3" or 3.5" intake for cst4?

Discussion in 'Mazdaspeed 3 General Discussion' started by TripppleP, Apr 21, 2020.

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  1. TripppleP

    TripppleP Greenie Member

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    What size intake is best for the cst4? I have a 3" JBR aluminum ready to go. Would I be better off with the 3.5" prior to getting my final tune done?
     
  2. KiwiFlavor

    KiwiFlavor Greenie N00B Member

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    What is your power goal? Are you going to upgrade in the near future?

    3" would suffice but 3.5" will leave room for upgrades in the future. Just remember that they will need different mafcal.

    Take this from someone who had 4 different intake setups lol.
     
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  3. SharksInSpace

    SharksInSpace Planets and shit. Silver Member

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    You "should" be okay on the 3" with that turbo, but in colder weather I ended up coming right up to the limit of the MAF when I had a 3" on cst4. If it isn't a budgetary concern, going 3.5" would pretty well future proof you unless you go for like a 600+ build later down the road.
     
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  4. JohnnyTightlips

    JohnnyTightlips Motorhead Silver Member

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    Adding to this one of the nice things about the 3" is that it is easier to get in and out with stock battery as well. With the CST4 on stock fuel you will not be running out of MAF in normal conditions on a 3" but you will start to get close.
     
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  5. TripppleP

    TripppleP Greenie Member

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    I think I'm narrowing my goal to around +/-400whp area. I would like to have the cst4 and decided to stop there and Not do any meth or aux fuel. At least for now. I do have the 3" JBR intake so if I do not need larger at this time then it saves me. There is a decent sale at JBR and I"m buying FMIC pipes so I would grab the 3.5" intake if it was ideal. But from what you guys are telling me I should probably be good with just the 3" for now. I just don't want the intake be my limiting factor when everything is said and done.
     
  6. JohnnyTightlips

    JohnnyTightlips Motorhead Silver Member

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    The intake will not be the limiting factor on the CST4, it will be more efficient with a larger intake but we are talking differences that you won't see on the street. That being said, if you have the money and the time and can sell the 3" for some cash you might as well go 3.5 Main thing you will need to do is move the ECU out of the way to fit it if you keep stock battery.
     
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  7. pwdunmore

    pwdunmore Greenie Member

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    3.5" all the way, unless you have feelings about relocating the ECU.

    Why go to all that work and leave something on the table that is easy to swap. Just my opinion.
     
  8. Awafrican

    Awafrican Moderator Gold Member

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    As @JohnnyTightlips said marginal gain on the 3.5" for that turbo. When I come to swap in a bnrs3 on my car it'll be 3" Because I don't want to deal with the ecu and daily my car in the winter for smaller battery isn't an option. And unless you're going for top performance or racing why spend the extra money again? But that's my 2 cents.
     
    Awafrican, via a mobile device, Apr 21, 2020
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  9. Easter Bunny

    Easter Bunny Professional Engineer Motorhead Platinum Member

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    You already own a 3" why not just keep using it?
     
    Easter Bunny, via a mobile device, Apr 22, 2020
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  10. Awafrican

    Awafrican Moderator Gold Member

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    I think this is the entire point of this thread... Lol
     
    Awafrican, via a mobile device, Apr 22, 2020
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  11. Bigelow

    Bigelow Greenie Member

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    Well prolly same reason a guy with a hot wife cheats. Justs wants something new.
     
    Bigelow, via a Samsung mobile device, Apr 22, 2020
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  12. krimsonviper

    krimsonviper Forward! Greenie Member

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    Or he’s tired of her shit and doesn’t wanna deal with it in order to put it in
     
    krimsonviper, via an iPhone, Apr 27, 2020
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  13. Gegi

    Gegi Greenie Member

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    I have the CST4 with the CS3" intake on the stock fuel system. I'm around 4.12V on the MAF at WOT, so I think there's some room for more air. If you daily I think you should stick to 3" as it is enough and easier to work around.
     
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