The 408 would be most expensive because you would have to build it from highly expensive components. But, being a small block, it will bolt right in. The 440 would be cheap because you can find one out of a motorhome making great power already for $300.

MPG, horsepower, and torque are whatever you chose to make them. A mild-moderate 440 and a 408 will probably be pretty similar in those three regards, except the 440 will do it cheaper, and probably be more reliable. No experience here from me, but we are comparing a very industrial motor to a full custom build, and everything that comes along with it.

 

390 4 speed
http://www.youtube.com/watch?v=OWhzg...eature=related

 

^^^ I love the way that motor sounds when he lifts off the throttle! doesn't seem like much of a truck motor though...

 

a 408 does not seem like much of a truck motor either but they still put them in. i think even just a reasonably built 318 with a standard transmission could get decent gas mileage and not cost too much to have built. since his truck is only 2wd i don't think it would make too much of a difference. there will be way more power than is needed for street use.

 

It all depends on how it is built. Most 408's are built with the dragstrip in mind, but if i build one for mine, it will be a moderately powerful motor up top with extreme low end and mid range as the goal. A longer stroke naturally wants to be a more torquey motor, but not if you build it with a high RPM top end. I'm sure either 390 or 408 could be built in multiple configurations to fit whatever the builder wanted it to do.

 

So a moderatley built 440 might be the cheapest way to go? If it's out of a motorbike or something what all would need to be done to it? I'm assuming a motorhome 440 wasn't exactly built to go fast XD

 

*motorhome not motorbike

 

That would be one sweet ride.

 

Floor a 70's dodge motorhome with a 440 and you'll be doing 80 before you'd think.

Apparantly many (all?) of them had Magnum/6 pack internals, but used a 4 BBL carb, so i doubt you'd need to do much (or anything really) to it to make it go.

 

Say i went with a 440, what all would i need to do to get it in there and what would i have to upgrade/change? Engine mounts, water pump, oil pump, rad, etc. As for carbs, 4 BBl or 6 pack?