Project Viper GTS: Part 7 – HeatShield Products

style=”line-height: 20.8px;”>HeatShield Armor is also easy to cut with regular scissors.  Later in the article, we will demonstrate the proper steps to make for a clean installation.  Ideal locations are wrapping the entire exhaust header or manifold, or anywhere you need to prevent heat from radiating out of the exhaust.  For Project Viper, there are a ton of locations to use this.

It’s no secret that I’m a carbon fiber nut, and when I saw this product, I had to try it.  LavaShield is rated for 1,200*F and is a thin peel and stick insulation that can be used anywhere the ‘gold’ foil is used.  LavaShield is a woven fibrous cloth made from basalt fiber, one of the few minerals that is the result of magma cooling. The rock is crushed up then super-heated into fine strands to make the base fiber that is woven into sheets.

Lavashield outperforms all the ‘gold’ and ‘silver’ finished products out there and makes for a great alternative that is more subtle and looks like carbon fiber.  HP StickyShield outperforms LavaShield but if you don’t have the room for 1/8” StickyShield, or you don’t want a shiny heat reflective product in your engine bay, or need the benefits and like the look of carbon, LavaShield is your solution.

Now that we know what heat management products we are going to use, let’s take a step back and look at the Viper side sill heat problem and solutions:

Problem:

The Viper’s side sills get extremely hot and actually discolor and burn the paint because they enclose the red-hot catalytic converter and the side mufflers with zero air flow to cool the exhaust.  There are two common paths that can be taken to solve this problem:

Solution A) Increase airflow and heat dissipation

There are kits out there that require cutting the fiberglass end caps off of the front and rear of the side sills and installing louvers or mesh at the to improve airflow.  Airflow is a great insulator but you have to be moving for this to have any benefit and from our testing, the side sills get the hottest after they have heat-soaked with the car idling after a hard run.  Opening up the ends of the sills will not have much of an effect on this heat soaking condition and can allow for debris and water to get in to the sill which I would like to prevent.

If you don’t drive the car in the rain (and most Viper drivers don’t) and you don’t mind routinely servicing the car and removing the side sills periodically to clean them out of debris, venting the sills might not be a bad solution, especially on a track car.  To take this a step further, some people drill holes in the bottom of their side sills to further vent them, which should help the heat soaking issue more than just opening up the front and back of the sills, but this solution does nothing for heat radiating into the cabin.  Some Vipers have been reported to have caught fire from debris getting stuck in the side sill and ignited by the hot exhaust.

Since I don’t want to cut the side sills, buy new ones to paint and cut up, routinely clean the side sills and check for debris, and since venting the sill does not reduce the radiant heat from the exhaust to the cabin, or insulate the cabin from the hot exhaust, this was not a solution for me.

Solution B) Insulating the hot exhaust from the car

The second option is to insulate the cabin and exhaust with heat shielding.  Like a thermal jacket, layers and air are great thermal insulators and HeatShield Products use this principle to create layers of insulation material to keep the heat inside the exhaust and out of the chassis.  By wrapping the exhaust, heat stays inside the exhaust (which keeps the exhaust flow and energy up, which is good for power) and does not radiate out and in to the chassis.  Stacking insulation on top of the factory heat shielding creates even more layers to further insulate the cabin and keep heat out.  This is even more crucial when there is little to no airflow like in our Viper’s side sills.

Creating these layers should be more effective at reducing the cabin and side sill temperatures when heat soaking at low speeds and when stopped in traffic, which from our testing is when the side sills get the hottest.

Exhaust “Wrap” Concerns:

There is a common concern regarding ‘old-school’ header wrap (that comes on a roll) trapping moisture and causing increased corrosion of the exhaust in older cars, Hot-Rods and Harleys.  These vehicles have often used very poor quality mild steel that are already prone to falling apart, and when you add heat to the system by wrapping the exhaust, the extra heat prematurely exposes flaws in the material and causes increased deterioration of the cheap metal.  If you have a cheap corrosion-prone mild-steel exhaust, keeping the heat inside the exhaust with any kind of ceramic coating, wrap, or shield would likely make it worse.  If you have a higher quality modern or aftermarket stainless steel headers and exhaust, the effects of increased heat on a quality coating or wrap should not be a concern short of sustained 2,000*F temps on a turbo application.

HeatShield Armor was originally invented nearly a decade ago for industrial exhaust systems on heavy duty trucks that needed to be pressure washed regularly for highway patrol inspection.  Unlike the ‘old-school’ header wrap, HS Armor can hold up to pressure washing at 1,000psi inches away with no issues, so regular use and driving in the rain should not be a concern at all.  This is possible by using water-resistant BioCool™ insulation and having an outer aluminum layer which encapsulates the exhaust and makes it extremely water resistant. Any small amount of moisture that may work its way past the aluminum outer layer would be quickly be burnt off from the hot exhaust.  HeatShield Armor has not had an issue with increased corrosion over the years of use on industrial vehicles so we feel comfortable using it on the high quality stainless steel Corsa Exhaust and the small section of factory 1990’s Mopar exhaust.

Now that we know what the problem is, have a path for a solution, and have good insulating products, it’s time for some benchmark testing to get a baseline temperature reading.  Our testing was conducted by doing 2 hard hot laps around a racetrack, coming to a stop, and letting the car heat soak and idle for 5 minutes.  We chose this test method because we noticed the side sill temperatures would slowly rise as we were taking the measurements and it took about 5 minutes for the side sills to reach equilibrium and stay consistent.  Here are the results:

The front, top corner is the hottest part of the side sill and where paint starts to discolor on most Vipers.  The front exhaust hanger mounts right behind this, so it will be difficult to reduce temperatures here since there’s heat transfer through conduction of the hot exhaust touching the hanger, which touches the chassis, which touches the side sill.  At 276.2*F, our clear bra started to shrivel and over time, the paint will start to discolor.  The corner of the sill (right) registered 255.2*F.

The (left) image is where the exhaust makes a 90-degree bend into the front of the giant catalytic converter.  The temperature is 164.6*F.  The (right) image is right in the middle of the cat at the closest point to the side sill, just before it flares out.  This is the hottest point in the side sill other than the leading edge, at 198.9*F.

The middle of the side sill (left) is where the side muffler sits and where we recorded 160.8*F. At the back of the side sill, the exhaust has already dissipated a lot of heat in to the cabin and side sill. This is where the exhaust makes another 90-degree turn behind the occupant’s seat.  We recorded 128.6*F.

We did the heat shielding simultaneously with the exhaust installation in Part 6 – Corsa Exhaust & Kooks Green Cats so we have to thank Will from RareFab for his continued expertise, quality craftsmanship, and meticulous attention to detail.  I guess there’s a reason I often see Lamborghinis and Ferraris in his shop.

Once Will removed the side sills, we were able to inspect them and assess the damage.