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Hi I have just bought an SE and have ordered a cat back 2.5 inch Magnaflow system.
How can I improve the CAI without excessive intake roar. I'm an old fart and can't handle it. On my previous NA8, which had a ROTREX supercharger fitted, I had a CAI that picked up air from the cowling in front of the windscreen. It last about 10 minutes because the intake noise was amplified by the cowling and perhaps the glove box. I realize that the SE intake is at the front so is it less noisy.
Cheers
Steven

Just put the filter in the front bar

Dann

Hopefully the exhaust will drown it out

I'm not sure how much an enclosure helps. Lokiel?

A custom CAI Box will muffle the sound a bit.

Here's mine:


Details: http://mx5cartalk.com/forum/viewtopic.php?f=57&t=41091&start=310

To quiet it even further I could add sound absorbing foam on the inside of the box like FM does on their turbo hush kit: http://www.flyinmiata.com/index.php?deptid=4524&parentid=0&stocknumber=22-60110

I found that once I got a 2.5" exhaust, the intake noise quietened down to a point that I had to deliberately listen for it to hear it - of course it may have been by that time my brain had filtered it out.

Thanks, but how does the exhaust relate to the sound of the CAI, or are you saying you can't hear it over the exhaust

Lokiel wrote:A custom CAI Box will muffle the sound a bit.

Here's mine:


Details: http://mx5cartalk.com/forum/viewtopic.php?f=57&t=41091&start=310

To quiet it even further I could add sound absorbing foam on the inside of the box like FM does on their turbo hush kit: http://www.flyinmiata.com/index.php?deptid=4524&parentid=0&stocknumber=22-60110

I found that once I got a 2.5" exhaust, the intake noise quietened down to a point that I had to deliberately listen for it to hear it - of course it may have been by that time my brain had filtered it out.

The larger exhaust improves air flow.
The noises most people complain about with the CAI are the whooshing/farting noises when the BOV dumps the air back into the intake.
With better flow, there's less pressure in the intake so the dumped air is not forcing itself as hard into the intake - which is quieter.

Lokiel wrote:The larger exhaust improves air flow.
The noises most people complain about with the CAI are the whooshing/farting noises when the BOV dumps the air back into the intake.
With better flow, there's less pressure in the intake so the dumped air is not forcing itself as hard into the intake - which is quieter.

Thank you, I learn something every day
Steven

I have the Begi intake but i'm yet to install it.

What ever turn around time they quote, triple it.

I've been thinking about this myself a bit lately and have come to the conclusion that the dramatic performance improvements experienced by SE owners upon installing a CAI is more about airflow than 'cold air' per se.....

The factory intake system for the SE is heavily restricted, not only is the air-box the same as a non-turbo NB, it has a small intake funnel, then exits the air-box via a small diameter tube through a number of sharp bends (one very small) and a 1.75" tube all the way to the turbo inlet which is also 1.75".

There are three different 'off the shelf' options out there;

1) AEM
2) BEGi
3) Flyin Miata



1) The AEM setup, offered by MX5 Mania in Sydney, is the most popular and offers the best performance upgrade by anecdotal evidence.
It does have few short comings however - It's (by all reports) loud, and it's illegal with the pod filter exposed and relies on a baffle that seals against the bonnet to ensure a cold air source from behind the passenger side headlight.

I have one of these, which I haven't installed yet, as part of a second hand purchase of a Mania stage 1 kit.
Looking at it, it fully replaces the stock intake path, with an expander from the 1.75" turbo inlet to a 2.25" inlet tube with barbs for various inlets. This then couples to a 2.25" to 2.75" expander which runs into the MAF and onto the POD filter.

This in effect creates a 'trumpet' from the turbo inlet and, I suspect, accounts for most of the reports of excessive noise from this setup.



2) The Bell Engineering (BEGi) setup retains the factory inlet elbow on the turbo which then expands to a 2.25"(?) extended tube that runs all the way to a smaller pod filter which is enclosed in a dedicated 'cold air box' behind the passenger side headlight.

This has the advantage of being more 'legal' with the pod filter enclosed and less loud as it has less of a 'trumpet' on the inlet and the filter is 'shrouded'.

There are however quality control & reliability of service issues with BEGi so buyer beware......



3) The Flyin Miata setup is very similar to the AEM but has the middle section ducting longer and recurving back towards the firewall.

This is the worst of all options as it's hard to see where it gets any 'cold air' from (there's no baffle to separate the filter from the engine bay) and is just as loud as it replicates the AEM 'trumpet' design.



So what do I plan to do?
I'm not particularly fond of any of the above options...... So I'm going to kludge something together myself!

Looking at the great work done by Matty it appears a lot of the problems (on the non-turbo NB he tested) were associated with the pre-filter side of the airbox.
See this thread; http://forum.miata.net/vb/showthread.php?t=288496

Now as mentioned, I already have an AEM setup, however, if I had to choose one of the 'off the shelf' options it would be the BEGi.
So I'm planning to keep the factory inlet on the turbo as that's required by the BEGi setup.

What I plan to do is to couple the bulk of the AEM setup to the factory intake elbow of the turbo with a small piece of 1.75" tubing.
This will then be coupled to the top side of the factory airbox with a high flow air filter and some sort of ducting (from the highly modified lower half of the factory air-box) to the back of the passenger side headlight for a 'cold air supply'. I won't know how it'll work out until have the chance to 'position' stuff inside the engine bay......
This will still result in some 'trumpeting', similar to the AEM, but hopefully nowhere near as badly.

If it doesn't pan out, I'll probably go for the BEGi setup, I have preserved the factory inlet elbow specifically with this in mind.

It'll be a little while yet before I have a go at setting this up (other mods to do first) but I'll be sure to post what the results are!

Billybunter tried both the BEGI setup (quieter), and the AEM and reported that the AEM definitely had more go from a butt dyno perspective. The AEM also isn't that loud really, unless you're comparing it to stock.

Think of a "fully sik drift Supra bro", and the AEM sounds like a kitten sneezing in comparison.

Personally I like the look of the enclosed box, and will be going down the path of (totally copying) Lokiel's enclosed setup down the track, but will need to take myself off to "some level of fabricating skill" school first!

Thank you all, food for thought
Cheers
Steven

I have ordered the BEGi CAI.T hank you all for your advice
Steven

Bit late to help in your decision I know but for what it's worth I've got the begi intake. My experience with begi was great. Delivery was fast and all the parts were made beautifully. The difference after I fitted it was amazing and goes to show what the car was capable of. As far as noise went it was quote nice and not to load. The only thing was that it started to sneeze on gear changes. As the factory bypass valve is pretty average I'd also suggest that you look at getting a new one and do that at the same time.

Sent from my SM-N9005 using Tapatalk

Nice post!

The hose from the intercooler pipe, std, to the elbow that attaches to the inlet manifold is perished. Does anyone know where I can get a silicone replacement bar the US of A
Had a chat with Lachlan at Chiptorque this morning, I will have him do their ECU flash in a couple of weeks when the CAI arrives. I have decided on Exhaust, CAI, MTB around 10 lbs. Std intercooler will remain, after all it is only a shopping trolley
Cheers
steven