Retro-fitting engine brakes

The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.
See posts with no answers
W

woodpidgeon

Active member
Joined
Oct 28, 2008
Posts
25
Aint progress great...

But just another quick question regarding engine brakes.  Can they be retrofited, because looking at the specs  on the for-sale websites they don't seem to be that common or are they standard and not mentioned?
 
Check out this file in our library on Engine, exhaust and transmission brakes. It would seem to me that the only one that could be retrofitted relatively easily and at least cost would be an exhaust brake, aka Pacbrake. Even then, it won't cheap.  *

Most diesels come with one of the types explained in the article.
 
Most late model RVs come with Exhaust or engine brakes already installed, but they used to be optional on all but the high end models. An exhaust brake can be installed relatively easily on any turbo-charged diesel engine. See http://www.pacbrake.com/index.php?page=motorhome for the PAC product or http://www.dieselperformance.com/index.php/product/index/145P for the BD product. These are two of the leading aftermarket exhaust brake manufacturers.
 
For practical purposes...is the 'tow/haul' feature on my E450 Super Duty Ford's transmission any different than an 'engine/exhaust' brake?  Obviously the mechanics are very different but does one do anything that the other doesn't, other than slow you down?  How is the engine brake applied?  I find the 'tow/haul' feature to be exceedingly useful and very efficient, especially on long downhill grades like the CA Grapevine. 

Thanks

BT
 
Thanks, Roamer...I thought it must be but never having driven anything with an engine/exhaust brake, I wasn't sure.  Is the engine brake applied with the brake pedal - (kicking down) - as with the tow/hall and, for that matter,  releasing cruise control?

BT
 
Buddy Tott said:
Thanks, Roamer...I thought it must be but never having driven anything with an engine/exhaust brake, I wasn't sure.   Is the engine brake applied with the brake pedal - (kicking down) - as with the tow/hall and, for that matter,  releasing cruise control?
Click to expand...

Buddy

There are a number of variants. In either case the brake is applied by taking your foot off the accelerator pedal (zero fuel feed). With an exhaust brake (think of sticking a potato in your exhaust pipe),  there might be a toe switch to engage the brake instead. Engine brakes (think the old Jake Brake) work by changing the engine valve timing to create a backpressure within the cylinders.There is usually a 2 level switch to engage the system which then works on either 3 or 6 cylinders. Both types turn off the cruise control and downshift to lower gears when possible (avoiding high engine revs). When running in cruise and the exhaust/engine brake active, cresting a hill or other times with zero fuel feed will engage the brake and cut off the cruise. Some versions will automatically reengage the cruise control when the speed drops below the set cruise speed.
 
There are various ways to activate them, but typically it is as Bernie says or by touching the brake pedal or a combination of both. Some systems are programmable as to which way they work.
 
RV Roamer said:
There are various ways to activate them, but typically it is as Bernie says or by touching the brake pedal or a combination of both. Some systems are programmable as to which way they work.
Click to expand...

Gary

Unless the pedals permit left foot braking, you have to take your foot off the accelerator (zero fuel feed) in order to brake. Unless you have the foot control, the exhaust/engine brake is applied before you touch the brake pedal :) I've gone done many mountains without touching the brake pedal, but under braking control. There may be systems out there that are activated by touching the brake pedal, permitting you to freewheel, but I don't know of any.
 
BernieD said:
Engine brakes (think the old Jake Brake) work by changing the engine valve timing to create a backpressure within the cylinders.
Click to expand...

Bernie,

That's quite different from the way Jacobs explains it on their web site. Theirs works by opening the respective exhaust valve near the top of the compression stroke. That's also how the CAT tech demonstrated it to me when he had the valve covers off our boat engines; My engines don't have the Jake brake, but the tech showed me where the solenoids go and explained how it works. Maybe others work differently?

I was about to edit the article in our library based on your message, then decided to investigate why I had it wrong; The article wasn't wrong.
 
Unless you have the foot control, the exhaust/engine brake is applied before you touch the brake pedal
Click to expand...

Yes & no, Bernie. Cat engines, for example, can be programmed to apply the rake in multiple ways. One is as you describe, while another requires a tap of the brake pedal to activate and does not automatically brake on zero throttle. A device called The Brake Switch (www.brakeswitch.com) makes a Cummins engine or exhaust brake work off the brake pedal instead of the accelerator. 

Both methods have rather small advantages and disadvantages. Personally I I like th brake pedal method, but it is not enough advantage to get me to rush to spend the money to change mine over (it's not expensive if you install it your self).
 
Tom said:
Bernie,

That's quite different from the way Jacobs explains it on their web site. Theirs works by opening the respective exhaust valve near the top of the compression stroke. T
Click to expand...

Tom

I'm not sure I see a difference. Opening the exhaust valve in a different position than during the normal combustion function is a change in valve timing. Isn't it? I have no problem with the Jacobs description, technically it is more accurate as to what happens.
 
The difference is releasing compression vs creating back pressure.
 
I have no dog in this fight:  Seems to me that creating back pressure is achieved with the exhaust brake.(The compressed air has nowhere to go).

The Jacobs (Jake Brake) alters the valve sequence, releases the compressed air in the combustion chamber so that it won't push the piston back down; hence the slowdown in motor speed.

  How is my logic?

carson FL
 
100% right Carson. Just a desire on my part to pass along accurate information.
 
Thanks Guys...just wondered...which leads me to my next question but slightly off thread.  Why do Jake Brakes make so much noise when applied?  I used to live near a country road in No. Ca, with a long  but not steep,  gradient on a right hand bend going downhill.  The logging trucks made a pretty loud noise when the (I assume) Jake Brake was applied.  You could hear them a half-mile away.  It sounded like the truckers were throwing out and dragging anchor instead of applying brakes.

BT



 
You live and learn every day. I had always been told that the engine brake worked by creating backpressure. Tom is right that the brake works by releasing compressed air in the cylinders. Found an excellent description here. What confuses the issue is the name used to describe the device; "engine compression brake.
 
Why do Jake Brakes make so much noise when applied?
Click to expand...

I suspect it's those releases of "highly compressed air" via the exhaust that the Jacobs site mentions in their explanation of operation. The exhaust tubes probably function as a horn, like those guys blowing their long horns in the Swiss Alps, but with a bit more gusto and more frequent blasts of air.
 
Thanks Bernie. I learn something new here every day. Hopefully, I learn at a higher rate than I forget  :(
 
You must log in or register to reply here.

Latest posts

Members online

Total: 1,251 (members: 34, guests: 1,217)

Forum statistics

Threads
131,976
Posts
1,388,562
Members
137,726
Latest member
CampMike2270
Back
Top Bottom