Build it, we will buy....DO IT

[KAlder]

Why hasn't anyone engineered a compression brake for our Cummins? I know the first answer will be "It won't fit under the cowl". Ya know, I HATE body lifts, but for a compression brake... . I would have the body mount bolts in the dumpster in three seconds flat! Talk to us, I know there has to be tons of people interested. DO IT.

 

[rattlbox]

i am in. that would be great

 

[TAbbott]

As to why no one has done it, I believe Cummins asked Jacobs and PacBrake (the only aftermarket manufacturers of compression brakes, to my knowledge) not to. And I think that might have been because the oem's asked Cummins not to.



For a lot of people, a real compression brake, coming in all at once on a wet or slippery road on an unloaded truck would be a prescription for disaster. An exhaust brake takes a little time to build pressure and is far gentler than a real compression brake, and thus more forgiving.

 

[SHobbs]

Can the compression brake be used only on 3 cylinders or 4 or 5? If all 6 would be a disaster then could you scale it down? I would like to have one myself.

 

[johnnyMac]

Can the compression brake be used only on 3 cylinders or 4 or 5? If all 6 would be a disaster then could you scale it down? I would like to have one myself.

You could have a 3 position switch and on/off, to control a compression. The three would be 2,4,and 6 cylinders. Also, you could have the compression cut-off automatically below a certain rpm, say 900 or what ever so you couldn't lock up.

 

[HighRanger]

I would think that with all the modern circutry ie: rubicon lockers only work in 4 lo and below certian mph... . that they would be able to make it safe for the less knowledgeable. Just my two cents.

 

[TAbbott]

Also, can you imagine the oems trying to meet the noise specs with real Jakes? Or, can you imagine the yahoos running straight pipes and cruising the neighborhoods at all hours seeing just how high the old decibel meter could go? It might just be a P/R deal where the decision was made that it just isn't worth it... .

 

[nickleinonen]

it could be done, but it would cost more than twins & exhaust brake & new tires...

when camless diesels make it to the pickup truck market, exhaust brake will be a breeze to do. .

with the arrangement we have now, you would need a 2 piece spring loaded expanding exhaust pushrods, and some hydraulic actuators to push down the exhaust rocker [spring loaded rod will keep it seated when exhaust lobe is down and rocker is actuated]. . probably some new rocker arms for the ex would be needed that would have a location or flat on it to allow a roller from the hyd actuator to roll down on it. . i suspect about 3" min would be needed on top of the rocker height at present to clear the mods. plus then you would need to plumb in engine lube oil feed and a brain box to actuate based on engine crank/cam signals. . pwm control the actuators and you wouldn't need a 2/4/6 selector switch. . it could just control the time and volume that gets ejected out the actuated exhaust valve

 

[DCreed]

I would think the rocker arms themselves could be made to electromagnetically "bend" at a hinge at the pivot point and then lock back together for normal operation, similarly to the axle lockers. possibly even fit under stock valve cover?

 

[HoleshotHolset]

It's just sad that a 40-year-old 2-stroke Detroit Diesel 6-71 or 6V-53 (or any variation thereof) can have a real engine brake...



Nick - how are the DOHC Cummins engines (ISX, etc. ) setup for engine brakes? My exposure to these engines is embarrassingly low.



Matt

 

[Highfinance97]

It's just sad that a 40-year-old 2-stroke Detroit Diesel 6-71 or 6V-53 (or any variation thereof) can have a real engine brake...

Matt

He has a point even the small 4 cyl has them



Michael

 

[Highfinance97]

For a lot of people, a real compression brake, coming in all at once on a wet or slippery road on an unloaded truck would be a prescription for disaster. An exhaust brake takes a little time to build pressure and is far gentler than a real compression brake, and thus more forgiving.

I believe(dont quote me) This 80's Ram has this 4 cyl detroit in it and it has a engine brake and has no problems



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and if we do have problems like locking up the rear wheels in slippery stuations Cant we just have a high/low setting like the big rigs, and leave the high setting in the hands of the operator??





Michael

 

[HoleshotHolset]

You can even put a engine brake on a tiny little 3-53 (since the 6V-53's had them and all the parts interchange... ).



We're still up against some pretty major issues with our B5. 9's and ISB's when it comes to the possibility of adding an engine brake. Had the engine been designed with an engine brake in mind from the get-go, we'd be golden.



Even the C 8. 3L (or ISC) doesn't have provisions for an engine brake... D'oh! The next jump from there would be like an M11 or an ISM... that's too big for a pickup.



I don't think excessive compression braking would be a problem - and like a few folks have said - you don't need to have all 6 holes working all the time. Even ~500hp 14+ liter engines only provide ~300hp braking power...



Beers,



Matt

 

[nickleinonen]

i can't remember how the isx top end is set up. . one cam is dedicated to exhaust brake iirc [left side cam] and the right has the lobes for the exhaust/intake/injector rockers. . i need to dig out some of my school books to see how it actually is setup. .

http://www.cummins-sp.com/document_library/Spec_Sheets/Engines/ISX_565_600.pdf

1st cam runs the injectors. 2nd cam runs the ex & in. . also has dedicated lobes for the exhaust brake. .

the isx has up to 600hp brake effort

 

[johnnyMac]

i can't remember how the isx top end is set up. . one cam is dedicated to exhaust brake iirc [left side cam] and the right has the lobes for the exhaust/intake/injector rockers. . i need to dig out some of my school books to see how it actually is setup. .

http://www.cummins-sp.com/document_library/Spec_Sheets/Engines/ISX_565_600.pdf

1st cam runs the injectors. 2nd cam runs the ex & in. . also has dedicated lobes for the exhaust brake. .

the isx has up to 600hp brake effort

Yeah, they're supposed to give the same braking horsepower as the engine makes, i. e. a ISX Signature 600hp "should" make 600 braking hp. In the real world it isn't that good but it's pretty darn good.

My friends who have them have a lot of solnoid issues and are generally in the 250 to 350 range on the "compression" i. e. "Jake".

I still think a 3 position with an on/off and say 1000rpm cut-out should be easily doable. JMHO

 

[WDimig]

It's just sad that a 40-year-old 2-stroke Detroit Diesel 6-71 or 6V-53 (or any variation thereof) can have a real engine brake...



Nick - how are the DOHC Cummins engines (ISX, etc. ) setup for engine brakes? My exposure to these engines is embarrassingly low.



Matt

matt - the ISX has 2 camshafts, one to actuate the injector rockers, which would be on the driver's side of the engine, and the second cam, drives the intake rocker, the exhaust rocker, and the exhaust brake rocker, on the passenger side of the engine. yes, there are 4 rockers total, im trying to rember how the exhaust brake rocker works, it was explained to me once, if i remeber correctly, there is actually a lobe that drives the rocker, when a tech a cummins runs, or "adjusts" the overhead on the isx, they set the injector preload, set lash on the intake, and exhaust valve, and on the exhaust brake rocker, ther are 2 different lash setting. the first one uses the adjusting screw to find the lash between the cross head guide pin, and the engine brake lever actuator piston. once that is set, we have to simply check the running clearance, that is crucial, if the running clearance bewtween he two rollers is not right, there can be severe engine damage. so basically the rocker is spring loaded, this keeps the rollers from coming in contact with each other, when the brake switch is flipped, the solenoid pushes down on the rocker assy, making contact with the camshaft and the rocker roller, this happens while the exhaust valve is coming backup obviously, thus the cam lobe is at the highest point of lift, causing the valve to stay open for the duration of the lift of the lobe. this causes the engine braking, and when the solenoid is off, the clearance betweenthe rollers is acheived. im pretty sure that is the way the interbrake works, im going to talk to my buddy at work tommorw, who knows all there is to know about the isx, and make sure i described the function correctly.



wes

 

[HoleshotHolset]

Dang - I didn't realize the ISX braking HP was the same as the output! NICE!



Anyone have a diagram of the ISX camshafts/rockers and/or compression brake solenoids?



Thanks for the info! Good reading here...



Matt

 

[WDaniels]

From talking to a cummins mechanic he said that there wasn't enough room under the valve covers. The area of the head where the valve covers are is way to small. Don't know if its true but its what he told me.

WD

 

[Pacbrake]

you guy's have no idea how many times this topic has come up in our new products meeting and just never gets on the drawing board. If there is enough intrest we are always willing to consider developement, it has to be cost effective for both us as a manufactuer and you as a consummer. Keep feeding this and I will keep bringing it up to engineering.

 

[Highfinance97]

Vote #1

If there is enough interest we are always willing to consider developement.

YOU HAVE MY VOTE







Michael