Let's talk air filters & air intakes and how they affect an engines tune..

[Hart_Rod]

K&N? Spectre? AEM?

What do you have and why are you using it?

What about air intake tubing? 3"? 4" straight? bends?

I bring this up because I never realized the drastic affect that changing the air intake tube and the air filter would have on how the motor AND transmission runs.......!!!!!! I was using a temporary K&N setup on my LS3 in my 68 and had the motor/tranny tuned pretty well. I finally got around to building a cold air intake for it and used a Spectre filter due to size of the box. After getting everything built, I did a test run on and could not believe the difference it made in the truck!! All the fuel trims were messed up, the transmission was shifting all weird, looks like everything we did to the tune was wrong and needs to be done again! Gen IV's are very particular to airflow, and I knew that changing the intake setup up would require some fine tuning, but not to the extent that it did. What do you guys think has the most affect on the engine, the shape of the air intake or the filter you put on? Just thought I would bring this up to generate some discussion and remind people to make sure they finish up the intake setup prior to any tuning.

Here's pictures of what I had initially and the cold air intake I built. Fire away!!!!

[truckdude239]

i wouldn;t think that would make that much diifereance

[Indian113]

I would think that the colder the air the denser it becomes. I have a spectre and I'm very happy with it. I did use it from the beginning and my motor is tuned for it.

[71chevystep4x4]

Hell if I know, but your engine is BADASS!!!!

[Andy4639]

I will say this about a air setup.

Pulling air from under the hood isn't a cold air setup.
What I mean is a open filter on the end of a tube behind the headlight isn't going to change much from just a filter on the throttle body. The air that it does pull in is going to be hot engine air more than cool fresh air. Even the ones with the little side panels aren't going to gain you anything. The air will come from the least restricted area of the engine compartment which in turn is going to be hot air.

This is what I'm speaking of. This is worthless as far as gaining you anything other than the cool factor!




Here is my setup, and I have been thinking about swapping the plastic tubing for some regular metal tubing for under the hood temp reasons. I built this myself with a 94 Caddy airbox with one 4" ninty and 2 4" couplings from Lowes. It is pulling air from infront of the radiator support behind the grille so it is fresh clean air. I need to go junkyarding to find a lid that would fit with a better opening straight across so I can get a straight shot over to the ninty into the throttle body.

[BR3W CITY]

So often I will say that the intake you run on a blower doesn't matter...since your just dumping air into a big friction heater anyway. While IAT's are always important, the impact of this changes on each setup. I've noticed the A2w and aftercoolers can really "level" the air charge out pretty well, especially with their ability to resist heat soaking like the A2A will.

In any case, the colder air you start with makes less work for the cooling device of your choice. You always see turbo cars with the big inlet right on the front, no filter, or just mesh. Why? Because that will shoot for the coldest/fastest moving/cleanest air.

Mounting an air intake really long and low like the imports used to do really wasn't as awesome as it seemed. Instead of a short tube moving warm air, you had a very long tube attempting to suck colder air usually out of the lower valance area. This is goofy imo for a couple reasons. First your putting the filter in a place which the car direct air away from. The underside of a car doesn't scoop air anywhere aside from the radiator/evap/trans cooler area in the front, and usually the brake discs. The filter sits in a dead air spot, sucking cold but nasty air from near the ground. This is where the dust/rocks/salt/plastic bags/road spray and grime all like to sit. You'll see that those long tube cai filters get NASTY.

If you want the optimal design for an intake, its really pretty simple.
1. Use a tube close to or just slightly larger than the size of the tb/maf. Going smaller leaves flow on the table, but going much larger doesn't net you much and usually results in restrictions at the MAF and TB, which creates air turbulence.

2. Keep the routing simple, minimize the number of bends and allow shallow angles for the MAF and TB so the air can smooth out. Works a lot like an exhaust in that sense.

3. Use a shield to seperate the space for the filter from the general engine bay. I still lack in this area on my swap, but the small shield does more for ensuring cold clean air than any crazy-long tube ever will. Even the cheap ebay intakes we modify come with them, and if not, making one isn't a terrible job.

[TR65]

I have a pretty complicated intake setup, mainly because I don't like cone filters and wanted to use a classic big round paper filter.

I found the same thing that the fuel trims were way off. I am not a tuner but I decided that the MAF calibration was not accurate anymore with my non OE intake system. So I played with the MAF calibration until the fuel trims were correct. Have run it for a couple of years with that and no problems.

TR

[Andy4639]

Originally Posted by TR65

I have a pretty complicated intake setup, mainly because I don't like cone filters and wanted to use a classic big round paper filter.

I found the same thing that the fuel trims were way off. I am not a tuner but I decided that the MAF calibration was not accurate anymore with my non OE intake system. So I played with the MAF calibration until the fuel trims were correct. Have run it for a couple of years with that and no problems.

TR

That is sweet!

We need to hook up sometime after I get mine back from Hawks. I'm just down the road in Liberty SC.

[Hart_Rod]

Thanks for the feedback! I plan on putting some air holes in the front of the box that go through the core support and I have a lid that will enclose the filter also. Also, what filters are you guys using? How big? Oil or Dry?

[Matt Cramer]

Originally Posted by TR65

I am not a tuner but I decided that the MAF calibration was not accurate anymore with my non OE intake system. So I played with the MAF calibration until the fuel trims were correct.
TR

That is one pernicious tuning issue for those running a MAF. Any bends directly upstream or downstream of the MAF can change the flow distribution through the tube and throw the MAF calibration way off.

[BR3W CITY]

I use oil but only if the filter looks tired after a few uses washings. I don't do it everytime, and when I do, I make sure it has at least overnight to chill. I don't like using it then driving right away , because too much of the oil can stick to the MAF and screw up readings.

[jamesjones]

Good info here guys thanks. I was just planning on running mine sandrail style...



I'm going to have to make plans to build a CAI now.

[Andy4639]

K&N oil filter. I let it dry pretty much over night as well before and I guess now with the MAF senor I will make sure it dries good. Thanks for the heads up on that tid bit!

[mattcrp1]

I am a little unfamiliar with the adaptive strategy that GM uses on their control set ups. Was the original fuel trim difference noted after a drive or on start up?

[BR3W CITY]

Originally Posted by jamesjones

Good info here guys thanks. I was just planning on running mine sandrail style...



I'm going to have to make plans to build a CAI now.

You can get away with it in certain cases where space is super limited (boat style), but if thats the case you can also look at the F-body/camaro style collector boxes that comes straight off the TB.

Most the trucks have room to fit some 3-4 inch tube tho.

[Andy4639]

I ran across article on sand rails using the LS motor they seem to run the filter right on the throttle body a lot of times. They seem to have issues also with the trims. The tuner from what I read can correct this though. He may not get all of it taken out but what I read they were fine with it after a tune.

[truckdude239]

heres mine i dont like the way it sitts on the hose but it works for now i my shorten it a few inches

[ls1c10]

i'll will be using one from a sand rail.
Duel K&Ns

[BR3W CITY]

Thats gotta be tuned SD, that path would never work with a MAF (twin maf lol!)

[Andy4639]

Originally Posted by ls1c10

i'll will be using one from a sand rail.
Duel K&Ns

That is wicked looking but if you have a 67-72 truck you better have a big cowl hood on the truck! Mine is pretty close to hitting now.

[ls1c10]

Originally Posted by Andy4639

That is wicked looking but if you have a 67-72 truck you better have a big cowl hood on the truck! Mine is pretty close to hitting now.

It fits under a stock hood, im using a ls6 intake,

[Andy4639]

Man I would have never thought it would after seeing mine. Thats cool though!

Here is a add on my local craigslist TR65. You missed a nice meet yesterday, we had 15 trucks I think show up.


http://greenville.craigslist.org/pts/4301096703.html

[ls1c10]

Originally Posted by Andy4639

That is wicked looking but if you have a 67-72 truck you better have a big cowl hood on the truck! Mine is pretty close to hitting now.

It fits under a stock hood, im using a ls6 intake,

[Matt Cramer]

Originally Posted by jamesjones

Good info here guys thanks. I was just planning on running mine sandrail style...



I'm going to have to make plans to build a CAI now.

I'm running that for now as a make-due setup to get the engine up and running. Used one of the short little Spectre filters for it. After I get it running, I'm going to check what my air temperature sensor readings are and what the MAP sensor sees at full throttle to see if there's some room for improvement with a cold air intake.

Note that I'm running speed density, so I don't have to worry about the MAF.

[Wasted Income]

Speed density rules. MAFs are ghey.

I cut a big hole in my core support and my IATs dropped 20 degrees after I did.

This is the best pic I have handy.