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2013 5.7L 300c AWD - What can I do to have a transfer case that’ll handle 600hp?

174 Views 6 Replies 3 Participants Last post by  Korben
Hey, new to the forums. Did some searching around before I posted, but sorry if this ends up somehow being a duplicate anyway. I’m not claiming to be or trying to sound like an expert, so please excuse me if my post ends up sounding like mindless rambling.

The gist of it is: I want an AWD 300c that makes 500whp, which after parasitic losses are accounted for, will probably require around 600 crank HP, depending on how efficient the drivetrain is. Based on what I’ve read, this can be done either with a 5.7L with 7-9 lbs of boost, or a 6.4L with 5-6 lbs of boost.

Assuming all that works out, the one wall I’ve been running into is the transfer case. Apparently, in the past 12 years of the existance of the 2nd gen LX platform’s existance, no one’s made an upgraded transfer case for the 300, Charger, or Challenger. I usually look for Charger parts if I can’t find something specific for the 300, and that still didn’t get any results I needed… aside from learning that apparently trying to push 600hp through an LX transfer case will cause it to grenade itself. Bummer.

I'm willing to go as far as it takes; 8-speed transmission swap from a Grand Cherokee (I checked, apparently it fits, and even if it doesn’t I know a shop that’ll build a high torque 8-speed from a V6 300/Charger), twin turbo kit, full exhaust system, differential upgrades— again, whatever it takes. But I haven’t found any consensus on how to get an LX transfer case to handle the power. Any ideas?

Thanks in advance.
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I've wondered the same myself, and have been keeping an eye out for information on how much the transfer case can take and so far I don't know of anyone who's broken one with HP. Neglect yes, the pre-'09 version yes, but no '09+ If you have I'd like to see it. By my estimation and all evidence that I've seen they'll easily handle 600HP. There's several AWD 300s and Chargers out there making that kind of HP and more. There's a YouTube channel named dasllamas, he has a 600+ HP AWD Charger you may want to check that out.

I'm also curious what you mean by " 8-speed transmission swap from a Grand Cherokee (I checked, apparently it fits". I haven't seen anyone put an 8 speed between the V8 and transfer case in an LX. Junkyard Dave did it, but he used the transfer case and front axle from a Jeep. The Jeep stuff is very different and requires the car sit higher as it's not integrated into the pan and the driveline is on the drivers side.

I think the main reason nobody has broken a transfer case that I know of is basically I don't think it can really be done. The rear drive portion is directly driven and as strong as the transmission output. The front drive portion is limited by front traction and how much torque the clutch can apply. Simply put the tires will spin, or clutch will slip before anything mechanical can break.

Also the computers in these cars limit driveline torque. There's parameters that limit torque per gear and can be adjusted using software like HP Tuner. This can act as a limiter to prevent over torque in low gears. If you have one now you may have already noticed this feature. The car stock limits torque in 1st gear but maximizes that limit when the car is put in autostick. Mine doesn't have a lot of HP upgrades but in any reduced traction condition(wet roads) it will spin all 4 tires off the line in autostick. Probably would in the dry as well, but I'd have to tie it back all Hoonicorn style and I haven't yet done that.

As I figure there's 3 slightly weak links in the drivetrain.
1. The transmission, it's a stout transmission factory rated for 428 lb·ft, used by Mercedes and Chrysler/Jeep in applications far more demanding than our cars. But at 600HP you'll be asking a lot if you really drive it hard.
2. The front axle disconnect. If it's in RWD mode when you really hit it, and it tries to connect for AWD it's not going to handle it well. This is solved by simply using the Tazer to always keep it in AWD. Mine made a horrible noise once when I threw it sideways on pavement while still in RWD mode. It survived but I'm not going to do that again.
3. The rear diff, easily upgraded.
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Thank you so much for the reply! So the transfer case issues I read about was on a Charger forum, but I should’ve mentioned: I read that they were doing an 800+ hp build, not a 600, but there were anecdotes about them not handling even 400 all that well. I’m guessing it’s from, as you mentioned, a hard shift between RWD and AWD. Anyway, in terms of the Grand Cherokee transmission: someone who works at my local Chrysler dealership told me they were about the same size as the LX’s AWD transmissions, which is really all I had to go off since I couldn’t find much in the way of tech specs for either. I may be wrong, but I’ve read that the transmissions used for the Hellcat Durango / Trackhawk, and the SRT Durango / SRT Grand Cherokee (8HP95 and 8HP75, respectively) aren’t the same ones used for the RWD hellcats, so for me it passed the sniff test. Again, I’m no expert, so I apologise if I got something wrong. With that said, I’m hoping to get rid of the 5-speed regardless, so I was kinda banking on the Durango/GC transmission fitting.

Anyway, if the transfer case can handle 600hp, even wit the caveat of avoiding a hard RWD to AWD shift, that’s genuinely exactly what I need… though if you can point me in the direction of a transmission and differential solution, that’d be much appreciated :)
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If you can find and link that Charger forum thread I'd like to see it. I've read many people saying they can't handle high HP, but when asked nobody so far can point to an example of someone actually breaking one. I'm sure it's possible, enough HP, abuse, removing all the safety limiters, etc. I just haven't seen it.

All the 8 speeds are versions of the ZF 8HP, how much they vary between version I don't yet know. Nor do I know yet if there's a version that will accept a V8 at the front and our transfer case at the back. Probably, but I haven't search that out yet. One day I'd like to swap in an 8 speed but it's not even in the research stage yet for me.

Transmission and diff upgrade stuff is all out there, you can search that out. The only aspect I'd add that I disagree with many on is the need for a limited slip diff. The BLD software in these cars is fantastic making a limited slip actually detrimental for most applications.
I believe it’s 4Matic components maybe something from a Benz?
I believe it’s 4Matic components maybe something from a Benz?
Pre-'09 yes but post '09 it's a Borg Warner model 44-40. The benz stuff works differently, it's full time with a center differential. The BW44-40 functions much like the BMW xDrive but actuates faster and has different programming.

Back in the day Chrysler had an advertisement claiming it was the most advanced AWD system in it's class. It was true then and as far as I can tell is still true today. Benz recently came out with a new system they call 4matic+ that works much like ours and they put in AMG cars. The new BMW M cars also now have a system with programming much like ours. For 5 times the money you get a system that's almost as good. I don't think either of those have a front disconnect though.

It's not an AWD system I'd use for serious off roading, but for performance driving and slippery roads it's near perfect for a driver that can handle it. It has shortcomings though for timid drivers.
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