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Discussion Starter · #1 · (Edited)
I know some of guys here have been talking about 7k rpm shifts with tuning and I am also aware not all of you are in touch with the Hellcat community beyond this forum.


There is growing concern that raising these shift point above 6500 is leading to a growing number of catastrophic failures at the rod-piston wrist pin connection in the 2018+ motors, Hellcat and redeye 6.2’s. There has been more than a few similar failures with raised shift points and even some with stock shift points.

I just want to bring this problem awareness to this forum, as I said, because some here are only get their Trackhawk/hemi 6.2 info here.

Also keep in mind, that asking for a shift at 6500 rpm in 1st or 2nd gear likely means you will be shift above 6700 rpms. This also needs to be factored as well.


Just something to think about before you agree to a tuner setting your shift that high. That last 20-30whp might get real costly.


This is what is happening:

https://www.allpar.com/news/2019/09/exclusive-details-on-the-burned-f8-challenger-at-woodward-45785




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good info, thanks.

I know a number of guys on these forums (which is still by far the minority of owners overall) are enjoying their modded THs. I'd like to think a few mods would not wipe out a block. But, I have other modded vehicles in my garage if I want to go _really_ fast, and as much as I really do enjoy driving this thing... I'd like to keep it 100k miles. So every time I get the urge to mod, I pause because of this type of evidence.
 

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Glad to know about this because I had thought about getting mine raised to about 6500 in the future, but not at a catastrophic failure cost for a little added power at the top.
 

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Discussion Starter · #4 ·
I’m certainly not saying don’t mod. I’m all for mods. I’m doing them myself.

The only info I want to put out here is that pushing that envelope into that rev range can cause problems. Adding 100-200hp is a huge leap as it is and piling onto that with another 400-500 rpms could find that weak link quicker then we think.

The “evidence” is not rock solid here , but for the 2018+ builds, the oem wrist pin went to an APR unit apparently, which only adds to the speculation that the area is a known weak point.

Again, just some info that has recently come to public light. Do with it as you will.

And yes, I’m aware many people run up to 7k rpms and haven’t had issues.


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I’m certainly not saying don’t mod. I’m all for mods. I’m doing them myself.

The only info I want to put out here is that pushing that envelope into that rev range can cause problems. Adding 100-200hp is a huge leap as it is and piling onto that with another 400-500 rpms could find that weak link quicker then we think.

The “evidence” is not rock solid here , but for the 2018+ builds, the oem wrist pin went to an APR unit apparently, which only adds to the speculation that the area is a known weak point.

Again, just some info that has recently come to public light. Do with it as you will.

And yes, I’m aware many people run up to 7k rpms and haven’t had issues.


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A lot of what you are saying makes sense. One thing that makes me speculate in regards to the link you posted above. It this driver was admittedly bouncing the car off the rev limiter in 3 gears. I would question if his rev limiter is spark or fuel cut hrmm
 

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Discussion Starter · #6 ·
A lot of what you are saying makes sense. One thing that makes me speculate in regards to the link you posted above. It this driver was admittedly bouncing the car off the rev limiter in 3 gears. I would question if his rev limiter is spark or fuel cut hrmm


There are few more detailed scenarios that I have been following on various forums as to what happened, but the short is, that doesn’t seem to matter. There have been no other signs of cause for these failures, heat/detonation/fueling/etc... they all seem to come back to rpm’s.

One very detailed account of the failure even has logs to show a problem that developed the week before the actual failure. Again, speculation is rpm over shoot on the shifts being called for at 6700 and not happening until after the motor spun past 7k.


One of the most interesting aspects of all this, the #7 piston seems to be a common piston to fail. Not all failures are at #7, but there seems to be a connection across these failures.




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I have seen many posts with Trackhawks set up to shift at 6700-6800rpm. When I got mine tuned by a well know tuner, he expressed keeping it at 6500rpm max. Said from the failures he has heard about in the Hellcat engine, most of them had excessive rpm as part of the problem. He stated this was from all the Hellcats 2015+. Not sure if their is any difference in a Hellcat motor from 2015 to current. Also, when tuning, at least with HP tuners, you don't just command 6500rpm and it shifts at the rpm. You have to use a formula for shaft speed and the actual gears to get a number to command the shift point. You would adjust up and down from there in small increments to get the desired shift point. You also have to command the maximum threshold in a different table or it will bang the limiter.
 

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To be fair... a LOT more people are modding their hellcat motors now compared back to 2015-2017..... The platform has a lot more research, and a lot more parts available now then ever before... With that comes with the homegrown tuners, youtube garage stars, Self made tuners.... and people trying to be a bit faster then the last... I am sure that has to account for a bit more of the failures we are seeing...

With so many more people modding, i can understand the higher number of failures.... But anytime you increase boost, rev high, put higher performance parts on.... MOST of the time you are reducing the lifespan of the motor by introducing more torque, and heat and stress on the motor.

IMHO if your modding your car... have a back up car, or at least a spare pile of change ready for your new motor, trans, or whatever else breaks!
 

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Discussion Starter · #9 ·
Pay to play, for sure.
I’m also looking to limit the paying portion as much as I can also. ... lol


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My shifts were at 6250 for 1-2 and 2-3 and then 6500 there on out.... ran like a dream...... till we broke the rear! yay drag radials lol
 

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Yeah, the tires broke ur drivetrain. I want grippier tires but it’s better they slip than break my jeep. You’ll get there man. Just keep lighting that money on fire. I’m gonna have to go over ur build again n see what driveline components you upgraded
 

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Discussion Starter · #12 ·
My shifts were at 6250 for 1-2 and 2-3 and then 6500 there on out.... ran like a dream...... till we broke the rear! yay drag radials lol


4-5 modded TH heading to atco tomorrow night it looks like John. I may not be one of them, but it should be a group of guys if you make it out .


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John, you think the drag radials broke the rear end or did you have some wheel hop?
TBH i think it was 25k miles of me driving it hard..... and then throwing a 2650 on it that broke the rear..... and the rear isnt "destroyed" its still putting down 2.5 0-60 back to back in 90 degrees..... The driver side, rear axel has some play in it (Back and forth) so obvsiouly something isnt right.... The last thing i want to happen is to lead to catasrophic failure on the drag stip... So we just replaced it out of precauation.... Once we remove the rear, I will inspect it to find the root of the problem... As of now... until the rear gets here next wed.... They are just gonna be tuning the car for daily driving and not WOT pulls.

FYI, even though the truck has the new super charger.... She drives and feels like 100% stock... Its crazy!!! Ill get some videos up of the launches soon! I want to make sure my truck is done first, because i have a feel lots of people are going to start contacting this shop for trans tuning..... As it doesnt miss a shift.... and it doesnt over rev, and never stops pulling. Cant wait to show you guys!
 

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TBH i think it was 25k miles of me driving it hard..... and then throwing a 2650 on it that broke the rear..... and the rear isnt "destroyed" its still putting down 2.5 0-60 back to back in 90 degrees..... The driver side, rear axel has some play in it (Back and forth) so obvsiouly something isnt right.... The last thing i want to happen is to lead to catasrophic failure on the drag stip... So we just replaced it out of precauation.... Once we remove the rear, I will inspect it to find the root of the problem... As of now... until the rear gets here next wed.... They are just gonna be tuning the car for daily driving and not WOT pulls.



FYI, even though the truck has the new super charger.... She drives and feels like 100% stock... Its crazy!!! Ill get some videos up of the launches soon! I want to make sure my truck is done first, because i have a feel lots of people are going to start contacting this shop for trans tuning..... As it doesnt miss a shift.... and it doesnt over rev, and never stops pulling. Cant wait to show you guys!
How much will you be running when it's all dialed in? I am contemplating a 2650 to make up for elevation. My concern is can the stock rods hold up to 20+.

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How much will you be running when it's all dialed in? I am contemplating a 2650 to make up for elevation. My concern is can the stock rods hold up to 20+.

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Looking for 23lbs once dialed in.

OBV at 23 lbs anything can happen... but we dont expect any catastrophic failures in the motor yet.....

I am aware I am at the brink and have prepared accordingly, but i do not expect to blow the motor... I plan to run it like it is for a year or so and then rebuild/spray and go for some 8's =D

But as we all know, anything can happen up at this HP range... But man does that 2650 drive nice....
 

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Looking for 23lbs once dialed in.



OBV at 23 lbs anything can happen... but we dont expect any catastrophic failures in the motor yet.....



I am aware I am at the brink and have prepared accordingly, but i do not expect to blow the motor... I plan to run it like it is for a year or so and then rebuild/spray and go for some 8's =D



But as we all know, anything can happen up at this HP range... But man does that 2650 drive nice....
Hell yeah! 23#s is going to be a beast. That's what I need. At my elevation it would be right at 20#s.

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