Exhaust Gas Temperature Sensor
The EGT sensor should be placed close to the cylinder head exhaust ports and
before the turbocharger. Typically we tap the exhaust manifold with the 1/8 NPT
tap and thread the EGT sensor directly into the exhaust manifold. The 1/8 NPT
pipe thread seals fine if the exhaust manifold wall is thicker than 0.120"
(3mm). For a thinner exhaust header wall, you may need to weld an
additional 1/8 NPT steel bung. We offer steel and
stainless steel bungs.
The cast iron exhaust manifold could be drilled and tapped without removing it from the
car by carefully drilling then tapping the 1/8 NPT hole while having an
assistant rev the engine to 2000-3000 RPM. The turbocharger creates enough back
pressure to blow the shavings out.
Be careful! If you try hard enough, the
shavings will fall into the exhaust manifold and find their way out through the
turbocharger blades or get sucked back into the cylinders and cause a serious
damage. If you do not feel comfortable tapping the exhaust headers
on the car, remove them!
Drilling the exhaust manifold without removing it from the car may damage the
turbocharger or the engine. Do it at your own risk.
Place the EGT wires as far as possible from the ignition
components such as plugs, plug wires, and coils. Since the ignition components
carry thousands volts they are a very powerful sources of EMI noise. The EMI
be inducted into the EGT wires. The Zt-2 has a sophisticated common noise
rejection circuit, however the EGT signals are in mili volt levels (0.001V)
where the ignition carries tens of thousands (10000) volts and placing the EGT wires
near the ignition components may result in false peak EGT readings.
On turbocharged engine the EGT probe should be placed before the turbo.
A high temperature drop occurs across the turbocharger which will throw off any
EGT readings taken after a turbo. This temperature drop is variable and so the
preferred EGT probe location is before the turbo.
The EGT probe is subject to an extremely violent high
temperature / high pressure environment. Over time it could be possible for an
EGT probe to degrade and potentially send fragments into the exhaust system and
turbo charger. The tip of the EGT probe is designed to slowly burn away
and EGT probes normally quit working before degrading to a dangerous point.
We have never seen our EGT probe fall apart, never the less we recommend
you periodically inspect the EGT probe for signs of damage.