@cleatus12r Obscure is acceptable and OK with us. We know that only a few tuners are willing to even put out a decel tune, but the fellas above are looking for a different route to go about making a exhaust brake option, not necessarily a tune. That is why I titled the thread "T4 with exhaust brake?" instead of "T4 decel tune?" So, the need to cover your backside is not pertinent in my opinion, but I am outside looking in, so the view is probably obscured (see what I did there?).

I see this as the mouse trap conversation. Those 7.3L tuners that have created a great and working mouse trap (decel tune on whichever platform) cannot complain or file a copyright infringement claim on these fellas creating a new and improved mouse trap for a different operating platform. The hardware and software are different with what these guys are doing compared to what DP or any other tuner offers.

Back to deciphering your answer, which is completely on me and puts zero liability or responsibility on you...


Question was...
Perceived answer was...
Translation as I understand it is, yes there is a secret squirrel community for tuning the 7.3L. We all know that, but we all don't know the inner workings, only a couple do.

Question was...
Perceived answer was...
Translation as I understand it is, yes the EBPV is commanded 100% shut or 100% open based on the selection of the decel tune by the driver.


Again, no one is asking you to give out any trade secrets or condemn yourself in the secret squirrel society. Although, we do appreciate your input. Things like maximum "safe" stock back pressure is something that could be shared with each other here if/when identified.

Maybe when the DP decel tune is selected it closes the EBPV even when in neutral or park at a standstill. Perhaps someone can try this and see visually how much the EBPV moves when the tune is selected. Someone with a DP decel tune could try this and see what happens, or if they don't want to because it might cause a failure of some sort, they are not obligated to try it. Either way, this thread is a prime example of what this FTE sub-forum and community are here for. Coming up with great ideas, having a discussion with ideas from left field thrown in, then some fabrication and trials with testing.

Thank you for your input and for following along. I am not interested in an exhaust brake for my T4 system, but I am sure interested to see the finished product when these fellas get it ironed out. In just a few days they have gone from "hey what if" to "hey, this could work"...

 

Based on what cleatus12r and Sous said, I take back everything I said earlier about not needing the extra safeties.

Standby for DP decel tune test report.

Edit: I should mention that I want the exhaust brake to function as a T4 EBPV as well because of MN winters. That is why I want the EBPV signal from the PCM to activate it.

 

I was answering questions regarding another tuning company's stuff to simply try to let them know what has been sold for years and that a custom made, slammed-shut butterfly in the exhaust should be ok.



The reason I'm not saying too much is because it doesn't take long for previously alluded-to tuning company to twist arms shutting-down threads and get people banned, not to keep things secret-squirrel-ish.

 

Oooooopsie

 

Understood and we ALL appreciate your efforts to keep things legal and on the up and up... I know I am just a moderator here, but in my opinion you are very far and away from infringing on any companies intellectual property or divulging information concerning their tuning practices. Again, these fellas have taken a turn from what the other company is marketing, selling and modifying.

The hardware is different, the proposed operation/activation is different, the software is different, the only thing the same is the actuation of a butterfly valve in the exhaust system, which in my opinion could in no way be considered a violation.


This is great information for the fellas to use. This means that they don't have to figure out a way to vary the amount of blockage the butterfly valve will incur on the exhaust system.

I apologize for the short off topic discussion above, but at least you guys now have a confirmation on the proposed function of the butterfly valve and a warm fuzzy that you can proceed with a 100% open or 100% closed function switch.

 

This link may not help, but it might... I was on the RiffRaff site looking for exhaust systems for a fellow FTE'r and came across this section for our trucks...

https://www.riffraffdiesel.com/exhaust-brakes-1/

There might not be anything useful to you fellas in there, but there might be something that sparks an idea or an "ah ha" moment.

 

Oof. The more I look at off-the-shelf solutions, the more I want to go the way @brokestroke has and build one myself. The brake alone is almost as much as the T4 kit.

 

Decel tune at idle test result:

So I tested the decel tune parked at idle. In this situation, it appears the tune limits EBP to around 23psi.

 

That is all the pressure that is created at an idle. I bet if you went out and drove it and got it above 2500 rpm you'd see close to 50 PSI. This is exactly the reason why the back pressure valve, or any exhaust brake for that matter, is not effective at low RPM.

Don't forget the value you are looking at is an absolute value. That means you take your 23 PSI and subtract your barometric pressure from that. You are only at about 10 PSI of back pressure there which will do nothing for you in the way of braking if that's all that was ever created.

 

Good point. I shall repeat the test and observe just how much the EBPV moves by this time. I forgot to do that the last time. I will also repeat the decel tune test going down a hill to see just how high the pressure gets. I have upgraded valve springs so I should be relatively safe going up to full scale deflection on the EBP Sensor.

 

IMO the best bet is to find one on ebay for a DT466 or similar for $500, hook it up to a pump and a wire in a dump valve.

 

I'll have to google that to see what it looks like. On the way out now so later I hope. Thank you. So that would mean a air pump to, and maybe a tank for a reservoir? Boy price keeps going up.

 

What about this?

 

That's cool. Would the vacuum pump on my truck support that? mine are manual hubs.

 

Probably...but I think it would be pretty easy to reconfigure it for pressure instead of vacuum.