ZF8HP70 fails 1>2 shift under WOT

[Enthusiastic]

Hello!

Could you share your tune and log?

DodgeBoy.
YouTube: https://www.youtube.com/@dodgeboy2785

DodgeBoy, I responded to your email. Thanks.

[LilSick]

i fixed another hp70 tune at the track tonight

scat w 3500 convertor that had lost 1-2 shift

lemme know if you need help

[Enthusiastic]

how did that dyno session go?

Had delays due to fuel delivery issues. Dyno scheduled for next week. The compression is lower on this forced induction 6.4L (9.7:1) to run on 93 octane pump gas. Hoping for 550-650 (Dynojet dyno), or 450-550 (Mustang Dyno) as a baseline range with only 63lb injectors and 10psi boost.
Adding another 300Hp with bigger injectors and a smaller supercharger pulley may not be a good idea for the stock ZF 8HP70

[Enthusiastic]

i fixed another hp70 tune at the track tonight

scat w 3500 convertor that had lost 1-2 shift

lemme know if you need help

OK. Thanks!

My first pre-dyno test was a 5.0 Mustang yesterday, on a second gear rolling start. Smoked it. I got a lot of WTFs and laughs. Since the new "stock" Mustang comes with anything from 315 to 480 HP, it probably was not the top performance stock version at 3,752 lbs. The fat 6,600 lbs. of Durango with 3 passengers in it without SRT or Hellcat badging was not supposed to do that

[shak3r]

i fixed another hp70 tune at the track tonight

scat w 3500 convertor that had lost 1-2 shift

lemme know if you need help

How did you fix the 1>2 shift?!? It wont help me now, but I'm sure others would appreciate the info

[LilSick]

it sounds crazy

spoolboy knows, he did not call me nutz

some of the switches got reversed somewhere during the latest revisions

thx hpt

[Enthusiastic]

how did that dyno session go?

DYNO RESULTS - 562WHP (SAME AS STOCK HELLCAT DURANGO):

Example Stock Hellcat Durango Specs and Dyno Reference Comparison:
Using an 8HP95 (900Nm) transmission, a "stock" 2021 SRT "Hellcat" 6.2L Durango produces 562WHP/531WT (according to Hennessey Performance) on 93 octane pump gas with stock tune, 9.5:1 compression ratio, 11.6 lbs. boost, and 57lb (600cc) injectors.
https://www.youtube.com/watch?v=n4WenoBjHjo

My Specs and Dyno Numbers:
Using an 8HP70 (700Nm) transmission, My 2017 Durango with forged 6.4L (392) produces 562.87WHP/524WT (Dynojet, yesterday) on 93 octane pump gas with a conservative tune, 9.7:1 compression ratio, 9.8lbs. boost, and 63 lb. (661cc) injectors. My 6.4L engine has 2 lbs. less boost than the reference 6.2L Hellcat motor and seems to have the same power but only RWD with the 8HP70.

Additional 6.4L Power Options:
If I reduce the supercharger pulley size by 1/4" from 3.75" to 3.5" using the same 63lb injectors, this should increase the boost to the same as the Hellcat and exceed stock Hellcat power by 50WHP for a total 612WHP. The 63lb injectors may be close to their limit and may require 80lb injectors. Also, this may be too much for the 8HP70 transmission.

A 1/2” pulley reduction to 3.25” would increase my boost to 13.8lbs. and increase the power to 662WHP or 100WHP over a stock hellcat Durango. [UPDATE 01-18-2024] Done. Boost is now over 13 PSI, estimated 680WHP

0-60:
The 6.4L Durango weighs at least 6,300 lbs. with larger engine, SRT aftermarket 9.5" wide rims, and 295/40ZR20 tires. Not sure what the 0-60 would be as I have to let off throttle before the 1>2 shift to avoid limp mode, then I can go WOT. The stock Hellcat Durango claims a 3.6 sec. 0-60 on a perfect run, if actually possible, without special tricks including no rear seats, cold day, special tune, launch mode etc. Regardless, off-the-line using the same tires with even HP, the AWD 8HP95 Hellcat will do better than the RWD 8HP70. I should be able to get under a 4.0 sec. 0-60 on the RWD Durango with the current configuration.
However, with more HP (smaller supercharger pulley) past the 0-60, I should be able to reel-in the stock Hellcat even with groceries .

[DodgeBoy_8HP]

DodgeBoy, I responded to your email. Thanks.

Perfect! I just replied to you.

Thanks.

[Enthusiastic]

Perfect! I just replied to you.

Thanks.

I will be holding off on the tune. I found a deal with a great discount for a beefed up, tested, tuned, and installed 8HP70 good to 900WT (Ft Lbs. Wheel Torque). The highest I may ever get is 640WT. This should be plenty of room for longevity. Thanks!

[LilSick]

900 ft lb that means it comes with sipples billet drums

dont get burnt

dont pay 5 grand for a stock trans

[Enthusiastic]

900 ft lb that means it comes with sipples billet drums - this is good, right?

dont get burnt - ? Generalized statement. knife is sharp. Assumption of no research. Parts, knowledge, and labor to install is not free

dont pay 5 grand for a stock trans - ? Price assumption, incorrect, much less, price includes install. Your first statement contradicts your "stock" statement. Confusing statements.

No mention of this in our private conversation

[LilSick]

on the phone i tried to suggest you learn how to set up scanner a lil better and log and find out if what you have is really shot before you swap it out

[james1595]

i fixed another hp70 tune at the track tonight

scat w 3500 convertor that had lost 1-2 shift

lemme know if you need help

Hiw did you fix it? Ive got the factory convertor in my 5.7 and it wont shift until i hit the rev limiter

[LilSick]

which version were you using when you wrote the last calibration?

[miccrohurst]

I have a 2015 Ram cammed, procharged, and 3600 stall circle D. I am having this issue. How did you fix it?

[DodgeBoy_8HP]

I have a 2015 Ram cammed, procharged, and 3600 stall circle D. I am having this issue. How did you fix it?

In the past couple of months I have worked with a lot of RAM swaps (to ZF 8 speeds). It is quite a common issue.
The solution is a full transmission re-tune: Combination of torque converter, shift pressure, shift timing, shift RPM and line pressure.

Each case is unique (under my eyes). There is no "one size fits all", once every single engine and transmission are unique.

Thanks.
DodgeBoy.
YouTube: https://www.youtube.com/@dodgeboy2785

[LilSick]

I am having this issue.

How did you fix it?

not by rewriting the entire tune

just by playing with a few switches

i think they got switched in the software update

which version are you using???

[james1595]

not by rewriting the entire tune

just by playing with a few switches

i think they got switched in the software update

which version are you using???

If i posted my trans tune, could you look to see if anything looks off? Ive tried to fix it and had multiple Professional tuners look and try to fix but nothing worked.

[LilSick]

sure

email me the current tune and a good log

[james1595]

sure

email me the current tune and a good log

I sent you an email with the most recent log and tune that was in it at the time