Water-cooled engine P&ID: removing outlet orifices drops coolant pressure and boiling margin

When simplifying a regeneratively or water-cooled engine P&ID, check which restriction sets coolant channel pressure. An orifice downstream of the cooling passages holds back-pressure in the channels and raises the boiling point; an orifice upstream only sets flow and leaves the channels near outlet-hose pressure. Deleting the downstream orifices while keeping upstream ones can turn a small subcooling margin into widespread boiling and a reduced burnout margin. Verify against the cooling model's assumed outlet pressure before accepting the change, and if flow meters are removed, plan a water flow test to measure branch flows.