Thread: Exhaust manifold whistle

Originally Posted by twr7cx

You are correct, there is no performance benefit in terms of the motor having more power or torque, etc, but I found there is an indirect benefit of performance once my ceramic manifold was fitted. As it significantly reduced the EGT I was able to give more throttle, or throttle for longer, on some of the hills resulting in the vehicle traveling up faster or quicker. That's a performance benefit side effect. There's a hill on the highway on my way home from work or the city each day, previously I would have to back right off about 85% of the way up due to EGT getting too high, now I can leave the vehicle on cruise control at 110km/h and even when I hit the peak EGT is still low enough not to be a concern. Same pyro probe and gauge fitted at the same location on the manifold.

That's interesting, I hadn't thought it through that far, and my D2 doesn't have the EGT monitored. The D1 does, and I've got so used to it that I'll have to do something about it on the TD5 when it comes home. Thanks for that.

Originally Posted by johntins

That's interesting, I hadn't thought it through that far, and my D2 doesn't have the EGT monitored. The D1 does, and I've got so used to it that I'll have to do something about it on the TD5 when it comes home. Thanks for that.

By keeping the heat in the manifold there is more energy to spin the turbine.
It's heat energy that does our work, as the gasses expand the heat energy (enthalpy) is converted to kinetic energy spinning the turbine.

A similar effect is if you coat the dump for about 3' after the turbo, gas velocity is higher than an uncoated pipe (heat energy is retained, as the gasses continue to expand they cool and lose velocity) so it scavenges a little better as the lower backpressure helps the turbine (and hence compressor) spin a little faster.

I think it was Beaudesert Exhaust I spoke to once about ceramic coated dumps. I was quizzing the owner on coating dumps as I wanted to do this on the Defender.
It was a totally unexpected side benefit, they were only looking for lower underbonnet temps in GU Patrols and they made slight power gains, so they backed to backed it against uncoated dump pipes and it was a consistent boost and power improvement.

Originally Posted by rick130

By keeping the heat in the manifold there is more energy to spin the turbine.
It's heat energy that does our work, as the gasses expand the heat energy (enthalpy) is converted to kinetic energy spinning the turbine.

A similar effect is if you coat the dump for about 3' after the turbo, gas velocity is higher than an uncoated pipe (heat energy is retained, as the gasses continue to expand they cool and lose velocity) so it scavenges a little better as the lower backpressure helps the turbine (and hence compressor) spin a little faster.

I think it was Beaudesert Exhaust I spoke to once about ceramic coated dumps. I was quizzing the owner on coating dumps as I wanted to do this on the Defender.
It was a totally unexpected side benefit, they were only looking for lower underbonnet temps in GU Patrols and they made slight power gains, so they backed to backed it against uncoated dump pipes and it was a consistent boost and power improvement.

Makes perfect sense when you think it through. What about the turbine housing? You coat that as well?