I've decided that since I already have a "decent" 3.9L V6 in my 1997 4x4 Dakota (decent meaning only 84,000 miles on it), I'm going to go ahead and see if I can rebuild it for some modest HP gains. The bottom end isnt too difficult, but I'm thinking about the small intake and exhaust valving in the heads. Does any one have any idea how much machining the heads for 2.02 intakes and 1.60 exhaust valves would be? Ballpark maybe? Milling them to maybe a 63cc chamber? I'm getting a bit frustrated trying to find a more aggressive cam for the V6 but still looking. A custom cam is prohibitively expensive, even for the planned 100,000 additional miles I may get from this engine. Basically, I want 250-300 naturally aspirated HP from this motor and my "budget" is around $1500-$2000 including boring it .30 over, KB 167 flat top pistons, zeroing the deck, etc., etc. Any ideas would be appreciated. Thanks

 

spend 2k on a 5.9 motor swap and start there. seriously.

 

Thank you, Thunder, for your reply. I have read many of your posts in several other threads and have always appreciated your experience. I know I should just swap it out for the V8 but with having to completely replace the interior, stereo, speakers and wheels and tires, I am trying to maximize what is "good" on the truck with the budget I have available, which is @$3000. My brother-in-law builds racing engines and he wants to help with the machining and the actual build, so I need to find the parts. I know $3k isnt anything for a motor build, but that's what I have. Thanks again.

 

you dont need to scrap the interior with a motor swap...

 

Lol, Thunder! No, no, no. The interior has just recently been vacated by a family of rats. The smell of the feces and urine was pretty overwhelming and I have found nothing that would alleviate it except gutting the interior of any and all absorptive materials and buying new. So thats at least part of my budget; new seats, carpeting and headliner, plus re-wiring the factory radio harness and installing a new radio and speakers. Then on to new tires and rims and a bedrug for the bed. Hope to have it off-roading by September. So no, I know I dont trash the interior with an engine swap. but thanks for the comment. ...and I still need to find a cam and dreaming of a stroker crank for the 3.9L V6.

 

I honestly don't think you can squeeze 300 hp out of a 3.9 magnum. I have the same motor. I'm getting maybe 190 with minor upgrading

 

Hey Nick. Again, I'm not sure because I havent done this with my own hands before but I have read on this and other dakota sites that some other guys have. I'm just thinking that if I bore it .040 over, put some kb167's in it, zero the deck, balance the block, machine the head for 2.02 intakes, mill it for about a 60cc chamber for about 9.5:1 compression, a moderate street cam, machine the intake manifold for better flow and maybe a 650cfm carburetor I might get maybe 250-275 hp out of it. Yeah, yeah, why not just buy a 5.2L V8 and be done with it? Maybe I will, but I have this engine in hand, it's relatively young and I have lots of other things to do to make this truck even drivable with my budget. I asked on this website because I know some of the people here are very knowledgeable and most are pretty friendly, which I cannot say for a few others. wow. thats a long reply.

 

with a few mods my 4.7 made 181 to the tire, on the dyno.


there are a couple turbo'd 3.9 on youtube they are from brazil i think.

 

I wish I had the resources and know how to do all of that man, I wish you the best! Keep a picture/video log for sure