gimpyrobb
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hmmmm...
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Exhaust Brake on an M35A2
- Thread starter Chris Deuce
- Start date
DieselInfantry711
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Pressure regulated.... Looks like maybe your idea of a smaller pressure relief butterfly inside.....
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why not just engineer custom rocker arms that will act like a jake with an electronic controller?? you only need 6 of them, should not be that hard to do.
rustystud
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The cost would be considerable.
Chris Deuce
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So I ended up making a pressure relief valve in the butterfly plate for the exhaust brake and designed it for 25-27 psi backpressure. Still need to take it out for some testing/fine tuning after I figure out the front drum brakes, but glad to say it's done. I also installed a pressure gauge tapped off the exhaust to make sure I keep it below 30 psi. I think the electronic rocker arms would be a cool and effective way to do it, but would be very costly and would add another electrical system to fail. Trying to keep this as reliable as possible.
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rustystud
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How did you test the pressure relief valve ?
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i don't see why. simple concept just kick open the exhaust immediately after injection. make rockers with small hyd plunger actuator on valve end, sensor on crank and cam electronics would be easy.
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do you think that spring is going to be happy running at 1200°F??
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Looks like the spring is on the wrong side of the butterfly. Look at the flow arrow and look at the bevel of the butterfly.
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Ever seen compression brakes and how they work? Not simple by any means, it all needs to be timed or massive engine damage will result.
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spring should be on turbo side. looks right to me. timing for an exhaust brake is very simple. i realize it needs to be exact but the days of electronics have been here for quite a while.
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would be easy to calculate. area of drill holes times 30, set spring to open at that pressure. so if those are 1/2" holes and there are 4 of them it should take 23.55 lbs pressure on stud to open valve meaning it would open at 30 psi.
Last edited:
DieselInfantry711
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I bet that thing will sound interesting as the relief opens and closes while using the brake. Such a simple fix to a seemingly complex problem!
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rustystud
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That's what I was thinking to. I suppose it would last for awhile but sooner or later that spring will loose it's hardness.
Chris Deuce
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It shouldn't have too much problem surviving the heat, but the pre-loaded force may decrease as the spring reaches those temperatures. I'll have to test it out at those temperatures and report back. It does have an interesting sound when it's working, more of a "pshhhh" when operating, but not too loud. That's exactly how I calculated it. I setup 3 3/8" holes and 4 3/16" holes to fill the area, calculated the total area times 25 psi to get the preload needed, calculated preload desired on spring and the associated preloaded height and compressed it to that height. Left the preloaded pressure at 25 psi to account for increased pressure when the relief valve opens. Based on the area requirements it should run around 27 psi when the relief valve is fully opened.
rustystud
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To help save your spring you could install it on the other side of the flapper valve. That way when it's closed the heat will not be hitting it straight on.
Chris Deuce
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The way the butterfly valve in the Pacbrake is setup and the way it turns wouldn't leave enough clearance on the other side, there's just barely enough clearance as is.
Another Ahab
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You've heard that noise before, and here's the explanation for all the racket:
https://en.wikipedia.org/wiki/Compression_release_engine_brake