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Old 04-15-2008, 02:25 AM   #1
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Default Head choices for 1.8

I will preface this by letting everyone I am new here - and not YET with a Maita.

However, I like to pre-game my purchases (I get nearly all the capitalistic thrill of the purchase without the hit in my pocketbook or the warm feel of new toy on my pillow).

I am interested in learning about cylinder heads for the 1.8.

After doing a search on old threads - what I think I learned is this: there are two head variations that work on 91-00' 1.8L Miatas. The 94-97' head, and the 99-00' head. The 00' head is superior in flow... (not including the new 01+ VVT head for obvious reasons)

Are there any aftermarket heads available, or is the only choice 99-00' or earlier and customizations thereof?

Are there any businesses that are particularly well regarded in porting/polishing cylinder heads for Miatas? How about camshafts etc? Do you go through the usual hotrod suspects? (crane, etc)

I imagine most people keep the motor stock when adding the turbo. Are there any combinations though of camshaft etc. that seem to work particularly well?

Thanks all!

Last edited by Chiburbian; 04-15-2008 at 02:45 AM.
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Old 04-15-2008, 02:42 AM   #2
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I don't have an real answers for you but I do have a correction for you.

there is the 94-97 1.8L head
the 99-00
the 01+ which as the VVT
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Old 04-15-2008, 02:43 AM   #3
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Thanks - I will fix my original post.
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Old 04-15-2008, 02:55 AM   #4
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I can make a miata head flow more than the Amazon River. To do it right, you have to do the head work, then flowbench it, then have cams ground that are tailored to the head's flow characteristics.

Your best bet is to buy a few books on head porting, learn what works and what doesn't, then do your own headwork. There's A LOT of misconseptions out there. For example, larger exhaust valves in our heads are 100% pointless. Intakes are 99% pointless. It's not the weak link by any stretch of the imagination. Also, most 1500 dollar head jobs FAIL to address the two main inadequacies our heads suffer. Read up.
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Old 04-15-2008, 03:04 AM   #5
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Then that answers my question I think. I can do lots of custom work and get great gains, but there is no turn-key that is the default power setup except the 99-00' head swap.

But I do have one question - in your opinion, what is the biggest weakness of the 99-00' head?
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Old 04-15-2008, 03:09 AM   #6
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The only weakness I know about is just the solid lifters. When at Mazmart talking to Ben, we go on the subject of solid lifters and Paul was talking about how they are changing the formula of motor oil and its not going to benefit solid lifters.

Maybe Ben remembers more and can add to it.
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Old 04-15-2008, 03:56 AM   #7
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Quote:
Originally Posted by Cogz View Post
Then that answers my question I think. I can do lots of custom work and get great gains, but there is no turn-key that is the default power setup except the 99-00' head swap.

But I do have one question - in your opinion, what is the biggest weakness of the 99-00' head?
Poor attack angles and shrouding. Shrouding you can fix. (Most don't know how to unshroud an engine) To correct the runner angles would be more involved and involve welding. To do it right it would require destroying a head to find all the jackets and galleries. Bowl work is very important too, and usually ignored. Bowl work and unshrouding will net you about 2x what a FM headjob will get you, if done properly.
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Old 04-15-2008, 04:28 AM   #8
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How many 1.8L Miatas were made? Surprised nobody has created a modified head yet for it... (I know I know, the market must be too small...)
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Old 04-15-2008, 09:51 AM   #9
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Quote:
Originally Posted by Cogz View Post
How many 1.8L Miatas were made? Surprised nobody has created a modified head yet for it... (I know I know, the market must be too small...)
Like a friggin million. I don't know. A lot. There weren't any other options in the US after 1993. It was either 1.8 or 1.8.

Just to clarify (you probably know this):
90-93 1.6 only.
94-05 1.8.

I'd like to add, that aside from 99-00 heads, 04-05 Mazdaspeed heads were very similar to 99-00 heads, except they had COP (no VVT).

FWIW, is it true that VTEC gets pulled off a Honda when fitting a healthy turbo? I'd think that a successful aftermarket head might include a form of VTEC, which wouldn't be all that useful on this forum. I could be wrong.
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Old 04-15-2008, 10:03 AM   #10
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No, a lot of people who turbo GSR's and Hype-R's retain the VTEC. Because the cams have 2 different lobe profiles, it's beneficial and allows more air.

On the flip side, there are "VTEC Killer" cams out there that do not have the dual lobe profile. These are meant for cars running in high rpms, when running high rpms (read-race cars) there is no need to have a dual profile lobe since the low rpm one is never used. So people take the higher flowing head/intake mani from the GSR/Hype-R and use a "normal" cam profile in it, this makes for better flow and no extra "dead weight" parts (vtec solenoid, oil usage, and other valvetrain bits associated with vtec).
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Old 04-15-2008, 11:12 PM   #11
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On 94-97 heads, I HEARD once or twice but do not know if it is true, that the exhaust cams from an automatic are desireable, as they have different timing/profiles from 5 sp cars. I know the compression on the motor is down, what, half a point, but any truth to the cam deal?
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Old 04-15-2008, 11:50 PM   #12
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Quote:
Originally Posted by Stein View Post
On 94-97 heads, I HEARD once or twice but do not know if it is true, that the exhaust cams from an automatic are desireable, as they have different timing/profiles from 5 sp cars. I know the compression on the motor is down, what, half a point, but any truth to the cam deal?
I have never heard that but there is the good old exintake cam for the 1.8s
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