Since day one, we have been concerned about heat management in the engine bay of the Elise/Exige. Unlike a front engine vehicle, these vehicles do not benefit from massive amounts of cool high pressure air saturating the engine bay as the vehicle drives. True, these cars do have fresh air intakes on the sides of the vehicle, but these do not channel enough cool air to the rear of the engine, where the hot exhaust components are located. The exhaust manifold and turbocharger generate a tremendous amount of radiant heat, and if not controlled, many nearby components are susceptible to thermal failure.
We experimented with several solutions to this issue. First, we decided that under no circumstances are we ever going to ask a customer to cut or permanently modify their vehicle to install any of our parts. With that said, we knew that we had to protect the fiberglass clamshell body of the car, and not remove it. Our exhaust manifold does come relatively close to the clamshell in some areas. Lotus noticed that this is also the case for the stock exhaust, so they fitted heat reflective material on the clamshell in the area of concern. While it does help, it was not going to be adequate in protecting the fiberglass body from the increased radiated heat from the turbocharger kit.
Our first solution was to insulate the manifold and attempt to retain as much thermal energy in the exhaust gasses as possible. This reduces heat transfer into the engine bay and promotes quicker turbo spool. We built laser cut stainless steel sheet metal heat shields that would encapsulate the manifold and contain the heat. See picture below:
Testing of this solution required us to drive the car at levels that would get the exhaust system to its maximum temperature for extended periods of time, not something achievable with street driving. Track testing at Portland International Raceway was performed and the lessons learned were invaluable. We discovered hoses and plastic components had melted, and it was obvious something more needed to be done.
Manifold after a single heat cycling
Solution 2 consisted of protective sleeves over all necessary hoses, a tighter fitting heat shield (less gaps in between pieces) and ceramic coating the manifold, turbine housing, and downpipe elbow.
Testing was once again performed, this time at Thunderhill Raceway where ambient temperatures were exceeding 100°F. This was a bonus, as it would really put our system to the test. Results were promising as we experienced no melted components. But things were still getting very hot. We thought we could do better.
Ceramic coated manifold
Ceramic coated turbine housing
After track testing, we removed the turbo manifold for more R&D work, we noticed the ceramic coating on our manifold was flaking off. We knew right away, this was not a good solution.
Soon after, we contacted a company that makes thermal protection devices for all sorts of industries. Their products are used in many industries including: military helicopters, C.A.R.T. racing series, 24hours of LeMans, NASCAR and exotic sports cars. They use several aerospace technologies during construction that are proprietary only to them. We contracted this company to build a custom heat shield for our application. See picture below:
These shields are constructed from multiple layers consisting of metal foil, ceramic fiber, and silica fabric, custom fit for our application and sewn together with Inconel thread. Based on testing data, this product should dramatically reduce the amount of heat radiated from the manifold and turbocharger. If these heat shields perform as described, we will be including them with all of our turbocharger kits.