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guest
Rating: N/A
Votes: 0 (Vote!) | | Posted on Saturday, August 06, 2005 - 9:49 pm: | |
I saw a sign on the Lincoln Tunnel helix telling truck and bus drivers to "use low gear" when descending the incline. Question is how efficient is low gear in a diesel. Since diesels do not have throttle plates, how great is the braking power? From what I understand, low gear cause a increase in RPM, hence increase in engine friction but it is not as powerful as constriction braking on a gas engine. Ayone can give some insight? |
Tom Caffrey (Pvcces)
Rating: N/A
Votes: 0 (Vote!) | | Posted on Sunday, August 07, 2005 - 12:54 am: | |
Guest, gas engines don't have nearly the compression (slowdown) that diesels do without any engine braking aid. The gasoline engine throttle plate only delivers about 10 psi or a bit more of pressure drop to aid slowdown.
Double the compression ratio and often a much greater displacement for any horsepower rating for diesel than gas contribute to a much greater no throttle drag.
On top of that, diesels shut the fuel off completely when in compression until they are nearly down to idle speed.
I recommend you go for a drive in a diesel powered rig and then a gas one, and see what you think. I believe that ought to settle the question. Do try to match the rigs for weight.
In spite of their extra drag, diesels are much more efficient than gasoline, possibly except under very light loading.
I hope this answers your question.
Tom Caffrey PD4106-2576
Suncatcher |
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