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Discussion Starter #1 (Edited)
Greeting to you all

This subject has probably been discussed many time and in numerous threads throughout all challenger forums.

But the reason I am opening it again is to once and for all have a clear vision on how to safely super/turbo charge the infamous 6.4 392 engine without tearing it apart.

Now I know the majority simply would advise not to waste money and brain cells due to the weakness of the engines internals. In fact all of you probably would advise trading it for a hellcat. Now if that was easy and accessible to everyone. this discussion wouldn't be opened over and over.

So, yes I regret not buying a hellcat. not just because its more powerful. but I was a rookie and did not realize the politics behind it. Dodge probably realized that everyone would go to the cheaper alternative and buy a 6.4 and modify it and it would leave the hellcat with a handful of buyer, thus maybe intentionally giving the 392 weak internals that do not handle boost. So by modifying your 6.4 would probably empty your pockets and you would have saved a lot of money by simply buying the 6.2 supercharged Hemi.


Now all that aside (regret, Money wasting and headache). I cannot replace my 6.4. it is not that simple in counties outside of the U.S.

I am left with an ultimatum. Boost my 2016 srt 392 challenger :')


Now, Other than forged pistons, rods, Fuel system and gaskets. What other parts/internals do I need to take in consideration to make my 392 engine withstand at least hellcat power. I'm not talking 1000+ HP. something within the 650-700 Whp.

And if it helps. how could you even improve it to 1000+ HP I am guessing of course changing more internals.


I would really appreciate help from you guys who have had experience with such matters.

And if you cant be bothered to help out, I am pretty sure there are threads that are clear as crystal on the steps and parts needed.
 

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So, yes I regret not buying a hellcat. not just because its more powerful. but I was a rookie and did not realize the politics behind it. Dodge probably realized that everyone would go to the cheaper alternative and buy a 6.4 and modify it and it would leave the hellcat with a handful of buyer, thus maybe intentionally giving the 392 weak internals that do not handle boost. So by modifying your 6.4 would probably empty your pockets and you would have saved a lot of money by simply buying the 6.2 supercharged Hemi.

Wow I didn't realize dodge put that much thought into their designs, intentionally building a weak link in the 2011 Apache engine to help with sales on the 2015 Hellcat platform.


On a serious note, Luke at Steve White is a forum vendor and does exceptional work, reach out to him.
 

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2017 challenger hellcat A8
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The 392 does not have weak internals but rather a piston design not ideal for forced induction. As noted, Luke at Steve White Motors is a good source (I used). There are others such as high horse performance with a good reputation.

HellCat power levels require internals to the same standard as a hellcat.

I don’t know what year SRT you have you must also have all the externals that can support the power levels; half shafts, differential, drive shaft, etc.
 
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Problem is that when you boost you are adding more power and heat. The 6.4 ring gaps are meant for NA so when things get too hot (tune is not conservative on fuel) the ring expands until the gap closes. You can bust a ring landing on a 5.7 just as on a 6.4.

I doubt the engineers would purposely put in weaker components...otherwise why go through the trouble of adding squirters and forged crank?
 

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Problem is that when you boost you are adding more power and heat. The 6.4 ring gaps are meant for NA so when things get too hot (tune is not conservative on fuel) the ring expands until the gap closes.
Wouldn't a 180° thermostat help with the heat? Wouldn't water/meth injection help. What about E85 or something we have, 93 octane that has 30% ethanol. Doesn't that run cooler than gas? With all 3 of those things maybe the heat is lowered enough that the ring gap is no longer an issue?
 

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:frown:Edit
 

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Wouldn't a 180° thermostat help with the heat? Wouldn't water/meth injection help. What about E85 or something we have, 93 octane that has 30% ethanol. Doesn't that run cooler than gas? With all 3 of those things maybe the heat is lowered enough that the ring gap is no longer an issue?
180F thermostat does not help as much as running water/meth and 93 exclusively. Don't forget the SC heats the air as well. Intercoolers help but you will still see about +30F above ambient IATs. I have a coworker running a procharger on his BMW without an intercooler and his IATs are north of 150F...the air charge is hot.
 

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Get a custom cam. Pushrods. New valve springs retainers ect. Also new timing chain arp studs for the main caps and arp head bolts or arp studs for heads


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So what is your goal of having a 700hp car? Racing (road or drag)? Weekend car or daily driver? 700hp is going to take a build, time and money. There are numerous ways to achieve the goal and the method you choose will impact how the car behaves.
 

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Wouldn't a 180° thermostat help with the heat? Wouldn't water/meth injection help. What about E85 or something we have, 93 octane that has 30% ethanol. Doesn't that run cooler than gas? With all 3 of those things maybe the heat is lowered enough that the ring gap is no longer an issue?
A thermostat only regulates the minimum operating temperature. Just like a house without an air conditioner, you can set your home thermostat to 68 but if it's 105 outside, you can bet the temp in your house is still going to get hotter than 68.
 

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Like ChallyTatum said above, there is no weakness in the 392 it's just an engine that wasn't "designed" for boost.

The biggest issue is the ring gaps. If you were to do nothing else than tear down the block and gap the rings

loose for boost, I would be willing to bet it would handle more boost without any issues.

But that's not what happens.. No one is going to tear out the stock rods and pistons to gap the stock rings for
boost and re-assemble the engine. If you are tearing it down that far you just throw billet rods and pistons at
it and then you know those components along with the crank will be good up near the four digit hp figures.

Some engines can tolerate boost better than others. The 392 is a fairly high compression engine and it just

does not tolerate all that cylinder heat with the stock ring gaps.
 
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If you are looking to build a solid 392 that can lay down 700 horse at the wheels then you've got some
shopping to do...

Forged Billet Pistons
Rings gaped for boost
Billet H Beam Rods
ARP Main Studs
ARP Head Studs
Valve Springs
Cam
Pushrods
Gaskets
Blower
ATI Damper
ARP Damper Bolt
Blower Assembly
Fuel Pump Upgrade (Return System)
DSS 1000HP Half Shafts
If Automatic, SHR Viking Trans and Converter
DSS Aluminum Driveshaf
Boost Gauge
Wideband o2 Gauge
Long Tube Headers (Not 100% needed but you will pick up mid/high range HP)
Sticky Tires
Wider Rims

A very forgiving Wife!
 

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That was a great article I hadn't seen! Thanks for sharing that! :)
Lord knows how reliable (like others have said just because it did not blow up on the dyno does not mean it's bomb proof) that engine will be but impressive power made considering it cost ~$18k.
 

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Lord knows how reliable (like others have said just because it did not blow up on the dyno does not mean it's bomb proof) that engine will be but impressive power made considering it cost ~$18k.
Yeah those were big numbers for sure. I'm kinda of the mind set that at 1K HP you should be running a billet
4340 crank and also billet 4340 main caps. I'm sure it will hold up but things can go sideways at those levels.



My friend's Coyote made 804 at the wheels and his factory forged crank dropped the snout, spun it clean off
and they say those cranks are good for 1K granted, he's running a BIG blower and lots of boost so it's a lot of
strain on the end of the crank.
 

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This was a great Article, but honestly the same engine could be built for substantially cheaper. A 6.1 Intake would be a better purchase in my opinion along with a Fore fuel rail setup. If someone was going to do this with a 6.4 it could be cheaper to find a used one that already had ring land issues. Especially if you are planning on replace with the MMX drop in (which is a good idea). I bet that engine could be built for half of what the Article says you would pay. All of this being said if you don’t know how to work on things yourself. It may end up costing you a whole lot more that what is reported as well. Once again the information is spot on. I’m just pointing out that it can be built for less with some fore thought.


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Why not relocate the Evaporator coil for the A/C so it cools your intake and your intake air charge?
 

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If you are looking to build a solid 392 that can lay down 700 horse at the wheels then you've got some
shopping to do...

Forged Billet Pistons
Rings gaped for boost
Billet H Beam Rods
ARP Main Studs
ARP Head Studs
Valve Springs
Cam
Pushrods
Gaskets
Blower
ATI Damper
ARP Damper Bolt
Blower Assembly
Fuel Pump Upgrade (Return System)
DSS 1000HP Half Shafts
If Automatic, SHR Viking Trans and Converter
DSS Aluminum Driveshaf
Boost Gauge
Wideband o2 Gauge
Long Tube Headers (Not 100% needed but you will pick up mid/high range HP)
Sticky Tires
Wider Rims

A very forgiving Wife!
a good list to go from......
Luke
 

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Why not relocate the Evaporator coil for the A/C so it cools your intake and your intake air charge?

You could do something like that and use a Killer Chiller. Or you could plumb in some Methanol

Injection. Methanol boosts the Octane and cools the intake charge temp at the same time.
Plus if you tune for Meth you can typically pull another 50 horse out of the engine. The only
thing is if you run out of meth you need to baby it till you refill.
 
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