RDanley;
I have both a Pre-Turbo Pyro and a Post-Turbo Pyro. That 200 degrees you add on is not a good idea. It's a blast to see the difference in the rate of change between a pre-turbo pyro and a post-turbo pyro. The Pre can (and does) streak up-wards and the Post will fairly lag behind. Cruising at Interstate speeds at 2000 RPMs empty, my Pre is reading 650 degrees with 10 psi of boost, my post is only reading about 575 degrees. However, the more boost I run, the bigger the differences. When I pull my trailer on the Interstate on flat ground, the difference is more like the 200 degrees you mentioned, but that's with the pre reading about 850-900 and the post only reading about 650 or so. So you see, with a change of 200-250 degrees pre turbo, post only raises 75 degrees or so. This difference gets greater on my truck when both the boost and Pre EGTs increase.
So all in all, think about the "Add 200 degrees" with a grain of salt. 900 Degrees post for short amounts of time shouldn't be a big deal. I doubt you're running very hot. Also, one thing to remember out there folks, your Cummins will most likely NOT explode the instant it hits 1300 degrees
. I have only seen one cummins that died of excessive heat. The guy had it bombed up to about 375 hp (12 valve), towed heavy and had the pyro post and didn't really watch it. Eventually, it EGTs got so hot as o melt the Al. fins on the compressor fins of the turbo, it also blew out the bearings of the turbo, but I think that happened later... . Why? Because the guy let it go for a few weeks, still pulling heavy, with NO boost!
He eventually cooked his 5th and maybe 6th pistons (it's been a while). But the think to take from this is that he probably didn't do any damage until AFTER the turbo melted. I'm sure he was cruising at above 900 degrees post for a loooooong time to melt those fins.
Overall, what I'm trying to say is that I don't think anyone should put in a Post-Turbo Pyro instead of a Pre-Turbo mounted one. I've watched both gauges on cool downs, and here's what I see. The Pre-turbo gauge cools down rapidly until it reaches the point of being about 25-50 degrees higher than the one mounted Post-Turbo. This implies that the shut down is at the end of a towing session, race or pulling session, through normal driving, by the time I'm in the driveway, the Pre-Turbo gauge has already dropped down untill it is close to the Post-Turbo. At this point, just let the Pre-Turbo cool down to 250-275 and your Post-Turbo temps are very close to 300 degrees, if not lower. Now, all this is with the stock HX-35/12 cm3 and a 4" downpipe-4"-5" exhaust. I can only guess how a larger turbo can affect this relationship.
Josiah
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