Friday, April 04, 2008


After some indecision,* and more than a little work, I installed a Speedhut boost/vacuum gauge in my proper sports car this week. Here's a photo of the gauge nestled in its new home:**

I'm quite pleased with the appearance of the gauge. It almost looks as if it had been installed at the factory and even glows the same color as the stock gauges when the lights are on:

So, what have I gleaned from this gauge? I set the warning light at 7.5 PSI and found that appropriate application of my right foot would illuminate it pretty reliably. After adjusting the light to 8.0 PSI, I was unable to light it. So, apparently, Mia's peak boost is somewhere between 7.5 and 8. Depending on the reference you believe, the Mazdaspeed Miata is meant to deliver 7.5 to 8.5 PSI of compression. Thus, I'm in the right ballpark. I know the stock bypass valve on the MSM is prone to leak at high boost---or high engine speed, I forget which---so I might look into replacing mine to see if I can eek out a little more boost.

I think I'll put off installing an oil-temperature gauge in the right-center vent. I like being able to point one vent from each side at me. Besides, I effectively need to drain the oil to put the sensor in, and I'm not planning an oil change for another 3000 miles.

* Thanks for your input, Nick, Stingray, and Ken.

** The eyeball vent that was evicted from that fine abode now sits, lonely and unloved, in a zip-top bag in my draw of Miata parts.

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