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Midterm Review. R. Bortignon. Piston port timing VS 4 stroke valve timing. 4 stroke engine. piston port engine. 2 Stroke Diesel Engines. 1. Compression. Power. Exhaust. Scavenging. 2 Stroke Diesels VS 2 Stroke Gas Engines. Diesel Engine Operation.
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Midterm Review R. Bortignon
Piston port timing VS 4 stroke valve timing 4 stroke engine piston port engine
2 Stroke Diesel Engines 1 Compression Power Exhaust Scavenging
Diesel Engine Operation • diesel’s have higher thermal efficiency than gasoline engines • in a diesel, thermal efficiency goes up with increased engine load
Gasoline Injection • maintains a nearly constant 14.7:1 air-fuel ratio • the volume of air & fuel is varied to change engine power output • during heavy engine loads (low manifold vacuum) more air/fuel is delivered to the cylinders • during light engine loads (higher manifold vacuum) less air/fuel is fed to the cylinders
Reminders… • drop off completed mechanical labs in my box • fill in “engine info” sheet on the last engine you worked on • fuel must be drained out of fuel tanks • engine stand brackets need to be removed • Engine Assessment Guide due this week! • should be generic, not manufacturer specific • should be applicable to both 2 or 4 stroke • 1 assessment guide handed in per team of 2 • “Engines of Unknown Condition” activities • moving away from lab based activity to examining & evaluating engine condition • use your assessment guide on the engine • bringing your own engine in? Peter or I must see it at least twice – once when it comes in, once when it leaves • engine must run – you will use the machine as it was intended • Peter, James, Phil & I will keep daily notes on your progress
Reminders… • 100 Hour Project • do NOT dump off parts in the auto shop or its parking compound • consult with me 1st for large items that need to be left in the shop • motorcycles, riding mowers should be pressure washed 1st • all fuel should be drained & dumped into the black barrel outside the shop labeled “Stale Gas” • you are welcome to dismantle, clean & examine/modify parts any time I am in the shop & you have free time
Scrap Metal Bin • any & all scrap metals should be placed in here… • large pieces need to be cut up or properly stacked so volume is maximized • bin is NOT a garbage can!