Just found a Spec Miata built head (never installed) from a '99. Includes intake and fuel rail.
Anything I need to know about putting it on my '97 block? Seller claims it's a 25 hp bolt-on, how accurate is this?
Pretty sure this is the way to head for CSP prep but I wanted to make sure before spending $500.
I'm not super knowledgeable about spec miata, but just from the idea of a 'spec' class, it doesn't seem like adding a 'spec' head on a stock motor would add 25 hp.
Sure, a head that has been worked over, ported, bigger valves, higher compression, etc, might give 25 hp, but that seems like it 'should' be specifically against the rules. Just shooting from the hip here.
It'll bolt on for sure, but you'll need a 99/00 intake manifold as well. It's certainly a better head, but likely not 25 HP different.
It also won't be CSP legal as you technically need to swap the engine as an assembly. The 94-97 and 99/00 pistons are different.
As noted, 25 hp is fiction. Even Mazda only found 9 hp when they added that head AND increased the compression.
There are at least three intake manifolds you can use (1999-00 VICS, 2001-05 VTCS, JDM "flat top" yo) but the 1994-97 one needs to be modified. Turn to your copy of Mazda Miata Performance Projects for details.
It's the '99 VICS intake. The head is shaved a bit.
Thanks Keith, these cars are such a blend of fun and frustration.
VICS is easy. Just throw an RPM switch in there to trigger the system, it gives a small (but free!) bump in torque or power.
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