Tuning with open downpipe - SRT Forums

lomedicojb · 07-06-2009, 02:10 AM

So I have a predator to tune with, and I've done some searching and here's what I've come up with....

I heard that after you've installed an open downpipe, you don't really gain power because the computer is used to not having that good of flow. So once I've installed a 3" downpipe with a cutout, I should open the downpipe and disconnect the battery, reconnect it, start the car, and drive it normal for a few minutes and then do some WOT pulls so the computer can relearn with the much better flow. So here's my next question... After I've let the computer relearn with the better flow, and then I close it, will the car run worse than a normal car with closed downpipe? If not, will it relearn again over time for the closed pipe so that when I go to open it, it won't be fast like it should?

Basically what I want to know is... To actually have the car be faster with an open downpipe, I have to have the computer relearn the better flow. So once it's done that, will it stay that way even when the downpipe is closed?

Adionik · 07-06-2009, 03:57 AM

You do not have to reset the battery every time you open your dump

nutz · 07-06-2009, 04:28 AM

you will just lean out a bit

#1 you will need to add fuel (more air more fuel) watch the wide band
#2 you will need to remove some timing, more air and fuel with less residual means faster burn

these are just base lines but will give you a direction to go in, i would make a seprate base map for this and add 5-10% fuel and retard 2* to start across the board-then tune it acordingly

i dont know the predator but tuning is universal

lomedicojb · 07-06-2009, 01:28 PM

So since I have a predator, all I have to do is install the open downpipe, and then add 5-10% fuel, retard 2 degree's of timing, and then go datalog from there and adjust as needed? What parameters will I be watching for when tuning with the open downpipe other than my a/f ratios? I will probably be running it open most of the time, so if I have it closed, would I have to worry about hurting something when I go WOT? Or will the only concern just be not going quite as fast? Basically I will not be doing two tunes, I'll just tune for the open downpipe and hopefully it'll be ok when it's closed as well. If that's not going to work, let me know. I just don't want to have to pull over and switch my tunes all the time for if it's closed or open because that will get annoying?

lomedicojb · 07-06-2009, 01:30 PM

Quote: Originally Posted by nutz

you will just lean out a bit

#1 you will need to add fuel (more air more fuel) watch the wide band
#2 you will need to remove some timing, more air and fuel with less residual means faster burn

these are just base lines but will give you a direction to go in, i would make a seprate base map for this and add 5-10% fuel and retard 2* to start across the board-then tune it acordingly

i dont know the predator but tuning is universal

Do I adjust the fuel and timing for part throttle and full throttle, or just full throttle?

AnotherNeon · 07-06-2009, 01:36 PM

Quote: Originally Posted by lomedicojb

Do I adjust the fuel and timing for part throttle and full throttle, or just full throttle?

You can only tune for WOT, with the handheld. As for the open and closed aspect. With it open you will run leaner and make mroe power. Once you close it up the car will run richer. I have a cutout and when i open and close it I have no problems. If you get the AFRs to around 11.7 with it open you should still be in the 11s with it closed.

nutz · 07-06-2009, 02:06 PM

Quote: Originally Posted by lomedicojb

So since I have a predator, all I have to do is install the open downpipe, and then add 5-10% fuel, retard 2 degree's of timing, and then go datalog from there and adjust as needed? What parameters will I be watching for when tuning with the open downpipe other than my a/f ratios? I will probably be running it open most of the time, so if I have it closed, would I have to worry about hurting something when I go WOT? Or will the only concern just be not going quite as fast? Basically I will not be doing two tunes, I'll just tune for the open downpipe and hopefully it'll be ok when it's closed as well. If that's not going to work, let me know. I just don't want to have to pull over and switch my tunes all the time for if it's closed or open because that will get annoying?

well what i have given you is how to set it up for a tune, add some fuel and pull some timing. street tune and slowly pull fuel till you get to 11.5-11.3 at full boost and slowly add timing untill you get no knock (if you get knock retard pull a tiny bit out in that area)

if you want to be safe just leave it tuned for open header, it will lose a tiny bit of power but be safe

lomedicojb · 07-06-2009, 03:04 PM

sweet thanks.