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OldMachinist
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In a quick web search all the info I found says this is indirect injection. This was based on replacement heads I found for sale.
Thank you, I tried to find specs on the engine and bobcats that used them and seemed to have not luck. I didn't think to look at heads. Now the question is what would be involved in putting a Direct injection engine in a Bobcat that had a Indirect injection motor previously? Would this even matter as long as fuel and power we connected?
OldMachinist
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- May 24, 2006
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As long as you use an engine that's in the same general size and horse power range so you don't over or under power your machine. Someone may have to chime in here to better explain why they use the different types of injection. I know that some Kubota engines with the same model number have different injection types because I've seen heads for the same engines models offered in ether configuration.
The two will have the same block but different head, injectors and pistons. There is no reason why a direct injected engine wouldn't work. I personally have never seen one but it would do the same job. DI engines are a little louder than indirect injection. They do start easier though. I personally would stick with the indirect injection as they are more common, so parts will be cheaper and easier to find!
I really don't know what i'm talking about here, but could the only real difference be with emisions requirements? I believe that bobcat has to adhere to tier 2 emision requirements? although I don't think the laws are completely in effect yet, I believe bobcat may be getting a jump on this..........
I don't know much about the emission side but the 2 types are different how they inject the fuel charge. Now i will try and explain it as best as i can.
In-direct injection has flat faced pistons that compress all the air charge into a small pocket in the head called a pre-combustion chamber. As the air is compressed it becomes super heated Your fuel injectors squirt the fuel charge in here in a straight line like a small cone shape. The fuel ignites and the explosion travels out the pre-combustion chamber down and into the bore where it finishes burning. This type of setup basically extends the detonation of the fuel giving smoother running and less noise. The trade off is that the air charge when starting is cooled by the cold cylinder head, thats where the glow plugs are needed.
Direct injection injects the fuel charge straight into the top of the piston. The top of the piston usually has a recess cut into it with like a point at the centre. The injector is usually thin instead of stubby like in-direct injection ones are. Its spray pattern is more like what you see on the movies with automatic rifles with the blast that comes out from the sides with lots of little flashes. This style of injection detonates the charge in one hit as well, but its not slowed down. This style is generally more noisy but more efficient and easier to start. The cone shape machined into the piston helps create more friction for the air to gain more heat for easier starting. I don't think glow plugs are used on this style of engine, but i am un-sure on that.
I'm not touching on common rail which is direct injection but the noise does not apply here.
I had a deutz 2 cylinder DI engine, no matter how cold it was it would fire straight up every time. It didn't have glow plugs either.
