I know, I know. Why spend the time and money on the 3.9L V6 when a good 5.2L V8 can be had for the same money and get more performance out of it? I keep asking myself that too. One reason, at least for me is that I have the 3.9L and i dont have the V8. One question: is it true that the 3.9 is just the 5.2 with 2 cylinders cut off? Wouldnt the same .30 over boring and the pistons for it work on the V6? Zeroing the deck and working the heads for a 2.02 intake and 1.62 exhaust valves make more power on the V6 as it does on the V8? Or does it just not work the same with the smaller engine? I honestly want to know. I hope some of you guys who really know their stuff help me on this one. Thanks

 

Well I cant answer your question. Ok well I can part of it lol Yes the 3.9 is a 5.2 with 2 cyl's chopped off. Anyway I look at it this way why put money into a engine that after a couple hundred bucks be as powerful as a stock v8. I see the point of some people building up what they have because in some areas the v8s are a dime a dozen. I can get a v8 at my junk yard for 175.00 and they are insurance claims so getting info on them is easy since they have all the paper work, not like they are there cause they have a blown engine. Check your local yard and craigslist. At least with most junk yards they offer a 30 day warranty on engines and trannys.

 

Well a good reason is that the V8 does not just jump in without quite a bit of work. Lots of work for a Gen 1 4WD short nose, particularly if you like a clutch fan and AC. So let's hear more about getting hp and torque out of a 3.9. Stroker kits are nonobtainum. There is a UTube video of a guy that got 400 hp. Overbored 0.090 (safely), to the 360 4.00 bore, and offset ground the crank using Honda rods to get to 270 cubes. Then lots of head and manifold work. Just geting to 200 hp would be great relative to the original 125. Trying to find the details - what rods, pistons, who did the crank work, etc. But he hasn't responded.

 

​​​​​​well any time you change displacement in a higher diameter your going to increase horsepower at the same time torque will change also now the thing about torque, is after you increase horsepower you can drop torque by ft pounds you have to balance the two to get the most of each displacement change.

 

could you toss a link to said YouTube video? You've got me interested now

 

It will get expensive to try to get alot of hp out of the v6. Best option would be a pro charger or turbo. Parts availability is just not there. The cost to just get to a stock 5.2 hp level and torque will be low unless power adder.. It won't be cheap and likely disappointing results.

The v8 goes in the short nose first gen, just need an electric fan. I have a hemi in mine.

 

All else being equal, the work you put into a 3.9L, if it is the same as a 5.2L minus 2 cylinders, should net you 75 percent of the gains the same work to the 5.2L will get. But, that does assume aftermarket support which you generally don't see in a V6 engine unless the V6 is the large option for the car, and the car is popular in the hot rod market. The 2nd gen Dakota does not enjoy aftermarket support.

Since there's no aftermarket support, building up the 3.9L means you've got a ****load of money, and an unnatural lust for the 3.9L. If you really want a stroker crank, it's possible to have a one-off made. But, this ain't gonna be cheap. The guys that make the crank can probably help spec out the rest of the rotating assembly for you. Heads, you can probably have the ones on the engine reworked. If you get this far, there are some places out there that can build a set of headers for you. From there, the electronics should be able to handle everything, and you will want to find someone who can do a dyno tune for you. I'm pretty sure HP Tuners supports Dakotas, but you'd have to check into it.

So far as using an electric fan, there's absolutely no reason to be using a clutch fan on anything today. Electric fans have come a long way, and they have the advantage of being able to pull max airflow at engine idle which is not something a clutch fan can do. The OEMs initially used clutch fans because there were no electric fans, but when electric fans became necessary for wrongways engines they developed the tech. The only reason they didn't use them starting in the 1970s is the clutch fan was a lot cheaper to install than an electric. A clutch fan pulls way more air than it needs 90 percent of the time because it has to be able to keep the engine cool and AC working at engine idle. An electric can run max out or not at all according to the cooling needs of the engine rather than according to the engine speed, and it doesn't put a huge, heavy spinning thing off the end of the water pump snout which will let the water pump last a lot longer. On air conditioning, I've not converted a clutch fan to an electric fan yet that the end result wasn't better air conditioning at engine idle.

Not really sure why you're thinking it would be more work on a 1st gen, seeing as the 1st gen truck came from the factory with a V8. You want to see work, cruise around v8s10.org and see what they have to do to stick a V8 in. Part of it requires moving the radiator from behind the rad support to in front of it and they still have to use electric fans.

 

Just a few things to add.
1. I believe the op posted in the wrong section. 125 HP and a short nose sounds like a 87 to 90 first gen.
2. This post is 10 years old.
3. Assuming 87 to 90, he either has a carb (87) or TBI (88 to 90)
4 The TBI is not tunable
5. Could go carb, but no (stand alone) distributor is available to work with the odd fire 3.9 engine.
6. IMO instead of buying a 5.2, I would get the 5.9...…. Close to same price and more potential.