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Thread: My Custom Intake

  1. #1
    Senior Member Subcompact Culture's Avatar
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    My Custom Intake

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    I built a custom intake using several of the DIY threads here. Here's my recipe for building mine:

    1 Daox MAF adaptor (info here)
    2 Stainless steel hose clamps (any hardware store)
    1 2" ABS pipe (2-3/8" OD, 2.0" ID) cut to fit (24" section bought at Home Depot)
    1 2-3/8" to 2" silicone coupler/reducer (via Amazon)
    1 K&N RC-9380 universal clamp-on filter (full info here)
    Miscellaneous Simpson Strong metal tie strap, plastic bits found in my shed.


    Step 1. Test fit everything to make sure it all fits.

    Step 2. Mass air flow sensor using torx bit and move it out of the way.

    Step 3. Remove stock airbox. There is a hose clamp to loosen and there are three bolts and a pressure fitting. I mistakenly ripped the plastic airbox fitting on the back since I didn't know it was there. Oh well. But there are three bolts.

    Step 4. Measure how long you need your intake tube. I think mine ended up being about 10"12" or so. I used a hacksaw to cut it and filed down the edges. If you do this, be sure to clean out the pipe's inside of any shavings so they don't get sucked into the engine.

    Step 5. Insert Daox MAF adapter into the the OE intake pipe with the 180-degree bend.

    Step 6. Attach silicone coupler to Daox MAF adapter, then use hose clamps; one to the Daox MAF adapter, one to the pipe. Do not tighten all the way.

    Step 7. Attach K&N filter. using hoe clamp

    Step 8. Reinstall MAF sensor.

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    Now, you will notice your intake is saggy. I have created a crude bracket prototype, but it works. Basically it's galvanized metal strap (from the hardware store) and a C-shaped piece of plastic I had from a rollbar clamp. I bent the strap to the right shape, then drilled a hole in the end and a hole in the plastic C-clamp. After a couple of test drives, this works very well. I do plan on making a more refined (e.g. better looking) version of this in the future.

    That's pretty much it. More power? I don't know. Does it sound good? Yes. It sounds very pissed off.


    Last edited by Subcompact Culture; 02-11-2020 at 04:15 PM.

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  3. #2
    Just A Mirage!
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    Quote Originally Posted by Subcompact Culture View Post
    That's pretty much it. More power? I don't know. Does it sound good? Yes. It sounds very pissed off.
    Yeah, that's the first thing I noticed when I did my intake -- When you get up on the Mi-VEC (>4000RPM) it sounds real angry.

        __________________________________________

        click to view fuel log View my fuel log 2017 Mirage GT 1.2 automatic: 37.5 mpg (US) ... 15.9 km/L ... 6.3 L/100 km ... 45.0 mpg (Imp)


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    Senior Member Subcompact Culture's Avatar
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    Quote Originally Posted by phaux View Post
    Yeah, that's the first thing I noticed when I did my intake -- When you get up on the Mi-VEC (>4000RPM) it sounds real angry.
    It's funny you mention that. When I got home, I was telling my wife about how over a certain RPM it got really noisy. She asked, "Does it have something like VTEC?" Then I thought, oh yeah, MIVEC! At first I thought it might just be a vibration of some sort. But is that what I'm hearing in the upper RPM? I didn't know there was a change in tone with MIVEC. My Toyota Yaris has VVT-i (Variable Valve Timing, Intelligence) but it's continual and you can't hear it "change." (VVTL-i, where the "L" = lift, you can, but the Yaris doesn't have that).

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    Administrator Daox's Avatar
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    Looks pretty good! I like the support bracket too.
    Custom Mirage products: Cruise control kit, Glove box light, MAF sensor housing, Rear sway bar, Upper grill block

    Current project: DIY Nitrous oxide setup for ~$100

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        click to view fuel log View my fuel log 2015 Mirage DE 1.2 manual: 47.2 mpg (US) ... 20.1 km/L ... 5.0 L/100 km ... 56.7 mpg (Imp)


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    Moderator inuvik's Avatar
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    Now if someone would just package all those components together, hmmmm.

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        click to view fuel log View my fuel log 2015 Mirage ES 1.2 automatic: 40.4 mpg (US) ... 17.2 km/L ... 5.8 L/100 km ... 48.5 mpg (Imp)


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    Looks good! Although I gotta say, adding a custom intake seems to make the engine look even smaller.

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 42.5 mpg (US) ... 18.1 km/L ... 5.5 L/100 km ... 51.1 mpg (Imp)


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    Well, now I know how to support my intake instead of letting it wiggle around

    Anyways, it definitely sounds much better. Butt Dyno is telling me it's definitely better in the mid range. lol

        __________________________________________

        click to view fuel log View my fuel log 2015 Mirage DE 1.2 manual: 43.4 mpg (US) ... 18.5 km/L ... 5.4 L/100 km ... 52.2 mpg (Imp)


  9. #8
    Senior Member Subcompact Culture's Avatar
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    For what it's worth, I was able to get 47 MPG on the way to work today so I don't think it's negatively affected MPG, so long as I can keep my foot out of it.

  10. #9
    Still Plays With Cars Loren's Avatar
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    Science:

    The entire intake and exhaust system both work the same way. It's all about managing resonance.

    The flow of air is not constant. Intake (or exhaust if you're looking at an exhaust) valves open and close creating pulses of air. The trick is, air is flowing into the engine when the exhaust valve is open... and as soon as that valve closes, that moving column of air STOPS and bounces backward. When the valve opens again, then the column of air has to reverse direction and start accelerating again. That's the whole "problem" with intake and exhaust systems in a nutshell.

    On the intake side, the length and diameter of the intake runners is tuned for perfect resonance and flow at a certain RPM (and this is why a lot of performance engines will have variable length intake runners so that they can have "peak" power in multiple RPM ranges). Anywhere near that, the flow is going to be really good. And at harmonics of that RPM, flow will also be pretty good. The ideal for max torque is loooong intake runners. But, for packaging, they'll often make the length exactly half of that ideal, and because it's a harmonic, it still works.

    All of that also works in conjunction with the volume of the intake manifold plenum.

    Now, when you get to the atmosphere side of the throttle body... it's sort of a different "system", but the same rules still apply. Unless you're running a velocity stack right off of the throttle body (like a typical IRTB setup), you have tubing which creates a column of air, and you need to manage the resonance of that column of air.

    The stock intake system does this by keeping the tubing fairly small (just large enough, they did the math, and they did the testing) to keep that column of air MOVING at a higher velocity. They also incorporate one or more Helmholtz resonators. What's that? It's a little chamber that hangs off of the intake tube. It sort of buffers that intake flow. If a "reversion" starts to happen when the intake valve closes, the resonator absorbs that pressure spike, keeping it from flowing all the way back up the intake tube. Really, it works a LOT like a muffler on the exhaust. It's absorbing pressure spikes as they happen, and then releasing that stored pressure when the intake valve opens. If you're thinking that some genius could use that notion to get MORE air into the engine at a certain RPM range, you'd be correct!

    So, what have you done by replacing the carefully engineered stock intake system with a straight tube and a cone filter?

    You've removed any tuning that they did to keep that intake charge moving. You are now tuned for exactly whatever RPM range that the length and diameter of your intake tube works at. Will it make more power? Well... if the length of the tube is perfect for, say 6200 rpm... then maybe you'd see a couple more HP there. The problem is, EVERYWHERE ELSE, is going to see a decrease in torque. (and there might also be a torque bump at harmonics of 6200)

    What do you feel? Well, it's going to be subtle. Changes to the intake MANIFOLD would make a lot more difference. So, whatever you do isn't going to be night and day different. But, I'd guess you would normally feel every so slighlty LESS torque "everywhere", and then slightly MORE torque at those resonant RPM's where your intake works best. Oddly enough, feeling "same" and then "more" can be deceptive and make you think you're making more power. Where just the constant, smoother stock torque curve might not have any peaks that you can feel... but, it could be OVERALL faster. Hard to say without extensive testing!

    One thing is certain, however... the NOISE that you hear is reversion in the intake. Proper tuning of intake tubing length and diameter and use of a properly sized resonator would reduce or eliminate that noise... which is at the same time improving intake flow.

    Yeah, I've spent way too much time playing with intakes. I've learned to generally like stock intakes unless you're somehow adding a bunch of power (turbo, supercharger, etc). Just feed them with nice cool air from outside the engine compartment. Unless you're hypermiling, then you want warm air for better fuel atomization. (which is probably why the Mirage intake picks up right behind the radiator)

    Of course, this is all just, like, my opinion, man.
    Simplify and add lightness.

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  12. #10
    Senior Member Subcompact Culture's Avatar
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    I do not claim any horsepower gain, any engineering feat, or anything. All I know is I like the sound and that's good enough for me.



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