HOW DO YOU WORK THIS PROBLEM?
A FOUR-STROKE EIGHT CYLINDER IN-LINE MEDIUM SPEED DIESEL ENGINE HAS A FIRING ORDER OF 1-5-2-6-8-4-7-3.
IF PISTON #2 IS AT TDC AND IN THE FIRING POSITION, #4 PISTON IS ON THE____________?
THE USCG UNLIMTED EXAMINATION HAS MANY OF THESE QUESTIONS, FOR BOTH 4 AND TWO STROKE, IN-LINE AND V.
HOW WOULD YOU GO ABOUT WORKING THIS PROBLEM? I HAVE LOOKED IN MANY BOOKS BUT JUST CAN NOT SEEM TO FIND OUT HOW TO DO IT.
THANKS FOR THE HELP!!!!!!
FIRING ORDER
- The Dieselduck
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Brain teaser hard on rum intake
I am sure you know that the answer is A - Exhaust. But getting there took some head scratching. But I believe I got it, but probably would not in an exam. I will try to convey what I did.
The firing order is for an eight cylinder so I assume that each turn of the crank has four cylinder firing, and the others on the exhaust or compression strokes. So all cylinders will have fired every two rev. In the first turn of the crank 1526 are firing, then the next turn of the crank 8473 are firing each at 90 degree intervals. If you had a six cylinder, you would have three firing each rev at 120 degrees apart. This is to make sure the engine balanced.
Start at TDC Cylinder 1 - 1 starts power stroke, 8 starts intake; 90 degree - 5 is on power stroke, 4 intake; 180 degrees - 2 is on exhaust, 7 is in compression; 270 degrees - 6 is in exhaust, 3 on compression.
Crank is finished one rev, so now 8 starts power stroke, 1 starts intake; 90 degree - 4 is on power stroke, 5 intake; 180 degrees - 7 is on exhaust, 2 is in compression; 270 degrees - 3 is in exhaust, 6 on compression
Its more of a mental puzzle, which I hate, personally, but you can work it through logically. If you draw it out it makes a bit more sense.
The firing order is for an eight cylinder so I assume that each turn of the crank has four cylinder firing, and the others on the exhaust or compression strokes. So all cylinders will have fired every two rev. In the first turn of the crank 1526 are firing, then the next turn of the crank 8473 are firing each at 90 degree intervals. If you had a six cylinder, you would have three firing each rev at 120 degrees apart. This is to make sure the engine balanced.
Start at TDC Cylinder 1 - 1 starts power stroke, 8 starts intake; 90 degree - 5 is on power stroke, 4 intake; 180 degrees - 2 is on exhaust, 7 is in compression; 270 degrees - 6 is in exhaust, 3 on compression.
Crank is finished one rev, so now 8 starts power stroke, 1 starts intake; 90 degree - 4 is on power stroke, 5 intake; 180 degrees - 7 is on exhaust, 2 is in compression; 270 degrees - 3 is in exhaust, 6 on compression
Its more of a mental puzzle, which I hate, personally, but you can work it through logically. If you draw it out it makes a bit more sense.
Martin Leduc
Certified Marine Engineer and Webmaster
Martin's Marine Engineering Page
http://www.dieselduck.net
Certified Marine Engineer and Webmaster
Martin's Marine Engineering Page
http://www.dieselduck.net
- offshoresnipe
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- offshoresnipe
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In the USCG test, the exhaust stroke is the correct answer.
But the test also has many questions that have the wrong answers as the correct answer. The USCG will nottake the time to correct them. So not only do you need to know the correct answer but it helps to know which answer the USCG would like for you to give. Makes for much frustrations, and much drinking!
Regards,
Raymond
But the test also has many questions that have the wrong answers as the correct answer. The USCG will nottake the time to correct them. So not only do you need to know the correct answer but it helps to know which answer the USCG would like for you to give. Makes for much frustrations, and much drinking!
Regards,
Raymond
- ArkSeaJumper
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- offshoresnipe
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- ArkSeaJumper
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