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I thought they shared the same manifold. Same engine, same chassis design. Don't see why they would make a different manifold. Unless you had a 2013, the exhaust manifolds are completely different.
 

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Do you have the '12 or'13? If so the FW gets in the way. At least that is what Mazda says. I've wondered if it may be due to the cat more than the manifold. That 4-2-1 with a high flow cat would be a sweet upgrade on my '13 Sky 2.0.
 

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Discussion Starter · #4 ·
I have a 2014 Mazda 3 2.0 manual I heard that the cx5 manifold is slightly bigger or tuned different which gives it more umph. And the 3 engine bay didn't have enough room so the 3 is different manifold
 

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I doubt that could be the reason. If there is any difference between the two headers....I just took a quick peek of the two engine bays of the 3 and the CX-5 in my showroom and the space for the headers are roughly about the same and if they are different there's more than enough room in there....at least that's what I think.
 

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The '12 and '13 MZ3 Sky 2.0 did not have enough room for the header. They have a plane Jane manifold and only a 12:1 comp instead of the 13:1 that the header enables. The CX5 did have room and its Sky 2.0 has that upgrade. The '14+ MZ3 was designed with more room and gets that awesome new header to.
 

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wait.. so is it 12:1 , 13:1 or 14:1? I keep seeing conflicting information on this for the 12' and 13' sky. Im not happy either way I feel pretty much lied to because the brochure I was given for skyactiv when I bought my 13' says 13:1 compression. 12:1 isnt even really considered high compression. I wish someone would do a real comparison of the 13' and 14' engines and tell us the real honest to go truth and how it was achieved. Does the 12' and 13' even have the volcano shaped pistons?
 

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wait.. so is it 12:1 , 13:1 or 14:1? I keep seeing conflicting information on this for the 12' and 13' sky. Im not happy either way I feel pretty much lied to because the brochure I was given for skyactiv when I bought my 13' says 13:1 compression. 12:1 isnt even really considered high compression. I wish someone would do a real comparison of the 13' and 14' engines and tell us the real honest to go truth and how it was achieved. Does the 12' and 13' even have the volcano shaped pistons?
I don't know about the 2012 and 2013 models, but I know that in the US, the 2014+ has 13:1 comp ration. The EU version gets 14:1, because their fuel is cleaner and more pure than the crap we run in the states.
 

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This may help:

http://mazda3revolution.com/forums/401802-post3.html

This is how I understand it:

'12 & '13 MZ3 Sky: 12:1 due to no room for 4-2-1 header
All CX5 Sky: 13:1 because they have the header, not sure if there is a 14:1 version in EU
'14+ MZ3: 13:1 US/14:1 EU because the redesign made room for the header

They went with 13:1 in the US so that we could run 87 octane.

My question is was it really a problem with the header not fitting on the '13 or is the cat requirement the real impediment? The cat has to be close enough to the exhaust valves that it gets hot very quickly or cold start emissions will suffer. Might that header fit on the '13 if a smaller cat is used or if the cat is pushed down and out of the FW area? Just curious.
 

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I don't think it would fit in the 13 model since they don't have the tunnel space wide enough and long enough to accommodate the header. The firewall design is much different from the 13 then a 14 is. It could fit with some modifying but time and money would be the factor and how much of the firewall you'd have to modify to get it to fit. Also, would it still be able to achieve the suction that Mazda designed it to?

https://www.youtube.com/watch?v=rNtS8qyjIJU @2:05ish, they show the chassis and explain why it's different from the older model. Maybe this will answer your question Sly.
 
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Discussion Starter · #11 ·
What gains will we see moving ratio up to 14:1 I already use premium all the time anyway. Will there my much hp/ torque gains
 

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even if it does fit which most likely it won't you will need complete tune to gain full effect of the difference in manifold.
 
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