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Author Topic: Nev's Crazy Custom Stealth Short Ram Intake  (Read 7400 times)
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Third Gear
Posts: 176

« on: April 30, 2016, 11:37:08 AM »

Hi Folks.  Smiley

Down here in Oz we have some fairly well defined modification regulations so if you're going to modify your car you either have to have it all fully engineered (expensive and often difficult) or have it pretty well hidden.
Now most of the time it's not a real issue so long as you don't go too far overboard, however if you get the wrong Police-person on the wrong day you'll end up with a defect notice and a world of pain......  Cry

So we all know the factory intake is less than ideal....... So here's my attempt at creating a short ram intake solution (basically what every other aftermarket solution does) that appears as though it was installed from the factory.

Let me know what you think!  afro
Third Gear
Posts: 176

« Reply #1 on: April 30, 2016, 11:38:32 AM »

So...... Let's talk about Intakes.

It's fairly common knowledge that the factory intake on the the SE is, if we are being generous, less than ideal.
Most of us wouldn't be that generous......   Tongue

In fact they did such a good job that there have been no less than seven different aftermarket replacements available on a fairly low production run car, many are still available new even 10 years after production ceased!

So what was so wrong with it?
You can say a picture tells a thousand words so here it is (spread out a little for your viewing pleasure) in all it's convoluted glory.....

Needless to say the little IHI turbo fitted has a fairly hard time trying to suck air through that long, narrow, twisted noodle of an intake path! rolleyes
It's generally recognised that replacing that debacle with something a little more free flowing is worth in the region of 20 RWHP....... Simples!

So which of the off the shelf solutions am I going for? None of them.....
Why? Because I'm difficult!  afro

Each of the aftermarket options have their own limitations and drawbacks, some are not made anymore, some don't work with RHD vehicles, some feed the hot turbo outlet pipe straight through the cold air box, plus other little quirks and niceties.
Besides where's the fun in just buying (upwards of $500+ in most cases) and bolting on a kit? It's much better (most sane individuals would say painful) to create something from scratch so onwards.... time to reinvent the wheel!...... again.

Seriously though, none of the available kits quite fit my needs and desires and well...... I just don't like any of them that much.

I have a few requirements for what I'm trying to create;
- fully reversible (the factory intake will be removed and put in a box incase I don't like the final result)
- stealth (has to look as OEM as possible)
- relatively quiet (the price paid with all aftermarket options is an increase, sometimes significant, in induction noise)
- Cheap (I don't like waking up the moths in my wallet)

Wish me luck!  Azn
Third Gear
Posts: 176

« Reply #2 on: April 30, 2016, 11:41:25 AM »

So this morning I begun my little adventure in crazy custom stealth intake manufacturing!   shocked

Here's were we are starting from because, well you have to start somewhere.....

So obviously the first step is to remove all of the old intake system.

The turbo outlet pipe and oil catch can (hiding behind the airbox in this picture) were also removed because they were in the way.

While this resulted in a whole lot of free space, it's actually still quite restricted in there....

Now the next step is to work out what to put back in it's place.

For those who know me, you would realise I've been toying with this concept for a long, long time now. I've come up with any number of different ideas, some of which I've even partially mocked up before throwing them in the bin due to being impractical, unworkable or well.... just plain dumb.  rolleyes

The fundamental problem is you need to make a link between the turbo inlet and the coolish air source located behind the passenger side headlight from the guard. Unfortunately this coolish area is also where the factory hotside turbo outlet pipe runs, hence why a few off the shelf options have this pipe running through the airbox.

Have a look at the image below to to see the locations of the critical areas....

So, how to make something that fits in that space while still looking OEM?
That's the problem that I've been wrestling with over the last year and a bit!  help

Obviously the most significant OEM component is the airbox so being able to use that will go a long way towards achieving my 'Stealth' goals.
Unfortunately being the same unit as the one used in the Non-turbo NB's it's big, oddly shaped and the MAF outlet faces the radiator. Of course the turbo inlet also faces the radiator. This in combination with the relatively tight clearances when you factor things like AC & Power steering pumps is the whole reason why the factory came up with the noodle they did in the first place.

In my next post I'll take you through my design concept and show you how it's shaping up so far.
Third Gear
Posts: 176

« Reply #3 on: April 30, 2016, 11:44:34 AM »

Now with what I'm trying to achieve I've put a few design constraints on myself in the process.
- It needs to work with the factory ECU (at least for the moment)
- hence it also needs to work with the factory plumbing -> BOV recirculation, vacuum return from the EBC and vent return from the catch can.
- The MAF also needs to be retained which takes up even more space.

So basically I have to make as short and straight a connection as possible from the forward facing MAF (70mm) to the, also forward facing, turbo inlet (45mm).
I also have to provide for a 5mm and two 20mm openings in this link for the plumbing mentioned above.
While also looking at least sort of OEM, what a headache!   help

I tried many different concepts including reversing the flow of air through the airbox (no where to put the MAF), hiding the MAF and a pod filter inside the airbox (not enough room), repositioning the airbox to allow a simple U-shaped pipe to the turbo (not enough space, again), even using a completely different airbox (couldn't find one that worked in the space).

Finally late last year I had a brain wave and thought of turning the airbox 90* so the MAF faced the engine. It looked like it would fit (with some very heavy modification) with the MAF reasonably close to the turbo inlet and had the added bonus that the factory rubber elbow attached to the turbo inlet which alters the path to vertical could be retained making going back to stock a LOT easier! It would also make the intake path VERY short, shorter than almost every off the shelf solution out there..... Cool.   afro
So all I needed to do was work out some way of making a 90* bend in a pipe while also reducing the diameter from 70mm to 45mm while also providing the ability to tap a 5mm and two 20mm pipes into said pipe, all in the space of 250mm total length and look OEM in the process..... Yeah, this is going to be fun.   buck2

This was late last year and work was ridiculously busy so I knew I wouldn't have the time to do anything about it until my holidays (now, Yeah!).
However while pondering the concept and looking for solutions so I could at least start sourcing the required parts I spotted something in my miscellaneous collection of bits....
Hmmmmm, I wonder if that will fit?


Anybody here recognise what that is? Hard to get something more OEM looking than that!  Shocked
It will be interesting to see, being rubber, how well it resists collapsing when the turbo is on boost....

Now this would only get me part of the way there in size hence why I bought the metal reducer which I posted about back in December to get me the rest of the way down to the required 45mm.

So that gets me to today.

In the next post, construction begins...... You can see how it's all coming together so far.
Third Gear
Posts: 176

« Reply #4 on: April 30, 2016, 11:49:10 AM »

Now it's time to start getting really messy!  afro

The first task was to position the base of the airbox as everything else hinged of this and it is the component that requires the most drastic surgery.
I progressively removed more and more material from the base until I thought I had it in roughly the right position and drilled a hole in the plastic base to use an exisiting captive nut in the frame rail to secure it.

It ended up looking like this....

I then added the lid to see how well the MAF lined up with the turbo inlet.

Almost looks like it came from the factory like that!

Unfortunately there was a problem...... The bonnet wouldn't close as the whole lot stood too tall.  Sad

So out with the devices of mayhem again and I removed some more material.
Actually a whole lot more material.......

This is what was left by the time I had finished.
I even had to add a metal bracket so I would be able to secure the skeletal remains to the frame rail.

Now, air will enter the airbox via the gaping hole on the right side and the previous oval opening to the mid-left will be sealed.
I will also be fitting a 'wall' that will extend forward towards the headlight when installed to discourage hot air from behind the radiator moving towards the airbox opening.

Unfortunately this will not look OEM at all.
So I've come up with a semi-functional mis-direction that you'll see in the next picture.  Azn

The final step for today was to test fit the whole lot and see how well it works.
Here it is!

The elbow from the MAF lines up pretty well with the turbo inlet elbow and both being rubber should allow adequate flex for engine movement.
It does look like running the pipe from the turbo outlet to the front of the car may have some tight clearance issues but hopefully it'll work out....

So that's where I'm up to today, tomorrow I'll start the oh-so-fun job of plastic welding the airbox lower section back into a semi rigid piece, I'm so looking forward to that little job!  buck2
Third Gear
Posts: 176

« Reply #5 on: April 30, 2016, 11:50:17 AM »

I forgot to mention that during the first phase, while everything was out of the way, I popped the heat shield off the exhaust manifold to check the manifold to head nuts.
This is a known weakness and the nuts often back off by themselves resulting in reduced boost, odd noises and frequently a warped manifold.....

Nett result was that 8 nuts were nice and tight, the remaining nut required about 1/8th of a turn to get back to torque specs.
I figure this is a pretty good result given that over in the US they often find multiple nuts spinning freely on their studs! shockeyes
« Last Edit: April 30, 2016, 12:00:40 PM by Nevyn72 » Logged
Third Gear
Posts: 176

« Reply #6 on: April 30, 2016, 11:52:45 AM »

The first job for today was to make the third intake connection to the rubber elbow that attaches to the MAF.

This elbow very helpfully already has two fittings, one 20mm and one 5mm, the third opening has a metal 'socket' with a threaded centre hole which the IAT sensor used to screw into.
Now the opening is too small and isn't particularly suited to attaching a 20mm hose to.....

This is what it looks like.

So I removed the fitting and drilled the hole out to 13mm, mainly because this was the largest drill bit I own.  Tongue
I then found a bit of pipe from my magical collection of miscellaneous mystery bits and cut off a suitable length.
This was placed into the recess and expoxyed to within an inch of it's life with some of the evil bastard brother of JB Weld!..... That sucker ain't going anywhere.  rolleyes

This is how it ended up before a little cleaning.

Now while that was put aside to set for a while it was time to begin plastic welding....... Oh joy.
This didn't however last very long as after only 5 minutes the soldering iron stopped working. Bugger..... Off to Bunnings we go!

Amazingly I managed to leave Bunnings with only two more things than I was planning on actually buying, that must be some kind of record for me. laugh

There were three welding tasks to complete;
- Strengthen the airbox base and plug the old oval opening.
- Shape and attach the baffle to the airbox base that runs forward towards the headlight.
- Trim and shape the snorkel (which doesn't actually do much of anything apart from act as a distraction so it might as well look neat).

After few hours of shaping, cutting, sanding, welding and frequently burning my fingers they were largely done.
Hmmmm, burny, stinky, halucinogenic plastic fumes...... Oooh, a  Narwhal.... No sir I don't have any Tim Tams......  shockeyes

I cleaned them up a bit in preparation for a quick coat of Vinyl Dye to give them that factory fresh look.

Here they are awaiting the first coat of black.

So what's next?

Watching paint dry.......  Shocked

I'll see if I can achieve anything else this afternoon and post later but from here on it's largely assembly with some minor hose cutting and probably at least one nasty surprise!
Third Gear
Posts: 176

« Reply #7 on: April 30, 2016, 11:57:32 AM »

And Done!  cheesy

Since my last post I've now finished the install, YEAH!

First off was to start reassembling the top and bottom sections of the airbox with their ancillary fittings.
Then I fitted the bottom half of the airbox for the last time. You can see the baffle extending forward towards the headlight beside the power steering reservoir.

I then inserted the metal reducer into the turbo elbow and clamped it in place.
Once that was done I installed the air filter and fitted the top section of the airbox with MAF elbow installed.

This allowed me to just how close the two ends of the intake were and how much pipe would be required to join them..... It ended up being a little closer than I had intended but still good.

So now I needed some pipe, 55mm in diameter, with a bend.
Luckily the spares box came to rescue again in the form of the old cold side intake pipe. It even came with helpful bends.

I chopped a very small section out of the middle and fitted this between the two sections of intake pipe. Done.

So next was to fit up the rest of the connections and reinstall the oil catch can.

This meant raiding the spares supply yet again to find various clamps and hose lengths, fortunately I had pieces that were suitable, even with bends in the appropriate spots.  :wink:

It's all coming together very well and looks like this.

Now the sun is starting to go down but I'm oh so close so decide to power on to the end.....

This meant making the connection between the turbo outlet pipe (vertical) and the hotside pipe that runs next to the radiator.

The turbo outlet pipe is 1.5" and the hotside pipe is 1.75".
The factory setup uses a 90* elbow in 1.5" which attaches to a metal pipe with a 0.25" step in it followed by another 90* elbow in 1.75".

Now because I'm preserving the factory setup in case I want to change back and the metal pipe is integrated into the intake piping assembly I couldn't use that section. As a result I bought a replacement elbow for the turbo outlet which not only does a 90* bend but also increases in size from 1.5" to 1.75". This made it much easier to source a section of metal pipe as it only had to be 1.75" straight through. I ordered this pipe with a 15* bend and longer than the factory unit as I was expecting to have to route this pipe further over towards the engine to clear the intake MAF elbow. I was right.....

All I had to do was trim about 25mm off the factory 1.75" 90* elbow that attaches to the hotside pipe and it all lined up surprisingly well.

Here's the final result!  Smiley

Only one thing to do now...... Take it out for a drive!  drivingss

Backing out of the garage I was almost a bit disappointed as it seemed no louder than before, I was expecting more, or at least something. I shouldn't have worried.
First off was just some gentle driving to warm the car up and make sure everything was working ok, it wasn't. The coolant gauge wasn't working, I was wondering why it was taking so long to warm up. So I quickly pulled over, jiggled the connection on the sensor and all good. Now the temp gauge was functioning I could see I was already up to operating temperature so off we go!

First thought, the turbo whistle is definitely louder but not significantly, good. The BOV though is another matter....  angry9
Previously I rarely, if ever, heard the BOV operate and if I did it was muted and distant, not anymore. Now from relatively low revs it's quite intrusive though surprisingly at higher RPM much less so. The real issue for me is the noise it makes, somewhere between a bird chirping and a small dog sneezing. Given it's so unfamiliar I'll just have to wait and see if I can adjust to it.

Now for power.
Does it have more? - Hell yes!
Is it night and day? - No

However I'm still running factory boost so I can see what effect the intake has by itself. Normally when people replace the intake they also add a manual boost controller and up the boost from 7.5 PSI to ~10 PSI at the same time which increases the impression of more power.

That being said I was initially unimpressed with the power increase, thinking this was no better than before. What I didn't realise was that I hadn't gone over 5000 RPM yet so was inadvertently comparing full 5000 RPM+ power pre-intake with ECU strangled sub 5000 RPM power post intake. Once I made the transition past 5000 RPM my face looked something like this ->  shockeyes

Cool!  afro

So What's the final assessment?

I had a few requirements for what I'm trying to create;
- fully reversible (the factory intake will be removed and put in a box incase I don't like the final result) - Check
- stealth (has to look as OEM as possible) - I think we can definitely say yes to this one.
- relatively quiet (the price paid with all aftermarket options is an increase, sometimes significant, in induction noise) - 50% Will have to wait and see about the BOV noise.
- Cheap (I don't like waking up the moths in my wallet) - Total spend on all parts used was <$100 so yes, I'll claim this one.

I only went for a short dive this evening so will report back after I've the chance to go a little further afield.
Tomorrow? I need to tidy a few small details and clean up the bomb site that is my garage!  Roll Eyes
Fifth Gear
Posts: 7213

Midlife Crisis on Wheels!

« Reply #8 on: May 01, 2016, 04:46:46 AM »

Interesting project!  I wonder if there are any differences between the SE and MSM that would make this not work just as well?  My DIY intake on the track car is about as clean as you can get but I don't need to work around AC and power steering.

2005 Black Mica #290 8/27/04 w/Factory Hard Top
BEGi Intake, FM Downpipe.  Nice and calm with an edge...

1990 Red - MSM Drivetrain, Adaptronic EMS, Xida 700/400, 15x9 6uls, Full Cage, SGDP w/80mm Corksport exhaust, ~260whp @ 15psi on Forged Rods.  bow2
Build Thread:,24668.0.html

2000 BMW M5 - The Falcon - Daily Driver  reddevil

2003 E350 7.3 Powerstroke Ambulance for towing '90MSM to play dates.

1991 BRG - Daughter's daily driver.
Third Gear
Posts: 176

« Reply #9 on: May 01, 2016, 06:56:58 AM »

I seem to be having a conversation with myself here...... So I might as well finish it off.

Took the car out for a longer drive today and the BOV noise is not as loud/obnoxious as I remember it from last night.
It is also far less frequent and intrusive when you're not constantly trying to provoke it.  rolleyes

As for power, it definitely has quite a bit more, more than I thought last night.
On sections of road I frequently travel, where in the past I would have dropped back to 5th gear it now travels quite comfortably in 6th. Overall it also seems more responsive with the biggest gains in power from around 3000RPM upwards.

Boost now also appears to be peaking at around 8.5 PSI rather than 7.5 PSI previously (factory setting).
I wonder why this is as I'm still running the factory EBC. It's not boost creep as it doesn't keep rising.

In the end what did I actually do?
Well effectively I replaced the bit of Intake pipe between the MAF and the turbo inlet elbow.
Previously = 102cm + 9 bends
Now = 22cm + 2 bends

There were some changes to the airbox but these would probably have negligible effect.

In terms of what I have now, it's comprable to the AEM or Nitro Dann setups. Similar in length with the same number of bends (although those systems have straighter bends than mine) with the main difference being that they use Pod filters while I'm still running the factory panel filter (smaller surface area?) albeit probably the last 'high-flow' SE specific filter from Mazda in the country.
It's certainly shorter and straighter than other options like the Flyin Miata, Joe's and BEGI, but they also use Pod filters.

Overall I'm very pleased with the result from what was a highly experimental and speculative project and it's certainly unique!  Smiley

Now what to do next?
Third Gear
Posts: 176

« Reply #10 on: May 01, 2016, 07:01:48 AM »

Interesting project!  I wonder if there are any differences between the SE and MSM that would make this not work just as well?  My DIY intake on the track car is about as clean as you can get but I don't need to work around AC and power steering.

The only difference between the SE (in Australia) and the MSM (in the USA) is that the brake master, steering and ABS control modules are on opposite sides of the car.
Ironically this is why the FM intake doasn't work on RHD cars.
Otherwise they are largely identical (except our factory boost is set at 7.5 PSI and we got a 3.6 diff as standard).

I can't see anything that would prevent you from doing the same conversion to a LHD version of this car.  afro
Third Gear
Posts: 105

« Reply #11 on: May 02, 2016, 12:05:37 PM »

cool idea on the intake.  im jealous you guys have 3.6 gears from the factory.
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