Sound and Heat Insulating a
Diesel Hummer Conclusion

Insulate Engine Cover Article

Impressions Post Sound Insulation-

I have been fortunate enough to try both the Street Queen insulation plan along with the Practical and Utility insulation plan.

The Street Queen version was amazing. I had the floors and drive tunnel fully insulated and, with the interior partially stripped, I bolted the driver's seat back in and took the truck for a spin. When going over speed bumps, etc...you wouldn't hear the typical Hummer clanks and suspension noise. When you would shut the door, everything felt much more solid and less "rickety". There was a lot less echo and resonance in the interior. It was much more ambient. For some reason, just doing the floor and drive tunnel seemed to drown out the engine noise as well. If you were to combine this with Chuck's excellent Engine Cover Insulation Tutorial, I think this would be a very hard combo to beat.

The Open-Top, by nature, is a loud H1. Much louder than Hard-Tops and Wagons because of the convertible roof. The improvements were worth it. The drive tunnel no longer gets warm and I do not hear drive train noise. I eventually ripped out the floor insulation material because of the rain water that entered in through my door seal. I went back to the AM General rubber foam factory flooring. I did notice a bit more road noise, but it still is a lot quieter than before, and I have not insulated the engine cover yet!

Generally, the human ear can only detect a 3 Db difference gain or loss with regard to sound. It would be difficult to measure this before and after. The insulation is well worth it and having a cool drive tunnel makes driving the truck much nicer.

If I was you, I would leave the floor alone and do the drive tunnel via my tutorial and the engine cover via Chuck's tutorial.

The only salient reason you have to rip up the floor is if you have a Street Queen and you want ultimate silence, or if you have an older truck and want to get the vinyl floor cleaned out and the under floor area freshened up and dried out.

I agree with Chuck that the biggest noise contributor to the H1 is the inboard mounted engine. I look forward to adding the lead and fiberglass sheet, because I believe this will help tremendously.

With regard to audio industry sound damping, deadening and insulation products such as Dynamat and Cascade Audio, they should not be discounted when trying to get an H1 quiet. They will not fix the majority of the noise problems, but they have very valid applications. Similarly, if I had just used Maybach materials, I would have come up short also. It is very important to understand that it takes a multi-material approach. This will provide the best results and you need to look at what you are combating, and the surface that you are applying the material to. Developing a synergistic approach of materials working together to combat different contributors to noise is the key solution.

The real benefit of all of this was re-doing the interior. I must say, my Open-Top is much less utilitarian now than before. I had factory black vinyl seats in my truck. They held up very well over 25,000 miles and were in excellent condition, but I would slip and slide around on the vinyl. Furthermore, the vinyl did not breathe during the summer months. I ended up covering them with the Neoprene seat covers from Wet Okole in Hawaii as a temporary fix until I stripped my truck.

Now I have Mercedes leather and carpet installed. This significantly improves the user comfort and enjoyability of the Hummer H1. The extra padding and comfort reduces fatigue. The truck has a European luxury car ambience now.
Most wives and girlfriends complain about the lack of comfort in an H1. About 3/4's of my H1 buddies have wives or girlfriends that want nothing to do with the H1 because they think it is a piece of farm equipment. Put in leather and nice carpet and change the steering wheel and they will hush up and ride with you. With the engine insulation, you might actually have to engage them in conversation during long trips!

The leather and the carpet both hold up great. As long as you do the preventative maintenance. Griot's Garage leather care once a month. Conditioner quarterly. Carpet can be vacuumed and then cleaned with Griot's Garage clear interior cleaner. This clear interior cleaner is amazing. It works great inside the home, too. Having a clear cleaner that you do not have to worry about staining the material you are cleaning is very helpful. It works great and easily deep cleans Hummer Vinyl and Plastic. It should also be noted that leather is a long lasting and durable material. It is truly an organic and natural skin. Anything that is organic and natural will need conditioners. Do your part and your interior will look good indefinitely. It will get better with time.