So - the Dart project is at a crossroads. Might as well contemplate other engine options.

I haven't even finished the teardown for my '66 Dart's motor, and I've already found some bad signs:

This doesn't look like keeping the stock block is a good idea. So - I might as well weigh all of my options at this point. Goals are a street / strip build, probably around a $2000 or less budget.

1. A slant six set on kill.

Based on some other dyno reports, this motor may have been putting close to double the stock horsepower to the wheels when it developed rod knock, even though it was internally untouched and only on 5 psi of boost. Getting another slant six, doing a bit of internal work, and turning the boost up would make it pretty easy to go for triple the stock horsepower, or more.

Pros: There's the wow factor of a built slant six, the combination of the expected engine with totally unexpected power. The car is already set up for this engine, and the transmission in there is unique to the slant six so anything else would require both more fabrication and a transmission swap.

Cons: Triple the stock horsepower isn't as much horsepower as some other options would have. And good cores are getting rarer.

2. A basic small block Mopar.

Take a mid '90s truck 360, add a performance cam and replace the "beer barrel" intake manifold with something better, and find a suitable transmission, and this should be in the 350-400 hp range.

Pro: An easily documented swap with good power potential.

Cons: Suitable intake manifolds aren't cheap, and the stock EFI manifold won't clear the hood.

3. A Gen III Hemi.

Pros: Newer engine that may offer

Cons: Expensive. Probably not in the budget unless I score one cheap at Pull-A-Part.

4. Chrysler 2.4 Turbo.

Bit of a dark-horse choice, but I've seen them in RWD swaps before to good effect.

5. Something crazy.

If an apparently-working BMW S52, Mercedes V12, or something equally nuts turns up at basement bargain prices, all bets are off.

Not in the running:

LSx motors - I'm pretty sure I can get similar power out of a small block Mopar for less money and hassle.

Big block Mopar - getting tough to find and a tight fit in an early A body.

I am strongly leaning toward the slant six set on kill, but feel free to make the case for other options.

A Magnum 5.2/A500 swap seems like the easiest button if you don't stay with the /6.  /6 seems like more of a project although you're not far from where you want to be, just need to build another engine, and these things don't have nearly the parts support as a domestic V8 would.  I don't think anything else really makes sense.

I can Walk you though the 2.4 in a rwd application if you choose to go that route

I would fall into the "newest HEMI you can afford" camp.

My only case for the other options is that I would likely be willing to buy some of your slant six castoffs. I finally started the 1971 Barracuda slant six project that I've been planning for a few years. Im currently piecing together one functional engine from 2 poor cores.  Like you said, good used parts are starting to get rare!! Because of sentimental reasons (it's a family heirloom on my wife's side) my project is definitely NOT getting swapped for another engine any time soon. Maybe during a full resto down the line..

A magnum v8 with a cam is the easiest button. 

Seems like bang/buck goes to 318 or 360. Stout and can make good power without too much difficulty. Personally I like the slant idea better. If you can find a good block to work with that's what I'd do. 

MadScientistMatt said:

I haven't even finished the teardown for my '66 Dart's motor, and I've already found some bad signs:

This doesn't look like keeping the stock block is a good idea. So - I might as well weigh all of my options at this point. Goals are a street / strip build, probably around a $2000 or less budget.

1. A slant six set on kill.

Based on some other dyno reports, this motor may have been putting close to double the stock horsepower to the wheels when it developed rod knock, even though it was internally untouched and only on 5 psi of boost. Getting another slant six, doing a bit of internal work, and turning the boost up would make it pretty easy to go for triple the stock horsepower, or more.

Pros: There's the wow factor of a built slant six, the combination of the expected engine with totally unexpected power. The car is already set up for this engine, and the transmission in there is unique to the slant six so anything else would require both more fabrication and a transmission swap.

Cons: Triple the stock horsepower isn't as much horsepower as some other options would have. And good cores are getting rarer.

2. A basic small block Mopar.

Take a mid '90s truck 360, add a performance cam and replace the "beer barrel" intake manifold with something better, and find a suitable transmission, and this should be in the 350-400 hp range.

Pro: An easily documented swap with good power potential.

Cons: Suitable intake manifolds aren't cheap, and the stock EFI manifold won't clear the hood.

3. A Gen III Hemi.

Pros: Newer engine that may offer

Cons: Expensive. Probably not in the budget unless I score one cheap at Pull-A-Part.

4. Chrysler 2.4 Turbo.

Bit of a dark-horse choice, but I've seen them in RWD swaps before to good effect.

5. Something crazy.

If an apparently-working BMW S52, Mercedes V12, or something equally nuts turns up at basement bargain prices, all bets are off.

Not in the running:

LSx motors - I'm pretty sure I can get similar power out of a small block Mopar for less money and hassle.

Big block Mopar - getting tough to find and a tight fit in an early A body.

I am strongly leaning toward the slant six set on kill, but feel free to make the case for other options.

The 2.4L turbo engine swapped to RWD is fun(did that one myself) but not sure I would make that choice for anything with a curb weight over 3000lbs...there are other options though...why not a Pentastar v6 like the new base model challengers and chargers? Those are over 300HP from the factory and have both auto and manual tranmissions available

I'm heavily in the slant six camp here, but being a BMW sort of a guy I feel it worth pointing out the an S52 (along with many other BMW engines) is also a slant six, and I kind of like the idea of a BMW engine in a Mopar. Look at N55s for a more common option still capable of a lot of power.

Turbo slant six all day. Sure, maybe those other engines can get more power, but they will be less cool.

In a street car cool is worth more than HP. 

if a slant six fits, a V12 also fits.  and if you could somehow hide the V12 under a pair of modified slant six valve covers, well, Stampie would probably hit you with a week's worth of hand-whammies.  Live up to your name, bro!*

*I am in no way suggesting that you haven't already lived up to your name.

and if not V12, then put me in the BMW i6 camp.  so many trans options.

My opinion.

A V8 in a dart is a bellybutton. A boosted /6 would be an amazingly cool head turner.

I know it is sacrilege on this forum to be against the V8 swap but.....  Dang a big boosted 6er would be awesome.

Trailblazer 4.2L I6 swap if you want to stick with the turbo I6 theme.  The Nelsons seem to have those engines figured out.

Slant six all day.

We choose to boost to the moon not because it is easy, but because it is hard.

Another vote for keep it a 6. Be it an atlas, m52/s52/s54, stove bolt, whatever.

gearheadmb said:

Turbo slant six all day. Sure, maybe those other engines can get more power, but they will be less cool.

In a street car cool is worth more than HP. 

Make sure it's a noisy turbo

zzzzzzzzzZZZZZZZZZZZPEUW!

I used to work with a guy who had a Dart with a turbocharged, Megasquirted slant six.  It was a very cool car.

I'm still curious why the current block seems to have failed.

The slant 6 of course!   No other option, except maybe a viper v10.

If you wanna keep it an inline 6, go with the N54/N55. Can probably find a whole x35i for a cheap enough price at this point.

If you want cheaper BMW i6, go M52/54 with boost and you still get plenty of trans options.

What's bargain pricing for you?

1) Low difficulty and awesome

2) Low difficulty and boring

3) Moderate difficulty and less boring

4) Moderate difficulty and not boring

5) Moderate to high difficulty and awesome

Cast iron truck V10 with two turbos and heavy front springs.

pres589 (djronnebaum) said:

I'm still curious why the current block seems to have failed.

Probably frozen coolant.

The rod knock turned out to be a destroyed #6 rod bearing. Probably a combination of a clogged oil pick up and high RPM dyno pulls.

Turbo pentastar?  They're cheap, already push 300hp in different forms, and you have the means to make stuff run.  

My vote would be 2.4 Turbo or slant 6 because V8s are kinda boring to me (I completely understand it though and it's not a terrible solution).

A Jag or BMW in-line 6 would be different too, and I'd approve of that.  Maybe even one of those Aussie DOHC I6 mills would be wild, but completely impractical and expensive compared with a Mopar V8.

A V10 would be kinda from left field, but I'm not sure it would fit without a good bit of surgery....

If I did a /6 build I think I'd go looking for a late engine with juice lifters.  The performance advantage of solid lifters seems lost on an engine that doesn't like spinning over 5k.  The lighter crank is also appealing. 

I really couldn't see doing a different inline six that isn't a /6.  I mean, what's the point of staying with the configuration, when so many other easy buttons exist?