Swap A New Hemi Into An Old Mopar

Here's the 6.1 Hemi Jonathan LaPaglia swapped into his '73 Challenger. He performed this swap nearly three years ago. "It's not for the faint of heart," he says. Greater aftermarket support means the job would be easier today. We give him props for his superclean install.

Here's the 6.1 Hemi Jonathan LaPaglia swapped into his '73 Challenger. He performed this s

First off, here's the good news: The block drops right into place. Yes, with a simple pair of adapter plates bolted to the block, a new Hemi engine will go into any old Mopar muscle car. However, the problems start piling up when you begin to add stuff to the block--you know, essential things like an oil pan, headers, a cooling system, wiring, and a transmission. OK, this swap really isn't easy, but Mopar guys are always up for the challenge (pun intended). Anyone with a Summit catalog and a telephone can build a Chevy, and the Ford guys have it pretty easy, too. But die-hard fans of Ma Mopar are more like pioneers of the Wild West. They need to do more of their own engineering because there simply isn't the volume of parts available for their cars. Now, say you want to do something crazy like swap a new engine into your old Dodge or Plymouth, and you're really asking for trouble.

The new Hemi, referred to as the Gen III, has been around since 2003, and as more engines become available at lower prices, more guys are considering this swap. As more people do the swap, more parts become available to make the job easier--and the business of new Hemi swaps is literally exploding. We spoke with several companies that are making parts needed to adapt the newer engines to A- B- and E-Body Mopars with a minimal amount of frustration. Mopar freaks, pay attention. We'll give you the rundown.

Gen III
The new Hemi first appeared in the '03 Dodge 2500 and 3500 fullsize pickups as a replacement for the Magnum 5.9 (360-cid) engine. It displaced 5.7 liters, and even though the figure should be closer to 350 ci, Chrysler literature often lists displacement as 345 cid, for marketing purposes we're guessing, because the horsepower rating is 345 also. Coincidentally, those figures (345/345) are the same as the '57 DeSoto Adventurer, the first domestic mass-produced engine to make 1 hp per cubic inch as the standard (nonoptional) engine.

If you want to keep your old automatic trans, you'll need an adapter kit to line up everything correctly.

If you want to keep your old automatic trans, you'll need an adapter kit to line up everyt

In 2004, the 5.7 was an option for the midsize Durango pickup and made its first appearance in passenger cars with the '05 Chrysler 300C. In the '05 model year, a bigger-bore 6.1 (372-cid) version was launched in the SRT8 versions of the 300C and Jeep Grand Cherokee and was subsequently rolled out into Chrysler's other models as more SRT8 versions were developed.

To Swap Or Not To Swap?
The new Hemi is a cool engine that is better than previous Chrysler V-8s in nearly every way. It weighs less, is manufactured to tighter tolerances, is more fuel efficient, and has greater output per cubic inch. In fact, the 6.1 Hemi has the highest power-per-cube rating of any Chrysler engine to date. Knowing that, who wouldn't want one of these in his car? Of course, the resto and Concours guys won't, but the dude looking for reliable, tunable, modern performance wrapped in classic sheetmetal will find this option irresistible. JR Bouchillon of Bouchillon performance says he's sold more new Hemi engines than any other engine his company offers. And his is a family-owned, Mopar-specific business with a 40-year history.

So is the new Hemi right for your project? Old-school guys will say no, and we can appreciate that. The new engines lack the fist-to-the-gut impact of a Six Pack 440 or 426 Elephant Hemi. Plus, the new Hemi swap is by no means a drop-in, weekend job, so you're looking at hours (or years) of work or big bucks to send your car to a shop. Even if you do the job yourself, it won't be cheap. Among other things, you'll need a number of custom parts, new adapters and fittings, a revamped fuel system, and all the electronics to run the engine. If you are down with all that, the trade-off will be "a 425hp engine that gets 22 mpg that you can drive every day," according to Jonathan LaPaglia, who was one of the early adopters of the swap, dropping a 6.1 into his '73 Challenger. He speaks with authority, too. He did the swap himself, and he drives his Challenger every day.