Okay, maybe we're being a little harsh saying "dumbest engine swaps."
But saying "swaps that don't make altogether that much sense and are supplanted by alternatives that are more intrinsically facile" doesn't exactly roll off the tongue.
Granted, some of these swap ideas aren't exactly commonplace. And some actually have a cool factor that could outweigh the hassle and complexity of the swap. Nonetheless, they're swaps that we're asked about from time to time, so we feel the need to address them here. So before you grab the engine hoist and start ripping the diesel out of your tow rig for transplant into your flattie, or pull the trigger on that Viper V-10 from mopar.com, here's our take on the subject for the average reader.
Dodge V-10
The candidate: The 8.0L iron truck V-10 ran its course in 3/4- and 1-ton Dodge pickups from '94-'03. If you're contemplating an all-aluminum Viper V-10 take-out or crate engine, your pockets are deeper than most at-home swappers and you're probably having a shop do the work, so we'll concentrate on the 310hp/450lb-ft truck engines.
The perception: Gas is expensive and owners of these V-10 trucks that are getting long in the tooth are letting them go for $2,000-$3,000 which wraps all the needed swap components into one package.
The reality: Hey, it's a big engine with lots of packaging issues and it doesn't make a whole ton of power for its weight. Sure, the Viper engine is lighter and more powerful, but it's also exponentially more expensive. Although the aftermarket support isn't super-strong, Hotwire Auto (hotwireauto.com) will modify a factory Magnum V-10 harness for use in most Jeeps, but you'll still need to build motor mounts, upgrade the drivetrain, axles, suspension, and cooling to accommodate the additional torque, weight, and operating temps.
The exception: We've seen Wranglers with swapped-in V-10s that give a wow-factor that is good if you want to build a torquey show pony.
We think: If you're looking for that much additional weight and want 450-500lb-ft of torque off-idle, it makes more sense to consider a 454 or 502 GM or 460 Ford big-block. However, we do think the larger engine bay of an FSJ would make a cool home for the big V-10 and briefly considered going with a big iron Magnum V-10 in our Project J2008 '68 Jeep pickup.
GM 60-degree V-6
The candidate: GM stuck the little 2.8L piggy in everything from front-wheel drive cars, to S-10 pickups and Blazers, to Camaros and Firebirds. Later stroked to 3.1L and then punched to 3.4L, every version left any semblance of power, torque, and longevity at the door.
The perception: Why not yank a 2.8L out of a GM vehicle or '84-'86 Cherokee since they're plentiful in the junkyards? If it blows, you can grab a replacement pretty much anywhere. Or, why not upgrade a 2.8L Cherokee with a 3.4L Goodwrench 60-degree crate engine?
The reality: Even the "mighty" 3.4L GM crate engine offered as a power upgrade for the 2.8L puts out a measly 160hp and 194lb-ft of torque. Besides, reliability was never one of the 60-degree V-6's traits.
The exception: There is none. Move on.
We think: The 2.8L is so bad and underpowered it must've been designed by the French. Its only saving grace is that it shares the same bellhousing bolt pattern as Jeep's 2.5L four-cylinder. We'd rather have one of those.
4.6L Ford Mod Motor
The candidate: Ford began installing its new overhead cam 4.6L engines in '91 and had gradually phased out the older pushrod V-8s by the mid-'90s with 4.6L and 5.4L V-8s and 6.8L V-10 two-, three-, and four-valve versions of the engines. The 5.4L truck engines are powerful, but the more-common 4.6L versions found in standard Mustangs, Town Cars, and Crown Vics are sort of dogs, with power levels in the low- and mid-200hp range.
The perception: Since these engines litter the boneyards nowadays they represent a great high-revving source for a fuel-injected engine.
The reality: There's very little aftermarket support for the 4.6L, 5.4L, and even 6.8L engines in the way of wiring harnesses, stand-alone ECUs, motor mounts, and other components that would ease in swapping. Furthermore, the overhead cam design of these engines translates into an exceptionally wide package that's sure to have interference issues in most engine bays. And despite the perception, the 4.6L and 5.4L doesn't like to rev any more than most standard V-8s. It's just that they make comparatively poor torque down low in stock trim, so you really have to wind 'em up.
The exception: Perhaps if you scored a supercharged 5.4L out of a Lightning pickup or Cobra Mustang the hassle of figuring out the wiring and ECU and fitting it into the chassis would be worth it, but otherwise check earlier 5.0L Mustangs or 5.8L trucks if you've got a Ford fetish.
We think: There's no wow factor and no really good reason to run a Mod Motor.