AWD launch...

[Midnightsun300c]

Greetings fellow AWD'rs:

I would like to start a discussion about getting a good launch with our AWD's. I have had my best success with 100% release of the brake with a simultaneous 100% throttle. Any attempt to brake torque doesn't seem to work with the AWD, or at least on my 300. This is somewhat perplexing because I can't figure out why? My Chrysler shop says that the TCM is the same part number for the SRT 8, C and C AWD. I have tried the SRT 8 1-2 shift flash, ESP and Torque Management delete both with wiring and flash, and a higher stall torque converter with no success. In every case it seems that the PCM/TCM combo goes into lock down mode if there is any brake and throttle at the same time.

To start with, is my experience unique? Has anyone else had the same problem?

Secondly, if you have experienced this same limiter in your AWD, have you found a solution or work around?

Thirdly, has anyone had any success with a higher stall speed torque converter?

Lastly (for now), what kind of 60' times are you able to get with your AWD? My 60' times have been abysmal! I just went out and ran the 1/4 mile with my Flashpaq and even though I hit 110 mph with an ET of 12.66" my 60' time was 2.04"! Before you beat me up to bad for posting Flashpaq numbers they can be used as an indicator. My prior experience has been that the Flashpaq starts recording at 1 mph. I believe most of us are probably at 2-3 mph before we clear the last beam at the starting line if we stage shallow. As a consequence the Flashpaq gives a slower 60' by .1-.2"? I believe the Flashpaq also clocks the speed at exactly 1/4 mile instead of 33' before, like at the track. But even if you adjust my Flashpaq numbers to 60'=1.84"; ET=12.44"; TS=109 mph, it still is an abysmal showing in the 60'!

I would greatly appreciate any feedback even if it is just to commiserate.

[done]

I think that an ET of 12.44 would actually make you the fastest AWD in the country, even ahead of LouZ's 392 stroker. I think you need to get on an actual track. I think that in the high 12's would be about where you will be based on your mods. However, the track will tell the truth.

Anyway, to your question, I disable ESP and then launch at 1200 RPM. Any higher or lower slows the run down. My best 60' times are at 1.9.

[Gabe]

I launch with no brake-torque, just jumping off the brake and onto the gas pedal ... that gives me (according to EVIC) 0-60 times under 5 seconds every time, and before the Diablo tuner I got track times of 14.4 and 14.2 as my best times the only time I took it to the track, October 2007.

I have noticed that brake-torqueing the vehicle causes a slight bog after the initial jump off the line and then the car starts taking off strong, and this slight bog is minimized if I don't brake-torque at all.

edit: my 60' times are all in the 2.0-2.2 range, usually right around 2.1

[Midnightsun300c]

I think that an ET of 12.44 would actually make you the fastest AWD in the country, even ahead of LouZ's 392 stroker. I think you need to get on an actual track. I think that in the high 12's would be about where you will be based on your mods. However, the track will tell the truth.

Anyway, to your question, I disable ESP and then launch at 1200 RPM. Any higher or lower slows the run down. My best 60' times are at 1.9.

I probably should have prefaced those times with the fact that it was 15 degrees, sea level, with 29.2" of mercury. I was just trying to show the disparity between my ET and 60'. By my calc's that would be about .3 help so your guess is right in line with what I would guess would be my corrected time at the track this summer of 12.8.

Regardless of what my corrected time may or may not be I would like to be able to brake torque or find some other way to launch closer to the thick spot on the torque curve.

One of the real benefits to our cars should be that the increased traction and distribution of torque to four wheels will give us a better jump of the line, shouldn't it be? At least to the point of compensating for the extra 250 lbs.

Anyway, it sounds like we are in the same boat as far as launch techniques are concerned. What are your thoughts on improving?

[done]

I probably should have prefaced those times with the fact that it was 15 degrees, sea level, with 29.2" of mercury. I was just trying to show the disparity between my ET and 60'. By my calc's that would be about .3 help so your guess is right in line with what I would guess would be my corrected time at the track this summer of 12.8.

Regardless of what my corrected time may or may not be I would like to be able to brake torque or find some other way to launch closer to the thick spot on the torque curve.

One of the real benefits to our cars should be that the increased traction and distribution of torque to four wheels will give us a better jump of the line, shouldn't it be? At least to the point of compensating for the extra 250 lbs.

Anyway, it sounds like we are in the same boat as far as launch techniques are concerned. What are your thoughts on improving?

I am hoping that I can get a good CMR tune and hope that will help with that "slow roll" style takeoff we get. I suspect that getting the right AF in the lower RPM range may be the key.

I can only a little wheel slip now, but that is when I get the best times. Do you get any? LouZ was of the opinion that wheel slip and catch was the cause of his transfer case demise.

Get a real track time as soon as you can and use that as a starting point. Are you in Alaska?

[Midnightsun300c]

I launch with no brake-torque, just jumping off the brake and onto the gas pedal ... that gives me (according to EVIC) 0-60 times under 5 seconds every time, and before the Diablo tuner I got track times of 14.4 and 14.2 as my best times the only time I took it to the track, October 2007.

I have noticed that brake-torqueing the vehicle causes a slight bog after the initial jump off the line and then the car starts taking off strong, and this slight bog is minimized if I don't brake-torque at all.

edit: my 60' times are all in the 2.0-2.2 range, usually right around 2.1

That is exactly my experience. Prior to my engine work my 60' was down to 2.0" with headers, exhaust, tuner and any throttle/brake together action just made things worse.

I have tried a higher stall TC but with no benefit because I still couldn't brake torque. I seemed to be adding another .1" or two in getting up to the stall speed which negated the more efficient converter and more torque once I was at 2800 rpm.

I am hoping at least one of our members has found a way, maybe Starscan, to flash or eliminate whatever limiter is built into our PCM/TCM.

There was a time that I though the first real danger would be blowing up the front transfer case by trying to brake torque...but I haven't even got to that point yet. Murphy's Law says that I finally find a way to trick the TCM and I will strip the planetary gears on the very first brake torque.

Another thing that I used to be afraid of was breaking one of the wheels loose, getting it turning a lot quicker that the others, and then hooking up and snapping something. However, I have found with my recent endeavors with my Flashpaq launches that my AWD behaves amazingly like a 2WD. The back end breaks free and I can roast the back tire with no ill effects. The front tires just keep pulling and the back comes right back in line. I have lost communication with the TCM a couple times and had to cycle the key but nothing has snapped, hopped or squealed...always a good thing.

[Midnightsun300c]

I am hoping that I can get a good CMR tune and hope that will help with that "slow roll" style takeoff we get. I suspect that getting the right AF in the lower RPM range may be the key.

I can only a little wheel slip now, but that is when I get the best times. Do you get any? LouZ was of the opinion that wheel slip and catch was the cause of his transfer case demise.

Get a real track time as soon as you can and use that as a starting point. Are you in Alaska?

James at Promotion gave me an email tune that helped quite a bit but still is not quite there yet. I'm still suspicious that I am still a little lean. I've got a wide band but I am suspicious that the O2 sensor loop is keeping the average and eventual O2 count good but any quick change uncovers a lean base. One of my next experiments is tune the WOT fuel tables way fat and see if the KR at peak torque in first can be significantly reduced.

I can now elicit quite a bit of wheel spin however the asphalt and tires are 15 degrees. With a warm track and tires I don't know if I will get much at all. Much to my delight there has been no downside yet. With the Littleboy cam and my low compression I never have had any delusion that I would have a low end, but that's what I wanted in preparation of a PD twin screw. One thing that I do have now is a good top end. Thanks to the Predator and the increased rev limit I can stay right in the power band for the last 1260' of the 1/4 mile.

Yes, I am from the AK and our track doesn't open until May 1. Great DA's in the meantime though.

[Big Bob]

Hey Bruce...What Up.....I did not read all that preceded this post but so happy to hear from you......and knew that you would resurface as being the AWD guru



So happy that you found this place and welcome....

[Gabe]

That is exactly my experience. Prior to my engine work my 60' was down to 2.0" with headers, exhaust, tuner and any throttle/brake together action just made things worse.

I have tried a higher stall TC but with no benefit because I still couldn't brake torque. I seemed to be adding another .1" or two in getting up to the stall speed which negated the more efficient converter and more torque once I was at 2800 rpm.

I am hoping at least one of our members has found a way, maybe Starscan, to flash or eliminate whatever limiter is built into our PCM/TCM.

There was a time that I though the first real danger would be blowing up the front transfer case by trying to brake torque...but I haven't even got to that point yet. Murphy's Law says that I finally find a way to trick the TCM and I will strip the planetary gears on the very first brake torque.

Another thing that I used to be afraid of was breaking one of the wheels loose, getting it turning a lot quicker that the others, and then hooking up and snapping something. However, I have found with my recent endeavors with my Flashpaq launches that my AWD behaves amazingly like a 2WD. The back end breaks free and I can roast the back tire with no ill effects. The front tires just keep pulling and the back comes right back in line. I have lost communication with the TCM a couple times and had to cycle the key but nothing has snapped, hopped or squealed...always a good thing.

See, my experience with launching my AWD has been that a couple of times I'd chirp the front tires on a hard launch and with the ESP disabled by pushing the dash button (partial disable, I know)

I've never lost traction at the rear on a hard launch on pavement, only on slippery surfaces, and I don't test 0-60 unless I'm on dry pavement.

And as far as brake-torque, I did it on snow and got the rear wheels to spin - although not for long as I didn't want to do possible damage to the AWD system.


However, with the ESP turned "down" by pushing the dash button, on snow, backing up the rear wheels were just spinning once and I couldn't get the fronts to bite until I re-engaged ESP ... weird ...

[Midnightsun300c]

Hey Bruce...What Up.....I did not read all that preceded this post but so happy to hear from you......and knew that you would resurface as being the AWD guru
So happy that you found this place and welcome....

Thanks for the welcome and tell me about your recent exploits with your machine. When you ran your 13.1" what tires and wheels were you using? I've found that a 25" diameter works just right for the power I have now. 6,600 rpm just gets me across the line in 3rd. Have you monitored any 1/4 mile runs with your Predator. How much timing do you have on cylinder #1 through the rpm range? I am real happy with the 33 degrees at 6,600 rpms for my shift, although it is a little tricky, especially in 1st gear to stay under the rev limiter. What are your shift points? Have you been able to get your 300 to autokick beyond 6,200 rpm? I can't. Can you get more than 6,600 in manual? I can't. Do you have a wide band sniffer now? How is your AFR at 2-10 percent throttle and 1,500 rpm? How much wheel spin do you have at launch? If you've had any, what have been the side effects?

Anyway, good to hear from you again and to hear that your machine is back together. Now spill the beans on the paticulars...

[Big Bob]

Thanks for the welcome and tell me about your recent exploits with your machine. When you ran your 13.1" what tires and wheels were you using? I've found that a 25" diameter works just right for the power I have now. 6,600 rpm just gets me across the line in 3rd. Have you monitored any 1/4 mile runs with your Predator. How much timing do you have on cylinder #1 through the rpm range? I am real happy with the 33 degrees at 6,600 rpms for my shift, although it is a little tricky, especially in 1st gear to stay under the rev limiter. What are your shift points? Have you been able to get your 300 to autokick beyond 6,200 rpm? I can't. Can you get more than 6,600 in manual? I can't. Do you have a wide band sniffer now? How is your AFR at 2-10 percent throttle and 1,500 rpm? How much wheel spin do you have at launch? If you've had any, what have been the side effects?

Anyway, good to hear from you again and to hear that your machine is back together. Now spill the beans on the paticulars...

Thanks Bruce,....I am now working on redoing my signature to eliminate being the fastest AWD,,,,,I will respond after I contact HHP and ask for my $$$ back

[Midnightsun300c]

See, my experience with launching my AWD has been that a couple of times I'd chirp the front tires on a hard launch and with the ESP disabled by pushing the dash button (partial disable, I know) I've never lost traction at the rear on a hard launch on pavement, only on slippery surfaces, and I don't test 0-60 unless I'm on dry pavement. And as far as brake-torque, I did it on snow and got the rear wheels to spin - although not for long as I didn't want to do possible damage to the AWD system.

I still do not fully understand the transfer of power as it relates to the slip in the rear end and the application of power to the front drive line via the planetary gears. However, I am thankful that they seem to work flawlessly in allowing the back end to break loose and then hook up again under power.

However, with the ESP turned "down" by pushing the dash button, on snow, backing up the rear wheels were just spinning once and I couldn't get the fronts to bite until I re-engaged ESP ... weird ...

All of my wheel spinning exploits have been on dry but frozen asphalt via the complete disengagement of ESP with the Predator which removes the ABS as well, something that I am not too fond of. Thanks for all your feedback.

[Midnightsun300c]

Thanks Bruce,....I am now working on redoing my signature to eliminate being the fastest AWD,,,,,

Please don't. Officially I have not been to the track and have no slip. How much do your bags add to your weight? What was your DA when you ran your 13.1? You may have me beat when all is compared.

I will respond after I contact HHP and ask for my $$$ back

What? I know you are joking because they have built you one fine AWD and it seems worth every penny.

Did you replace your pistons with forged? or change your compression? Do you know if they balanced your rotating assembly when they put it back together or if they gave you a harmonic balancer upgrade? Although I do not have access to a dyno I think with my heads that 6,600 rpm is the far limit to giving me the best power band, not to mention torque and therefore I don't envision taking the rpms over 7,000 rpms. However, I made a point in having my bottom end ready in case I want to upgrade my heads in the future. Did you talk to HHP about the possibilities?

Again, don't waste your time changing your sig, spend it spilling the beans!

[Big Bob]

Please don't. Officially I have not been to the track and have no slip. How much do your bags add to your weight? What was your DA when you ran your 13.1? You may have me beat when all is compared. What? I know you are joking because they have built you one fine AWD and it seems worth every penny.

Did you replace your pistons with forged? or change your compression? Do you know if they balanced your rotating assembly when they put it back together or if they gave you a harmonic balancer upgrade? Although I do not have access to a dyno I think with my heads that 6,600 rpm is the far limit to giving me the best power band, not to mention torque and therefore I don't envision taking the rpms over 7,000 rpms. However, I made a point in having my bottom end ready in case I want to upgrade my heads in the future. Did you talk to HHP about the possibilities?

Again, don't waste your time changing your sig, spend it spilling the beans!

Ok.....................as far as forging......no......I didn't want to put the extra $$$ at the time and thought I wouldn't spray again, but did change the compression. This last time in the shop I put in a new Stage 2 5.7 Hemi with a 2800 TC , kept the nitrous and also swapped out my Superchip with the Diablo, then also swapped out my Zoomers cat-back for the Flowmaster 40 series and welded full 3" pipes threw the tips, so no harmonic balancer upgrade.
......I had my car dyno'd and tuned after that and was able to grap lot's more HP and adjusted the A/F ratio to about mid 12's on WOT. and my results were 356 max HP and 381 Torque
....as far as getting to 6,600 RPM's don't know how......even with raising my Shift points I can only go to 6,200 RPM's from the 5,800 RPM's
.....as far as weight......my car weighs in at 4600lbs.....the Air system, Lambo door hinges, Subs and the other Bling I got in the car doesnt help

......so thats the story.....I was waiting to hear from you in regards to your project car with your trials and tribulations that you have gone threw so far and with your knowledge I'm sure we will learn from you...

[Midnightsun300c]

I notice that you too tried the 2800 stall on your AWD. I went back to stock after trying mine for a few months. It seemed that it hurt my launch as much as it helped. Not being able to brake torque seemed to completely negate the real benefit to a higher stall. How has yours treated you? Do you get the feeling that the first 40' that you are turning fluid and bringing the TC up to speed as much as you are moving forward? It seems to me the only way to truly unlock the real potential of our AWD's is to figure out a way to raise the torque ceiling in our TCM. We will need to proceed with extreme caution as our transfer case may not be up to the challenge and that is more than likely the reason for the low torque tolerance that it has.

I think you are running about 200 lbs heavier than I am. I'm about 4,400 lbs. which should be close to .2 in the 1/4.

What was your DA when you ran your 13.1?

Did you ever run your Flashpaq at the track? If so, how did they compare?