Ceirwan
Well-Known Member
Car engines in general have a much nicer life than a boat engine, usually run up to temperature, lots of variations in the revs. Usually correctly serviced etc.
The average boat engine on a yacht sits in a damp salty environment, is quite often started but not allowed to heat up properly due to the sort use period, long periods with load load charging batteries, and sat at the same RPMs for prolonged periods.
As you said, high output can be achieved reliably, Honda's B16a from the early nineties will make it to 200/250 thousand miles if looked after, despite putting out over 100bhp per litre without a turbo charger & in some cases revving up to 9k rpm.
More modern engines have to cope with a lot more though, turbo chargers that bring in large amounts of torque at lower RPMs which puts a lot more strain on the bearings than an 80s era engine that doesn't make the power until a much higher rpm, and thinner oils being specified to try and meet ever more stringent emissions / economy targets.
My experience with BMW failures as mentioned above is that its usually the stuff attached to the engine, not the engines themselves. Cam chain stretch on certain models, made even harder because the chain was at the rear necessitating engine removal to replace. The piezo style injectors fitted to the E series cars were a disaster (and hugely expensive to replace), electric water pump failures, etc.
That said their turbo charged straight 6 is an absolute joy to drive, and the B58 variant is on the whole pretty reliable, even Toyota used it!
The average boat engine on a yacht sits in a damp salty environment, is quite often started but not allowed to heat up properly due to the sort use period, long periods with load load charging batteries, and sat at the same RPMs for prolonged periods.
As you said, high output can be achieved reliably, Honda's B16a from the early nineties will make it to 200/250 thousand miles if looked after, despite putting out over 100bhp per litre without a turbo charger & in some cases revving up to 9k rpm.
More modern engines have to cope with a lot more though, turbo chargers that bring in large amounts of torque at lower RPMs which puts a lot more strain on the bearings than an 80s era engine that doesn't make the power until a much higher rpm, and thinner oils being specified to try and meet ever more stringent emissions / economy targets.
My experience with BMW failures as mentioned above is that its usually the stuff attached to the engine, not the engines themselves. Cam chain stretch on certain models, made even harder because the chain was at the rear necessitating engine removal to replace. The piezo style injectors fitted to the E series cars were a disaster (and hugely expensive to replace), electric water pump failures, etc.
That said their turbo charged straight 6 is an absolute joy to drive, and the B58 variant is on the whole pretty reliable, even Toyota used it!
it's 18 years young with 3300 hrs on it. Spends most of its life between 1000-1200rpm
