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Old 07-19-2010, 06:34 PM   #1
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Default Exhaust port spacing/size: 1.6 vs 1.8

I found this info regarding exhaust port spacing, and want to verify that it's correct.

Quote:
The intake manifold, exhaust manifold, motor mount brackets and camshafts do not interchange because of the bore spacing differences.
Link to source.

I also found the 1.6 port measurements here, but so far nothing concrete for the 1.8.

Ultimately, what I'm wanting to do is have the option to cut the flange off a 1.6 tubular manifold and weld on a 1.8 flange if I end up with a 1.8 motor. I have a Mitsu flanged turbo and have found a cheap 1.6 mani for it, but not a 1.8, and was hoping they are close enough that this will work. I know I can buy a Garrett flanged mani for a 1.8 and an adapter plate, but that's still more expensive than doing it as described above if it's at all possible. I have yet to go to the Mazda dealer and overlay the manifold gaskets, but will do that if ultimately I can't find the answer. I figure somebody here will tell me it's not gonna happen though lol.

I also realize I can just swap the turbo flange on a 1.8 Garrett flanged mani, but the cheap 1.6 mani is a really compact log-style.
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Old 07-19-2010, 06:42 PM   #2
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the port spacing should be close enough to swap the head flange. ARTech has my turbo manifold tacked up to a 1.6 flange right now and is fabbing everything up. when he is done he will be breaking the tacks and welding on a 1.8 head flange!
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Old 07-19-2010, 11:58 PM   #3
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Quote:
Originally Posted by matthewdesigns View Post
Ultimately, what I'm wanting to do is have the option to cut the flange off a 1.6 tubular manifold and weld on a 1.8 flange if I end up with a 1.8 motor. I have a Mitsu flanged turbo and have found a cheap 1.6 mani for it, but not a 1.8, and was hoping they are close enough that this will work. I know I can buy a Garrett flanged mani for a 1.8 and an adapter plate, but that's still more expensive than doing it as described above if it's at all possible. I have yet to go to the Mazda dealer and overlay the manifold gaskets, but will do that if ultimately I can't find the answer. I figure somebody here will tell me it's not gonna happen though lol.

I also realize I can just swap the turbo flange on a 1.8 Garrett flanged mani, but the cheap 1.6 mani is a really compact log-style.
Won't work. The port spacing is off. To give you a quick idea, the whole BP motor is 2"-3" longer then the B6 motor.

Quote:
Originally Posted by WonTon View Post
the port spacing should be close enough to swap the head flange. ARTech has my turbo manifold tacked up to a 1.6 flange right now and is fabbing everything up. when he is done he will be breaking the tacks and welding on a 1.8 head flange!
Sean, take a good look at your photos, he sent you. Every port from the flange to your manifold, don't line up.

edit:::

Here you can see the gab distance there is.

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Old 07-20-2010, 12:08 AM   #4
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i didnt pay that close attention to it my bad!


there op your question has been answered!
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Old 07-20-2010, 12:31 AM   #5
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thats a sexy manifold.
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Old 07-20-2010, 01:50 AM   #6
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Linked info above works out to 85.7mm bore spacing for 1.6.

I measured a 1.8 gasket a couple weeks ago and got 91mm bore spacing.
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Old 07-20-2010, 01:55 AM   #7
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Thanks for the info guys, and for catching the detail in that photo wildfire! Looks like I'll be swapping turbo flanges if the need arises.
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