6.4 swap

[savage_46]

First off, I searched & didn't really find any answers to help. Could be cause it's late & I'm tired.

I'm considering swapping my engine out of my 16 1500. I currently have a chance at getting a low mileage 6.4 long block out of a grand Cherokee for ridiculously cheap. Which engine is preferred, SRT or HD for daily & fun driving? Currently, full bolt ons are planned no matter what happens. Whipple is also a possibility. But above all else, it has to be reliable & streetable in Alaska winters. I already know the timing cover, oil pan, intake & exhaust all bolt up with no issues. What can I expect from drivability & finding weak points in the drivetrain? Should I go for this engine, wait for a HD to come around, or not worth the hassle?

 

[tidefan1967]

I personally would go for the SRT version. Just remember you'll be a lot closer to the max torque that your 8HP70 can handle(I think its 516 lb/ft)so you can't go mod crazy without beefing it up somehow) and of course it drinks premium unleaded only. I guess the HD version would be OK but the extra 15 HP and 19 lb/FT of torque will be barely noticeable compared to the SRT. If your current 5.7 is in good shape I wouldn't bother with the hassle either way. If I had deep pockets I would do all the bolt ons including the supercharger and you'll make more horsepower than propably even the SRT puts out.

 

[huntergreen]

Will the electronics work with the 8 speed ?

 

[Wild one]

The 6.4 BG Truck block is a better block to work with if you're going to boost it.The BG 6.4 truck engine uses the same block as the Hellcat does. Matt Fikac has a whipple blown 422 stuffed into his toy,using the Hellcat block,Jay Greene has a 426 in his toy using the 6.4 BG truck block,Kurtis Holland /Charonblk is working on putting a 6.4 based 426 cubed BG truck block in his toy. There's another guy that put a 6.4 SRT in his truck,i forget his name though,and he's only on facebook,not on here.You might get more and better answers if you ask your questions on Nadodge or Tuned Rams on facebook,as that's where most of the guys with the high horse trucks are hanging out these days. If you butter up your local dealers,you might be able to pick up a warrentied 6.4 BG truck engine fairly cheap. The local dealers up here are selling the warrentied engines for 900 bucks Canuck,as that's what FCA pays them for the engines,and if you're gonna do a stroker big cube set-up,they make a great foundation to start your build.

 

[Hemi450hp]

Like said, if you plan to build the motor for boost in the future, then I would go with the 6.4 truck block. If you are just wanting to swap in a 6.4 with a few bolt ons, then I would go with the SRT 6.4.

You will need to keep your 5.7 front timing cover, wiring harness, oil pan, and intake manifold. Otherwise, everything bolts right into place. Stock PCM will be fine and can be tuned with Diablo or HP Tuners.

 

[Wild one]

You might want to phone Matt/Hemi450hp and talk to him about transmissions too.I think he's running a Paramount built 8HP70 .The 70 series is a fairly tough tranny,but if you go with boost on a big cube set-up,it'll probably need some help to keep it alive

 

[mohemipar]

6.4 SRT is great to take for what it is and have some fun. A few bolt ons and a good tune and you’ve got yourself a real monster of an N/A street engine. If you want to add boost as these guys said you want the HD 6.4. From what I’ve heard Mopar will be using the HD 6.4 as a base for the upcoming 426 Hemi.

 

[savage_46]

Does the HD 6.4 use forged rods & pistons?

 

[theviking]

Does the HD 6.4 use forged rods & pistons?

Depends on who you want to believe. FCA literature says it does use forged pistons. At least one engine builder stated it was in fact not forged after a teardown. In either case their is additional material (20%) above the top ring land and the compression is lowered to 10:1. Both of which will aid considerably in a boosted application. Rods use a forged powdered metal design but utilize a full-floating pin. Keep in mind the Hellcat also uses a powdered metal design so it's not necessarily an issue although I don't know anything about the practical HP limits for the 6.4 rods. The HD block and heads are essentially Hellcat parts so you're not likely to break anything easily.

The biggest issue I've seen with the BGE (HD) motor is the factory cam and MDS lifters. At least in an NA application. According to Modern Muscle Xtreme the geometry is such that you would have to swap it for a custom grind as none of the existing 6.4 SRT cams will work. Not necessarily an issue on a FI build since the factory cam seems to be boost friendly. But on an NA motor that would get expensive quickly.

 

[2010 Infantry Vet]

Does the HD 6.4 use forged rods & pistons?

No. Unless your running 20+ psi there is no advantage to using the truck block. If you plan on running boost, best way is to start with a 5.7, 6.1, or 6.4 block and use forged rods, pistons, and crank. That way you know it’s going to hold up under boost.

 

[theviking]

All 6.4 (and 6.1) motors already run a forged steel crank. Only reason to swap cranks is to run a stroker kit.

 

[theviking]

FYI, some additional info on the BGE (truck) motor.

 

[savage_46]

After thinking about it for the last week, I'm leaning towards the SRT engine. I really want to supercharge, but it's probably not the best decision for the foreseeable future.

How are these trucks holding up when pushing the limits of the 8hp70? I know the 516 ft lbs input limit will be reached real quick with LT headers & TB added to it. What about the auto t-case & LS diff?

 

[2010 Infantry Vet]

After thinking about it for the last week, I'm leaning towards the SRT engine. I really want to supercharge, but it's probably not the best decision for the foreseeable future.

How are these trucks holding up when pushing the limits of the 8hp70? I know the 516 ft lbs input limit will be reached real quick with LT headers & TB added to it. What about the auto t-case & LS diff?

There are plenty of places that build 8HP70 trannies. I saw one named hell something on facebook, but i forget the name

 

[2010 Infantry Vet]

After thinking about it for the last week, I'm leaning towards the SRT engine. I really want to supercharge, but it's probably not the best decision for the foreseeable future.

How are these trucks holding up when pushing the limits of the 8hp70? I know the 516 ft lbs input limit will be reached real quick with LT headers & TB added to it. What about the auto t-case & LS diff?

There are plenty of places that build 8HP70 trannies. I saw one named hell something on facebook, but i forget the name

 

[Wild one]

Southern Hotrods and Paramount are probably the 2 most update tranny shops on the ZF trannies.Southern Hotrods sells a rebuild kit that bumps the 70 up quite a bit.

 

[2010 Infantry Vet]

Hell raiser performance on facebook builds badass 8HP trannie. Check them out

 

[savage_46]

I've decided to go through with the swap. I'm taking black Friday off & plan on sleeping at the shop. Start on it Friday morning & anticipate ready to fire Saturday afternoon.

I'm assuming 1 7/8" headers are the way to go on the 6.4, right? Should I use the mopar SRT spark plugs, OE 5.7 plugs, or something else?

 

[theviking]

Personally I think 1-3/4 is more than enough for any NA build but doubt it's going to make a significant difference either way. I'd be more concerned with proper fitment than anything else.

What are you doing for tuning?

 

[2010 Infantry Vet]

Agreed for only 475 hp go with 1 3/4" headers. Now if it made 500 rwhp i would say 1 7/8"