Latestarter1
Well-Known Member
The 2848 in 800hp flavour is exactly the DE2848LE403 that I mentioned at the beginning.
Aside from smoking upon cold start, if you have any other remarks/experiences on them, I'm all ears.
I guess that on a Pershing they are bound to be stretched quite often...
Been off air for a good while, so many comments difficult to know where to start.
#1 Mechanical or electronic, or even EDC smart governor dumb pump, MAN or any other flavor of motor rules are generally the same.
Priority with mechanical and EDC motors is the 1,000 hour injector change out, it is vital as these injectors run real cold and will fail if not changed out. Never really understood it but pal at MAN MEC in the U.S always made a point of using MAN sourced Bosch tips and not Bosch aftermarket tip no clue if this was MAN B.S. or not however spitting a tip in the jug at rated speed is a lousy way of discovering the difference.
High output mechanical engines of any flavour with Bosch inline fuel systems have RQV or in some cases RSV governing which has no impact on cold start smoke. High output engines have retarded timing, low compression, highly efficient charge air cooling and high output piston cooling. Timing is linear on mechanical pumps rack is pulled into overfuel on engine shutdown and in many models of pump held in with a magnetic catch. In normal conditions this is all a recipe for a smoky start at best. However, some owners are manic throttle twiddlers both before and after start up, magnetic catch drops out and engine cranks over filling low compression pots with raw fuel before starting and whammy, smoke out! EDC does have a limited amount of timing advance to mitigate some start up smoke.
Electronically controlled engines have far more start up tricks as they have a 3D not linear timing/fuelling table pretty much eliminating cold start smoke, experience a Cat C12 starting at Artic ambient temperatures can be terrifying, ECM puts in a large slug of timing advance, so large that it sounds like the crankcase is full of little Trolls with hammers trying to escape, but almost no smoke.
As to overloading heavily weeded boats by application of excessive 'tight wire' is a killer. Remember your throttle lever is the same as a car cruise control. You set the rpm AKA road speed in cruise control. Below WOT engine fuel pump governor increases/decreases fuelling to hold set engine speed and with clean bottom has excess power to respond to propeller demand. As soon as vessel becomes heavily weeded propeller demand changes, but one has to remember that failing to reach WOT speed by say just 200 rpm governor is attempting to fuel for higher speed and the overfuel not liner but the propeller exponent. Driving a heavily weeded vessel hard can result in engines being overloaded by over 100%.
Electronically controlled engines have no magic levers to pull preventing overloading, once the data display reaches 100% engine load controls have no way recording anything greater, just remember that an engine at WOT displaying 100% engine load can actually be 150% overloaded. Nice feature of MAN display is EGT. A properly optimised engine correctly loaded will have minimal EGT’s at low D speeds, as the vessel transitions over the ‘hump’ EGT rises then falls slightly, then rising again with increasing rpm, however in an ideal world EGT levels out toward WOT. If you are hammering overloaded vessel ‘showing’ 100% engine load with EGT going into the Stratosphere you KNOW display is telling porkies!
As to MAN servicing costs one has to carefully look at the individual ratings, some call for a competitive 500hr service, however other ratings is 200 hrs, a matter of RTFM before commenting on service costs.
