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I'm just wondering if I should consider putting the time, money, and effort required to do this swap. What are the advantages of doing this and what is needed? I've been considering it as a possibility, but haven't been able to dig up any real info so far. Thanks in advance for the help.
 

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Discussion Starter #2
Also would it be better to get a 01+ head as opposed to a 99-00?
 

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Search button is your best friend. It has been discussed before. But in short 99-00 head are about the same as 01+ head except that 01+ head has vvt which will give you a lot more bottom end torque than any other head although it requires something to control it such as a vvt tuner box.
 

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99-00 will work. 01+ will have VVT and require some wiring and a bit more advanced of a swap. i would stick with a 99-00 drop it in wire up VICS to work at 4300rpm and you'll have instant power. its still a little involved though so do as you've been told and use the search. research reveals that it will be a moderate DIY project
 

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Anyone have any links to dyno sheets of what kind of power this head swap makes on an otherwise stock car or one with just bolt ons? I did some poking around but most of the threads I found were how-to discussions and boosted people showing how big a difference it made.
 

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the solid lifters alone are reason enough to swap, but the power comes from the fact that mazda engineered the ports much better so you achieve more airflow. the VICS system allows more air to flow at 4300+rpm by opening 4 smaller throttle bodies inside the intake manifold. altogether it is realistically a good 10-15 bhp gain but factor in that the NB lower end has higher compression pistons, so if you're comparing dyno sheets from the current motor to a 99 motor, remember that although the block is the same, the internals are slightly different.

89-93 1.6's were 8.5:1,
94-95 1.8s were 9.0:1,
96-97 9.5:1 with OBD-II timing control, and
99+ NBs had 10.0:1 with better heads.
 

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Discussion Starter #8
Thanks for the thorough explanation Laguna96. I appreciate it.
 

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A friend of mine added a '99 head to his '94 car a year or more ago. He did a lot of parts prep (new gaskets for the '99 intake manifold, head gasket, injector spacers, '99 fuel rail, blah blah blah). With a helper or two, one of whom is VERY well versed in Miata tech, and including a few parts runs, tool runs, beer runs, and whatnot, it took a casual couple of days.
If this is your only car, be prepared to have it not running for at least one full day...just in case.

On the subject of dyno runs, I'll say this: his "before" runs were made almost a year prior and with the timing bumped to 14 degrees or so, I believe. The "after" dyno was at base of ten degrees...so stock.
In dyno testing (I don't have his dyno plots, so sorry), I believe the gain was something along the lines of 8whp...maybe? again, that was before the timing got advanced again.
The car is now running a bit over 120 since adding Megasquirt.

Also, not to be a jerk, but let me make a few alterations to the compression ratios listed above:
90-93 1.6 - 9.5:1
94-95 1.8 - 8.7:1
96-97 1.8 - 9.0:1
99-00 1.8 - 9.5:1
01-05 1.8 - 10:1
Those are for US-market versions, of course. I have no idea what was available on other continents.
 
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