Why Ceramic Coat Exhausts?
Camcoat have been applying exhaust ceramics for over thirty years and have done many GT40 cars for car constructors (Tornado Sports Cars and Southern GT), exhaust manufacturers (SS Tube Technologies, Hayward & Scott, JanSpeed, Tony Law) and owners.
There are three main reasons why it makes sense to ceramic coat the exhaust on your GT40:
- To improve engine performance
- For aesthetic reasons
- To reduce heat-related damage
TO Improve Engine Performance
The hotter the exhaust gas, the lower the density which means quicker gas flow from the point of combustion to the exhaust tailpipe. Engine designers and tuners work hard to optimize the exhaust gas flow through the valves and cylinder head ports. The exhaust manufacturers work equally hard to maximize engine power or torque through selected design criteria. In the case of the GT40, there is a substantial amount of exhaust tubing in the form of 8 header pipes and twin silencers before reaching the tailpipe. Heat will be radiated all along this journey which is not what we are looking for. An effective way to minimize this heat loss is by applying ceramic coatings.
Camcoat do this by uniquely ceramic coating the inside (assuming no catalytic converters) with a hard, smooth ceramic. This provides the first level of heat insulation at source – the hot exhaust gas itself. The outside is ceramic coated with a range of options, the most popular of which for the GT40 is “Cermakrome”.
Not only do the ceramic coatings speed the evacuation of the exhaust gas but the thermal insulation provided will reduce the under-bonnet or engine cover temperatures. In many cases, this is where the inlet charge air is introduced into the engine so any reduction in its temperature, with accompanying increase in density, will improve engine performance.
The GT40 exhaust has been described as “a bundle of snakes” as the eight header pipes intertwine around the back of the engine and over the gearbox to twin silencers. This large surface area of very hot metal in the critical place just under the engine cover makes the GT40 an ideal candidate for benefiting from ceramic coated headers. One issue of these long, unsupported header pipes is the amount of metal movement due to constant expansion and contraction with the wide range of metal temperatures. In our early days of applying “Cermakrome” this led to occasional coating cracking due to the difference between the thermal expansion properties of the coating and metal, usually stainless steel. A modification to the coating material and application technique addressed this problem.
For Aesthetic Reasons
On a car like the GT40, where the exhaust is highly visible when the engine cover is raised, you do not want to see rusty or stained header pipes. With stainless steel you avoid the rust but it does “blue” at temperatures in the region of 300 degs-C. This appeals to some owners but not to all.
Camcoat’s “Cermakrome” ceramic coating addresses this issue. It is a water-based ceramic coating that after curing is mechanically polished to an almost chrome-like finish. It is highly resistant to corrosion having surpassed 6500 hours of the salt spray test without any sign of failure. It can withstand metal temperatures up to 760 degs C without losing its original shine or changing color. Above this temperature it does dull, a feature I have used on a race car to monitor individual engine cylinder exhaust temperature conditions. We have also applied “Cermakrome” on an LMP2 Le Mans race car exhaust and indeed it dulled but did not suffer any damage.
The other popular ceramic coating is our “Black Satin” which gives a finish as indicated by its name. This is our highest-rated coating at 1000 degs C so is best suited to track day and race versions of the GT40. Both of these coatings have a smooth finish which makes it easy to keep clean as they do not absorb oil and grease as do rougher ceramic finishes. In terms of life, we have had individual customer feedback of twenty years for “Cermakrome” and twelve for “Black Satin”. These may be exceptional as the life depends on whether the exhaust is new or used and if the rated temperature limits are adhered to.
Reducing Heat Related Damage
The subject of excessive under bonnet or engine cover temperature has already been addressed as a factor in decreasing engine performance.
IT CAN ALSO LEAD TO heat damage to components close to the exhaust header pipes. In particular starter motors, alternators, and electrical wiring. When carburetor float chambers get too hot the fuel vaporizes when the car is at a standstill, causing the engine to stop. Since it will not restart until the carburetor has cooled sufficiently this can lead to awkward moments in traffic.
Paintwork discolors and blisters with heat so the engine cover on the GT40 needs protection from the hot header pipes.
Another issue is driver and passenger comfort. You want the cabin temperature to be controlled by the car’s climate control system not by encroaching heat from the exhaust.
So, for an excellent car like the GT40 there are very sound reasons to invest in having the exhaust system ceramic coated – and you members do like the “Cermakrome” finish.
For any questions, including pricing, please contact Nick via:
Email: nick@camcoat.comPhone: 01925-445003