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Blew a coolant hose today during the first race. Replaced all the big hoses earlier this year, but overlooked the two hoses in and out of the heater core. One of them burst late in the race, and the engine got very hot, but the head gasket didn't blow. Still a little worried though, was about 2 seconds off from my times in the morning. Think we might have done some damage to the motor.
Dave Sparks's profile photoMelina M's profile photoDeryk Robosson's profile photo
Is there a particular reason the heater core hasn't been stripped from the car or is it a requirement to maintain the vehicle in a certain 'as from factory' condition?
How easy is it to do an engine swap rule-wise? Do you have to match the production year, output, displacement (like would they let you use an NB engine in a post-1992 NA)? Last I looked Miata engines weren't terribly difficult to come by nor insanely expensive, but I don't know if the rules and regulations would make a swap prohibitive.

Hope you're back up to speed (literally!) soon!
+Deryk Robosson Some people think there's an advantage to having the additional coolant capacity. This car has a big radiator, and I haven't had any cooling issue, so I'm inclined to seal it off and eliminate one more potential failure point. I'm pretty sure the Spec Miata rules don't allow for the removal of the heater core, but you are allowed to bypass it.
+Melina M Engine swaps are allowed, but 90-93 NA cars have to run the 1.6L engine to be legal in Spec Miata. There are a few modifications that can be done to the engine, but anything that isn't explicitly allowed is disallowed.

I have a replacement motor lined up, but it probably won't be ready for the next race weekend.
Wait, there are no 1.8 NAs in Spec Miata? I had no idea. Good luck with the fix and/or replacement!
+Melina M Yes, the '94's thru the 97's (I think) are 1.8L. But the rules are different for those cars than they are for the earlier NA's.
Ah yes, that is what I was referring to. I thought the 1.6 only came in the 1990-1992 model years, but perhaps I'm thinking of the years that Sunburst Yellow was available.

Do you happen to know if an NA that came with a 1.8 would be able to use an NB's 1.8? I think there was a jump in power even though displacement stayed the same.
I have a '93, the last year of the 1.6L. AFAIK, if you want to run in Spec Miata, you have to run the stock engine for that year. There are 4 slightly different sets of rules for each of the major model changes (90-93, 94-97, 99-00, and 01-05). NC's are in a separate class.

The biggest differences aside from engine specs are restrictor plates and minimum weight. The 1.8L run a restrictor and slightly more weight to try to equalize them against the 1.6L.

This year's SCCA rules for Spec Miata are here if you're interested in the nitty-gritty details:
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