RodInNS
06-10-2007 18:52:11
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Re: Ever wonder how an engine works? in reply to Tim B from MA, 06-10-2007 08:34:54
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The 2 stroke Detroits were all supercharged so far as I know. Some used turbo's to charge the air into the supercharger. The basic idea with those engines was that the piston uncovered the intake ports in the cylinder sleeve when the piston neared BDC. The exhaust valves open, intake air forces the exhaust gases out, exhaust valves close, cylinder fills with air, and as the piston rises past the intake ports, it closes off the intake, compresses the air until injection near TDC, then the power stroke.... and it repeats itself again. I could be wrong, but I'd say emission control on that system would not be great. There's too much happening in too short a period of time, and exhaust scavenging and intake charge are both limited because of this. The one and only feature those old buggers had was that they could make a lot of power off a relatively small number of cubic inches. I don't think they were particulairly fuel efficient, but they did make a lot of power per cubic inch of physical displacement. The downsides were numerous. Noise, profuse oil leaks, a gutless wonder at best... and a complicated fuel system with those damn unit injectors.... which were somewhat noted to stick, and could lead the engine to "run away" if they stuck at maximum for some reason. The best thing Detroit Diesel ever did was introduce the 60 series engine with DDEC. In that they succeeded in building a good performing, responsive, efficient, reliable engine with electronic controls.... and led the industry in doing it. At the same time they cleaned up the puddles and some of the noise. For the most part I don't think the 71's and 92 s will be missed on the highway, and the B Cummins obliterated the 53 series not long after it's entry onto the market in the mid 80's....Rod
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