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Thread: Hellcat Torque Managment Issues

  1. #1

    Hellcat Torque Managment Issues

    On the dyno I turn off everything in the torque management tables under general and the car is making a little over 900 RWHP.. All is fine, as I am only pulling in one gear with no shifts. Out on the street I will make a pull through a gear and let off before the shift. I have tested full throttle shifting with other cats with all TM off with over 1100 rwhp on spray and it works but the trans takes longer to shift. So to keep the trans happy and all shifts firm, I always add it back in. With this hellcat as soon as I return the general TM tables back to stock and go wot with traction and stability disabled the timing wont go past 1-3 degrees the entire pull, so I have something limiting it.

    Bad383TA

  2. #2
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    The transmission is probably burnt up. The 8hp's are not very stout. you really should be leaving at least some tm on in any hellcat you do

  3. #3
    The 8HP90 is a very stout transmission. However it's not very tolerant to abuse, due to the nature of how it shifts. If you take off torque management, expect a damaged trans. Spray through shifts? Burnt trans. This isn't a 2000 Camaro. Why does everyone think they're doing something great by taking out torque management? It needs to manage engine torque between shifts. On every shift you have two or more clutch packs intentionally slipping to manage shaft speeds between shifts.
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    Advanced Tuner Blue Bee's Avatar
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    Quote Originally Posted by Monzsta View Post
    The 8HP90 is a very stout transmission. However it's not very tolerant to abuse, due to the nature of how it shifts. If you take off torque management, expect a damaged trans. Spray through shifts? Burnt trans. This isn't a 2000 Camaro. Why does everyone think they're doing something great by taking out torque management? It needs to manage engine torque between shifts. On every shift you have two or more clutch packs intentionally slipping to manage shaft speeds between shifts.
    Agreed, it is a stout trans. Bad383ta, I understand you add it back in afterwards (TM), why shut it off to begin with? If you disable "use spark" it's not going to pull timing but you are killing that trans. With all the trans TM disabled the long soft shifts are nothing but slipping and putting blue spots on the clutches instantly, especially with that kind of power. Have you messed with all the torque tables? upped air limits? shortly after the shift the trans TM shouldn't be affecting timing so there must be something you are missing. It's hard to tell without a tune file.

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    Quote Originally Posted by Monzsta View Post
    The 8HP90 is a very stout transmission. However it's not very tolerant to abuse, due to the nature of how it shifts. If you take off torque management, expect a damaged trans. Spray through shifts? Burnt trans. This isn't a 2000 Camaro. Why does everyone think they're doing something great by taking out torque management? It needs to manage engine torque between shifts. On every shift you have two or more clutch packs intentionally slipping to manage shaft speeds between shifts.
    I disagree. There are a ton of damaged 8hps out there. Several that i tuned and left tm on. Almost all of the competitive cars in the hellcat shootout in mshs last year were running on hurt 8hps. Now everyone has gone built. They are not very strong on anything other than stock cats.


    And leaving all of the tm on in the cats does slow them down. Ive seen it first hand but it's a catch 22 as turning it off just expedites their failure.

  6. #6
    on an upshift, the oncoming clutch takes the punishment as it tries to pull the engine down to the RPM of the next gear at high pressure, generating a lot of heat. If the tire can hold traction during the large torque spike it will be the fastest shift but the stock clutch packs probably won't last long.

    The torque management is there to smooth the torque output and reduce the heat generated in the clutch.
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  7. #7
    I'd bet almost all of the competitive cars were on nitrous and spraying full tilt through the shifts as well, which pretty much renders torque management moot. They've got to be over 1,000 ft/lbs of torque. The 8HP90 is also in the Bentley Muslanne Speed taking around 811 ft/lbs of torque, compared to the Hellcat's 650. The aftermarket will get a handle on this transmission eventually.

    It'll be interesting to see how Dodge handles the Demon's 8HP. The 6 speed Tremec isn't nearly strong enough.
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  9. #9
    That was fast...
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  10. #10
    Haha yes perfect timing for this thread, but 18 months of work in the background...
    I count sheep in hex...

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    Quote Originally Posted by Monzsta View Post
    I'd bet almost all of the competitive cars were on nitrous and spraying full tilt through the shifts as well, which pretty much renders torque management moot. They've got to be over 1,000 ft/lbs of torque. The 8HP90 is also in the Bentley Muslanne Speed taking around 811 ft/lbs of torque, compared to the Hellcat's 650. The aftermarket will get a handle on this transmission eventually.

    It'll be interesting to see how Dodge handles the Demon's 8HP. The 6 speed Tremec isn't nearly strong enough.
    You could be right. The only car i can vouch for is our car. We spray it. It makes over 1100 whp so maybe not the best example ("for anything over a stock cat") but not through the shifts and I've left tm in it. It did not last very long.

    Pullied cats do make a bunch of torque btw

  12. #12
    Mind if I ask what gear gave up first? I have my own hunch.
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    Quote Originally Posted by Monzsta View Post
    Mind if I ask what gear gave up first? I have my own hunch.
    5th was the first to go.

  14. #14
    Whelp, hunch wrong. I figured "A" clutch, being the smallest would give up in 1st.
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    Advanced Tuner Blue Bee's Avatar
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    I would have guessed 3rd, 1 and 2 use both A&B holding clutches, 3rd only uses B. Makes me curious which gear would be the next to go..? If it's the C clutch that failing 6/7 would be affected as well, D was already "on" from 4th gear, interesting. I'd love to tear down one of these failed 8HP's because C is also on in 1&3. 3 clutches always on for each gear. Who do you have fixing these curt@injected?

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    Quote Originally Posted by Blue Bee View Post
    I would have guessed 3rd, 1 and 2 use both A&B holding clutches, 3rd only uses B. Makes me curious which gear would be the next to go..? If it's the C clutch that failing 6/7 would be affected as well, D was already "on" from 4th gear, interesting. I'd love to tear down one of these failed 8HP's because C is also on in 1&3. 3 clutches always on for each gear. Who do you have fixing these curt@injected?
    Bill @ paramount has done the last couple for us. The one in our car seems to be working pretty well thus far. The car went 179 in the half consistently and was going 9.50's(@full weight) our first time testing on the new trans on the 1/4 before we ripped the diff housing out of the car. We hadn't been able to put all of the power to it yet as we were creeping up on it but hadn't had any issues yet.

    The addition of trans tuning was helping us some though

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    It started having issues with the 4-5 early on last season. To the point where with tm on it would pull power for over a full second trying to engage 5th.

  18. #18
    Advanced Tuner Blue Bee's Avatar
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    yea I figured Paramount had a hand in it, that's cool though man, keep us posted on how they are doing. I have more and more customers concerned and asking how the 8HP is doing with power and if they can be repaired. Does paramount have all the "hard" parts as well? I'd like to keep to one place for getting all the parts, I was looking at a paramount converter for my personal car.

  19. #19
    Mint!!!

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    Quote Originally Posted by curt@injected View Post
    The transmission is probably burnt up. The 8hp's are not very stout. you really should be leaving at least some tm on in any hellcat you do
    does this apply to the 8hp70 transmission in the 392 cars (stock power ) , i know some guys running with all the TM disabled on the engine side (PCM) only..