Kubota Engines & Indirect Injection

[kjung17]

Re: Kubota Engines & Indirect Injection

Touche

 

[MMH]

Re: Kubota Engines & Indirect Injection

...Indirect injection engines also tend to be a little quieter. But both camps have claimed efficiency advantages, so I don't know whether either has any real advantage there. I do know that the new VW engine is direct injected and they made a big deal out of the efficiency gains of that approach when they introduced the TDI (which stands for Turbo Direct Injection) engine. I do know that it is a tremendously more efficient engine than the older ones, but computer control may be more of a factor than direct injection - I don't know.

I have always heard that the DI engines are significantly more efficient. That is why over the road trucks have been DIs for decades. One 'disadvantage' of DI was NOISE. This has been to a great extent mitigated by modern diesel injection systems (HEUI, common rail, etc.) There is much more to these systems other than 'computer control'. Modern injection systems enable a pre-injection event which minimizes the magnitude of the detonation that occurs in the primary injection event. The magnitude of the detonation is what caused the traditional diesel engine noise. Anyone remember the 'split-shot' PowerStroke injectors for the 96 & 97 model years? IDI would allow the pre-injection to occur in the pre-combustion chamber, thus were quiter. Remember how load the mechanically injected Dodge Ram w/ Cummins diesel was?

Now that the noise issue has been mitigated in 'modern diesels' and DI is more efficient, all auto/truck manufacturers are going to DI. No real need for tractors, especially CUTs & SCUTs. Think about it. Many of these tractors are operated less than 100 hours a year. So, let's call it 100 gallons per year. So even if a DI is 10% more efficient, we saved 10 gallons of fuel per year. Hard to justify an additional $3000 cost for advanced (and not needed) injection systems for CUTs.

Oh wait, there is the EPA angle. Soon we will require sophisticated injection systems, DPFs, urea injection, etc. The leftist wingnuts want to save the world by telling OTHERS what to do. No one will be able to afford a tractor. That's OK, they will be owned by the collective & controlled by the state. OBEY, OBey, obey...

 

[RoadHogg]

Re: Kubota Engines & Indirect Injection

I have always heard that the DI engines are significantly more efficient. That is why over the road trucks have been DIs for decades. One 'disadvantage' of DI was NOISE.

I believe one of the greatest things to consider when a manufacturer is deciding between DI or IDI is cost. I believe a DI engine is more expensive to build as the combustion chamber is built into the piston rather than the head. Comments about noise and efficiency differences certainly are also things to consider.

 

[MMH]

Re: Kubota Engines & Indirect Injection

I believe one of the greatest things to consider when a manufacturer is deciding between DI or IDI is cost. I believe a DI engine is more expensive to build as the combustion chamber is built into the piston rather than the head. Comments about noise and efficiency differences certainly are also things to consider.

I do not know for sure, but believe that cost is more expensive for IDI than DI. In a DI engine, the combustion chamber is the circular bowl that makes up the top portion of the piston. It is as easy to cast or forge this shape as a flat top, dome top, or any other shape. An IDI pre-combustion chamber is very often a separately cast and machine piece that then has to be integrated as part of the cylinder head. These inserts were typically made out of much harder and more heat resistant metals as they would get much hotter. Think about it, the fuel would be injected in the pre-combustion chamber to initiate combustion, but these pre-combustion chambers would not have the benefit of being cooled by air moving in & out like the rest of the piston/cylinder. I remember that most machine shops would refuse to 'deck' VW diesel cylinder heads because they would not stay flat. They would not stay flat because the precombustion chamber was made out of some hard alloy, and not soft as the rest of the cast iron cylinder head.

 

[RoadHogg]

Re: Kubota Engines & Indirect Injection

I do not know for sure, but believe that cost is more expensive for IDI than DI. In a DI engine, the combustion chamber is the circular bowl that makes up the top portion of the piston. It is as easy to cast or forge this shape as a flat top, dome top, or any other shape. An IDI pre-combustion chamber is very often a separately cast and machine piece that then has to be integrated as part of the cylinder head. These inserts were typically made out of much harder and more heat resistant metals as they would get much hotter. Think about it, the fuel would be injected in the pre-combustion chamber to initiate combustion, but these pre-combustion chambers would not have the benefit of being cooled by air moving in & out like the rest of the piston/cylinder. I remember that most machine shops would refuse to 'deck' VW diesel cylinder heads because they would not stay flat. They would not stay flat because the precombustion chamber was made out of some hard alloy, and not soft as the rest of the cast iron cylinder head.

I also am not certain but if you consider any "cheap" or what might be considered "disposable" diesel engine, it's almost always a IDI. One thing the IDI chamber does is to help protect the piston and con rod from the violent and uncontrolled detonation of the fuel, what causes that beautiful diesel knock we all love so much. A DI engine has a "moving" chamber, the head of the piston, so the piston and rod need to be heavier and thus more expensive.

I'm not an expert, just sharing my observations over the past 40 years running and working on diesel engines. Opposing view points are respected.

 

[EE_Bota]

Re: Kubota Engines & Indirect Injection

Spyder, As a technician, I feel a moral obligation to poke engineers whenever possible. A motor could be powered by a pump or compressor or some other exotic method. I cannot conceive a situation in which a motor is powered by an engine.

You need to leave the engineers alone. You know we don't actually get to drive the train, right? At least you get to work on it.
We get to draw pictures of it, and run calculations about it, and hear complaints from technicians about "I have to jack up the engine to change the filter." Well...what did you expect? How are we supposed to get even? We poke too.


A motor and a compressor are duties, not devices per se. A generator or a motor are duties, not a device per se. A pump or a motor are duties, not a device per se.

Most are "machines," and most are reversible. You may see tweaks, and ancillary devices added based on its current duty.

An interesting case is a turbocharger. A single machine, with two internal machines, but reversible, one performing motor duty, and one performing compressor duty.

Is a thermocouple a machine? Is it reversible?

Poking engineers is a tricky thing to do. We are so shot full of holes from technician / management crossfire, it is hard to find a place where your finger won't go straight through.

For the record, I am not an engineer. I only have an engineering degree. In NC, only a PE is an engineer. Go poke them, I don't mind.

(Interesting fact: A transformer is a linear motor, restrained from "running"....usually. )

.

 

[EE_Bota]

Re: Kubota Engines & Indirect Injection

I do not know for sure, but believe that cost is more expensive for IDI than DI. In a DI engine, the combustion chamber is the circular bowl that makes up the top portion of the piston. It is as easy to cast or forge this shape as a flat top, dome top, or any other shape. An IDI pre-combustion chamber is very often a separately cast and machine piece that then has to be integrated as part of the cylinder head. These inserts were typically made out of much harder and more heat resistant metals as they would get much hotter. Think about it, the fuel would be injected in the pre-combustion chamber to initiate combustion, but these pre-combustion chambers would not have the benefit of being cooled by air moving in & out like the rest of the piston/cylinder. I remember that most machine shops would refuse to 'deck' VW diesel cylinder heads because they would not stay flat. They would not stay flat because the precombustion chamber was made out of some hard alloy, and not soft as the rest of the cast iron cylinder head.

VW IDI were usually not decked because the head is warped. Decking it does not unwarp it, but leaves it warped. The problem is on the other side of the head, where the camshaft now must try to run in misaligned journals.

Decking of an unwarped head could be accomplished, but no reason to, and clearances are close, set by head gasket thickness.

I am not a diesel expert....just fairly sharp on non-TDI VW diesels.

Edit: Overheating failure modes of non-tdi were warped head, and piston smear on the cylinder wall. It's nasty.

 

[EE_Bota]

Re: Kubota Engines & Indirect Injection

+ Direct injection converts fuel energy into more power.
+ More efficent combustion.
+ Better fuel economy.
+ Heat efficency is increased.
+ 'Dramatically' improved oil usage.
+ Lower exhaust emissions.

Muhammad, not an expert here, but what I notice is:
most of the items in the above list are redundant because one is a cause, and the others are effects of the same cause.

The list could easily be reduced to : More efficient combustion. Heat efficiency is increased.

It's like: Stays cleaner longer. Goes longer between cleanings. Requires less cleansers. Less downtime due to cleaning. Less cleaning brush usage.

Opinion: Direct inject has potential to be more efficient. They will typically be more expensive to build and purchase, but less expensive to own, if they hold up.

Most diesels we have known for years are not direct inject, and they are pretty good. Few complaints about durability, but some complaints about emissions. More efficiency is always a good thing, but the old ones were not shabby. Very simple. No computer. Reasonable maintenance.

 

[kjung17]

Re: Kubota Engines & Indirect Injection

You need to leave the engineers alone. You know we don't actually get to drive the train, right? At least you get to work on it.
We get to draw pictures of it, and run calculations about it, and hear complaints from technicians about "I have to jack up the engine to change the filter." Well...what did you expect? How are we supposed to get even? We poke too.


A motor and a compressor are duties, not devices per se. A generator or a motor are duties, not a device per se. A pump or a motor are duties, not a device per se.

Most are "machines," and most are reversible. You may see tweaks, and ancillary devices added based on its current duty.

An interesting case is a turbocharger. A single machine, with two internal machines, but reversible, one performing motor duty, and one performing compressor duty.

Is a thermocouple a machine? Is it reversible?

Poking engineers is a tricky thing to do. We are so shot full of holes from technician / management crossfire, it is hard to find a place where your finger won't go straight through.

For the record, I am not an engineer. I only have an engineering degree. In NC, only a PE is an engineer. Go poke them, I don't mind.

(Interesting fact: A transformer is a linear motor, restrained from "running"....usually. )

.

That's why I love this site. Witty and thought provoking. I owe my livelihood to you engineer types.:thumbsup: If it weren't for you guys, machines would be simple and monkeys could fix them.:laughing:We used to be mechanics. You folks got to screwing around with the machines and now we're technicians.Today's technicians have to be computer/electrical/mechanical/hydraulic/pneumatic experts, understand principles of 2-stroke and 4-stroke/gas and diesel engines and be able to figure out how all of these systems work together or why they're not. :laughing:Interesting fact about transformers, never really thought of it that way.

And yes I do get seat time on some really cool machines.

 

[MMH]

Re: Kubota Engines & Indirect Injection

I also am not certain but if you consider any "cheap" or what might be considered "disposable" diesel engine, it's almost always a IDI. One thing the IDI chamber does is to help protect the piston and con rod from the violent and uncontrolled detonation of the fuel, what causes that beautiful diesel knock we all love so much. A DI engine has a "moving" chamber, the head of the piston, so the piston and rod need to be heavier and thus more expensive.

I'm not an expert, just sharing my observations over the past 40 years running and working on diesel engines. Opposing view points are respected.

Good arguments. All things being equal, a DI will have to be built more robust than an IDI, thus more expensive. There are good examples of both engines. Older (from the 70's up to the 90's) automotive diesels tended to be IDI's, I think because of noise. Older pickup trucks were both. A little more of the form follows function logic, so the noise was an acceptable trade off. Modern automotive & pickup diesels tend to be DI because of the performance/efficiency advantage and the noise being addressed w/ sophisticated injection systems. These sophisticated injection systems are necessary for emmision control anyway.