2nd Gen stock ported air box. Check it out!

[scottyaurorav8]

A dremel, a little patience and there it is. LOL. Took about 2 hours, but I knocked out that waffle pattern inside and I hafta say, it does accelerate better/smoother than before. Figured id try for every little bit of gain possible since theres not much we can do to thee cars. What do you guys think?
Too bad we couldnt port out the center piece in the MAF....hmmmm....thats a huge restriction. Be nice if it was just the metal wire straight across without that big plastic piece :/

Attachments:

[lanceslambos]

lol you can cut out the maf screen if you wish. i did.

[scottyaurorav8]

No not the screen, im talking about that huge plastic divider right smack in the center of the MAF, behind the screen. Looks like the reader wires go into it so it wouldnt be possible, I dunno. But knocking that out would allow for more flow im sure. Do the wires connect through it or just to it?

[poofables]

May 27, 2012 6:59:57 GMT -6 scottyaurorav8 said:

No not the screen, im talking about that huge plastic divider right smack in the center of the MAF, behind the screen. Looks like the reader wires go into it so it wouldnt be possible, I dunno. But knocking that out would allow for more flow im sure. Do the wires connect through it or just to it?

I haven't looked that hard at our MAF, but typical GM MAF has the wire going right through the center.

[scottyaurorav8]

Well if thats the case, I am going to knock out the center with a dremel then and be really really careful once I get near the wires. I've had MAF's where the inside is just wires across without a big plastic center piece restricting flow.

[Aurora40]

You might update the title to "ported airbox". It sounds like you ported the intake manifold.

The waffling on the surface of the airbox is likely just to reduce whistling, etc. I doubt it creates any restrictions to flow. You could cut down the separator between the two chambers, that pipe between them doesn't seem super large. But I can't prove that really makes a difference either.

[sall]

There used to be a dyno before and after with airbox gut and K&N drop-in panel filter on the Classic on dred98's website. IIRC it was about 7 HP gain. However, dred98s website is no longer up. I thought I reposted the info here awhile ago but cannot find it. I don't know what the waffling was for exactly but the resonator is what cuts down on noise.

[lanceslambos]

Jun 9, 2012 18:16:15 GMT -6 sall said:

There used to be a dyno before and after with airbox gut and K&N drop-in panel filter on the Classic on dred98's website. IIRC it was about 7 HP gain. However, dred98s website is no longer up. I thought I reposted the info here awhile ago but cannot find it. I don't know what the waffling was for exactly but the resonator is what cuts down on noise.

yes it does and it also holds warmer engine heated air for easier starts in wintertime like in stop and go situations

[poofables]

Jun 7, 2012 18:03:30 GMT -6 scottyaurorav8 said:

Well if thats the case, I am going to knock out the center with a dremel then and be really really careful once I get near the wires. I've had MAF's where the inside is just wires across without a big plastic center piece restricting flow.

Shouldn't be an issue, though it could be set to read the air volume knowing that the piece is there and be compensating for it. Might not. Only one way to find out. Scan tool with and with out it in place.

[scottyaurorav8]

Poofables, I did a google search on that and your right. It was programmed for the center divider, removing it would lean the car out, unless you get a MAF-T / mini AFC to adjust it but im not sure if you could use something like that, could you?

[schlotzky]

Jun 9, 2012 18:16:15 GMT -6 sall said:

There used to be a dyno before and after with airbox gut and K&N drop-in panel filter on the Classic on dred98's website. IIRC it was about 7 HP gain. However, dred98s website is no longer up. I thought I reposted the info here awhile ago but cannot find it. I don't know what the waffling was for exactly but the resonator is what cuts down on noise.

I had saved the text before the site went down. Unfortunately I didn't save the pictures or dyno charts.

Aurora 4.0 Northstar - K&N Filter & Air Box Mods
By Greg Garnes
I drive a 1998 Aurora, with the 4.0L Northstar engine and 4T80e transmission. This article documents improvements to be gained by use of the K&N panel filter, details air box modifications I have performed, and documents improvement from modifying the stock air box.
Air Box Mods: The modification to the air box was to remove the plastic insert in the bottom of the air box. I believe it is there for sound reduction. I then used a dremmel tool (wear goggles!) to cut the plastic hole in the bottom of the air box larger to match the existing hole in the metal under the air box. Next, I removed the inner plastic liner from the top of the air box (again this is for sound reduction). Then I just installed the air box with a K&N filter.
How I tested: The tests consisted of one with the stock air box (a spare) with a new paper filter, a second test with the stock air box with a new K&N filter, and a third test with the modified air box with the new K&N. A fourth run confirmed the results of the third run. The tests were on a chassis dyno, so the power is at the wheels.
________________________________________
• Stock airbox and paper filter vs. K&N drop-in panel filter:
Stock versus K&N Panel filter
• Stock air box with new paper filter: (Blue line) 189 HP, 204 ft-lbs torque.
• K&N panel filter alone: (Red line) +7 peak HP, +4 peak torque. Gains of 3 to 4 HP throughout curve past 4,000 rpm. Gains of up to 7 ft-lbs in the 5,300 to 5,760 rpm range.
________________________________________
• K&N Panel Filter vs. K&N Panel Filter and Airbox Mods: K&N panel filter vs K&N panel filter & airbox mods
• Modified air box with K&N panel filter: +1 peak HP (at best), +3 ft-lbs peak torque. Gains of 6 HP from 4,600 to 4,900 rpm, plus gains of 2 to 3 HP throughout much of the HP curve. Gains of up to 8 ft-lbs of torque from about 4,640 to 4870. Past 5200, no additional torque. (Ignore the Max torque reading on the upper right corner of the graph. For some reason, it seems to be using the HP graph against the torque curve.)
Total gain: +8 peak HP, +7 peak torque. The surprising bonus was how much the air box mods fattened up both curves and added considerable area under the curve. The total gain in the torque seems to be as much as +10 in that 4,640 to 4,870 range and as a result, also extended the peak torque (or near peak) out through this rpm range.
________________________________________
RPM through the gears
Stock filter and airbox vs K&N Filter and Airbox mods: Horsepower
________________________________________
RPM through the gears
Stock filter and airbox vs K&N Filter and Airbox mods: Torque
________________________________________
I highly recommend making these modifications to any Northstar engine. I believe the Aurora 4.0 (mine is a 98) and the Caddy 4.6 are virtually the same except that the 4.0 has a smaller bore. I also believe the layout under the hood to be very much the same. My experience is no extra noise / almost no noise for around town driving, and no extra noise on the highway. You get a nice throaty sound when punching it. My Aurora (when stock) pulls air from behind the front fender. Now I am pulling it from there and the area below the box - which turns out to be the same air as behind the fender. The air is separated from the engine compartment and is cool and fresh. In addition, I've run some tests with 2 different paper filters driving in the rain and have not yet found any considerable increase of wetness on the filter. I do carry an extra stock air box just in case for a long highway drive in a down pour, but the modified box will probably do just fine.
I really like to think of having transformed the Aurora from a 250 HP, 260 torque car to 260 HP and 270 torque, with much fatter power curves - all with some really simple improvements.
Future Projects: the opening in the bottom of the box could be made much larger by cutting the metal. Additional improvements would be cutting and filing some cross bracing on the inside of the outer box (on one side they run opposite to the air flow and probably cause turbulence). The sharp edge on the round hole exiting the box could be rounded off a little too.