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#1
posted to rec.boats.building
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diesel back pressure
i have read of the importance of insuring that manufactures specs on back pressure are not exceeded, but i can find no numbers for my yanmar 2gm15. does 48" from bottom of water lift to top of transom gooseneck using 1.5" hose sound excessive? john |
#2
posted to rec.boats.building
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diesel back pressure
That really applies when the diesel is turbo charged and run under heavy
loads for long periods of time . Back pressure is what keeps the exhaust valves from burning .Your situation poses no problem.I am diesel mech. for Mercedes. Sal "John Knox" wrote in message ... i have read of the importance of insuring that manufactures specs on back pressure are not exceeded, but i can find no numbers for my yanmar 2gm15. does 48" from bottom of water lift to top of transom gooseneck using 1.5" hose sound excessive? john |
#3
posted to rec.boats.building
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diesel back pressure
John Knox wrote:
i have read of the importance of insuring that manufactures specs on back pressure are not exceeded, but i can find no numbers for my yanmar 2gm15. does 48" from bottom of water lift to top of transom gooseneck using 1.5" hose sound excessive? john I don't know. How far down does the outlet drop from the top of the transom gooseneck? My 1/2/3 GM installation manual quotes 27 inches of water maximum exhaust backpressure. This is _not_ the same as the vertical lift. It can be measured by tapping into the exhaust elbow and comparing to ambient pressure. Evan Gatehouse |
#4
posted to rec.boats.building
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diesel back pressure
Evan Gatehouse2 wrote:
: John Knox wrote: : i have read of the importance of insuring that : manufactures specs on back pressure are not : exceeded, but i can find no numbers for my : yanmar 2gm15. does 48" from bottom of water : lift to top of transom gooseneck using 1.5" hose : sound excessive? : john : : I don't know. How far down does the outlet drop from the top of the : transom gooseneck? : My 1/2/3 GM installation manual quotes 27 inches of water maximum : exhaust backpressure. This is _not_ the same as the vertical lift. : It can be measured by tapping into the exhaust elbow and comparing to : ambient pressure. : Evan Gatehouse i don't think that the drop will have any effect on the back pressure - i am thinking of installing a vetus transom gooseneck which is an enlarged chamber with an inlet at the top an an outlet at the bottom - the back pressure is going to develop from the waterlift to the maximum rise with no reduction due to the fall in the outlet. |
#5
posted to rec.boats.building
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diesel back pressure
Because the vertical column will not be full of water, it is an engine and
there is a lot of exhaust gas, the vert. rise is not the same as the backpressure. Measuring the backpressure will be prone to error because you need to measure static pressure without getting any dynamic pressure. I owned a boat with the 3GM30 engine. Exhaust hose was 1.5 inches and the rise was at least 48 inches. No problem with engine was ever noted. Of course the waterlift muffler has to be large enough to accommodate the water that will flow back after engine shutdown. Dave "John Knox" wrote in message ... i have read of the importance of insuring that manufactures specs on back pressure are not exceeded, but i can find no numbers for my yanmar 2gm15. does 48" from bottom of water lift to top of transom gooseneck using 1.5" hose sound excessive? john |
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