WHAT MOTOR!!!!!
 

Im going to do a swap into my 85 K5 Blazer. It is automatic. 4 speed. Im debating if i should put either a 6.2 6.5 or a 4bt cummins. I also want to make it manual unless that will just be to much. I want your oppinion about everything and all the advice you can give! THANK YOU! I need power.

if ur needing power, i would go with a 6bt cummins

That is what i am wanting but i have to try an keep this project as cheap as possible.

For power, defintely a 6bt. I believe it will also be cheaper to pick up a 6bt. Your main issue/concern should be weight. My setup added approx 700-800 lbs. Before I installed the eng crossmember, I could push the eng and twist the frame. I even have the thicker 3/4t frame under my burb. The 4bt might be a better choice for you. See my build this section. Good luck. Brian

The mechanical 6.2 or 6.5 would be the easiest swap.

Out of the two which one would you recomend? The 6.2 or 6.5?

I'm going to get crap for this, but I don't care. I've put on hundred of thousands of hours on ONE 6.2 engine and with proper care and fluid changes regularly, I've never had to crack the engine open for anything. Just glow plugs, one IP and one set of injectors.

But that's my luck.

What kind of power can you push with those and whats a turbo like on one of them?

put a 4bt in it it should do what you want if not turn it up a little

Save yourself a LOT of heartache...go with the 6BT. While the 6.2 and 6.5's are reliable in stock form, they are far from being able to make any kind of serious power. Also, once you turn up the power on them, they lose their reliability pretty quick (poor head design and weak crankshafts.) Yes, it would be much easier to put either one in than to go with a Cummins Swap, but only due to the fact that GM bought them and had them fitted into their chassis.

The 4BT is little more than a 6BT with the front 2 cylinders lopped off...capable of making quite a bit more power and torque than the 6.5TD without sacraficing reliability. Great for fuel mileage...30+ mpg in a full sized rig (so I've heard; i've never had one) The 4BT is going to be fairly difficult to find, and because of that, they tend to be a tad more pricier than a 6BT out of a dodge...

The 6BT...well, it is, for obvious reasons capable of making much more power than any of the others listed above. In stock form, the 6BT makes more power and torque than a 6.5TD that has been turned up quite a bit. I have owned both, and put a TON of money into the 6.5; when I blew it up for the 2nd time, I swapped to a 6BT and could not believe how much more power was available (before I turned it up at all!!) While the 6BT is the heaviest of your choices here, I believe the power to weight ratio more than makes up for it...and still gets fuel mileage in the 20+ mpg range...