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Old 11-07-2017, 10:31 AM   #5
Ski in NC
Technical Guru
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City: Wilmington, NC
Country: USA
Vessel Name: Louisa
Vessel Model: Custom Built 38
Join Date: Jan 2014
Posts: 5,451
At high power settings, there is so much air entering turbos that it is in fact rather cool at the actual air filter.

At low power settings, it does get hot at turbo suction, but at low power settings there is no downside to that air being warm.

At high power the turbo compressor is more efficient if the air entering is cool, but only by a small amount. It roughly follows the ratio of temps using an absolute scale. So comparing 80F to 115F is really comparing 540R to 575R, or about 6% reduction in mass air flow.

Actual cylinder charge air temp is mostly governed by the charge air cooler (aftercooler) and that is not very sensitive to turbo suction temps, maybe by a few degrees. The 6% loss of mass air flow due to turbo suction temp will be reflected in a little less flow and little less manifold pressure, but since diesels run with such a high amount of excess air, not worth fiddling with it in my opinion. If exhaust is clear of smoke, still plenty of excess air.

Cooler intake air is certainly better, but not worth clogging your tight engine room with all sorts of large diameter plumbing.

And if you route it outside, the noise would be nuts.

You would also need some provision to coalesce out any entrained sea mist.

Unless your ER blowers are like 3hp or more, they won't do diddly compared to the airflow going into a turbo at power.
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