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Old 08-16-2017, 07:55 AM   #15
smitty477
Guru
 
City: Northport
Join Date: Aug 2015
Posts: 2,046
I do not have Cummin's engines but I have run pyro & boost gages on the last 3 boats with 6 cylinder 4 stroke turbo diesels. I have found them to be more valuable than any other gages on the boat. The EGT senders were always mounted immediately after the turbo outlet and the boost was read after the intercooler in the intake manifold area.
Readings are always within 950 max on the EGT with the gages beginning to move in the 1500 rpm area and builds to about 900 between 2200 and WOT of 3100. ON a really hot and humid day readings will rise to about 925 and when towing a larger RIB and maybe with a little bottom growth on a hot day readings will rise to 950 at max.
The gages always move in tandem with the boost gages so that they are just about equal at engine rpms that are within 25 or so.
I have always swapped gage sender lines at eth ages upon any installation to know that they are reasonably calibrated at the start.
Some things that will cause an EGT variations:
- sender not centered in exhaust flame kernel
- sender wires/connections not secure
- prop variances
- ambient heat and humidity
- a dozen barnacles on the prop or shaft
- air intake or boost
- exhaust restrictions due to design or condition
- Fuel or valve timing
- Poor injection patterns

IMO EGT and boost gages should really come on every marine turbo diesel 4 stroke.
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