The PCM can reduce torque for shifts with spark, fuel, and throttle.
When increasing the power of the engine, it seems that torque management should be preserved for transmission durability.
For example, in a scenario where nitrous is being used, fuel shut off and closing the throttle both sound like bad ideas.
Can the spark torque management remove enough torque (including the additional torque from the nitrous) to keep the transmission happy?
If in doubt, multiply everything by 1.1.
The transmission actually sends the torque request to the engine over CAN, but it is based on the assumption that the engine torque model is accurate and that it will be accurately honored by the engine. If the model is inaccurate, the transmission won't know it. That could cause issues.
Right, I'm familiar with the need to fudge the torque model on forced induction applications or that nitrous would not be factored into the torque model since it is outside of the control of the PCM, so actual torque would be much higher than calculated.
I guess my question is, if you turn OFF the ETC and FSO and leave only the SPARK torque management, can it reduce torque enough with just the spark to keep from hurting the trans during shifts?
I'm trying to plan out a nitrous setup and it seems best to spray through shifts, but at the same time I'm worried about the trans from a torque management perspective and the engine from a FSO & ETC perspective. Don't want to shut off fuel or close the throttle with the nitrous activated.
If in doubt, multiply everything by 1.1.
Maybe...depends on how it is calibrated. The engine controller will ignore excessive spark torque reduction requests from the transmission because it is trying to protect the catalysts and exhaust valves. However if you have access to that variable, you're all set...
Would that be the cat temp air charge/rpm to temp table? 32929?Originally Posted by smokeshow
If in doubt, multiply everything by 1.1.
I have some more logging to do after a test flash, but it looks like the trans torque reduction (spark) follows the spark min torque reduction table.
If in doubt, multiply everything by 1.1.
Post your file?
If in doubt, multiply everything by 1.1.
Ah, yeah just go into Fuel>Temperature Control and Exhaust>Temperature and max out all of the thermal limits and minimize all thermal models for the exhaust and catalyst. Those are the main determining factors for denying a fast path trans torque request. Retarded spark burns up cats quick, so that's the first torque request to get denied. I'd also disable all overtemp enrichment, basically anything thermal related lol.
I feel sorry for your exhaust valves D:
Is there a better plan to accomplish this besides shutting the nitrous off and back on at every shift?
I don't have any good ideas for that one. I have a similar setup that uses a controller I built that is toggled by mechanical switches and monitors signals on CAN to determine the window for the nitrous to spray in. But I spray through the shift.
So you just spray through torque management? Do you have fuel, spark, or throttle disabled?
Back when i sprayed mine i had the ETC and FSO switched to off and only used the spark side to control the torque management. I also maxed out the cat thermal as described above and adjusted some of the torque management as you usually do with any tune. This setup ran good for a small 100 shot on a stock setup. i also sprayed through the shift. Now looking back and after learning more I would go into the trans side of things a quicken up the shifts as well as firm them up to help with the slip during shifts. I'm not up to par with the trans settings so i paid for a good TCM tune through TBR tuning on here. Now im running a whipple, cam, and e85. Im have installed a nozzle in front of the TB to spray a small shot to help with iat at the track but have yet to use..
6.4 Whipple Diamond pistons Manley rods, Demon Plus Cam
The more I learn about these 8 speeds, the more I wonder if the common technique of shortening the slip time is actually causing overlap and wear on the clutches and brakes.
If you look at the Demon and 1320 TCM tunes, they actually slow down the shift time when TQ management is reduced.
It's pretty obvious that more torque management allows a faster shift - but does a faster shift time equate to a quicker ET? Doubtful.
I wish we had all the channels needed to actually log shift times and see what's really going on in there.
Maybe if The Tuning School releases their Dodge Trans book this century it will offer some guidance.
Also, I seldom see people talk about resetting adaptives and doing a quick or slow learn after flashing.
Last edited by spoolboy; 07-25-2020 at 08:09 AM.
From some of the cars i've seen and the power levels they are at i would say there are some negatives to shortening the slip times but..... at these power levels +750hp i do believe that they benefit from this in regards to handling the power. This is regards to the HP70 even if this does create more wear it doesn't seem to effect overall longevity of the transmission. As the only time this is taking place is on WOT shifts, typical daily driving the car doesn't create much slip during these events. Again I'm sure someone with more experience might have a different view but i've seen a few cars with these TCM strategies making close to 1000hp live. Now at some point these HP70 just don't cut it and they give out, but i truly believe if your making less than 800 hp these trans in stock form benefit from this strategy.
Now do they ET better?? I would say so but how much i don't know. Quicker shifts means less time not applying power to the tires.
For me i can see the shift on my scanner by watching the spark advance dip and just use the elapsed time for shift times, i also log the commanded gear and actual gear to see when and how long it takes as well.
I would assume that the Demon and 1320 cars are still tuned to for the masses, as not all people like firm hard shifts so they keep them somewhat tame to make everyone happy but just my thoughts on that. Their are always room for improvement.
At the end of the day these are just suggestions from what experience i have and the few cars i follow and know how the car is setup along with my own tune and the people i have talked to.
6.4 Whipple Diamond pistons Manley rods, Demon Plus Cam
Reply With Quote