This is my situation. I have an 85 K5 Blazer and I will be going to college about 5 hours away and will be driving my K5. I am wanting to do a swap to get the best MPG without spending to much money. Right now I have a 305csb bolted to 700r4 to NP208 to 10 bolts. I don't really feel like changing anything except the motor and rear axle (12 or 14 bolt). I want to keep this project cheap. I am a senior in highschool and need to be able to pay for college but also do this. I need better than 8-10 mpg. I was thinking about 12 valve cummins but that is out of my price range. So I was starting to look into 6.2l and 6.5l diesels and doing a few upgrades. I mean I want to actually move when I press the gas but I don't need racing or anything. I would love to be able to dump a little smoke if its possible. So back to the real subject what do you guys think would be the best motor for my situation. Also maybe...maybe transmission. Thanks for all your help!

 

A 6.2 will get better fuel economy and is a stronger engine than the 6.5 but stock will have less power. 6.5 will be easier to come buy as a complete engine including the turbo. What I would look for is any one of them before 1994 because it will have a mechanical fuel pump.

 

Which one will be the easiest swap..? And what is the power/mpg difference between the two? Will it hurt the 6.2 at all if I threw a 6.5 turbo on it?

 

Any one of them 93 and older with a mechanical injection pump. The 6.2 will handle the 6.5 turbo and has stronger pistons in it. Heath diesel makes 500hp on a 6.2 block. The only problem is the 6.2 runs a taller injector which makes it have little clearance between the manifold and injector when a turbo is on it.

 

In college I had a friend that had a 1/2 ton chevy pickup with a auto. I think if he drove it nice he was upper teens to 20 mpg. But it had no power, had a hard time doing 65 in a head wind. We rebuilt the fuel pump and injectors ( we were in a diesel program ) checked compression we even tweeked the fuel pump above stock to see if that would help. He finaly got tired of it and put in a 350 gasser.

 

Putting a turbo on them helps a lot.

 

It wont make it a race truck, but it will make a significant difference.

 

I know this definitely is not the right place but on another thread on a different forum people are saying its totally not worth it and I should just put in a BBC... I know I wont be getting 20mpg but 16 is better then 10 still..? Anyway I could pull 16 out of a 454? With everything geared right?

 

With 36" tires and an 8" lift, you should easily get 16 mpg out of a big block - coasting down hill with the engine idling, or driving off a cliff. Other than that - forget it! 8" of lift creates a big air gap underneath the vehicle and gives you the aerodynamics of a brick outhouse. 36" tires offer some great traction - and an equal amount of rolling resistance. If a 305 cannot give you better than 10 mpg, it's quite possible that even a 6.2 diesel won't do much better. You just don't have the vehicle set up as a streamline, efficient machine.

Drop it to the ground and put a ground flow kit on it, complete with an air dam to keep air out from underneath the vehicle. Get some skinny tires, disconnect the front drive, lighten it up and put a spoiler on back to deflect air back down behind you. That'll help your aerodynamics and improve your MPG numbers. It'll also ruin the vehicle!

If the 305 is solid, I'd suggest sticking with it until college is finished. If you like the vehicle and just dislike the fuel efficiency, just don't drive much. A 6BT would be nice, but a 4BT should be plenty. It'll be easier to afford and to actually do the work then. You'll be way ahead if you can finish college in 4 years and play with vehicles afterwards. Money and time are usually tight during the college years - if they aren't you are probably slacking off too much! I understand the interest and desire - completely.

 

no way. I dont think even with 2wd, stock height, and stock tires, you could get 16 out a carbed 454. But like the guy said earlier, with that much lift and big enough tires, you're not going to see that good of mileage. Your best bet would be a 6BT or 4BT, but Im doubtful if even one of those could get you to hit 20mpg.