Exhaust Manifold Thermal Coating

I’ve been interested in learning if putting a thermal coating on the exhaust manifolds makes any significant difference in the temperature radiated from the exhaust manifolds.

As luck would have it I have a set of ceramic coated exhaust manifolds, but at the time that I had acquired them I was on a tight schedule replacing turbo’s on the S4 and so I had not been able to establish some good baseline data.

Additionally I’ve found that people modifying theirs cars are a very optimistic group.  If I was to use an Infrared thermometer to take external temperature readings of the exhaust manifold at various points in time, and find no difference between the thermally coated manifolds and stock uncoated manifolds, the optimists would pronounce that the surface temperature of the exhaust manifold is not important, it is what happens to the temperature of the gasses inside the exhaust manifold that matters.  If I was to measure the exhaust gas temperature of the thermally coated manifolds against the stock manifolds and find no difference, then what would really matter would be underhood temperatures, that would of course be lower since the thermal barrier slows the passage of heat from the interior to exterior of the exhaust manifold, even though the surface temperature might be the same between the coated and uncoated manifolds.

Desiring to be thorough with the next opportunity to do this evaluation I assembled a few additional sensors so that I could check readings better.  On hand I now have an Infrared thermometer, an air temperature probe, a high temperature K-type thermocouple, and RS6 exhaust gas temperature sensors installed on my S4 to record the full range of exhaust gas temperatures.

Audi RS6 EGT sensors going into B5 S4
Audi RS6 EGT Sensors for B5 S4

I also have a stock set of exhaust manifolds currently installed on my S4 and a set of ceramic coated exhaust manifolds available for installation at my earliest convenience.

As a warm up for the more thorough testing I started my car with the air temperature probe placed 2.25″ from the exhaust manifold and took readings every minute with the Infrared thermometer to produce the chart below.

Exhaust Manifold Thermal Coating Testing
Exhaust Manifold Thermal Coating Testing

 I made some more readings the next day.

BoostManager RPM Signal

Finally, after a number of attempts to get the BoostManager software to register an RPM signal I had success tapping into a previously used wire that connects to a fuel injector.  Eurodyne was very helpful throughout the process offering suggestions on where to try tapping the wire.

With the manifold pressure and rpm now being sent to the controller I can start to fine tune the water-methanol pump duty cycle table to better pair up with the K03 airflow and injector fuel flow.

Using the Injector Duty Cycle as a rough guide along with manifold boost pressure I setup the following table:


Next up I’ll be logging the car to see if I have any recurrence of the bog I previously experienced.

Ramp Jack Stand Safety


It was brought to my attention that someone thought this photo showed a very unsafe setup for working on my car.

Audi B5 S4 engine installationThe reason given was that if something were to cause the parking brake to become disengaged, and someone were to come along and lean upon the vehicle while somebody was underneath, the vehicle could roll off of the ramps and crush the person beneath the car.

Being fairly safety conscious I was surprised to have it pointed out that I was working in a way that was described as “super dangerous”.


So I thought about the setup in the picture a bit more, and then tested it out.

At the front of the vehicle providing support are a pair of jack stands.  A single locking 2-1/4 ton pair and a double locking 3 ton pair.

jack-standsAt the rear are a pair of Rhino Ramps.

rhino_rampsThe suggested scenario involves several events occurring; the parking brake is deactivated, which allows the car to roll off of the ramp, and a person comes along who decides to lean against the car in a location and manner such that they can roll the car off of the ramps.


Based upon the likelihood of these three events occurring I believe the risk of these events leading to a catastrophic outcome are very remote.  The parking brake is only going to become disengaged if it suddenly fails, which is not likely if the parking brake system is not being worked upon.  Alternatively it is unlikely that some other individual will come along and disengage the parking brake while the car is elevated and then depart.  Even if this were to occur a quick check inside the cabin before commencing work would verify the state of the parking brake.  Finally, even if someone were to come along and decide to lean upon the car they would have to do so along an axis that the car can roll, and with sufficient force to move the car off of the ramps.


I decided that I would assess how easy it is to roll the car off of the Rhino ramps.  I thought this might take a little effort since the platform that the wheel sits upon is a slight bowl and the four sides all have ridges of varying heights that the tire would have to roll up and over.  The most likely way that the car could exit the ramp is the way it entered, down the sloping side.

To test the effort involved I drove the car up onto the Rhino ramps and put the tires onto the top platform where they would normally be positioned during work.  I then recruited an assistant to sit in the vehicle prepared to apply the brakes if needed.  Next I went to the rear of the vehicle and leaned against the trunk to see if the vehicle would roll off of the ramps – it didn’t budge when I leaned against it.  I then proceeded to push against the trunk.  Moderate force again resulted in no movement from the car.  Finally I leaned over, placed my shoulder up against the car, and bore down as hard as I could.  The car moved forward perhaps an inch, but when the tire touched the front ridge the movement was halted immediately.


Being safe while working underneath a vehicle is important.  Taking steps to mitigate the risks involved is a smart thing to do.  I don’t believe the setup I use for working under the car poses significant risks.