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I was driving and day dreaming yesterday on the highway, and I heard a Jake brake. thought, I wish I had one of them, how can I do it??? So.... here is my thoughts/design on a Jake brake for a PSD....Now I know a Jake is a mechanical device that opens the exhaust valve @ TDC, just prior to Injection. so it realy isn't a Jake.
A switch, activated @ idle, that locks the TC, closes the Exhaust valve, AND kills 4 of the cyclinders. since these trucks are HEUI injectos, it wouldn't be hard to tap into the wires for four of the cyclinders with 120V AC relays, and when activated, they would open the wire, thus shutting off the fuel. relays close, the circuit to the injectors is restored, and they fire.
Now what is the firing order of these things, I am thinking every other cylinder, to keep it somewhat smooth/even.
a closed EBPV,and 4 dead cyclinders has to make a better engine braking effect then just a EBPV, maybe not. maybe there is so little fuel at Idle/no load that it won't matter. thats why I wanna know what you guys think.
I would be concerned about problems developing from relays in the injector wiring. May cause problems down the road. From the information that is on the banks website, I would think the T/C lockup and EBPV would improve braking significantly by themselves that interupting the injectors would be minuscul.
On second note: I too wonder if on deceleration if it fires any fuel, simple based on if you're dropping from say 80 off the interstate to a red light using the brakes, it almost seems the engine dies during the hard brake, then resumes as you get below 25 or so.
No I do not believe they "shut down" just revert back to the Idle fuel mapping. This would be a question for J Tipton.
I don't see any problem with a relay in the circuit. if it is designed for 120 VAC it will work fine, there air tight, water proof. The engine bay temps might be an issue. I guess I will have to build something and play around on some of the long hills around here. see how it works.
I still need to know the firing order of these things. Any one know???
True jake brakes work off the exhaust valves. There is no braking efect by shuting down injectors alone. The braking with the jake is the compression of the engine with closed exhaust valves.
actually they don't leave the exhaust valves closed but rather open them right at the top of the compression stroke so that the engine does the work of compressing the air but doesn't get the power benifit from firing that cyl so that it litterly turns it into a big air compressor
444dieselrod, I wouldn't bother with all that work. It would be for nothing. As the earlier posts explain, the exhaust valve has to open at TDC to release the pressure. If not that compressed air just pushes the piston right back down and pretty much negates any "braking" that the compression stroke just created. You must vent the compression pressure at the right time for it to work. And with the injectors being commanded off during coasting already, you would be duplicating something that is already in place by design.
So that leaves us with what????
I've done the EBPV mod on my truck and it works ok when the engine is turning more than 2500 rpm. Makes a huge difference when going down a mountain pass with a trailer.
Cookie, how would they dry fire. there still would be oil, and fuel in them, just no fire.
Kwik. thats kinda what I was looking for. I was hoping that the frictional losses of the compression stroke would be enough to give a braking effect, but you are right, the compressed air would just force it back down, but not as much as the powerstroke.
they shut off??? call me dumb, but when do they "turn back on" then, say your doin' 60 mph, you let off the throttle, they shut off??? is it just for a split second then, cuz I don't see how the truck wouldn't die within seconds if they shut off everytime the Idle verification curcuit was restored. my '96 unlocks the T/C at this time also, so the truck drops to idle imediatly if I let off the throttle.
Cookie, how would they dry fire. there still would be oil, and fuel in them, just no fire.
Kwik. thats kinda what I was looking for. I was hoping that the frictional losses of the compression stroke would be enough to give a braking effect, but you are right, the compressed air would just force it back down, but not as much as the powerstroke.
they shut off??? call me dumb, but when do they "turn back on" then, say your doin' 60 mph, you let off the throttle, they shut off??? is it just for a split second then, cuz I don't see how the truck wouldn't die within seconds if they shut off everytime the Idle verification curcuit was restored. my '96 unlocks the T/C at this time also, so the truck drops to idle imediatly if I let off the throttle.
Diesel Rod
They do shut off for as long as you have your foot off the throttle and the engine is doing more than 1300 rpm. Next time you are coasting down a hill, open the window and listen. You can hear them come back on as the engine slows down.
They do shut off for as long as you have your foot off the throttle and the engine is doing more than 1300 rpm. Next time you are coasting down a hill, open the window and listen. You can hear them come back on as the engine slows down.
Just decelorate from highway speed with your window down. You'll hear the injectors come back on at around 1300 rpm. You can turn them on and off at will at any speed greater than that by simply touching the throttle enough to bring it off of the Idle Verification Switch.