A week or so ago, I bought a used Perrin turbo blanket ($50), thinking that I’d use it instead of having to buy an aftermarket heat shield when I install my CNT downpipe. I did not want to have to modify the stock heat shield (cutting is involved, which would make the heat shield less effective).
So, I’ve been doing a lot of research, trying to determine if there are any real consequences in using a turbo blanket. The premise of using a turbo blanket is to keep the radiant heat of the turbo inside the hot side of the turbocharger, which would make the heat stream more effective. A possible consequence would be that the resulting heat would put the heat level outside the normal heat range of the hot side of the turbocharger, which could cause premature failure of the turbocharger. Another possible consequence would be that the additional heat could cause an engine that was recently stopped to coke any oil that is in the cooling system on the hot side of the turbocharger (this could be debunked due to the fact that modern turbochargers usually are cooled by both oil and water, such is the case for GR/GV Subaru STIs).
My finding is that there is no solid evidence that a turbo blanket will kill your turbocharger. Turbochargers are built to take very large measurements of heat, so adding a heat blanket should not overburden the turbocharger. Heat also makes the turbocharging system more efficient (the more heat, the better the turbo reacts to the demand for boost).
The main reason I want to use a heat blanket is so that my IC won’t be heat-soaked, since it is above the turbocharger (it is top-mounted). A heat-soaked IC would more than likely cause a pull in timing during the hot months of summer or in stop-go traffic, or even at local track events.
There’s a crap-ton of information regarding this topic and I can’t seem to find any solid consequence for using a turbo blanket, so I’m probably going to install my used example when I go to Stage 2. I’m also going to buy a top-tier heat shield, and I’ve evaluated a couple here.
Also, note that I’m well aware that there are cheaper variants of this style of turbo blanket (PTP). In doing my research, I also found that Perrin has allowed PTP the right to sell what is essentially a Perrin design (when I find that URL again, I’ll link it here). As well, there are apparently new versions of these blankets. They’re essentially made from ground lava rock, which allows these variants to retain heat more efficiently.