Windwalker |
05-14-2010 12:21 PM |
Quote:
Originally Posted by Jackrabbit379
(Post 480828)
I've heard it both ways. I don't see how it would wear a motor. The Jake brake holds the exhaust valves open, on the compression stroke. In other words, when the pistons are at Top Dead Center on the compression stroke, the exhaust valves are open, while the intake valves are still closed. I don't know where the excessive wear would be. If any, I would imagine it would be the valves, or rocker arms, maybe.
Jake brakes work better with straights. http://serve.mysmiley.net/evilgrin/evilgrin0010.gif
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A bit less than accurate, but not critical...:)
Quote:
(1A) The intake valve opens and air is forced into the cylinder by boost pressure from the turbocharger.
(2A) Air is compressed to approximately 500PSI by the engine piston. The energy required to compress this air is produced by the vehicle's driving wheels. Near top dead center, the Jacobs Engine BrakeŽ opens the exhaust valves, venting the high pressure air and dissipating the stored energy through the exhaust system.
(3A) On the downward stroke, essentially no energy is returned to the piston (and to the driving wheels). There is a loss of energy. This loss is how the retarding work is done. (4A) Normal exhaust stroke.
Jacobs Vehicle Systems - How the Jake Brake Works
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The only damage I know of that comes from using the jake brake is if something goes wrong with a spring, and the jake remains in operation when you apply throttle. Then, you stand to brake the top ring of the piston.
I was told that the myth of engine wear comes from someone that did not like the noise generated by the brake in use. In order to try to get he drivers to reduce the use of the brake, "You'll wear out your engine prematurely". The fact is that you do not put any more "load" on the engine than normal use. As a matter of fact, you put MORE load on the engine when climbing a hill, because you have far more pressure in the combustion chamber when the fuel ignites than you do simply from bringing the piston up to the top of compression. This increases the load on the connecting rods and all crank journals.
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