Would you hellcat swap your 70s MOPAR???$$

[Yeya93]

I am in a position where I can potentially purchase a hellcat engine with transmission at a somewhat affordable price  (currently unsure of the year model). Initially, I was going to rebuild a 440 engine, but since this came upon my plate, I am now debating on changing my plans to instead purchase the hellcat engine. BUT, since I do not have any experience in this, I was wondering if someone on here could give me some insight on the transition?

Currently, on my 70 challenger, I upgraded to

- QA1 suspension (Handling Kit, Level 2, Mopar B/E body
- Ridetech 4 link bar rear suspension
- Borgeson Power Steering Conversion Kit 999065
- Silversport transmission A41 Kit (A41 AUTOMATIC OVERDRIVE TRANSMISSION FOR MOPAR, STAGE 2 (550 LB-FT) WITH OPTIONAL 11-3/4' CONVERTER (2000-2400 STALL))
- 3:55 sure grip differential
- 8 3/4 housing
- Wilwood disc brakes front and rear
- Wilwood master cylinder / brake booster

Thanks, and I will appreciate any help provided

[Chryco Psycho]

Having done a number of these swaps sure . I would install a hellcat !
Overall it is very easy to do , there are a few problems to work around but very soable , the 3rd one I did was 303s 70 Cuda , there is a thread here detailing the swap , you need a mount kit , I would suggest TTI headers , you will need a Milodon oil pan & pick up , Wiring is straight forward using the Mopar wiring , you need a tanks inc tank with in tank fuel pump , & you need to be creative with the drive by wire  gas pedal .
Hood clearance will ikely be an issue .

[Yeya93]

Thanks for the reply @Chryco Psycho . Will the QA1 crossmember work for a hellcat engine; or will there have to be some modifications to be done. Also, can the unibody handle the torque?

[Chryco Psycho]

QA 1 uses the same mounts as the original K frame so you just need the correct adapter mounts , no problem .
I would look at this as a pkg so I would install inner fender braces , lower rad brace , subframes , torque boxes & stiffen the chassis as much as possible , first these were barely designed for that kind of power & second they are now 50 years old , help it as much as possible !!

[Yeya93]

@Chryco Psycho i appreciate the insight. I'm leaning more towards getting the hellcat. i just thought there needed to be some major engineering that needed to be involved which i wouldn't even know where to start. my uncle is the brainiac behind the project. i shared with him the feedback i have been provided by you and others, and he says that it is definitely feasible and totally possible. thanks again!

- julio

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[7212Mopar]

Of course it is possible and have been done by many. It will sound just like any Hellcat on the street. It won't sound like a 60-70s muscle car. But you have a 707HP and engine don't leak oil.

[Cuda416]

Hell to the YES...

I'm going with a lowly 6.4L... no supercharger... 

[Purepony]

No doubt ! Hell yeah !!

[Dmod1974]

I'm actually in the middle of going this route too.  The only downside for me is that classic, lumpy idle will be no more.  But the pros outweigh the cons all day long to me.

[Skdmark]

Will his 8-3/4  handle a Hellcat motor?
I would think that an S60 would be needed.

[GoodysGotaCuda]

I've considered it since I am already on a Gen III platform, it's not a huge jump for me. I likely won't make any moves unless the 5.7L bites the dust for some reason.


It will add quite a bit of value to the car, unlike many modifications. I do wonder about the ability to really put the power down, my basic 5.7L bounces off the traction control quite often on sticky 295s, a respectable street tire. Without traction control, much of any real throttle below 60-70mph may be dicey with the Hellcat. Just be ready to ride the lightning.

[Chryco Psycho]

The 8 3/4 will hold up pretty well , it comes down to 2 things essentially the gen 3 makes less TQ or at least down low , the peak TQ #s may be higher & traction , , with ladderbars & slicks & About 700 HP I was able to destroy a 8 3/4 every year or so but I was lifting the front tires over 2' & running the 1/4 in 11s at 118 MPH , the tires become the fusable link , once traction is lost the load on the diff is far less !

[jimynick]

I'd do it, and I'd also see if I could score the diff out of the donor car. Failing that, as mentioned, I'd look to a Dana or it's clone. CP makes a good point regarding traction. What's the sense of having 700+hp if you can't hook it up? Burnouts are cool, but doing it everytime you jump on the gas could get lame in a while. Just my 

[70 Top Banana]

For me, I bought a Dana. I had a friend help me with the inner tubs as we widened them just enough to get a tire that would not go up in smoke every time I tapped the gas. We made the car good and stiff too. I did not have a hellcat but A 392 scat pack motor that we "messaged"and topped off with a Arrington Performance supercharger.

[torredcuda]

Money no object - maybe. I`d like to make mine more driveable long distance and a cammed, big carb small block with an A833, 3.91 gear and Flowmasters could use a lot or improvement in the department. Since mine is "just" a lowly `72 318 model I can do whatever I want for mods with no regrets.