06 SRT Magnum Tuning Questions

[MagnumSRT8]

Got a few questions, when tuning, what timing roughly is best for peak power? I know every car is different but just looking for a rough estimate, debating on whether to add more full or pull a few degrees of timing. Right now im running 93 cai tune, +6 low +11 mid and +12 high still getting 1-2 degs in the mid and up to 3 above 4800.

Another question, when you write a tune, and modify a few things, then go back in and say add more fuel, is that fuel that you add the second time written ontop of whats already been added the first time? Eg. if i add +3 all across then write the tune, then go back in and write the same tune would i be +3 across the board or just +3 over stock?

[Quick]

Well, my feeling (may not be right) is that timing is the rough adjustment (large knob) and fuel is the fine adjustment (small knob) -- all within limits. I'd keep adding fuel until around 15 to 20% before I pulled timing. Then I'd pull a degree of timing and start over with the fuel adjustment.

In you example of re-writing the tune it would be exactly the same as the first time.
The Predator does NOT modify the tune file that's on the Predator. When you make adjustments they go into a different file which is sort of a list of the changes you made. Then when you write the tune the Predator takes a copy of the tune file, applies the changes to it and then writes THAT to the car. If you were to write the tune to the car again it will do the same thing. Take the "base" tune file, apply the changes to it and write it to the car. So in your example you'd still be +3 over stock the second time.

There is only 1 change list. That's why if you select a different tune on the predator it will ask you if you want to "reset parameters". It's asking if you want to clear the change list you made while working with the previous tune.

Now... let's say you add +3 across the board and write it to the car. Now the car has +3 over stock.
Then you upload the "last tune written" to your PC. That tune file will have +3 over stock.
Then you download that tune back onto the Predator (it will go in the Custom Tune section). Now that custom tune will have +3 over stock. If you select it, it will be the "base" file and will contain +3 over stock without any modify parameter changes made to it. If you were to then go to Modify Parameters and set the slider to +3 and write it to the car, you'd be at +6.09 over stock (the extra .09 came from adding 3% on top of 103%)

That help?

[QuickRT2SRT]

I was runing similar fuel adds on my 07 Charger SRT8 using the 93 CAI tune and when I had it on a dyno last week it showed the AF ratio as being around 10.9 to 11.1 which was so rich it had to be costing me hp. I reduced the fuel to get the AF where it should be and ended up with +5, 0 , 0 on fuel when I was finished to get the AF at 12.3 in the mid rpm range and 12.5 in the high RPM range. Now I am back to having lots of ST and LT KR - even have a lot of ST every time I even hit part throttle (around 40-60% Throttle pos). So if I add fuel back I am back to running real rich which isn't good. How do I know how much timing to remove to get it under control? Oh yeah... I am running 93 octane BP fuel and have an AirRaid SRT8 CAI, catch can, 176 deg tstat and all else is stock.
TIA.

[MagnumSRT8]

These cars love fuel. I reset my tune and started all over. Ended up running +6 low +16 mid and +17 high i think. Almost beat my best time at the track like that. Ran a 12.78@109mph

[QuickRT2SRT]

Thanks for the help MagnumSRT8.

[MagnumSRT8]

I used to play around pulling timing a bit, while not adding as much fuel, never did me any good. Left all my timing alone and just added fuel this time, works for my car, but they are all different. Just log ST KR and add fuel a bit at a time.

[DGatzby1]

When you had it on the dyno, did you just try the canned 91 CAI tune with no changes? Might be surprised, I have been.

[Quick]

QuickRT2SRT, did you try logging the stock tune?

[QuickRT2SRT]

Never did log the stock tune... guess the thought never occurred to me since I wasn't planning on running it except when I have to take it to the dealer...

[Quick]

Never did log the stock tune... guess the thought never occurred to me since I wasn't planning on running it except when I have to take it to the dealer...

You might be surprised. You will normally see a good bit of knr with the stock tune. Maybe bumps of up to 4.5 or so of ST knr. Keep in mind that you cannot make a direct comparison since the knock sensors are desensitized a bit in the canned tunes but if you're getting an abnormal amount of knr with the stock tune (compared to "normal" with the stock tune) then you may have something else going on. Like gas, oil, or something else? Easy enough to check.