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Discussion Starter #1
So I'm told that the 392 Hemi's torque is edging close to the torque limits of the HP70 transmission. This is a problem for me as I eventually want to do a cammed 426 stroker build on my SRT. The obvious potential cures for this are to A) build up the HP70 for around 5 grand, or B) swap in a Hellcat HP90 8 speed that I can purchase used for 2 grand.

How difficult would it be to swap in a Hellcat A8 and make it work? What kind of tuning would have to be done?
 

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I still have the HP70 on my 426 build with new high stall torque converter & trans. tune. After a summer of a little track & strip time, so far so good. I’m taking a wait and see attitude while keeping my eyes peeled for an HP90 deal in the mean time.

I believe it would be a straight across swap for fit & finish. Prob. a good time for a Redeye driveshaft too.
 

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Discussion Starter #3
I still have the HP70 on my 426 build with new high stall torque converter. After a summer of a little track & strip time, so far so good. I’m taking a wait and see attitude while keeping my eyes peeled for an HP90 deal in the mean time.
Good luck to you, is your 426 NA or FI?
 

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I’m an old school N/A guy. Anyone can make power with boost :)

Currently working on a new 426 build project over the winter. Was lucky enough to snag an aluminum 426 Hellephant block. Going to put on Thitek heads and a Holly Sniper intake. Shooting for Hellcat HP on an N/A power plant.

Here’s a vid. clip with my current 426...

 

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Discussion Starter #5
I’m an old school N/A guy. Anyone can make power with boost :)

Currently working on a new 426 build project over the winter. Was lucky enough to snag an aluminum 426 Hellephant block. Going to put on Thitek heads and a Holly Sniper intake. Shooting for Hellcat HP on an N/A power plant.

Here’s a vid. clip with my current 426...

Damn man...that'll be sick. I bet she'll pass anything but a gas station 😂
 

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How did you get the hellephant block? I heard they have not delivered any of the motors due to camshaft issues.

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My engine builder was able to snag the block for me last fall. Since it's the block only, had no connection to assembled engine deliveries. FCA said he can't get any more as they are now reserving them for Hellephant engines and race teams.

I did a shake down cruise to South Dakota last summer on the new 426 and averaged over 21 mpg. Pretty surprised at that.
 

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Discussion Starter #8
My engine builder was able to snag the block for me last fall. Since it's the block only, had no connection to assembled engine deliveries. FCA said he can't get any more as they are now reserving them for Hellephant engines and race teams.

I did a shake down cruise to South Dakota last summer on the new 426 and averaged over 21 mpg. Pretty surprised at that.
Damn, that's pretty impressive. Was it relatively flat terrain? I'm also imagining your 426 is non-MDS?
 

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Just get a trans tune from Satera. He has cars making a lot more power and living with the stock 8hp70 once they've been tuned.
 

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Discussion Starter #10
Just get a trans tune from Satera. He has cars making a lot more power and living with the stock 8hp70 once they've been tuned.
So it's the tuning that's the issue? Not the internals? Cause I heard that the trans was slipping on some builds that exceeded 530 torque
 

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When the trans is tuned properly, it won't slip until a higher torque rating. Contact Hellraiser Performance and I beleive they will tell you 700wtq is about the limit for a stock 8hp70 with a tune.
Just like transmissions of yesteryear, more clutch apply force provides more holding power. Getting that additional pressure is not quite as straightforward as turning in the screw for line pressure.

If you don't want to do that, Hellraiser also has pioneered the 8hp90 swap, but it's going to cost around $10k last I heard vs a few hundred dollars for a tune.

Hellraiser and Satera work together.
 

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Damn, that's pretty impressive. Was it relatively flat terrain? I'm also imagining your 426 is non-MDS?
I can get around 20-22 with my H/C 426 if I’m driving conservatively. My hp70 is holding up so far as well. I do plan to upgrade in the future, but it depends which way this build goes. If I stay na I don’t think I’ll worry about the Hp70, if I do the turbo build I may go for a th400.


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Discussion Starter #13
When the trans is tuned properly, it won't slip until a higher torque rating. Contact Hellraiser Performance and I beleive they will tell you 700wtq is about the limit for a stock 8hp70 with a tune.
Just like transmissions of yesteryear, more clutch apply force provides more holding power. Getting that additional pressure is not quite as straightforward as turning in the screw for line pressure.

If you don't want to do that, Hellraiser also has pioneered the 8hp90 swap, but it's going to cost around $10k last I heard vs a few hundred dollars for a tune.

Hellraiser and Satera work together.
How is it 10k?? The trans can be had for 2-2.5k and the software tuning is about another grand, what else is required that makes it so expensive?

I'm also imagining that a stock HP70 trans will wear out more quickly over time if tuned to hold around 550-600 lb. ft. of torque?

This car is my only car and my daily, so whatever I do to it I have to make sure it's built to be reliable for the long haul.
 

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Discussion Starter #14
I can get around 20-22 with my H/C 426 if I’m driving conservatively. My hp70 is holding up so far as well. I do plan to upgrade in the future, but it depends which way this build goes. If I stay na I don’t think I’ll worry about the Hp70, if I do the turbo build I may go for a th400.


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That's pretty impressive. And that would be a great transmission swap for a drag car
 

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There are a lot of things besides the transmission that have to change. Start googling as I don't know it all off the top of my head.
 

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I’m an old school N/A guy. Anyone can make power with boost :)

Currently working on a new 426 build project over the winter. Was lucky enough to snag an aluminum 426 Hellephant block. Going to put on Thitek heads and a Holly Sniper intake. Shooting for Hellcat HP on an N/A power plant.

Here’s a vid. clip with my current 426...

aluminum block???
 
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