Downshift or exhaust brake?

[opnspaces]

I was just thinking after reading a post about gas vs diesel trucks where somebody mentioned they liked diesel because of the exhaust brake. I've never had a diesel, always gas. If I come up to a long downhill I have always downshifted and kept the speeds where I wanted them with only an occasional push on the brake pedal.

For those of you who have driven both, is a diesel with an exhaust brake that much better at controlling speed going down a grade? Or is this just another Ford vs Chevy type of question?

[ShinerBock]

Me Again wrote:

I do not have to tow via a pyro gauge anymore.

Me neither with the new turbo. It keeps the EGT's a lot lower than stock and is almost like I hit a wall at 1,100F where the stock turbo would keep climbing.

[ShinerBock]

Cummins12V98 wrote:

ShinerBock wrote:
I have been without an EB for about a month now. I missed at first when getting off the highway when I used to use it to slow me down, but I am not missing it so much anymore. Especially considering the turbo I replaced it with has lower drive pressure, less EGT's, has more air flow, and is way more reliable than the VGT. Actually being able to hear the turbo spool is another plus.

I probably won't be putting the BD EB kit on anytime soon unless I plan on towing in the mountains again which I don't foresee anytime soon.

So basically you have a hot rod pickup now.

When I want it to me.

My main goal is to make it a more reliable in all the ways I use it, and increase longevity since I plan on keeping it for a long time. I would rather fix it before it leaves me stranded on the side of the road like my brother's stock truck did.

This why I turned off pilot injection to reduce the amount of times the injectors fire which reduces wear. I removed the VGT turbo(which was throwing a code) for a more reliable fixed geometry turbo that reduced drive pressure and lowered EGT's for better sustained towing and increased efficiency. The turbo I chose has greater air flow than stock putting less of a strain on the engine internals and the head gasket creating more power at lower boost levels than stock. I removed the EGR from dumping exhaust back into my engine which in itself gave it a hp increase and made it more reliable.

I also have the ability to change the power/fueling/timing/duration of the truck depending on how I am using it at that time with a selection of the switch instead of running an all around generic tune meant for all situations towing or not. If I am towing then I select a lower power level that keeps my temps at safer levels than stock while having more sustainable power on tap. When I am not towing, I can select higher power levels if I choose and make it a hot rod. Or I can leave on my economy tune (which still has slightly power levels than stock due to removing all the emissions hardware/software that was making the engine less reliable/efficient) that adjusts the timing and duration for optimum efficiency for my turbo.

So in short, it can be a hot rod if I wanted it to be or it can be slightly higher than stock power levels at the selection of a switch. It just depends on how froggy I am feeling that day and what I am towing. I modified the rest of the truck to safely and reliably handle it. Some people spend their money on useless(to me) motorbikes and such, while I spend it on modifying my many vehicles I have had. It's what I like to do.

This is why I tell people that stock trucks are generic safe trucks with nannies to keep even the dumbest drivers from blowing them up. When you modify, you better know what you are doing, have supproting mods, and know how to drive it properly or you will cause damage. Modified trucks are for the more advanced users. Kind of like back in the day with the hot rodders that build their rides instead of buying them.

[Me_Again]

Cummins12V98 wrote:


So basically you have a hot rod pickup now.

I will take a Tow Rod over a Hot Rod. My 2001.5 was a bit of both, but those days are gone now.

I do not have to tow via a pyro gauge anymore.

[Cummins12V98]

ShinerBock wrote:
I have been without an EB for about a month now. I missed at first when getting off the highway when I used to use it to slow me down, but I am not missing it so much anymore. Especially considering the turbo I replaced it with has lower drive pressure, less EGT's, has more air flow, and is way more reliable than the VGT. Actually being able to hear the turbo spool is another plus.

I probably won't be putting the BD EB kit on anytime soon unless I plan on towing in the mountains again which I don't foresee anytime soon.

So basically you have a hot rod pickup now.

[Cummins12V98]

JIMNLIN wrote:
I don't know about the 6.7 Cummins but my '03 5.9 HO HPCR engine Nv5600 tranny with a 11200 lb 5er or a 16k GN stock trailer going down steep grades with the Cummins at 2800-3000 rpm at 55 mph without the Jacobs EB on is like shifting to neutral down the hill. Results of doing it both ways were hot smoking brakes at the bottom of the grade (not Rocky mountains).

Some years back before VVT and VGT came in use exhaust brake mfg advertised 180 hp for braking performance on the 5.9 Cummins/other diesels.

Then the new 6.7 Cummins came out and Dodge advertised exhaust braking at 230 hp.
I haven't seen any advertising from Ram/Ford/GM on the new diesels engine braking HP but sound like its more on the current diesels now.

My 15 has about ZERO braking relying on the engine with the trans in Tow Haul. My EB somehow was off going down 15 from Vegas to SoCal and it was a bit scary until I figured out my issue.

[ShinerBock]

I have been without an EB for about a month now. I missed at first when getting off the highway when I used to use it to slow me down, but I am not missing it so much anymore. Especially considering the turbo I replaced it with has lower drive pressure, less EGT's, has more air flow, and is way more reliable than the VGT. Actually being able to hear the turbo spool is another plus.

I probably won't be putting the BD EB kit on anytime soon unless I plan on towing in the mountains again which I don't foresee anytime soon.

[Me_Again]

JIMNLIN wrote:
I don't know about the 6.7 Cummins but my '03 5.9 HO HPCR engine Nv5600 tranny with a 11200 lb 5er or a 16k GN stock trailer going down steep grades with the Cummins at 2800-3000 rpm at 55 mph without the Jacobs EB on is like shifting to neutral down the hill. Results of doing it both ways were hot smoking brakes at the bottom of the grade (not Rocky mountains)

That is what I have been saying from the beginning of this thread!!!! If our exhaust brake on the 2001.5 stopped working, I stopped and cleaned the vacuum solenoid before continuing in our Western States mountains.

The same action would occur with the 2015 exhaust brake stopped working, that is I would get it repaired before continuing on.

I do not know if the rotating mass of the Cummins has something to do with, or if it is something else, however it is like you say(shifting to neutral).

[JIMNLIN]

I don't know about the 6.7 Cummins but my '03 5.9 HO HPCR engine Nv5600 tranny with a 11200 lb 5er or a 16k GN stock trailer going down steep grades with the Cummins at 2800-3000 rpm at 55 mph without the Jacobs EB on is like shifting to neutral down the hill. Results of doing it both ways were hot smoking brakes at the bottom of the grade (not Rocky mountains).

Some years back before VVT and VGT came in use exhaust brake mfg advertised 180 hp for braking performance on the 5.9 Cummins/other diesels.

Then the new 6.7 Cummins came out and Dodge advertised exhaust braking at 230 hp.
I haven't seen any advertising from Ram/Ford/GM on the new diesels engine braking HP but sound like its more on the current diesels now.

[Cummins12V98]

You guys are making my head hurt.

[4x4ord]

Me Again wrote:
Despite what 4x4ord thinks, the Cummins alone does very little at holding back speed on hills. That's my story, as I do own one!

What I think is that the Cummins exhaust brake is likely very similar to the Ford. I think downshifting alone will give you roughly 100 reverse hp at 3000 rpm and with the exhaust brake turned on there will be about 185 reverse hp. So if you are going down a grade with your Cummins and the engine is holding back the truck and trailer in 4th gear at 3000 rpm then you would likely have to drop to 2nd gear to get the truck to hold back that same load without the exhaust brake turned on.

[Cummins12V98]

"So Ron, next time you are on a hill, click off the exhaust brake and report back. Chris"

UH..........NO!

[4x4ord]

Me Again wrote:
I really do not care about slowing down that muck, what I want is to the exhaust brake to do a good job of holding the speed i want going down a hill or mountain. At 24,500 combined with the 3.42 gears it does good job in 4th gear and in 3rd gear on curvy hills like Cabbage Patch. Despite what 4x4ord thinks, the Cummins alone does very little at holding back speed on hills. That's my story, as I do own one!

So Ron, next time you are on a hill, click off the exhaust brake and report back. Chris

I realize you want the exhaust brake to hold back on a grade. The purpose of measuring the time it takes to slow the truck down is to calculate the reverse hp that the engine brake generates. If it generates 180 reverse hp at 3000 engine rpm on level ground without a trailer it will generate 180 reverse hp at 3000 engine rpm holding back a 20,000 lb trailer going down a steep grade.

[Me_Again]

I really do not care about slowing down that much, what I want is to the exhaust brake to do a good job of holding the speed i want going down a hill or mountain. At 24,500 combined with the 3.42 gears it does good job in 4th gear and in 3rd gear on curvy hills like Cabbage Patch. Despite what 4x4ord thinks, the Cummins alone does very little at holding back speed on hills. That's my story, as I do own one!

So Ron, next time you are on a hill, click off the exhaust brake and report back. Chris

[Cummins12V98]

Looks like I was doing 45mph, my gears are 4.10.

Towing and solo makes a difference on how much boost there is.

You are speaking a different language! Give me mph numbers to go by. Will be towing again on the 25th.