At first I was too embarrassed to tell this story, but I've decided it needs to be told.
I've never claimed to be a genius with cars, bought the Miata as a learning tool. So here is a learning experience. This summer I and a friend did a 1.8 swap in my 90, one of the parts I didn't plan ahead for was a 1.8 cat. So after the engine was in (for the second time, first cheap oil pump didn't work) I had to wait for Levnubin to get a cat for me (Tks BTW).
The car hadn't moved in almost a year and it was killing me to not be driving it. So I started taking it to the grocery store, and to pick up my boy from school. Little short trips, 1\2 mile or less. Sounded like a boat, with the DP just dumping it under the car. I didn't think this would be a problem, as I had heard that some track cars don't run any cat or muffler. I had new suspension on it (see sig) and was dying to see how it felt on the great mountain roads out side of town.
The need arose to travel down the mountain, the wifey knowing how bad I wanted to drive my car dared me to take it, calling me a ***** for being scarred of getting a ticket. So we went, down the mountain was uneventful, to many cars on the road to do anything. On the way up it was about 9pm, on a warm summer night, top was down and no one was in my way
After about 10 min of spirited driving up a steep grade we pulled off the look at the view of LA and have some "fun". When we stopped, my wife says "whats that noise?" After a second of investigation I found the gas cap to be hissing. This is not uncommon from the elevation gain, so I cracked it a bit and whent off to check out the view.
When we returned it was still hissing, this kinda worried me a bit, but it was a hot day\evening (probably 95* at 9pm) and we just drove 5K feet in 10 min, so I just opened it a bit more expecting it to relieve the last of the pressure and then we'd go. But it didn't stop, it got worse. So in an act of brilliance I unscrewed the gas cap entirely. Just in case there is anyone reading this not screaming at your monitor "DON'T DO THAT!" Well, Don't EVER do that. It blew a geyser of gas 2 feet off the back of my car, after yelling "Oh ****" and jumping back, I realized that this wasn't good either, so I jumped back in forcing the cap over the flowing gas, stopping it.
We pushed the car off the huge puddle of gas, cleaned everything off as good as I could with the roll of shop towels I had in the trunk. I started it with my wife standing 50' away. Driving mildly and stopping frequently to vent we made it home OK.
1. Even thought the PD dumps several feet in front of the gas tank, the heat has nowhere to go but down the exhaust channel into the tank area.
2. The heat generated at 6-7K RPM is SIGNIFICANTLY more than ~4k.
Just my observations, I hope it was a entertaining story, and perhaps a lesson to some other