If you feel your drivetrain is up to the task, I don't see why you couldn't give it a shot and see how it goes.

On the cumulative part. When I asked Bullydog about that, they said you can get another 20 horse stacking with a 70 horse EZ, indicating that it was not cumulative. I have been talking with a Bullydog dealer that has stacked it with just about every pressure box out there and said that they have found it to be cumulative on the 03s and 04s, but not on the 04.5s. Don't know why the difference. This guy is monitoring rail pressures when he stacks, so he says it is easy to see how the truck treats the combo. Lots of varying info out there still.

On the other hand, I stacked the Bullydog with the VA duration box and it was totally cumulative. Nice power gain with the VA on 50hp and insane when switched to kill. Engine ran very rough though and smoked a lot. Way to much duration going on. That is probably why Bullydog recommended that I not stack with a duration box. Since when do we ever listen to them?

Also, been told that Bullydog is working on the flat spot around 2K RPMs. Supposedly it is right at the end of a map (whatever that means) and has proven to be a bear, but they are working on it. They are also working on a new "Extreme" mode that is 50hp stronger (probably from pressure) that they will make available for the 03 HOs and up when it is ready, but may not be available for the 235 and 250hp trucks because of the 47RE. Time will tell how they treat that one.

 

based on what I know, when you stack a pressure box it definately will be cumulative with the downloader. but the downloader can't make rail pressure arbitrarily large -- there's only so much power available from actually raising rail pressure via software. I've been trying to piece together information from all the mfgs so I can accurately describe how pressure boxes work. but its been an uphill battle. there's information out there not being revealed so its taking me a bit longer to get to the bottom of it. esp for the aggressive boxes and the pressure relief valve. But I'll get there, not to worry.

 

AK. keep up the good work and lets compare notes. Its not yet clear to me that software can dial up pressure like an aggressive pressure box can. In other words, there are some consequences of external pressure fooling that may not be availble via software. So I expect the "cumulative rail pressure" part would apply, certainly, but only below certain rail pressures. the "cumulative power" part may not work because there are some interactions between what you do in software and what can be done externally.

 

the ECM (with or without modified code) dials up a certain pressure to try and satisfy the fueling tables. it then compares actual pressure to the table and adjusts the CP3 accordingly to make sure both agree. So lets assume that the ECM under modified code wants 25,000. so it fires off a requrested pressure command for 25,000 psi (stock is 23,000 plus some change).

Now put on an external pressure box. this is over simplified but ok for illustration purposes. if the box was designed to go above 25,000 then it will map 25,000 to something less than that (for discussion's sake, say 24,500). Lie to the ECM I mean. voila, the ECM is not satisfied anymore (because it wants 25,000 and only sees 24,500) and so it fires off a higher requested pressure command to the CP3. when rail pressure reaches 25,500, the box sends something less than that (say 25,000) and the ECM is now satisfied because "actual" pressure matches what the fueling table calls for. ECM is fat dumb happy and satisfied. The fueling table called for 25,000, and it had to fire off a requested pressure of 25,500 to get there. all because the box lies.

Thats an example of cumulative pressure. what happens at the higher HP levels and at higher fuel pressures is a bit different. I've about got it figured out but still going through validation steps. hey, you let the data lead the way and don't let anyone fool you along with your ECM...

 

it is only cumulative under certain circumstances, so if you're looking for a generality, no it is not.

Sometimes I don't sleep at night when a box mfg tells me a story that doesn't make sense and I have to grind the gears in between the ears to figure out what really goes on, who's spouting technobabble, etc.

 

Wow Doug, you are one hard worker. I really thank you for all of your research and free sharing of information. You have made alot of CTD owners much more informed and consious. Thanks for all the good info I am sure you have saved a ton of headaches and uninformed purchases.

 

your welcome. those who have been following the fueling box updates and some of my posts may notice a lower level of activity from me lately. this is only because sometimes my day job demands more, and because I'm not as apt to post intermediate results and progress. I found that it confuses too many folks.

 

Hey Doug...do you think the BD downloader and the VanAaken pressure box would be a good combo? From reading your summary and what has been posterd about the BD it looked like (at least to me) a good matchup.

 

I'd have to see a torque curve of the downloader, but this might be a good combo. hard to say with out more information. the VA pressure box has good torque rise down low and pretty weak (30 HP or so) on top. thats great for towing, but will disapoint the racers.

if the downloader also has a strong low end with pressure, its possible that the combination might hammer the pressure relief valve too much, I don't know. But consider that the downloader is intended to be stacked with a Bullydog pressure box -- which is not known for low-end strength ( it is known for high-end HP). This is all speculation but it could suggest that the more traditional pressure boxes might be a better stack. I expect that the downloader can fuel strong down low already.

there's so much activity now going on, experimenting with the downloader, that its difficult to keep up with the information flow. you can do all sorts of wild stuff, make power and all of that, but I don't see anyone carefully examining what really goes on before they try. At the very least, I would like to see torque curves before I stacked two enhancements. I think someone has already stacked a TST with it now thats timing advance for ya.

 

Thanks Doug....the reason I brought this combo up is because in one of the posts I read here (or the other site) made mention of the fact that the BD didnt use pressure on its low setting (1st program) and only slightly higher than stock on the middle setting (2nd program). Knowing what I do about the VA and its pressure from your summary made me wonder then about the match.

 

I have my downlaoder coming tomorrow along with my outlook, I can't wait. Has anyone seen milage increases with the downloader? My friends torque dog has given him @2-3 mpg better in normal driving. I have a 2500 lb slide in camper and was wondering if running at 90 or 130hp settings would be detrimental to the drivetrain with the outlook watching temps (stock 48re) and taking it easy. I may end up putting a perf valve body in after the warranty gets closer to being expired.