Is pilot injection easier on the engine than standard injection on a diesel?

[The motor guy]

Over the years they've quieted down diesels to the point where they're as quiet as a gas car. I would think all that sound reduction also equates to less strain on the internal components of the engine. In the old days the fuel injectors injected all the fuel at one in one or two pulses, now the injectors gradually inject the fuel in 3 or 4 shots on every combustion stroke, making them as quiet as a church mouse. Opinions?

 

[The motor guy]

Do you think it adds a lot of life to the engine, or not really?

 

[BMWTurboDzl]

The old BMW M57 used piezo injectors ( 7 pulses per sec). iirc cheaper solenoid injectors which can pulse 5 times per sec. I don't think it has any bearing on engine longevity other than their failure rate (flooding the combustion chamber causing the engine to go boom).

 

[The motor guy]

The old BMW M57 used piezo injectors ( 7 pulses per sec). iirc cheaper solenoid injectors can pulse up to 5x/sec

Yeah but they didn't start using them on diesels until they came out with common rail in 2003

 

[BMWTurboDzl]

Yeah but they didn't start using them on diesels until they came out with common rail in 2003

DI allows for better metering which improves power and emissions so I don't know if longevity has been improved. That's the only reason to use it. I don't think trying to make a determination of longevity via sound at idle is in any way valid.

 

[The motor guy]

DI allows for better metering which improves power and emissions so I don't know if longevity has been improved. That's the only reason to use it. I don't think trying to make a determination of longevity via sound at idle is in any way valid.

Yeah if you keep driving it with a bad injector

 

[Cujet]

I don't think the injection cycle has much bearing on engine lifespan.

If one advances a diesel injection timing event to excess, the rod bearing can't handle the load and some very strange cavitation damage results. As a general rule, the rest of the components don't seem to suffer. It looks a lot like the picture below.

In general, a well maintained and properly operated old school diesel engine can last an amazingly long time without metal fatigue or failure. Keep in mind that when heavily loaded, the shock related noise is quite a bit smoother.

 

[MichiganMadMan]

Over the years they've quieted down diesels to the point where they're as quiet as a gas car. I would think all that sound reduction also equates to less strain on the internal components of the engine. In the old days the fuel injectors injected all the fuel at one in one or two pulses, now the injectors gradually inject the fuel in 3 or 4 shots on every combustion stroke, making them as quiet as a church mouse. Opinions?

I worked on Diesels at the time this happened and we ended up with the same or higher cylinder pressures. There were points where the engine would rattle so loud that we backed timing off, but with pilot injection it wasn't necessary. We still had the same cylinder pressure limits to calibrate around, so it likely "came out in the wash": Any changes in the rate of pressure rise (which causes the audible combustion) were likely offset by timing being advanced overall. Emissions team handled a lot of that anyway, I was working on cold start stuff where we had HUGE pilot injections and were driven more by trying to keep it running quiet and as smoke free as we could until it warmed up.

 

[The motor guy]

Did they advance the timing for emissions purposes or to try and control the smoke for dpf reasons?