Premuffler question

[dw1]

Has anyone else wrapped some of their exhaust system?

Background:
On my '87 3.2 I eliminated the catalytic converter and replaced it with a Fabspeed premuffler.

I wasn't too concerned about the elimination of the cat's heat shield until I put 17 inch wheels and wider tires on the car. Because of the proximity of the tire inner sidewall to the premuffler, I wrapped the premuffler using DEI exhaust/header fiberglass wrapping. I did this in the past with muscle car headers to reduce underhood temps and perhaps get a slight bit more power.

After the wrapping, the premuffler temperature is lower and the exhaust sound seems a bit different - maybe quieter or maybe the audio frequency distribution shifted a bit. (Fyi, I have the premuffler feeding a Dansk 1-in-2-out muffler with 84mm outlet pipes).

The car isn't driven much in the rain and the premuffler is stainless steel, so I am not much worried about the wrap holding moisture and causing rust

Downsides? Comments?

[911obgyn]

Nice job wrapping, no downside i can think of except the corrosion bit.

[Showdown]

I’ve wrapped various bits of my exhaust and added heat shielding to the back of my fiberglass to keep it from being affected by heat. It’s working this far but my concern wasn’t performance based; I just didn’t want to melt anything.

[spedrcr]

dw1

I'm considering wrapping my sport cat pipe as well. Been reading a few threads here and there isn't much data to rely on so wondering if you used a IR pyrometer to measure temps pre-wrap and post-wrap? I believe I have an early version of the Fabspeed sport cat pipe (see below) and thought I might leave the cat bulge unwrapped.

I recently tested using my hand on the bumper after installing a DEI turbo blanket over my muffler and it's much cooler to the touch.

[dw1]

spedrcr,

Good question about the temperature drop. I did some measurements, but they were of the shock absorber, the tire rim and the tire sidewall, because that is what I was most concerned about reducing heat transfer to.

In general, these temperatures went down 35 - 85°F, depending on how long I drove the car and where I made the measurements.

I also found that the more complete the wrap, the better.

Fyi, the measurements were made with a low-cost optical pyrometer that has quite a bit of variation in spot size with distance because of the difficulty in mounting thermocouples to the surfaces for more accurate readings, so area averaging may be reducing the actual temperature drop. Of course, "your results may vary" as they say...

I'm happy to hear that the DEI turbo blanket made a nice difference. I've always been uncomfortable how hot the rear bumper gets, so I'll certainly consider that for my 911.