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It will depend where the thermocouple is placed as to what sort of reading is obtained.

Pre-turbine will be significantly higher - you would see up to 150 degC differential across the turbine.

Then the further down the dump, and to some extent the angle + depth of intrusion into the gas flow will impact the reading obtained.

That said, running @ ~ 12.2:1 AFR @ full load and high rpm on an acceleration run will get me 810-820 degC with the probe placed 100mm post turbine and probe at least 40mm into the pipe.

  • 2 weeks later...

I get up to 800 deg C using a 1.6mm K-type thermocouple mounted in the exhaust manifold...

One thing you need to remember is that the thermocouple indicate the temperature of itself at the junction, and not the gas surrounding it. So the indicated temperature will be slightly lower than what the actual temperature is... How big the difference is will depend on the size of the probe and rate of increase of the exhaust gas temp...The smaller the probe the better from a measurement point of view, but vice versa in reliability sense..

Also most thermocouple readers are digital and update at different speeds..If you get a temperature peak between in between updates you may miss the actual peak reading...

IMO Due to all the variables involved EGTs are best served as a warning that something has changed (ie sudden change in EGTs) rather than an overall indication of whether your tune is perfect or not...

My EGT's will go over 900C if I stay in the throttle long enough. I have a greddy EGT gauge, the probe is mounted about 3-4 inches from the head right after cylinder 6's runner.

This pretty much freaks me out. It can only be retarded timing, or a lean condition contributing to the high EGT's right?

I'd love to get this sorted out.

Wont 950C+ start to melt cast pistons?

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