We had purchased the Blockit Mat set for our 2009 C6 coupe many years ago, placing it under our Lloyd trunk mat and putting the small panels behind the seats. Eventually I removed the main mat because I couldn't discern any sound difference and it slightly reduces trunk space especially at the rear, but I left the small pieces behind the seat. When we got our 2017 C7 coupe, I carefully trimmed the C6 mat to fit the C7, taping small pieces from the cutoff areas to fill the tiny gaps, but didn't have the behind-the-seat panels. Again, installed under our Lloyd trunk mat. Again, my ear could discern no difference between with or without this Blockit.

Keep in mind that my experience is not actually a test of the C7 Blockit Mat set. Our C6-converted-to-C7 mat was 5/8" thick, the C7 Blockit mat is 1". I didn't have the behind-the-seats panels to install. And I was keeping the Lloyd mat on top. I was simply trying to discover if the "free" converted C6 mat would quiet our C7 at all, and get a better feel for the effectiveness of any "lay in the trunk" sound mat.

On 10-21-2018 I ran my tests from 11:30 to 12:30, (noon-ish). Car is a 2017 2LT Z51 A8 Coupe with transparent top (which lets in more noise). Car had 20,140 miles. Tires were Michelin AS3+ ZP runflats with 9,800 miles and 8/32"-9/32" tread remaining, they are about the same loudness as our factory PSS runflats. Climate fan was set manually to avoid variations in noise. The horizontal sunshade is installed in the trunk but not the front vertical piece. Weather sunny, 40', wind SW at 12 mph. All runs were made with the Lloyd trunk mat in place over the Blockit or laying directly on the stock carpet when the Blockit was removed.

Sound meter was a Decibel XPro app on an iPhone SE, held above the center console about even with my ear, same position each run. I used the "A" scale, which weights higher frequencies more to approximate the human ear. This app records several parameters, I simply used the Average reading for the duration of each run. I can't check the absolute accuracy precision of this unit but I can tell you it's very consistent. So the "real" decibel levels might have been slightly higher or lower than I recorded, but the important thing was to simply compare sound with and without my Blockit. I think it did a good job of that.

A total of eight runs were used, a couple of others had to be discarded because of traffic or other extraneous noises that ruined the run.
Cruise control was allowed to stabilize at 60 mph before entering the recording area.

The test was run both directions (North and South) on a 1/3 mile length of well used but still smooth asphalt. Each run was approx. 20 seconds, always staying on the same piece of road for each direction. Results:

Northbound runs with Blockit installed: 69.2 and 69.0, average 69.1 dbA
Northbound runs without Blockit: 69.2 and 68.9, average 69.1 dbA

Southbound runs with Blockit installed: 69.8 and 69.8, average 69.8 dbA
Southbound runs without Blockit: 69.6 and 69.8, average 69.7 dbA

Let the flames begin.

 

Nice Job Jim

Thanks for going through the effort and sharing the results.
I have considered some sort of sound deadening but i was thinking it would require more than just one panel over the rear floor
Thanks for confirming...

It seems that the biggest gains are in the wheel wells and that takes a little bit of work to get a neat and effective result.

BTW- I just saw a Block-it panel sell in the "parts for sale" section, there is a market - good luck

 

Yes, I'm boggled that no one has come up with some kind of carpet & sound insulation to quiet things down by covering the wheel wells. And hide that cheesy looking plastic that gets scratched up on the first road trip.

 

I thought you liked the Blockit in your C6. You posted a few positive comments regarding it back then.
However with your C7, I think part of the issue is your car already seems to be quiet with nothing in it.
At levels of 69 db, that’s pretty darn quiet.

Annoying tire/road noise usually kicks up a higher level than that. Here is a link to someone who also like yourself used a C6 mat (which doesn’t fit ) in a C7. They had a louder interior. But the Blockit made a difference. They had much better results.
He got a 4 db drop with his Iphone app. He mentioned the reduction was even higher (1.5 more) with his actual sound meter. But it was easier to print the results with the Ipone app for the forum. Still very impressive.

Here's the link:
https://www.corvetteforum.com/forums...tion-test.html

I think some of the other issues is that your mat is 10 years old and is an old design.
The product since then has been greatly improved on.
The mat your using is a thinner 3/4" mat. The New C7 is 1" (However the foam on both mats crushes down to about 1/8" so you don't lose cargo room).
The new C7 has more barrier which also helps with sound deadening.
The C6 mat you used does not fit the C7 properly. It’s a completely different shape. I understand you cut and pieced it together but you also were missing the 2 pieces for behind the seat.

Either way, the Blockit is designed to help with annoying tire/road noise and some aftermarket exhaust. Its not for ever scenario.
I think in your case even the new correct blockit would only make minimal difference.

 

Your quotes for me are accurate.
Initially I thought that our C6 mat was working in that car, but eventually realized that different conditions (pavement, tires, speed, wind, etc) made assessment more difficult. When I tried doing mat-in and mat-out comparisons under identical conditions, then my ears couldn't tell any difference and I took out the mat.

When we sold the C6, the two pieces behind the seats were glued in under the "wall" carpet and I left them there, I think they are useful but don't have any measurements. I plan to put some Dynamat under the wall carpet in our C7.

I would have preferred to do some testing at higher speeds and different pavements, but the logistics of that in my area are difficult.

If you manage to make a curved sound-deadener-carpet that can be installed over the wheel arches in the trunk, sign me up!

 

Same opinion regarding noise reduction although my approach was a little different...

In my C6 GS I had a double layer of Second Skin Luxury Liner Pro, so 3/4" thick, under a Lloyds mat and also behind the seats. This stuff is Heavy! Noticed no difference in sound. Left it in there since I'd pull the Lloyds mat out and pile my track stuff on top of the Luxury Line Pro that basically protected the carpet. I took those pieces and did the same as you....cut them to fit my C7 GS and installed them under the new Lloyds mat. No difference in sound that I can tell. I'll leave it in there to protect the carpet when hauling my track stuff.

The noise comes from the wheel wells and then bounces around the hatch area. A mat on the floor of the cargo area just isn't going to do anything. I got a bigger reduction in noise on my C6 GS when I ditched the Goodyear runflats and installed non-run-flat Michelin Pilot Super Sports.

Second Skin does say that the LLP is typically installed on top of even more products to get the full benefit. Given that LLP looks nearly identical to the Block-it mats, I'll imagine the same recommendations could apply. By itself...meh.

 

Exactly the same results my tin-ear gets, though others "hear" differently and at least one post here presents slightly better results for Block-it using a phone app, as I recall. Personally, I think most who claim better performance are experiencing cognitive dissonance and make their perceptions fit their spending, but to each his or her own (including me).

Bottom-line, though, I'd never buy the product again.