Common rail vs mechanical injection

[CausticUrbanCoast]

I’m no authority on this topic, but it seems like most people I know who have had turbo issues were on gasser engines. I have never had issues with my diesel turbos. There are so many diesel turbo trucks in service that it seems like failures are uncommon on diesel motors.

As it seems on gas, it is only us unlucky few.

 

[rScotty]

Higher pressure allows higher pressure injectors which allow them to open and close faster. Higher pressure injectors have larger nozzles to deliver more fuel because they open and close faster. Hydraulic and electrical control allow injector solenoids to open and close faster and are also timeing advanced based on load - so they are variable timed injectors.

On pressurized rails with electronic or hydraulic injectors, the diesel compression is lowered from the normal 21->23:1 ratio incase there is a miss. Most mechanical diesels have been running at 21 through 23:1 for almost the last century. (Theoretical maximum is 25:1).

I never disagreed that higher volume injectors could be used more efficiently than lower volume. I only compared apples to apples - the same size injectors will yeild the same maximum power no matter what the source injector pump or fuel rail provides.

It is the same for two engine blocks with domed or dished pistons, the fuel supply does not mater as long as it is adequate for the application.

Believe what you want.

 

[Hay Dude]

I’m no authority on this topic, but it seems like most people I know who have had turbo issues were on gasser engines. I have never had issues with my diesel turbos. There are so many diesel turbo trucks in service that it seems like failures are uncommon on diesel motors.

Because they rev them higher, run them red hot, then shut them off.

 

[Hay Dude]

I have a couple NA diesels, and they have their place. On smaller equipment, like mowers, they are simpler and can be shut down immediately to hop on/off mower without turbo concerns. They are cheaper to maintain because less pipe/plumbing and clamps to fail.
However, exclusively buying non-turbo diesels because of a perception of failure is not realistic. The upside is way too great and honestly, there’s so few NA diesels produced over 50HP I can’t imagine there’s much available unless you want to buy 40 year old equipment

 

[Username Taken]

Turbochargers rule. Not only are they more efficient, they make more power in the form of torque (which is what tractors want) at a much lower RPM.

Are they perfect? Heck no. Especially the VGT (variable geometry turbo) but I doubt you see many of those on tractors. But they've come a long, long way in the design of turbo engines. A long way.

When you own a turbo engine, you gotta keep in mind that if you're working it long and hard, you can't just immediately turn it off whenever you're in the mood. You gotta let it cool down (idle) for 2 to 5 minutes so the turbo doesn't cook the oil onto its bearings. Not good.

When you shut a turbo engine off, the turbo loses air flow, which is a big factor in its cooling. So it just sits there and bakes everything. Let it cool off

It's also important to run good oil in them. I run synthetic in my 6.7L Cummins. The wife's turbo'ed Edge gets the oil changed at the Dealer. Mostly because I'm too darn old to be crawling underneath a car with somewhere around zero ground clearance. Plus, all the tests done on Ford's oil came back really good. It's good oil.

Cheap oil will cake on the turbo's bearings over time and that's not a good thing.

 

[Username Taken]

I have a couple NA diesels, and they have their place. On smaller equipment, like mowers, they are simpler and can be shut down immediately to hop on/off mower without turbo concerns. They are cheaper to maintain because less pipe/plumbing and clamps to fail.
However, exclusively buying non-turbo diesels because of a perception of failure is not realistic. The upside is way too great and honestly, there’s so few NA diesels produced over 50HP I can’t imagine there’s much available unless you want to buy 40 year old equipment

Even on naturally aspirated engines, I always let them cool down for a period if they've been worked hard immediately prior

I warm them up slowly, too. I don't go full throttle on a cold engine. Uncool

Just me

 

[neilkingent]

another aspect of direct injection (common rail) vs indirect injection injection (mechanical) is the location in the combustion chamber fuel is injected. Indirect injection is what the name implies, fuel is injected indirectly into the combustion chamber and is not as efficient as DI.
Also mechanical is what the name implies, a mechanical pump and an extra cam to operate the injectors. Both systems have pluses minuses and both can be costly to repair. You can put me in the column of turbo fan boy as well. Diesel engines do not like to breath on their own like a gasoline engine does.

 

[Tx Jim]

another aspect of direct injection (common rail) vs indirect injection injection (mechanical) is the location in the combustion chamber fuel is injected. Indirect injection is what the name implies, fuel is injected indirectly into the combustion chamber and is not as efficient as DI.
Also mechanical is what the name implies, a mechanical pump and an extra cam to operate the injectors. Both systems have pluses minuses and both can be costly to repair. You can put me in the column of turbo fan boy as well. Diesel engines do not like to breath on their own like a gasoline engine does.

A lot or older diesel engines that don't have common rail fuel injection systems are direct injection. My '91 JD 4255, '11 Kubota M7040,'81 Ford 6700 have mechanical inj pumps with direct injection

 

[Hall00]

another aspect of direct injection (common rail) vs indirect injection injection (mechanical) is the location in the combustion chamber fuel is injected. Indirect injection is what the name implies, fuel is injected indirectly into the combustion chamber and is not as efficient as DI.
Also mechanical is what the name implies, a mechanical pump and an extra cam to operate the injectors. Both systems have pluses minuses and both can be costly to repair. You can put me in the column of turbo fan boy as well. Diesel engines do not like to breath on their own like a gasoline engine does.

Mechanical injectors fire from fuel pressure

 

[Hall00]

Turbochargers rule. Not only are they more efficient, they make more power in the form of torque (which is what tractors want) at a much lower RPM.

Are they perfect? Heck no. Especially the VGT (variable geometry turbo) but I doubt you see many of those on tractors. But they've come a long, long way in the design of turbo engines. A long way.

When you own a turbo engine, you gotta keep in mind that if you're working it long and hard, you can't just immediately turn it off whenever you're in the mood. You gotta let it cool down (idle) for 2 to 5 minutes so the turbo doesn't cook the oil onto its bearings. Not good.

When you shut a turbo engine off, the turbo loses air flow, which is a big factor in its cooling. So it just sits there and bakes everything. Let it cool off

It's also important to run good oil in them. I run synthetic in my 6.7L Cummins. The wife's turbo'ed Edge gets the oil changed at the Dealer. Mostly because I'm too darn old to be crawling underneath a car with somewhere around zero ground clearance. Plus, all the tests done on Ford's oil came back really good. It's good oil.

Cheap oil will cake on the turbo's bearings over time and that's not a good thing.

6.7 turbos are water cooled, so that helps.

Coking oil in bearings is pretty hard to do, but I understand the sentiment.