Thanks Tony,
I have another query, Mark did a ton of research to mimic the flow characteristics of the G1503 Sherwood throughout the RPM range of the 4BTA and the result using a half cam in the pump he chose combined with gear ratio’s resulted in virtually identical numbers,Mark and I have spoken on the subject and Ive asked others with different opinions given,do you see any advantage in using a full cam in the pump to up the flow it can provide.
Whilst some say increasing the flow builds a bigger safety factor into the equation, others say it may
Overpressure the cooling system
Risk of water being forced back into the turbo (that would probably be dependent of exhaust design)
It may result in colder running temp’s producing more wear/unburnt fuel/poor economy and smoke
Increase back pressure
My observations from owning the engines since new and now @1500 hours.
My engines will not come up to temp without load (normal) but for me the only way to get to operating temp now is get the boat operating briefly on the “hump” after an idle period transiting the harbor and really load them up briefly …….or gradually increase RPM’s. Increasing RPM’S gradually still will not result in achieving the desired temps in a reasonable timeline, one could argue either way what is the better process – load them up briefly and get the temps fast or spin them up to achieve the temps, for me the first is the better and faster approach.
I don’t start my engines until im ready to untie, I get the boat in gear and some load on the engines ASAP. I have 180 d thermostats, my impellers are @ 400 + hours and the G1503’s have never been rebuilt from new, (I did replace the seals in one pump @200 hours) the other has never been touched.I have pressure gauges on the pumps and I can clearly see that are operating now at about 70% compared to when they where new (Ive monitored this decline in pressure) The engine with the HWS hooked up to it takes longer that the other to come up to temp,I assume this is due to what essentially is a larger capacity cooling system on that motor.
In winter the engine temps drop down very quickly when coming off cruising RPM’s yesterday my temps had dropped to 150d in the 10 minutes of idle time through the harbor (winter) In summer temps drop from 185d to180d in that period and will stay there regardless of how long at idle speed.
Reading articles on the subject (and I may have misinterpreted this) apart from the woefully designed G1503 is the 4BTA marine cooling system as designed adequate,I realize the thermostats are ultimately governing the operating temps and everything is variable dependent on load and other scenarios.
In your opinion should I go ahead and set this up with a higher RW flow capacity?
Thanks
.
