tchuck's custom intake

[tchuck]

Hey guys (and girl),
Ever since I received my Stillen cold air intake several months ago I have been pondering the idea of designing my own air box. I love the higher flow of the Stillen product, but several aspects of this design leave me wanting more. I am now fully committed to this project and would like to see what I can come up with. Maybe it will turn out great, maybe not. Only one way to find out... I’ve spent countless hours researching this subject online and have already modified my Stillen box in a couple different ways (neither of which I’m really happy with). I’ve also begun working on a fully custom prototype air box. I will post some pics as this project progresses.
Here's where you guys come in:
I'd like to gather as many opinions on air box design as I can in order to address this thing from as many angles as possible. What do you like and dislike about the various options out there? What would you like to see in an intake system that isn't currently available?
Thanks in advance and please try to be objective, constructive, and explain your answers. "Some intake FTW!" isn't really going to help me very much. "Some intake FTW because of the location of the filter!!!" would be much more useful.
Here are my thoughts on the few intake systems I have tried.

1)
INTAKE MODEL
-Stock FX intake

APPROX. RETAIL PRICE
-$0

MODIFICATIONS REQUIRED
-none

PRO'S
-enclosed filter box
-factory fit and finish
-it comes with your FX

CON'S
-restrictive
-muted intake sound
-complicated and heavy

SUGGESTED IMPROVEMENTS
-replace filter with higher flow version.
-decrease restrictions in intake tract

2)
INTAKE MODEL
-Stock FX intake with K&N drop in filter

APPROX. RETAIL PRICE
-$47

MODIFICATIONS REQUIRED
-removal of stock filter

PRO'S
-enclosed filter box
-factory fit and finish
-higher flow filter than stock
-lifetime cleanable filter
-1 min installation

CON'S
-restrictive
-muted intake sound
-utilizes complicated and heavy stock intake system

SUGGESTED IMPROVEMENTS
-increase surface area of filter.
-decrease restrictions in intake tract

3)
INTAKE MODEL
-Stillen CAI with z-tube

APPROX. RETAIL PRICE
-$230

PRO'S
-high flow K&N filter with large surface area
-good sound
-high quality velocity stack
-eliminates restrictive stock intake system

CON'S
-Open to the engine bay
-unpleasantly loud above 5K rpms (in my opinion)
-flimsy plastic air box construction
-includes "mystery bracket" that must by altered to fit anywhere
-lackluster fit and finish (power duct doesn't fit right, box only utilizes one of the 4 factory mounting points, "extra" mounting holes in the box)

 

[jbaker1121]

Honestly, add a ztube and a K&N and you are good to go..... stay away from metal too..IF you want make the airbox fully enclosed, I have seen someone take two stock airboxes (the square one) and put them together, or attach the stock to the stillen...

 

[tchuck]

Honestly, add a ztube and a K&N and you are good to go..... stay away from metal too..IF you want make the airbox fully enclosed, I have seen someone take two stock airboxes (the square one) and put them together, or attach the stock to the stillen...

JB, you're killing me man! :tears:
If you read the whole post you will find that I have a Stillen CAI (includes K&N filter) with a z-tube right now and one of the reasons I'm not happy with it is that it's not enclosed.

EDIT: What do you mean by "the square one"?

 

[gto]

But really. Why spend so much effort on your intake. Stillen box isnt that bad. The gains are minimal any way you go. A good tune will give you the best results on N/A with some bolt ons.

 

[Dr.2K]

I, as many others, have been down this road and for all the work and time spent on this mod, in the end it just did not make enough difference. And at times the stock intake outperformed other modified designs. But go ahead and give it a try and post your designs and outcomes of your research.

 

[gto]

I know. feels like been there done that. But something new to spark the intake mod could be fun to see. Go for it man!

 

[pmanliu]

I know. feels like been there done that. But something new to spark the intake mod could be fun to see. Go for it man!

like the days of the dude who connected a vacuum hose to his intake and ran it to the lower part of his front bumper... pretty creative

 

[gto]

lol, memories

 

[tchuck]

I saw that guy with the vacuum hose. That's not exactly what I have in mind but I have to admit I kind of like the ram-air inverted snorkel deal.
Basically I want to retain the z-tube, Stillen velocity stack, and the large K&N filter while adding the filter protection of the stock box, along with a sound that neither provides. The Stillen CAI is definitely the closest thing to what I want but honestly I think the open design of the air box is lazy.
I also really enjoy doing this kind of stuff and am not at all bothered by the (very real) possibility that this may simply end up as entertainment for you guys.

 

[Logan]

like the days of the dude who connected a vacuum hose to his intake and ran it to the lower part of his front bumper... pretty creative

The hose dealeo was interesting.......but two of the guys were working on building enclosures and there might be something to be gleaned (love the word glean) from all that effort. As JB said I'd def stay away from fabbing a metal sweat box but an enclosure that keeps the cool in and the heat out would be beneficial. We are talking incremental gains here BUT we are all a bunch of fanatics at heart so have a party TCHUCK, if you come up with something super slick I'll buy it........

 

[tchuck]

The hose dealeo was interesting.......but two of the guys were working on building enclosures and there might be something to be gleaned (love the word glean) from all that effort. As JB said I'd def stay away from fabbing a metal sweat box but an enclosure that keeps the cool in and the heat out would be beneficial. We are talking incremental gains here BUT we are all a bunch of fanatics at heart so have a party TCHUCK, if you come up with something super slick I'll buy it........

Fear not, I have no plans for using metal. Though many respectable tuning companies use metal for intake systems. ARC, Injen, and Kinetix are just a few that come to mind.

"Gleaned"... Ya learn something new every day.

EDIT: I don't mean the infamous Injen intake for the FX. They've done a lot of great stuff over the years aside from that.

 

[jumbosrule]

+1 on what the forum veterans are spouting.

I'd tell you the Stillen design is open for good reason - to remove all restriction in airflow. If you assume you should have free airflow to the filter element, then you should have about the surface area of the filter able to flow into the box. The two OEM vents don't cut it.

The area in which the Stillen is open is towards the left and down - away from the engine. When the car is moving this works, drawing air from the bumper area. When the car is at idle, the hot air from the engine easily makes it into the intake. The material of the stillen box is also heat resistant, especially as compared to metal.

Just an idea, but it might be easier for you to build an air dam to separate the air box from the hot engine bay. Would be more simple to design and fab, plus it would take advantage of the existing Stillen box, making it even more effective.

Like Logan said - we're all just FX fans. Come up with something that improves performance or efficiency and you've got our attention!

 

[turbocad6]

air is flowing at such a rate that it would't make too much difference if it was metal really, even if it did heat soak a bit it wouldn't be so bad under driving conditions & wouldn't make much difference by itself, to me it's more important to suck cool air in the first place.

I'm def going to build my own airboxes, factory systems don't flow enough & then aftermarket systems increase flow by just opening everything up & sucking from a low pressure point in the nose right next to the hot airflow from the radiator, niether is ideal really.

there are a few things to watch out for. the factory system isn't ideal, it's off to one side behind a headlight, & they do at least seal the box, which any good design would be to me, but then they use a very restrictive funnel to try & suck air from the top of the grille area. if you look at the front of the fx, you have to suck air from one of the air flow points... the only high pressure points in the fx nose is the grille or way down low under the bumper facebar in the lower grille. that's it. you need that air & you have to capture it ideally for the best intake. the factory fx setup does this much better than any of the aftermarkets believe it or not, but it's way too restrictive.

a really good design that is going to take 100% of it's air from a front opening is going to be in danger of sucking water into your engine too. that's why a low snorkel is nice for getting at this high pressure free flowing air but it is a nightmare for rain & snow... I've seen guys suck up water into an intake & bend rods & blow engines, so anything you do you want to at least take that into acount too. the factory system is baffled in such a way that water even if it did make it's way there would #1 be minimal, & then I'm sure there are a few drain holes at the bottom of the box too so chances of getting a significant amout of water all in the intake at the same time are slim to none, but the better job you do the more this risk goes up, especially if your taking air from down low.

a good setup is going to be ducting from an opening in the nose to a sealed box with the air filter in it or plumbing the air filter itself to behind one of the openings in the nose. to do anything more than what's already available for the fx you'll need to do some custom work for sure, probably wind up removing the bumper & cutting some of the radiator support in the process, but there is def room for improvement over whatever is commonly available now.

 

[tchuck]

+1 on what the forum veterans are spouting.

I'd tell you the Stillen design is open for good reason - to remove all restriction in airflow. If you assume you should have free airflow to the filter element, then you should have about the surface area of the filter able to flow into the box. The two OEM vents don't cut it.

The area in which the Stillen is open is towards the left and down - away from the engine. When the car is moving this works, drawing air from the bumper area. When the car is at idle, the hot air from the engine easily makes it into the intake. The material of the stillen box is also heat resistant, especially as compared to metal.

Just an idea, but it might be easier for you to build an air dam to separate the air box from the hot engine bay. Would be more simple to design and fab, plus it would take advantage of the existing Stillen box, making it even more effective.

Like Logan said - we're all just FX fans. Come up with something that improves performance or efficiency and you've got our attention!

I don't mean to sound cocky, but given enough time for research, development, and trial & error, I think I can do better than Stillen on this project. IMO their design focus was performance and cost, whereas mine lies in a mixture of performance, sound, and filter protection. Not to mention the fact that I have no deadline and their design to work from!

Here's my thought on the flow issue: The MAF sensor tube is the smallest opening in the intake tract at hair under 3" in diameter. The throttle body might be "smaller" due to the butterfly, but either way they are close. Obviously the K&N velocity stack/cone filter flows way more than the stock filter but regardless it can never be more than that +/- 3" tube will allow. You could put a 10 foot diameter cone filter on the end of the intake and the MAF sensor tube will remain the limiting factor. Therefore, I only need a 3" opening on my air box to allow the same flow as the Stillen CAI. Further, unless I replace the MAF sensor tube, the only way to increase the "amount" of air would be to draw in colder, denser air. Whacha think 'bout that?

I also very much respect the opinion of the vets and appreciate all the input. This is exactly why I created this thread.

 

[david]

i took a 3" pipe drilled a hole for the sensor and added a open cone style filter. $35 for all of it. sounds great. 0 dyno proof but it sounds great!!

 

[turbocad6]

the aftermarkets have limitations, they need to be bolt in, preferably easy to bolt in & require no modification to the vehicle for them to hope to sell the numbers they do, & there not going on race cars, there going to the masses who are just doing intake & exhaust anyway, they need to be better than stock & as far as airflow they are, but you won't see a serious race car with a stock unmodified stillen thing on it, they'd be just throwing power away... you can improve it with home depot supplies & some creative cutting if your so inclined...

the flaw in your 3" logic is it's not just the 3" that you have to consider, that is only part of the equation. the equation for flow is diameter X length of tract, so if you used a long 3" duct after the sensor you will be restricting flow to it... you want your duct to be larger, you want your radius's to be larger too... the whole idea is to build a slight positive pressure in the air box even under full throttle where the engine is vacuuming all you can feed it while under driving conditions.... any less than this is restriction, too much more than this is a nice ram air effect but that can introduce other tuning issues too so you don't necessarily want to put a huge duct through the hood & force obscene amounts of air in there either...

 

[tchuck]

air is flowing at such a rate that it would't make too much difference if it was metal really, even if it did heat soak a bit it wouldn't be so bad under driving conditions & wouldn't make much difference by itself, to me it's more important to suck cool air in the first place.

.....

a good setup is going to be ducting from an opening in the nose to a sealed box with the air filter in it or plumbing the air filter itself to behind one of the openings in the nose. to do anything more than what's already available for the fx you'll need to do some custom work for sure, probably wind up removing the bumper & cutting some of the radiator support in the process, but there is def room for improvement over whatever is commonly available now.

Turbo strikes again!
That is EXACTLY what I was thinking. Exactly.

---------- Post added at 07:07 PM ---------- Previous post was at 07:05 PM ----------

...
the flaw in your 3" logic is it's not just the 3" that you have to consider, that is only part of the equation. the equation for flow is diameter X length of tract, so if you used a long 3" duct after the sensor you will be restricting flow to it... you want your duct to be larger, you want your radius's to be larger too......

That's a good call. Thanks.

 

[StuLax18]

The only time you have to worry about isolating hot air from the intake is when you start from a stop. Basically, for the first couple seconds, you suck in all that hot air that was building up while you were sitting there. But, once you get moving, it takes in cooler air that is coming from outside.

On launch, the ECU pulls timing because of the hotter air with an open cone like the Stillen.

Hopefully I got that correct for the most part. Some of it I heard from Tony at Motordyne.

 

[tchuck]

The only time you have to worry about isolating hot air from the intake is when you start from a stop. Basically, for the first couple seconds, you suck in all that hot air that was building up while you were sitting there. But, once you get moving, it takes in cooler air that is coming from outside.

I agree that the air inside the bay becomes hotter when you're not moving, but the majority of air coming into the bay does so through the radiator and it absorbs heat in the process so that air is almost always warmer than the outside air. Unless you live in a really hot climate, which I don't. Either way, why have it suck warm air at all if you can avoid it?

On launch, the ECU pulls timing because of the hotter air with an open cone like the Stillen.

I thought it altered the fuel delivery? Maybe it does both, I'm not exactly sure but I know it somehow compensates for differences in incoming air volume enough to handle everything between a filthy stock filter and a brand new K&N filter without REQUIRING a tune. I am hoping it can handle what I'm planning without a tune. If not, I'll get one. No big deal.

 

[Logan]

+1 on the K&N drop in, I also pulled mine a couple months later and replaced it with a JWT pop charger. I have bitched about this before but I wish I'd run 25mm spacers in the front and 20's in the back as the front inset is slightly greater and I'd prefer them to be a bit more flush (so they are similar the the rear). Also in a perfect world I'd probably have installed Eibachs for the extra drop over the H&R's as I am setting up to cut the fronts 1/2 coil and replace the rear upper rubber mounts with lowers.....Everything else I am pretty pleased with.