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Test Pipe Build, Heat Shield Install & Downpipe Wrap- May 2011

Y'all know how important heat control is on a turbo car. By making the most of the enormous amount of heat a turbocharger expels, you'll see benefits like faster spool and longer life for hoses and other heat-sensitive parts underhood. The previous owner installed the GBodyParts.com 3" stainless steel downpipe, which is an excellent piece of work. I would've definitely bought this myself if he hadn't already. There is also an upgraded Precision Turbocharger installed, which sports a physically larger turbine housing compared to the stocker.

All of this stuff looks and performs great but undoubtedly produces more heat than the stock parts. To keep all of this heat in check I decided to re-install the stock Grand National heat shield and wrap the downpipe. Since I had to remove the downpipe to wrap it, now was a great time to fab up an off-road pipe too, for when I'm off-roading, of course!


The catalytic converter had been hard-welded onto the downpipe outlet and Hooker catback exhaust inlet which makes removal of the downpipe for future work/maintenance impossible, so the first step was to break out my beloved sawzall and let the cat out.

Here's the cut at the downpipe outlet.


You can see the oval piping used at the inlet of the Hooker cat-back exhaust. Typically there is a rectangular flange here that bolts to a flange at the back of the stock cat. Since we didn't have any of that stuff, part of the job would require adapting some 3" piping to fit this shape.


Here's everything roughly mocked up.


With the downpipe off, I donned my welding gear and went to work throwing some fire onto the thick 3" 3-bolt flange. I've said it 100 times before- I love my trusty Lincoln MIG.


Not too bad if I do say so myself! I used this weld pattern to get as much surface area between the pipe and flange as possible. I'm definitely still learning, but I feel like my work gets a little better every time.


The test pipe and flanged catback adapter are done! It's all 3" round piping and I hammered out the oval shape to mate up to the Hooker catback pipe.


A little side-by-side comparison between the cat and the test pipe. Which one do you think flows better?


Almost done! The only thing I hadn't done yet in this picture was weld the flanged adapter to the catback exhaust inlet. That was tricky because I had to do it on the car, but I was able to lower the exhaust enough to get a nice clean bead on it. I also sprayed everything with my favorite Dupli-Color Low Gloss Black ceramic engine enamel. I chose to use flanges so that I could have lots of options in the future. I can run the cat setup, run the test pipe (only when off-road, of course) toss in a dump pipe that bypasses the catback for drag racing or even rig up an electic cutout.


Next I pulled off the downpipe to give it a nice warm fiberglass Snuggie. I used Summit Racing's 2" black heat wrap. I've used this same stuff on my other cars and it has held up well. I also ordered up a gang of Ideal clamps, which I've found to be impervious to the heat. I've also used these on my turbo pipes and have never had one fail on my other cars, even when running over 30psi. I've tried the little metal zip ties designed for exhaust wrap, but found them to be more trouble than they were worth.


This is an easy modification that really works well. It's also fun and challenging to keep the wrap tight and get the proper overlap. I've done a few now and am getting decent at it.


All done! I only used three clamps and it's very tight.


Here it is mounted up. The picture angle makes it look like the downpipe is touching the A/C lines, but there's lots of room.




Using the great template on the gnttype.org website, I cut the downpipe side of the stock Grand National heat shield. I actually used a simple jigsaw to get the job done and cleaned it up a bit with the grinder. The template was a huge help! The larger Precision turbo required a few small modifications to the stock heat shield mounting bracket and a little trimming to the turbo side. After that it was a perfect fit.

All done! I cleaned, sanded and painted the heat shield with some Dupli-Color cast coat aluminum ceramic spray paint before bolting it back on.


Well that's all for now, thanks for reading and there will be another update soon!

-Tom