Exhaust Break
Junior User
Joined: Jan 2011
Posts: 58
Likes: 0
Just traded my Dodge 3500 for a "11 F350, both were dually. I noticed on the Dodge I could see significant boost from the turbo with the brake on and decsending a hill. I do not see this on the Ford which it seems that I would if if the turbo was part of the equation. Literature indicates the "engine brake" of the Ford equates to approximately 100 hp force being applied. Have no idea how that compared to the Dodge. As already state the Dodge quits working below 25 mph and not at all in first gear. Good and bad to both I reckon.
Posting Guru
Joined: Apr 2004
Posts: 1,399
Likes: 1
From: Corinth, TX
you don't see pressure indicated on the boost gauge because of where the pressure is measured. It's still working, though 
I agree with the general consensus - the system we have works great. I've had it "save" me a couple times descending a slight grade into an unexpected stoplight or something similar. Not emergency stops, just shorter distances than I would have liked... the engine brake kicked in and slowed me down much quicker. I've also used it for long grades, to maintain speed without working the service brakes.
I think the *only* complaint I have is that it only works in tow/haul. I mean, that makes sense... but I like to turn off t/h for long stretches of flat ground - keeps the torque converter from locking up unnecessarily. I have to remember to turn it back on before descending a hill, if I want to use the engine brake. Not that big of a deal, but a couple times I have attempted to use it when not in t/h
I agree with the general consensus - the system we have works great. I've had it "save" me a couple times descending a slight grade into an unexpected stoplight or something similar. Not emergency stops, just shorter distances than I would have liked... the engine brake kicked in and slowed me down much quicker. I've also used it for long grades, to maintain speed without working the service brakes.
I think the *only* complaint I have is that it only works in tow/haul. I mean, that makes sense... but I like to turn off t/h for long stretches of flat ground - keeps the torque converter from locking up unnecessarily. I have to remember to turn it back on before descending a hill, if I want to use the engine brake. Not that big of a deal, but a couple times I have attempted to use it when not in t/h
Super Moderator
Joined: Aug 2003
Posts: 25,479
Likes: 742
From: Isanti, MN
I disagree.
Myself and some others have done a total of 4 different test meets where we drug 10-11,000 lbs up and down a steep hill with nearly every engine configuration ever put into a Super Duty. This included a 5.4L, 6.0L PSD, 6.4L PSD, 7.3L, 6.8L, 6.7L PSD as well as an unlucky Dodge that blew up going up the hill on our latest iteration.
Ever since 2003 and the introduction of the TorqShift 5R110 transmission we've had a tow/haul option at our disposal. This has always provided engine braking going down hills with trailers, and works pretty well. The 6.0L and 6.4L PSDs have no exhaust brake like our 6.7L trucks are claimed to have, yet downhill performance is VERY similar.
I don't find my new 6.7L truck to have any noticeable increase in braking force when going downhill than my 6.4L truck did. I'm not saying it's not there, just that it's not as significant as I think it should be.
Just my opinion, your mileage may vary.
Myself and some others have done a total of 4 different test meets where we drug 10-11,000 lbs up and down a steep hill with nearly every engine configuration ever put into a Super Duty. This included a 5.4L, 6.0L PSD, 6.4L PSD, 7.3L, 6.8L, 6.7L PSD as well as an unlucky Dodge that blew up going up the hill on our latest iteration.
Ever since 2003 and the introduction of the TorqShift 5R110 transmission we've had a tow/haul option at our disposal. This has always provided engine braking going down hills with trailers, and works pretty well. The 6.0L and 6.4L PSDs have no exhaust brake like our 6.7L trucks are claimed to have, yet downhill performance is VERY similar.
I don't find my new 6.7L truck to have any noticeable increase in braking force when going downhill than my 6.4L truck did. I'm not saying it's not there, just that it's not as significant as I think it should be.
Just my opinion, your mileage may vary.
Posting Guru
Joined: Apr 2004
Posts: 1,399
Likes: 1
From: Corinth, TX
could it be that the feature wasn't advertised on the 6.4L? It seems very possible that Ford just started touting this "new" system to compete with the button on the dodge and chevy.
I have not towed with a 6.4, but I can definitely feel the engine brake working on my 6.7L. I'm very satisfied with the way it works. This is why I wanted to make the point that it's not an exhaust brake. If you're expecting it to work like the butterfly version described above, you're going to be disappointed. It's not the same thing. But then, it was never claimed to be... some people just *assumed* that it would be.
I'll re-state my opinion on the matter - I think the system we have works well. It's not an exhaust brake, but it does function as designed. If you need more, you can always add an exhaust brake.
I have not towed with a 6.4, but I can definitely feel the engine brake working on my 6.7L. I'm very satisfied with the way it works. This is why I wanted to make the point that it's not an exhaust brake. If you're expecting it to work like the butterfly version described above, you're going to be disappointed. It's not the same thing. But then, it was never claimed to be... some people just *assumed* that it would be.
I'll re-state my opinion on the matter - I think the system we have works well. It's not an exhaust brake, but it does function as designed. If you need more, you can always add an exhaust brake.
Postmaster
Joined: Sep 2006
Posts: 2,598
Likes: 5
From: Maryland
There seems to be a lot of confusion about what an exhaust brake really is. I'm not going to argue the ins and outs of how the 6.7 system works, but I will say that it is by definition an "exhaust brake". It's not a butterfly system, but it does use the VGT system of the turbo to both restrict the exhaust and build boost thus creating more compression braking in the engine.
Jacobs is an engine brake and uses the valve timing to basically convert the engine into a big air compressor. Anything else that takes action downstream of the exhaust manifolds is an exhaust brake.
The 6.4 did not have any exhaust braking because of the configuration of the twin turbos. The 6.0 was not programmed to have this feature from the factory, but aftermarket tuning can utilize the VGT to create some pretty impressive exhaust braking. My 6.0 would literally make 15 lbs of boost under exhaust braking at 50+ mph in 3rd gear. The downside of both exhaust braking and engine braking is that they are most effective at higher rpm. You just aren't going to feel much out of them at less than 3000 rpm unless you have something like a 3 stage Jacobs on a large Cummins.
By the way, if you push it hard enough, the 6.7 will make boost when the imaginary exhaust brake is active.
Jacobs is an engine brake and uses the valve timing to basically convert the engine into a big air compressor. Anything else that takes action downstream of the exhaust manifolds is an exhaust brake.
The 6.4 did not have any exhaust braking because of the configuration of the twin turbos. The 6.0 was not programmed to have this feature from the factory, but aftermarket tuning can utilize the VGT to create some pretty impressive exhaust braking. My 6.0 would literally make 15 lbs of boost under exhaust braking at 50+ mph in 3rd gear. The downside of both exhaust braking and engine braking is that they are most effective at higher rpm. You just aren't going to feel much out of them at less than 3000 rpm unless you have something like a 3 stage Jacobs on a large Cummins.
By the way, if you push it hard enough, the 6.7 will make boost when the imaginary exhaust brake is active.
Posting Guru
Joined: Apr 2004
Posts: 1,399
Likes: 1
From: Corinth, TX
I agree that technically speaking, it is an exhaust brake (since it uses exhaust gasses to assist in braking)... but that term has a connotation associated with it for most people. The system we have does not match up with what they are used to... so they think it is inferior.
It's a bit like Xerox making printers. They do... and if you told your average person that you just bought a Xerox, he would expect it to make copies. He would be disappointed that it only prints. It's still a Xerox... but it's not what people think a Xerox is. Not a perfect example, but it helps get my point across.
It's a bit like Xerox making printers. They do... and if you told your average person that you just bought a Xerox, he would expect it to make copies. He would be disappointed that it only prints. It's still a Xerox... but it's not what people think a Xerox is. Not a perfect example, but it helps get my point across.
Super Moderator
Joined: Aug 2003
Posts: 25,479
Likes: 742
From: Isanti, MN
could it be that the feature wasn't advertised on the 6.4L? It seems very possible that Ford just started touting this "new" system to compete with the button on the dodge and chevy.
I have not towed with a 6.4, but I can definitely feel the engine brake working on my 6.7L. I'm very satisfied with the way it works. This is why I wanted to make the point that it's not an exhaust brake. If you're expecting it to work like the butterfly version described above, you're going to be disappointed. It's not the same thing. But then, it was never claimed to be... some people just *assumed* that it would be.
I'll re-state my opinion on the matter - I think the system we have works well. It's not an exhaust brake, but it does function as designed. If you need more, you can always add an exhaust brake.
I have not towed with a 6.4, but I can definitely feel the engine brake working on my 6.7L. I'm very satisfied with the way it works. This is why I wanted to make the point that it's not an exhaust brake. If you're expecting it to work like the butterfly version described above, you're going to be disappointed. It's not the same thing. But then, it was never claimed to be... some people just *assumed* that it would be.
I'll re-state my opinion on the matter - I think the system we have works well. It's not an exhaust brake, but it does function as designed. If you need more, you can always add an exhaust brake.
I believe most of what I saw in the 6.0 and 6.4L is simple compression braking provided by the engine at high RPMs. Either engine will downshift to 3,500 RPMs if possible coming down a hill to provide maximum braking force. My 6.7L does the same thing, and I believe the majority of braking force comes from the same compression braking we see on the 6.4L/6.0L trucks.
I'm sure the turbo exhaust braking has it's effect, but it's not as much of an improvement as I would have thought. Still, I belive it's perfectly adequate for any towing we'll ever see. It's just not as tolerant for making bad decisions coming down a hill as a more agressive one would be.
Cargo Master
Joined: Aug 2010
Posts: 3,229
Likes: 64
Locked converters allow the engine to use the torque more efficiently and keeps trans temp down by not having the TC slip.
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Posting Guru
Joined: Apr 2004
Posts: 1,399
Likes: 1
From: Corinth, TX
on long stretches of flat ground, you don't need that lockup. I originally thought it was best to leave it in t/h all the time, but once I read through the manual and saw that suggestion, I did some research... it's actually (slightly) better for mileage and reduces strain on the transmisison. The TC won't slip very much at all on flat ground unless you go to pass someone. Keep in mind that this is strictly cruise mode. If I'm heading WEST from DFW, I use this tactic. heading EAST or SOUTH... not so much
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