1997 Mazda MX-5 Miata: The Beauty Of Dual-Purpose Cars, Pt. II
July 13, 2011
Remember a few weeks back I observed some pinging in Project Miata, and did the only thing I could which was to retard the ignition timing? Of course you do. It solved the ping, no doubt. No amount of flogging, flooring, or otherwise hooliganistic behavior will elicit that hamstring-jerking rattle of detonation.
Partially. Recall that retarding an engine's ignition timing means that more of the combustion event occurs while the hot, burning mess is escaping through the exhaust valves. This, in turn raises exhaust gas temperature (EGT).
Who cares, right? Your ass cares. Higher EGT means higher cylinder head temperatures, which places extra demand on the engine's cooling system. If your cooling system is in a Miata then it inherently sucks to begin with. A couple degrees of ignition retard alone aren't enough to send things into a tailspin, but throw an intercooler in front of the radiator and add hot weather and you've got a recipe for a swampy ass.
Which was precisely the situation I found myself in as we crept along in traffic, just before making the decision to bail on Highway 101. The ambient air was in the low 80s-degrees F, with some humidity. The needle of Project Miata's temperature gauge crept off its usual "11:30" position over to the 12:30 position, and if you've been a regular reader of Project Miata, you know that this is not a good sign. Immediately I shut off the aircon and entered a staredown contest with the temp gauge.
It recovered. But this didn't bode well. The weather at this point isn't nearly as hot as it will be later when climbing the Tejon Pass (a long, long grade that ascends to the high desert), nor as dry, nor is the air as thin here at 670 feet above sea level as it will be when we exit I-5 at Frazier Park (4600 feet). And a big chunk of the drive from that point is literally through the middle of the desert until we reach Highway 101, or about, oh, 140 miles.
To date Project Miata has seen loads of hard driving, but always in pre-summer conditions and always around sea level. The cooling system is in good nick; all ducting in place, t-stat functions normally, the radiator was replaced with one of those thicker stock replacement jobs shortly before we bought the car, the cap holds pressure and it's topped up with 60/40 water/glycol.
Anyway, by the time we exit at Frazier Park I've found that our engine's propensity for self-immolation even at a steady cruise is manageable as long as I'm strategic about when I use aircon (flats and downhills) and how rowdy I get with the throttle. And when I hammer it, I blast the heat. In the desert. At midday. In summer. Yeah, this is going to be a sticky drive.
Still, there's fun to be had. Cerro Noroeste is a fast road that demands your attention, as there are a couple of blind, decreasing-radius sphincter-clenchers along the way. The road's largely untraveled, too, save for the motorcycle in front of us that's dawdling along at ten under the limit and not watching his mirrors. Dan in his Exige easily makes his way around the bike and is out of sight in seconds. I'm in no position to use full throttle, so I have to wait til Sleepy McBikerton wakes up and waves me by.
This road's smooth, and the rhythm of the turns is sort of hypnotic. Relaxing, even though you're focused. Funny how that works. As you pile on cornering loads the steering remains faithfully linear, so you don't steer Project Miata so much as think the car through corners. It's pointy and predictable and goes exactly where you aim it without having to first heave a bunch of mass into action. I've pontificated about lightweight cars before, and it is this lack of inertia that characterizes the experience.
After Cerro Noroeste we make our way north on 33. It's hot. Did I mention this? We refuel in Taft, where it's deep in the 90s but feels like a thousand degrees in this car's inherently warm cabin. Project Miata's part-throttle power delivery in these conditions exhibits some lumpy grumpiness, in part due to the retarded timing. And after just a few of Highway 58's spectacular twisting corners taken at speed, the temp gauge is marching right over to 'H'. I have to back way off. Major bummer, as this is the best section of 58, itself one of California's prime driving roads.
Cerro and 58 are smooth roads, and it's easy to make a suspension that works well there. Bump absorption and recovery is yet another test of a chassis, and perhaps we'll encounter some of those later in the trip. Also, how will the cooling system hold up on track? So many questions.
--Jason Kavanagh, Engineering Editor