Per feedback on the gen6 Camaro forum, I have created versions of an intake tube plug that will fit V8-engined cars.
Presented here are versions with and without the Chevrolet bowtie on their faces.
The version that has an o-ring groove is designed for a standard "116" size o-ring (15/16" OD, 3/4" ID, 3/32" cross section).
All versions should be RTV'd in place to make a good air seal.
These were tested and confirmed to fit by the kind courtesy of Sean B. (@Texan.1LE) who also provided the photos of printed plugs and a V8 installation.
Please note that the V6 versions are for 30mm intake tube holes and the V8 versions are for 24mm holes.
The firewall plug works for both V6 and V8 cars.
There are also a couple of alternate versions of my Gen6 Camaro V6 sound tube removal plug set (the original versions are at- https://www.thingiverse.com/thing:3127222).
They are intended to improve upon the originals while being even simpler to install and much less expensive because no purchase of a rubber plug is needed.
There is a video that concerns what to do it you suddenly notice rattles and road noise because it is now much quieter inside (see below). :-)
I recently learned that apparently there is a GM firewall block off plug, part number 23342796, originally meant for 2.0t applications.
You may wish to purchase one of these rather than printing one such as mine.
However because it typically sells for around $18 (plus shipping) I would still print my own if I had to do it again.
My design also has more robust lock tabs than the GM version and a solid center.
Curiously they call it an "front intake air duct hole" cover when in actual practice no air should ever be passing through that opening at all.
Differences from the originals-
1) This firewall plug is solid (no center core) so it can be printed with a relatively low percentage of infill and still not need to be sealed.
2) The original set required the purchase of a rubber plug. These versions have custom made plug sets that seal from both the inside and the outside of the intake pipe. This puts less stress on the pipe while being even more hidden from the outside.
3) The seal onto the intake pipe is now merely a bead of silicone RTV around the plug flanges as shown.
New version of the firewall plug- (V6 and V8)
You will still need to put some 1/8" thick closed cell foam on the firewall plug, but that can be made up of strips if you wish.
I cut a gasket from 2" wide 1/8" thick "Frost King" seal tape as shown in the photos.
It works like a charm and that material is handy to have around for chasing rattles anyway.
I also added a 5/16" fender washer to spread the load of the clamp nut more evenly.
Again, this firewall plug will fit both V6 and V8 cars.
Version 1 of the V6 pipe plugs- (30mm intake tube hole)
The intake pipe plugs are fastened together with M3x35mm screws, but you can also use 6-32x1-3/8 screws or even drywall screws.
Just ream out the through holes in the bottom plug half to be a slip fit over whatever screws you use.
It is suggested that you use small washers on the screw heads to keep them from digging into the plastic.
Don't over-tighten them of course (because it's only metal threading into plastic), and there is no need anyway.
The upper plug inside the pipe may be a tight fit because the pipe shrinks a little where it is fastened to the main intake body.
If in doubt, scale both plug halves at perhaps 98% in your slicer. They will still fit extremely well.
Be sure to fillet the edges of the plugs with a bead of silicone RTV (see arrows in photo) to act as an air seal and just wipe off the excess after installation.
I used three screws in the design so that no single point of failure would allow anything to be ingested into the engine.
Version 2 of the V6 pipe plugs- (30mm intake tube hole)
This pair of plugs for the intake tube thread together without requiring any other hardware.
They will need to have their flanges filleted with silicone RTV to make a good seal like the other ones, then wipe off any excess after assembly.
The nice thing about these is that you don't need to thread them very tightly to grip and hold.
I made them a bit looser fit in the intake pipe tube and they are the ones that I am leaving in my car permanently.
Print these with 50%-70% fill so that they are strong.
While doing some other work on my car last night (11/5/19) I checked on these plugs and they had not loosened at all after many months of being in place. So this design works very well and is very secure.
All versions of V8 pipe plugs- (24mm intake tube hole)
All the variants of the V8 intake tube plugs posted here are installed from the exterior of the tube.
You may want to trim off the little anti-rotation tab on the tube so they will seat closer to the tube, but it is not required.
Be sure to use plenty of silicone RTV to make an air tight seal with the tube even if using the o-ring'd versions.
They probably should be printed in ABS due to the higher temperatures toward the top of the engine compartment.
I am still loving not having that ridiculous noise tube in my car......
Apparently GM is not too keen on them either as reportedly there are models of V8 Camaros now being shipped without them.
I hope this is something that you will like as well.
Thanks very much for viewing this.
Zyltech ABS (see notes)
25%-30% for the intake tube plug halves, preferably a little higher on the firewall plug such as 50%-60%
(color doesn't matter)
ABS is preferred due to under-hood temperatures, but others such as PLA, PETG or Nylon may work as well. I printed the last set of intake plugs in PLA and they are holding up very well.
A completely different (but related) subject......
If you are experiencing a mysterious door rattle problem that you just can't seem to find, check the two square plastic plugs and little round plugs along the bottom edge of the doors.
If they are even the slightest bit loose, they will rattle and drive you crazy.
Wrap one layer of electrical tape around the square and push them back in.
Put one piece of tape around one edge of the round holes and push the round plugs back in.
Also, the screws behind the inside door latch handles and their metal clips can creak (use foam tape between the door panel and the door itself).
The reason I mention all of this is that after I removed the sound tube and plugged up the firewall hole it became much quieter inside.
So even the tiniest rattles and squeaks then became more apparent and annoying.
There is a great YouTube video on this subject.
Search for: 2017 Camaro SS V8 Door rattling fix + dynamat (UK SPEC)
And the Gen6 Camaro forum mentions it as well.
All credit for these fixes is given to them.
Also, it is worth mentioning that there is a less expensive alternative to DynaMat available which is suitable for most applications-
I added this material inside the rear wheel wells (between the fiber liners and the metal) and underneath the carpet in the front foot areas in a couple of our cars.
All I can say is "wow, what a difference!"
It reduced tire noises greatly.
So I added it above the underbody fiber trim panels on the Camaro (below the seats and floor pan) and it dampened even more noises.
I then added it inside the doors and door panels just as was shown in dapperx's video and it made reductions in road and traffic noises plus the doors now have a really solid sound when I close them (before that they sounded a bit tinny).
I was able to do the whole car for around $60 US (three rolls of material).
It was worth every penny, and yes I can still hear the true engine exhaust noises if I accelerate briskly.
But the nuisance ambient noises are greatly reduced which makes driving much more pleasant, especially for long distances.