Calling science nerds and engineers, help me design a CAI for my Miata.

[DK Wolf]

So I know there are little gains to be had from modding the intake much more than stock. However I'd like to build a CAI for my Miata that doesn't cost $300, and won't suck up water if it rains.

I also want one that won't be prone to heat soak too much. I eventually want to move into longer duration races and would hate to have power robbed from me with hot air getting sucked in compromising performance.



I'm working with Zerek with Zerek Fab to help me get this together. Just running it by anyone else to see if anyone has any suggestions or ideas to pitch in. But here's where it's at for now.

Car in mind for now is the NA.

Primary target was to introduce cold air, and keep hot air from getting sucked in. I wanted to build something similar to the FMII intake shield design. Although I feel it could be improved with more thermal reflective material.
reference photo



You can see the shield surrounding the intake, and it's fantastic. it traps the cold air being sucked in front he headlight lid into that area and potentially blocking out hot air from making its way into it. Although I wanted room for improvement for anyone with either a vented headlight lid or a Turn signal intake to allow direct ducting into that area, and the option to turn down the ducting to avoid water getting into the intake area should it rain.


As you can see, here is a shitty vent idea from a TSI into the intake chamber.


at either the end or the light itself you could seal off the ducting during rainy days.

Here is another picture with a generic cross over tube example of where it would go.


I also don't know the optimal thickness for the cross over tube as that actually has a significant bearing on the powerband (I'll be on the hunt for more information, however if anyone would like to spoon feed me information, that'd be great).

I also wanted to potentially toy with the idea of just actually having the intake on the cold side altogether. Although I feel it wouldn't be appropriate to get that deep into it just yet. Maybe later on down the road after I see how this pans out.


The goal of this is to be inexpensive... and if it's good and making it is easy, I'll be more than happy to make more and probably sell it easily less than $200.


The material for the cross over tube has brought a little confusion for myself however. I would like to do aluminium as it's thermal reflective properties are pretty awesome when the exterior is polished, and it would cool quickly with its of air going in. I also wanted to see if there were any plastics options that did well against heat soak. I'm not sure about using silicone tubing as I don't know if the flex properties of the tubing will affect air flow and overall gains. But from what I understand, the intake should be as smooth as possible just like the exhaust to maximize airflow/velocity.



I will be paying out of pocket for dyno time to have Zerek test our model out to see which has the best gains, toying with a variety of piping sizes and types of intakes.



Zerek suggested using the "green intake", I don't have personal experience with them so I don't know.. he however has a pricing deal with them so it makes using them attractive. We were toying with K&N and HKS sponges etc. So I don't particularly know. Again, suggestions here would be awesome. Because we're going to end up buying a few different kinds and experimenting.

[Pfunk]

Have you looked at the prototype CAI that FM put together? I have one on my car. The intake feeds down, into the space behind the bumper near the right wheel. I've driven in all weather, no sign of water being sucked in. You could put something like that together on your own if you wanted. Just a thought.

[Stealth97]

Option 1 - which I have done- cut a 4'' hole just behind the headlight, into your airbox. Duct it to a hole in your bumper or front lip... Copious amounts of cold air. I sometimes get below ambient, and there is so much flow I see temps drop at 10 mph. No joke.

Option 2- the FM turbo coldside setup. I had this idea, proposed it to FM and asked for a quote.. Shortly after its a product, surprise!

[— Phatmiata —]

why not do a randall style Miata intake?

http://mazdaroadster.net/showthread....d-instructions!!!

[psulja]

Coldside CAI

90* silicone coupler off throttle body and a cone filter.

edit: if it'll work with pop ups.

[DK Wolf]

Have you looked at the prototype CAI that FM put together? I have one on my car. The intake feeds down, into the space behind the bumper near the right wheel. I've driven in all weather, no sign of water being sucked in. You could put something like that together on your own if you wanted. Just a thought.

I haven't seen the intake. A quick google search doesn't yield any results. Do you have a link or pic? Im quite curious.

Option 1 - which I have done- cut a 4'' hole just behind the headlight, into your airbox. Duct it to a hole in your bumper or front lip... Copious amounts of cold air. I sometimes get below ambient, and there is so much flow I see temps drop at 10 mph. No joke.

Option 2- the FM turbo coldside setup. I had this idea, proposed it to FM and asked for a quote.. Shortly after its a product, surprise!

What FM coldside intake? I've never heard of it.

I was thinking about option one previously, but its too much ducting. When you have an intake that close to an exterior opening it allows it to draw air from the outside as opposed to relying on the air to force its way in. So that way you'd still get cooler air at idle (although negligible).

why not do a randall style Miata intake?

http://mazdaroadster.net/showthread....d-instructions!!!

I thought about it. However it's so much piping and material that are prone to absorbing heat, especially being near the header.... it isn't something I'd want to do. Plus if I were to go to NASA events I have no idea if cutting there is against the rules.

Coldside CAI

90* silicone coupler off throttle body and a cone filter.

edit: if it'll work with pop ups.

I saw a picture. However I'd need to understand how it is on a dyno. Im sure there is a flaw with doing it with the intake so short. I believe a certain length is required for optimal velocity/resonance. What that is, Im not sure as Im looking for into it.

[psulja]

I saw a picture. However I'd need to understand how it is on a dyno. Im sure there is a flaw with doing it with the intake so short. I believe a certain length is required for optimal velocity/resonance. What that is, Im not sure as Im looking for into it.

I believe it gives much better throttle response with such a short distance from the throttle body to the filter.

The PO of my NB did some dyno runs to compare because designing this intake was his final project for his degree but I forget exactly what their findings were. I'll have to ask him about that.

[DK Wolf]

I believe it gives much better throttle response with such a short distance from the throttle body to the filter.

The PO of my NB did some dyno runs to compare because designing this intake was his final project for his degree but I forget exactly what their findings were. I'll have to ask him about that.

Info would be great. From what I gather the shorter tube allows for better low end torque as it just gobs air in. However, with the longer tubes it allows the air to reach an optimal velocity which has you gain a little HP on top (but sacrificing the gobbling ability down low *no sexual innuendo) intended*. Since my goals will be track minded, I'd like my power to be upper mid range, high end of the RPM band.

[Hyper]

if it was an NB i would suggest how i did my design.

[—Martin—]

FM cold air intake:

http://mazdaroadster.net/showthread....M-put-together

[— kung fu jesus —]

Ariles, does your NA have ABS?

Why not run a 180* elbow + straight pipe+ filter?

If you're going to run a crossover + heatshield, you now have 3 heat sources to defend: exhaust manifold + engine + radiator. The 180 elbow would be 1 (the engine...on the intake side) and you could possibly run the straight pipe through the fire wall to do cowl induction like the Randall. The extra length of that tube should also help with teh torques.

[BlitzWing]

From what I've been told changing the CAI is almost pointless due to the MAF being so restrictive unless its noise your after and reading your posts you want to see gains and better heat management.

I've heard story's from people who have made DiY kits based on the K&N typhoon design that they actually lost power at the low end and only gained a fraction above 5000 rpm due to the resonator being deleted so I think the idea of a vented headlight and a isolated area cut off from engine bay heat is your best hope if you want to keep it cheap. Maybe make a copy of the Racing beat U pipe and put a box around it.

Money no object for a CAI I'd take the Jackson racing kit and a MegaSquirt. Delete the MAF and just fab a scoop to push some air up over the rad into the intake. Actually I'd think with the air hitting the rad some air would naturally try to go around it so a scoop might not even be needed.

I guess it depends on your end goal. If your thinking about going for any sort of forced induction or ITB's don't waste too much time on the CAI and just remove the MAF you will get the gains and with a good tune see some results that any CAi could not give. PLus come turbo time you've gotten one of the biggest jobs out of the way.

[Flyin 92]

Buy an MSPnP, throw on a set of ITBs, fab up trumpets that poke through a hole in the hood and you'll be golden.

Or be less baller and run an intake similar to a Corvette with some sort of ducting that gets air from behind the front bumper.

[— kung fu jesus —]

I think you have that backwards. IIRC, longer intakes for more torque, shorties for higher hp. Helmhotlz resonators and what not...
With the MSPnP, I played with both using different combinations with JRCAI parts I had laying around. made a shortie with that elbow and a filter stuck on the end (no MAF). That cast elbow for the 1.6 is a great 'missing link' part for doing this. I eventually settled on an ARC chamber with the JRCAI on the end to place the filter near the headlight/TSI. No dyno, unfortunately, but midrange felt smoother.



in the end, you're just not going to make a lot of noticeable power with a CAI without the supporting mods.

[DK Wolf]

I'll need to check my info again.

I'll be having the supporting mods, MSpnp is on the way along with a full exhaust sitting at my house getting ready to be thrown on once Emilio is done borrowing my Maxim. I think I'll try the coldside CAI, but something a little more refined than just silicone tubes.

I'll also be deleting the MAF down the line, but still want to see the changes with it still on.