also replaced the filter with an AEM Dryflow and one of the couplers with an AutoZone special coupler...works just fine.

But at any rate, this will give you your midpipe and MAF adapter...although the MAF adapter looks like it may be made out of plastic...which, IMO, probably isn't best.

The CAI setup I bought came with an aluminum adapter.

 

It doesn't actually halt when it hits the valves, though. When it slams into the intake valve, a pressure wave is reflected back, then hits the valve again (oscillating). Helmholtz resonance is the specific term for the effect. Some intake manifolds are actually designed to take advantage of it during several RPM ranges. Runner length and plenum volume are the main contributors.

Regardless, having an efficient intake setup can make a huge difference as the reflection at the valve isn't enough to make it all worthless. I will hopefully be using a few different common intake setups vs an intake setup based on some of these fun physics concepts on the dyno sometime in the spring, probably in conjunction with a SSIM and high RPMs. Really interested to see how much of a difference can be made with just intake changes.

 

Well actually it causes a vacuum leak unless you also disconnect the breather from the other valve cover on the back of the IM. Both of mine are disconnected with a filter on them, and they do both drip a small amount of oil from time to time if I don't keep the filter clean, it usually just builds up in the filter. Going to have to come up with some kind of catch can for each of them.

 

i never understood either, stock box here

 

BPI velocity stack + AEM dry flow filter, a few couplers, and couple pieces of pipe... good to go.

 

sparks, what kind of piping is that?

I was thinking about moving my battery over and doing something similar, but I couldn't find the proper piping anywhere.

 

That is 3" exhaust piping. My current intake is all 2.87" or so, same size as the MAF.

Going to be using samco silicone stuff for my next intake, though

 

thanks for the cosmo link, brett. and yeah, you can seldom run the sh!tty stock filter they provide :/

sparks, that all black intake is FIRE! was it easy to move the battery over?

 

I had to build a custom battery tray and make brackets. Just takes being a bit creative.

edit: the reason I did that is because I still have my CAI hole opened up there, and fresh/cool air comes in through the lower grill opening
.

 

How exactly did you build it? I'd swear I've seen a few how-to's on relocating the battery tray either the way you have it, or sideways like another member has.

 

I used a summit aluminum battery tray and made some brackets to hold it up.

 

I was under the impression that the spot where the little filter is has positive pressure, which will not cause a vacuum leak. Putting a straight pipe on behind the maf, or hooking the MAF to the TB will not cause a vacuum leak. You will blow oil out where you have the little filter.

 

The 2 valve covers are connected, and there is another vent that goes into the back of the intake manifold from the rear valve cover. What this means is that if you only disconnect one side from the IM and put a filter on it, it will effectively be a vacuum leak. You can easily test it by taping a mostly inflated plastic bag over the nipple then starting the car... That is why you either disconnect both or neither. I have both disconnected and it doesn't blow oil out of the filter with any force, just slowly drips into it.

 

that doesn;t make sense. The exit from the cover goes to the pipe in the intake just in front of the TB. In front of the TB is a vacuum, air is being sucked into the TB. Air cannot be sucked into the valve cover and the intake at the same time when they are connected together. The exit from the valve cover probably has light positive pressure, and the intake side acts as a vacuum



The flow follows the green arrows, you are saying it follows the white arrows...

 

that appears to be the PCV. that hose is SUPPLY. there is no vacuum on that hose. the vacuum would be on a hose coming from the intake manifold

 

There was around a 6 month period where I would have agreed with you whole heartedly, while constantly searching for my mystery vacuum leak that I could never figure out... In stock form, the 2 valve covers are connected to each other by a hose and each valve cover also has a breather connected to the intake manifold. One of them hooks up right next to the brake booster on the elbow, the other on the front where your pretty little illustration tells me how wrong I am. Eventually someone will show up with a FSM diagram or something... If you disconnect one but not the other, the second one will cause a vacuum leak. If you wonder how I know, it's because I finally found my vacuum leak and haven't had a single problem since I also disconnected the breather on the back of the IM and capped it.

shdwonthsun knows what's up.

 

Now to derail the thread:

I need sprint boosters. 2 of them. And knight_yyz, I need them by tonight.

 

It doesn't just slam into the intake valve will it shuts.....Initially it flows thru the intake right out the exhaust during valve overlap (headers and a performance exhaust aid in the scavange effect at this point)the faster the exhaust leaves the faster the intake charge will be enter, due to the momentum and scavenging down stream! Decreasing the restriction on the intake side with aid of a larger free flowing air fliter and Velocity stack just makes things a lot easier in building up the velocity and fluid momentum! Oh yeah I don't want to hear too much growling and the throttle seems more linear with the Helmhotz resonator, so It'll stay for the time being until I make My own midpipe or buy one from Knight

 

You should also get a sprint booster from knight! It will increase your low throttle performance!

 

This is from a 350Z FSM, but our PCV system is identical. Notice the flow pattern....

 

Same ole line ! It's time for something new....Sparks!

 

There's nothing wrong with you wanting exhilarating, gut wrenching low throttle performance nor is there anything wrong with me making fun of you for it!

 

but the pcv valve is on the other valve cover at the back. Where you put your dinky filter is just an opening. There is no pcv valve.



pcv is circled, the brown line reps the hose from rocker to rocker, the two arrows vent to the intake manifold and is under vacuum.... your dinky air filter is nowhere near the pcv

 

bty , bend over and I'll show you where you can stick the damn sprint booster.

 

MY fun factor is excellent Part throttle response unless you drive around a HighBanked Oval @ WOT going to work or whatever! I live in the real world and I'm not saying I don't like WOT...That I do!!!!!! but rolling into the throttle and having the engine respond with excellent driveability is something I love....I Hate sluggish, non-crisp engine response!!!!

 

The point is that unmetered air is drawn in through the filter and goes out the PCV valve into the rear of the intake manifold if it's not connected to the intake, creating a vacuum leak. In stock form, it's only metered air that is pulled through the engine and goes into the back of the IM through the PCV.

 

It's somewhat difficult to increase performance and simultaneously decrease responsiveness. I aim for the best high midrange/topend powerband, but that certainly doesn't mean that it's not responsive when rolling into the throttle.

edit: oh and sprint booster would not only remove any lag in your response, but would also make 20% throttle feel more like 30% throttle and 70% more like 100%, meaning MORE POWA!!!!

 

The love.

I can feel it.

 

I went with a berk with the AEM but now it seems that the JWT could have done almost the same thing for a bit less cash.

 

this whole thread is so informative, also very confusing. Seems like everyone is talking about different ways this vacuum thing works. I'll just stick to my stolen Altima Nismo intake that was in my Sentra b4 i wrecked her.