Excessive TGT During Cruise
07-28-2014, 11:17 AM
#1
Excessive TGT During Cruise I have been struggling with this lately, my exhaust is extremely hot just cruising around like normal. I have a TGT probe just prior to the turbine flange. Idle is around 800-900F with around 30 degrees of timing. Light cruising at 75mph in OD at ~2400rpm is around 1550-1600 degrees. All pre-turbo pipes are doubled wrapped and the turbo has a blanket, but even when they were not wrapped temperatures were around 1450 degrees. Timing at cruise is 45 degrees. And fueling is closed loop at stoich.
I know low timing will cause excessive heat, but 45 degrees seems like a lot of timing to have this issue. Cam only has 3 degrees of overlap. Has anyone had to run more than 45 degrees during cruise to keep EGTs reasonable? Having the turbine glowing under the blanket at light cruise is a little excessive IMO.
I know low timing will cause excessive heat, but 45 degrees seems like a lot of timing to have this issue. Cam only has 3 degrees of overlap. Has anyone had to run more than 45 degrees during cruise to keep EGTs reasonable? Having the turbine glowing under the blanket at light cruise is a little excessive IMO.
07-28-2014, 01:03 PM
#3
Its mostly pump 93. I mix in c16 when I go to the track and also spray meth under boost.
I have a temp gun and at idle the temps are close so I trust the sensor, plus its pretty new. The housing glowing is a big give away as well.
I am not sure about temps under boost, too many other things to look at, but I expect 1700-1800 depending on how long the pull is.
I have a temp gun and at idle the temps are close so I trust the sensor, plus its pretty new. The housing glowing is a big give away as well.
I am not sure about temps under boost, too many other things to look at, but I expect 1700-1800 depending on how long the pull is.
07-29-2014, 05:17 PM
#4
9 Second Club
2 things...
can we assume the gauge is in fact accurate ? This annoys me...how do we test these thermocouples are accurate ?
Big/small turbo ? how much work might the turbo be doing at cruise ?
At 70mph cruise my twins, with EGT probe just before the flange ( single bank ) would sit around 600degC/1100degF, around stioch, pump fuel but I'm only 1500rpm at that point. Timing around 40deg.
GT9 cam, no overlap at all.
But...it takes very little more throttle/rpm's for it to get up to the 1300-1400degF range
EGT logged on the ecu with a different thermocouple, mounted just beside the gauge one seems to vary much more. It's supposed to be a fast acting sensor though.
The gauge one is a large tip Greddy gauge, and seems more heavily damped.
WOT seems to vary even more. Hence I struggle to believe their accuracy.
The one logged at the ecu isnt unusual to see close to 2000degF at full throttle. Gauge in car maybe 1800degF ( hard to watch it though )
can we assume the gauge is in fact accurate ? This annoys me...how do we test these thermocouples are accurate ?
Big/small turbo ? how much work might the turbo be doing at cruise ?
At 70mph cruise my twins, with EGT probe just before the flange ( single bank ) would sit around 600degC/1100degF, around stioch, pump fuel but I'm only 1500rpm at that point. Timing around 40deg.
GT9 cam, no overlap at all.
But...it takes very little more throttle/rpm's for it to get up to the 1300-1400degF range
EGT logged on the ecu with a different thermocouple, mounted just beside the gauge one seems to vary much more. It's supposed to be a fast acting sensor though.
The gauge one is a large tip Greddy gauge, and seems more heavily damped.
WOT seems to vary even more. Hence I struggle to believe their accuracy.
The one logged at the ecu isnt unusual to see close to 2000degF at full throttle. Gauge in car maybe 1800degF ( hard to watch it though )
