Compression "Jake Brake" for a 12 Valve!

[txquigly]

Ok everybody,
Here's something some friends of mine have been working on for a while now! It is an actual 6 cyl, hydraulicly actuated mechanical engine brake for a 12 valve cummins! It has a timed pump actuating 6 individual hydraulic cylinders mounted in a billet valve cover! I will post some pics later when they clear it, but here's the YouTube link for one of the road tests we did! This thing Really works! It's not just a "leaker" brake like the one sold for the 24 valve, but an actual compression brake like a "Jake".

http://www.youtube.com/watch?v=WncV8Hl3e_I

Hope ya'll enjoy this!

BTW: They are starting development for the 4 BT, the 6BT 24 valve, the IDI Ford and the 7.3 Powerstroke engines!!

 

[jaluhn83]

Interesting!

I'm really curious to see the mechanical side of how they did it and the engineering of it all.

I looked into something like this several years ago but never actually went anywhere with it. My biggest concerns were figuring out how to open the valves (which it sounds like you guys did with a custom pump system - ingenious) and then how to keep the hydraulic lifters from pumping up when you released the valve sping load. Also I never did really figure out how much clearance you'd need to keep valves off the pistons.

 

[Hydro-idi]

This looks like a successful jake brake to me. However, I heard from a couple of diesel mechanics that jake brakes are extremely ******* diesel engines if overused. Does anybody know why that may be?

 

[jaluhn83]

I can't think of any reason other than maybe wear on the injector cam lobes? (full size jakes typically run off the injector lobe)

I can see where a flapper type exhaust brake might be bad due to exhaust pressurization and lifting the exhaust valves, but can't think of any reason for a real jake to be bad if it's installed and used properly.

 

[chris142]

Jakes are only ******* the engine when the driver shifts with them on. Something about slowing the crank down too fast. What they said in truckdriving skool anyway.

 

[Devon Harley]

Ya it's bad to use while an have one while down shifting. Other than that can't go wrong I want one really bad!

 

[Hydro-idi]

Someone should start designing one for the idi enthusiasts

 

[Jake_IN]

Thats pretty neat. The only thing i noticed in the video that i was surprised about was how the jake brake didn't seem to pull down the engine much. I would have thought for not towing anything the jake would have pulled the truck down a lot faster. I know the old Mack i use to run, the jake in it would set you forward in your seat if you were empty. Still cool though

 

[89greendiesel]

 

[txquigly]

Someone should start designing one for the idi enthusiasts

Actually, they have "jig" engines set up for the 6.9/7.3 IDI engines, the 7.3 T444E powerstroke, the 4 BT and 6 BT 24 valve Cummins!

 

[txquigly]

Thats pretty neat. The only thing i noticed in the video that i was surprised about was how the jake brake didn't seem to pull down the engine much. I would have thought for not towing anything the jake would have pulled the truck down a lot faster. I know the old Mack i use to run, the jake in it would set you forward in your seat if you were empty. Still cool though

When test driving in slower gears like 3rd to 2nd, if your on a gravel road or parking lot, it'll slide the tires from the braking effect! Even on the Semi's I have driven, the brake is more effective at the slower speeds...."mass in motion tends to stay in motion"...kind of deal. There's also the "mass" issue of reciprocating forces between larger and smaller engines as to the effectiveness of "jakes" on most engines that run them. There's still some fine tuning to be done too like timing and lash adjustments, but who cares if it really works when it sounds That COOL!!! (But it DOES work!!)

 

[icanfixall]

Nice work... Hope it will work on our engines someday...

 

[Goofyexponent]

This looks like a successful jake brake to me. However, I heard from a couple of diesel mechanics that jake brakes are extremely ******* diesel engines if overused. Does anybody know why that may be?

I've driven a LOT of miles in big trucks, and I hear a lot of people talk myths about jakes. You can't overheat them...they simply let the compression out of the cylinder before it gets a chance to push the piston back down. They let the fuel out into the exhaust manifold (which is why when an engine is cold and someone jakes you get white smoke...unburnt fuel) and when it's hot you can get a little black smoke (unburnt fuel, but more so than a cold block)

You can't "wear a jake out" by using it too much. It will need to be adjusted earlier for lash, but they aren't somethign that wears out like brake shoes.

Shifting with the jake shouldn't be done at all if you can't time it right, but up hill, from a dead stop...I'd be using whatever aids I can to get the RPM down between shifts. A loaded riggoing up hill, you can't shift fast at all when moving from low gear to first and on through the low side. The truck doesn't want to move and you will miss the shifts. I will throw the fan on manual (a 3 foot diameter fan will bring your RPM's down faster) and if it's bad enough...I'll turn the jakes on and shift without the clutch. It helps you get it in gear a little quicker, or drop the RPM's faster to get the split to take faster.

The jake brake on my 2009 Pete (500 ISX, 18 speed) will bring 110 000 pounds going 50 MPH to a damn near stop while downshifting a 6% grade for about a mile. I don't even need to touch the brakes with all that weight on. Jakes can be the difference between making it to the bottom of the hill alive or not.

Remember this. No matter how underpowered you think your rig is, it will make it to the top. Getting back down to the bottom is the hard part. Anyone who tells you different, don't know jack about driving.

A jake is a stopping AID, not a "oh sh** I need to stop but i'm going too fast".

 

[Matrix37495]

I want one!

 

[oregon96psd]

Ya it's bad to use while an have one while down shifting. Other than that can't go wrong I want one really bad!

please explain how you use a jake for downshifting, slowing the engine is exactly the opposite of what needs to happen to downshift...