I have no intention of turbo charging my engine. I also don't intend to drag race my lead sled. I am doing this for greater fuel efficiency. Black smoke is the result of incomplete combustion. Supercharging or turbo charging push more air into the combustion chamber. By varying the pulley size you can adjust the boost pressure. They also come in different sizes, not just ones that run at extreme boost you know. Cold air into engine = more power. Just because an engine CAN make more power doesn't mean you will use this found power to make roostertails, that is why they made a throttle on this engine (I presume). Since I can, I started by making a fresh air breathing intercooler . I also made my own POP tester for the fuel injectors, so setting, and equalizing them is a breeze. Figuring out what CFM supercharger to use and pulley setup is only a matter of a little math.
Engines run within a specific air/fuel ratio. On a normally aspirated gas engine the optimum ratio for the most complete combustion is 14.7:1. For max power it's about 13:1 or 13.5:1. Over about 15.5:1 and temperatures rise inside of the combustion chamber, the valves burn and your motor stops motoring, or pre-ignition occurs and it blows holes in the pistons and your motor stops motoring. I'm not a diesel mechanic and I'm not qualified to say what a proper air/fuel ratio is for a diesel, but I know for sure that you can't just bolt on a turbo or blower and go, you must enrich the mixture to within acceptable parameters, and I also know for sure that all of that black smoke is not unburnt fuel, a lot of it is the impurities inherent to diesel fuel.
Engines run within a specific air/fuel ratio. On a normally aspirated gas engine the optimum ratio for the most complete combustion is 14.7:1. For max power it's about 13:1 or 13.5:1. Over about 15.5:1 and temperatures rise inside of the combustion chamber, the valves burn and your motor stops motoring, or pre-ignition occurs and it blows holes in the pistons and your motor stops motoring. I'm not a diesel mechanic and I'm not qualified to say what a proper air/fuel ratio is for a diesel, but I know for sure that you can't just bolt on a turbo or blower and go, you must enrich the mixture to within acceptable parameters, and I also know for sure that all of that black smoke is not unburnt fuel, a lot of it is the impurities inherent to diesel fuel.
Agreed. Most diesel engines don't have an ECM/o2 sensors to compensate for a lean/rich mixture. So all this needs to be done with floats and jets. In addition to your " pump shot" (tip in throttle response).
AFAIK all diesel engines are FI so there aren't any floats or jets, just injectors, injector pumps and computers to control the fuel flow. Floats and jets are carb parts.
I don't think you can just slap a blower onto a diesel engine; there are many parts that would need to be specific to a diesel running a blower to accommodate it. The clearance in the piston wall might not be correct; the size of the rod journals and main bearings may need to be larger; the injection pump may need modification and it's timing may need adjustment to provide the correct amount of fuel and prevent pre-combustion. The exhaust valves and manifold may need to be larger. The base compression ratio would need to be lower so you don't end up with too high of a CR once the blower is installed. These are the things I can think of off the top of my head; not saying that they all would need to be done but certainly it would be a big project that might only yield 20-30% more HP.
I don't think you would improve efficiency; most turbo/blower applications tend to decrease efficiency to achieve more HP in the same size engine.
and I also know for sure that all of that black smoke is not unburnt fuel, a lot of it is the impurities inherent to diesel fuel.
Not true, I'm afraid - diesel fuel does not necessarily have any more impurities in it than gasoline. When a diesel engine is running properly, it should produce no black smoke (although it does produce microscopic particulates). In fact, the black smoke is fuel that has not had sufficient oxygen to burn properly and has broken down into carbon.
Stuart
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Leith (rhymes with teeth) is the port of the City of Edinburgh in Scotland. A Leither is someone who comes from that area.
I must go down to the sea again, to the lonely sea and the sky - I left my shoes and socks there, I wonder if they're dry?
Diesels are unthrottled engines, the air intake is wide open all the time. Before electronic fuel injection, mechanical injectors basically just dumped a whole bunch of fuel in the engine when given full "throttle" at low engine speeds. They had a large amount of fuel remain uncombusted until the rpms rose and the air-fuel ratio evened out. That is why you still see older diesels pumping out black smoke when accelerating, but newer ones don't. The wonders of computers.
By the way, the famous GMC blowers, the basis for all the vane type blowers seen on drag racers, were originally made for GMC two stroke diesels.
I'm not a diesel mechanic and I'm not qualified to say what a proper air/fuel ratio is for a diesel, but I know for sure that you can't just bolt on a turbo or blower and go, you must enrich the mixture to within acceptable parameters, and I also know for sure that all of that black smoke is not unburnt fuel, a lot of it is the impurities inherent to diesel fuel.
You're right about one thing, you're not a diesel mechanic. jgeissinger got this one right.
Diesels have no throttle plates, no carburetor, no way of regulating the amount of air going in at all. Engine speed and power is controlled by increasing or decreasing the amount of fuel injected directly into the combustion chamber (unlike injecting into the intake air system on a gas motor). There is no ignition system on a diesel. When air is compressed, the heat in the air is concentrated in a very small place. The more you compress it, the higher the temperature. Just touch the head on an air compressor to test this out. Fuel is then injected in the right quantity and at the right time, and it spontaneously combusts due to the high heat. Turbocharging a diesel allows you to add more fuel and generate more power, it will not do much if anything to improve fuel efficiency in a sailboat application. The downside (besides the cost for no real gain) is that the engine already operates at a very high compression ratio. Turbocharging will raise the combustion pressures beyond the designed limits of the engine, and will prematurely kill the engine.
BTW, smoke from a diesel is caused by too much fuel when throttling up as explained by jgeissinger, and lack of proper injection timing from the old mechanical injection pumps. Smoke is not caused by impurities in the diesel fuel. Impurities in your fuel will make you buy a very expensive injection pump. Have you noticed that newer diesels in pickups and euro cars don't smoke? In a lot of the euro cars, you can't even tell that it's a diesel. Computer control of the injection pressure, timing, and multiple injection pulses per cycle have cured a lot of the usual diesel problems.
Unfortunately, these features are generally not found on marine diesels used in sailboats, since they can't tolerate a small sailboat marine environment very well.
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Computer control of the injection pressure, timing, and multiple injection pulses per cycle have cured a lot of the usual diesel problems.
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Sailingdog Telstar 28
New England
You know what the first rule of sailing is? ...Love. You can learn all the math in the 'verse, but you take
a boat to the sea you don't love, she'll shake you off just as sure as the turning of the worlds. Love keeps
her going when she oughta fall down, tells you she's hurting 'fore she keens. Makes her a home.
—Cpt. Mal Reynolds, Serenity (edited)
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