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View Full Version : New guy boosting a 3.9 Dakota!



httrdd
09-14-2012, 10:01 PM
He everyone i am looking at building a single turbo setup for my 2000 Dakota QC. Hope to pick your guys brains and help me with this build. I am not new to motor builds/swaps, but this one will be a little different. Lol.

I know there is a guy on here that built a turbo manifold, but if i cant get him i will build a down pipe off a after market header.

Force Fed Mopar
09-14-2012, 10:08 PM
Sounds interesting, what turbo you plan on using? And how are you gonna tune it?

MC#4
09-14-2012, 11:12 PM
Not sure what your plans are, i had a 50 shot of nitrous on my 3.9 dakota briefly and it was still painfully slooow...

httrdd
09-14-2012, 11:23 PM
Looking into options at the moment. Not trying to tear the tires off it, just trying to get more power for hauling and towing, but keep the mpgs nice as a dd. When i was doing engine swaps the megasquirt was what i was using and a preloaded tune.

A.J.
09-15-2012, 01:25 AM
Where do you live? Do you have emissions? If so '96 and later they plug into the OBD II connector to check for codes. If you run Mega Squirt they're not going to be able to plug into your OBD II connector to do their check.

I love my 5.9 in my '94 Dakota for towing but the best I've gotten on the highway is 15 mpg so I can understand your wanted to turbo your 3.9 to keep your mileage.

A.J.

httrdd
09-15-2012, 08:05 PM
Yep its not a work hogg, but having the power for an occasional 2000lb load it would he nice. It will also be used for light off roading. Truck is on a. 3" suspension lift and lower gears.Only visual emissions and not strict.

So suggest some things guys as i do my research. What size turbo would be best for stock block? What is the best way to control fuel and other engine management? Thanks.

1BADCOLT
12-12-2012, 01:34 AM
Hello, I to am working on a 3.9 Turbo motor for my 1978 Dodge Colt so I will be needing info also . I have non-magnum blocks to use and currently building one that has Hardbloc [Small-Fill] and 318 aftermarket H-beam rods and Forged Flattops I will be having cam built for turbo application . I have factory Alum singleplane intake offered for the 3.9 Non-Magnum and will be running Double-Pumper 390 HP on E-85 fuel , glad to join and look forward to the build and info from you Gents , thankyou Chris

The Pope
12-12-2012, 03:33 PM
http://www.bgchrysler.com/tuning-magnum-truck.aspx

They build boost computers for Dodges, like FWDperformance but for magnum trucks for instance.

Do the same mods to the 3.9 that you'd do to a 318. I would at least pull the intake, cut the runners down 2" and weld on the lower plate to seal it. Porting the heads is a good idea.

For boost I'd be lazy and get a magnum 318-360 supercharger used off Ebay, then add a frozenboost water to air unit to make it easy. The SC with V8 pulleys is going to push more boost, close to 12-14 not 8-9 PSI. So trying to push about the same air it'll attempt to make the same power. The intercooler and made some FFV injectors on the cheap would help. Anything more than a 40 lb injector you should look for 318 forged internals.

httrdd
12-28-2012, 03:51 PM
Thanks. I have a 3.9 block now to tear down I picked up. Gathering parts and such.

mpgmike
12-28-2012, 04:24 PM
Just a thought, you mentioned adding a turbo for better MPG. If you were to mount a pair of the less desirable Mitsubishi turbos from the '88+ 2.2/2.5, that should give you fairly good response with awesome midrange. Twice the manifolding, twice the oil supplies and drains, twice the coolant lines, and not twice the power. However, it could be cheap.

Good to know about BG Chrysler.com

Mike

httrdd
12-28-2012, 05:15 PM
Yea still trying to see what my best options are. Right now I am trying to clean up the block and gather parts. Why the Mitsu turbos?

mpgmike
12-28-2012, 06:13 PM
Cheap and plentiful, and sized close to what I believe your needs are.

Mike

httrdd
12-28-2012, 06:15 PM
Hmm ok I will look into it. How much crank hp can I get. Mid range boost should work for what I need.

mpgmike
12-30-2012, 02:08 PM
You should be able to safely boost at least 12-14 psi with the 3.9 without cooking the air. That would be about 80% to 100% increase in power.

Mike

Vigo
12-30-2012, 02:38 PM
Each mitsu's stock compressor side can support ~200hp 'comfortably' and 240hp if you're willing to deal with very hot air coming out of them. So consider your power maximum with 2 of them to be under 400hp with rudimentary tuning and intercooling, and maybe over 450 with perfect tuning and VERY good intercooling.

Having said that, i think you'll be satisfied way before the 400hp level anyway. 300hp on a low-rpm turbo motor usually means 400+ lb ft of torque, and in all likelihood you would jump for joy if it even had that! I probably would..

httrdd
01-30-2013, 07:45 PM
Ok I get ya. Once the weather breaks I will begin to document.

Staal dragon
03-28-2013, 06:19 PM
I currently am running a 2002 3.9 dakota (turboed) with 6lbs of boost. Rear wheel horsepower is 220. I had the kit done by P.I.E. in delaware. When I talked to Chris the owner he said that you could probably go to 8lbs before you would have to mess with internals, If anyone knows differently please inform me and let me know what would have to be done. Iwould like to take it to about 9lbs, that would take me to about 260RWHP.

Mopar318
03-28-2013, 08:00 PM
I ran 12psi on my dakota with the 5.2L.

It made enough power to do 12.8 sec 1/4 mile passes on slicks. Completely stock internals and heads. Only engine mods were some felpro head gaskets, M1 single plane intake, and a 58mm throttle body.

Force Fed Mopar
03-29-2013, 11:14 PM
Yeah I think it'll hold 9 no problem on a good tune.

nitrohog
03-29-2013, 11:54 PM
As far as tuning goes, check into sct. Sean at hemifever tuned my 99 Dakota r/t (nitrous not boost) via email tunes and I'm very happy with it. Chris at PIE would probably tune it for you as well. The general consensus for the magnum motors is 8-9 psi for the v6 and 10-12 psi for the v8s on the stock bottom end.

Vigo
03-30-2013, 02:56 PM
If they use the same rods and pistons they should be able to run the same boost unless the v6 manifold has problems with cylinder distribution.

nitrohog
03-31-2013, 08:57 AM
They did use the same rods and pistons, the 3.9 is more or less a 318 with two cylinders chopped off. I will however say that the stock intake was definitely not built for boost on either motor. They have problems with gasket blowout and the runners are a poor design. I've never messed with one but I've read a handful of build threads over the years.

Force Fed Mopar
03-31-2013, 09:46 AM
The intakes are actually a great design for the original application. They do not do good in the higher revs though.

They only reason I could think of why a 3.9 couldn't handle as much boost as the 5.2 is that the V6 crank harmonics might be different.

Vigo
03-31-2013, 05:41 PM
The 'barrel' intake is great for low rpm power, as Force Fed mentioned. In one way it's sort of lucky that you can even take the plate off the bottom in the first place because that's what allows you to easily modify them. You can shorten the runners in them fairly easily, and they have a good plenum volume. The downsides are that you cant easily port the runners to make them any bigger, and the runner entry sucks no matter what. The BIGGEST problem with those intakes, though, is that it's hard to modify them for a non-stock throttle body. The stock throttle body design will only let you go so big, and the biggest you can get is still too small for those motors. This is LESS of a problem on the v6 because you can bolt the biggest aftermarket v8 throttle body onto the v6 and then have a decent amount of flow into the manifold per displacement, but on the V8s it sucks. Turbos sure help in that department, though!

Ondonti
04-07-2013, 05:32 AM
http://www.bgchrysler.com/tuning-magnum-truck.aspx

They build boost computers for Dodges, like FWDperformance but for magnum trucks for instance.

Do the same mods to the 3.9 that you'd do to a 318. I would at least pull the intake, cut the runners down 2" and weld on the lower plate to seal it. Porting the heads is a good idea.

For boost I'd be lazy and get a magnum 318-360 supercharger used off Ebay, then add a frozenboost water to air unit to make it easy. The SC with V8 pulleys is going to push more boost, close to 12-14 not 8-9 PSI. So trying to push about the same air it'll attempt to make the same power. The intercooler and made some FFV injectors on the cheap would help. Anything more than a 40 lb injector you should look for 318 forged internals.
Would have been interesting if they had branched out more on SBEC tuning.

BTW, boost level does not dictate when the motor will blow up. The RPM you hit peak boost at (lower = worse for the motor), total amount of heat (leading to knock), amount of oxygen (how much fuel is needed), what your timing map looks like, octane. Changing boost changes all these things/requirements. 9psi with an larger turbo will make more power then a small turbo but the big turbo might blow things up at higher boost levels because the total power level is just too much whereas a tiny turbo just doesn't move a lot of air even if the boost numbers seem high (if the excess heat doesn't break things first). When you don't make a lot of power you don't necessarily blow up at medium boost levels....you probably will though if you are not careful.