Quote:
|
Originally Posted by sp00ln
It'll run about 150* cooler. But that's not the point, the point is to gauge normal activites. If you see anything ABNORMAL, you shut it down. Do you see my point or no?
|
Your point seems to be that as long as you can see abnormalities, the mounting point doesn't matter. But I don't see any possible scenario where placing the probe before the turbo can have a negative effect on determining exhaust gas temperature. There is no advantage to placing the probe after the turbo.
Placing the probe in the downpipe has several distinct disadvantages however; primarily the fact that with factory serial fuel rails, cylinder 3 will run leaner than the others due to a slight drop in fuel pressure. Leaner = hotter, but if you're measuring the mixture from all 4 cylinders, #3 could be running at 1700F while the others are at 1550. That's a pretty good way to pop #3, even though your gauge was only reading 1250-1300 the whole time.
Further, the turbo is not a constant. You can't always say "add 150 degrees to get the true reading" because that isn't accurate. During warmup the turbo is stealing MUCH more heat than that, and the turbo isn't fully heatsoaked until after the engine coolant has reached thermostat temp. Also, it absorbs more heat during high temp runs, because of the larger heat difference, than it does during semi-steady-state cruising. Putting the temp probe in the downpipe turns it into an educated guess, rather than an exact measurement of what's going on.
I think you mentioned the possibility of the temp probe breaking and ruining the turbo and/or valves. But that's only an issue with cheap, bottom-of-the-line stuff. Subaru owners are encouraged by the rest of us in the online community to avoid low-budget mods, especially when it comes to reliability-affecting parts like gauges. The DSM crowd in general doesn't think that way. That's why they have such a poor reliability reputation- it's not the motor, it's the mentality of the average person who mods it. Don't get me wrong, I'm sure there are more than a few 12 second DSMs with 70, 80, 100k miles, and more than a handful of WRX owners with blown motors from cranking their MBCs. But every experienced car geek knows this mantra:
When choosings mods, choose two of these three; power, reliability, and cost.
DSMers choose power and cost. We choose power and reliability.