PacBrake Exhaust Brake and High Idle + EGT's

[KaiHartman]

Spoke with Pacbrake the other day and they assured me that their exhaust brake was compatible with MY2005 trucks' factory high idle feature.



The past two times I've started my truck in below-freezing temps, I first started the engine (after waiting for grid heaters to do their thing), let the engine build oil pressure and sit for 30 seconds or so, then used my cruise to turn up the idle to 1100 rpm. Then, I turned the Pacbrake exhaust brake on.



Everything appears to work fine. However, I noticed quite a bit of fuel-smoke coming from the exhaust. I assumed it was due to the load being put on the engine and the fact that my computer-controlled truck was attempting to hold the 1100 rpm. Then, I glanced down and noticed that my EGT had climbed from 250 degrees at regular idle with no brake on to nearly 650 degress post turbo. Semi-worried, I turned off the exhaust brake and the EGT's dropped of course.



Anyways, it seems like my truck gets in a fairly aggressive fueling cycle when the exhaust brake places the load on the engine. I'm kinda worried that my EGT's would've climbed higher if I would've left the brake on. This has happened at least twice and I'm sure I can cause it to happen again whenever I turn the brake and high idle on together.



Questions:



Does anyone use the Pacbrake with the high idle feature to warm up the truck extra fast? How high (and pre or post measurement) have your EGT's climbed!? How long (max) should the truck be left like this if warming up? i. e. do we have to sit and babysit it to ensure that EGT's don't climb to unsafe levels everytime, or do they flatten out at a safe/reasonable limit?



With mods similar in effect to mine, does everyone else see fuel smoke when the high idle and ebrake is used?



Any other suggestions or inputs on this situation? Thanks!

 

[Bob V]

I use my Pac Brake and high idle. Get about the same EGTs pre tubo/

 

[KaiHartman]

one of my biggest concerns with using an exhaust brake is the decreased life of the turbocharger due to increased heat in the exhaust. Doesn't make me feel good, but I guess it's just a part of using one... .

 

[BHolm]

one of my biggest concerns with using an exhaust brake is the decreased life of the turbocharger due to increased heat in the exhaust. Doesn't make me feel good, but I guess it's just a part of using one... .

I've used the mopar Jake on both of my '06s along with the high idle. It does bring the EGTs up, the engine is under load, that is the whole idea, to build some cylinder temps and eventually coolant temp I run down the highway all the time with temps that high, I don't think it sounds excessive. My truck has less fueling than yours but the EGTs do just stabilize as the truck warms up, never had a problem. Ask Pac though if theirs comes off(the brake) when the coolant hits 170? The factory jake on the '06s will turn off once the coolant temp is up.

The other part of decreased life due to higher temps is that when using the brake to slow the truck, EGTs are down around 500 because the fuel is shut off too. Once again not much more than without the brake and well within the engines rated limits.

 

[Bob V]

Yes the pac brake does go off when the engine temp reaches 170. The controls for the Pac and the Jake are the same, cotroled by the ECM

 

[abrankod]

Are you sure it was fuel smoke? On a cold morning, with the higher egts generated by keeping the exhaust brake closed, the catalytic will "light off" sooner, causing water vapor to form in the exhaust much like a gasser. I see it quite often on very cold mornings with my Jacobs exhaust brake.

-Dan

 

[KaiHartman]

Are you sure it was fuel smoke? On a cold morning, with the higher egts generated by keeping the exhaust brake closed, the catalytic will "light off" sooner, causing water vapor to form in the exhaust much like a gasser. I see it quite often on very cold mornings with my Jacobs exhaust brake.



-Dan

Dan,



Yes, I'm fairly certain I can tell the difference at this point... lol.



Anyways, it's a result from the engine being loaded (of course) to initiate quicker warm ups..... but what do you mean by the catalytic will "light off" sooner? Are you referring to the reaction that occurs in the catalytic converter? I lost mine somewhere about 30k miles ago..... and still have the fuel smoke AND the steam on certain mornings when the truck is warmed up.



Think I'll keep using it with high idle for warm up... but I'm gonna keep an eye on the EGT's! I rarely (if ever) see over 700 or 800 deg post turbo even under full load. I use my head, of course, and pull my right foot up a lot hoping to keep the EGT's as low as reasonably possible to increase engine life. That's why I think 650 was/is excessive for my engine at only 1000 rpm. Probably due to over-aggressive fueling for my setup...



Anyways, THANKS for the input!



Best-

 

[BHolm]

Just an FYI, My totally stock '06 could easily hit 1000 degrees post turbo empty and did almost everyday. With the new materials used and oil cooling jets under the pistons, these engines can sustain 1400 pre turbo, reportedly a little more even. Sounds like you are running much more conservatively than you need to.

 

[KaiHartman]

Just an FYI, My totally stock '06 could easily hit 1000 degrees post turbo empty and did almost everyday. With the new materials used and oil cooling jets under the pistons, these engines can sustain 1400 pre turbo, reportedly a little more even. Sounds like you are running much more conservatively than you need to.

Thanks for the info! I'm sure you're right on both occasions, but just like anything else, the higher the temps you hold, the lower life you're gonna see out of every component that sees the heat (and keep in mind, the heat cycles which can lead to material fatigue much quicker since delta T will be higher!).



I know that these engines may be built to handle higher EGT's, but since my reading is post turbo and I want to be buried in my truck (in a LONG time, mind you:-laf) I'm gonna keep it cool. Thanks!