DodgeTalk Forum banner

Status
Not open for further replies.
1 - 10 of 10 Posts

·
Registered
Joined
·
208 Posts
Discussion Starter · #1 ·
Ive gotta stock 1998 Dakota with the 3.9 Magnum bone stock, an 33500 miles. I'm looking to get a little more punch out of her. Its gotta limited slip rearend an she likes to hookup an goooo!!, but not as much as I would like.... yet. Any Idea's? Thanks
 

·
Seriously.
Joined
·
1,446 Posts
welcome to the site! there's lots of ways you can go with your 3.9, and most all of the mod rules that apply to the 5.2s and 5.9s work for us too. getting it to breathe better is a good start; cold air intake, throttle body, intake manifold work (cut the runners a little and fill some plenum area, or just buy a modded one), better spark plugs & ignition, computer upgrades (superchips or custom flash, stay away from jet chips), then you can get into stuff like exhaust, headers, roller rockers, hotter cam, port & polish heads, etc etc. some have even done superchargers, most kits like vortec and powerdyne for 5.2s will bolt up to a 3.9. some guys have gone as far as fabbing up turbos or building strokers, strokerkits.com has crank, rods & pistons combo that'll turn it into a 4.7 v6! a member at dodgedakotas.com has built one, puts down 309hp and 322tq at the wheels. then there's drivetrain stuff, torque converters, transgo shift kits/complete valve body from thefastman or aps.

if you have 3.55 gears you could consider upgrading to 4.10, that was one of the biggest mods for me. this summer i plan a new cam & springs, since my timing chain/lifters/both are making some racket.

check out places like thefastman.com or hughesengines.com. hughes has a great article on 3.9 engines. good luck!
 

·
Registered
Joined
·
208 Posts
Discussion Starter · #3 ·
Thanks for the advice. I have already been thinking exaust and the intake but I will start looking it to the rest. Thanks again.
 

·
Registered
Joined
·
815 Posts
1. Either mod the TB yourself or get a Fastman.

2. Your truck has low miles, so replace the stock muffler with a Flowmaster 40. At 50k replace the cat.

3. CAI. I have a home brew ram air; Using the Airraid CAI, I cut the bottom off a bleach bottle, mounted it to the base of the filter, cut the top to fit the ram air tubing and used insulated flex tubing to route the tube.

4. Custom burn the ECU. Failing that, relocate the IAT to a cool airstream, consider modding the timing sensor bracked to allow for more advance, run premium fuel.

5. Remove weight. Increase the power to weight ratio. 100 lbs for a .10 is the general rule.

6. Get rid of the stock mechanical fan (if equipped) and go with electrics.

7. Tire size. Lower profile tires will have the effect of raising your gear ratio slightly. Of course it will also throw off your speedo.

8. Manual trans., manual trans., manual trans..

Have fun and drive like me. :cool:
 

·
Registered
Joined
·
208 Posts
Discussion Starter · #6 ·
My next question is probly dumb to most people but im not to informed on how an whay to do to make a vehicale run better other than a few basics so here it goes, what the heck is an IAT sensor an what does she do?
 

·
Registered
Joined
·
189 Posts
The IAT sensor reads the air temp so the ECU can adjust the fuel/air ratio at WOT. By moving it into a cooler airstream, the mix will be richer than if it's read inside the manifold (stock location). Keep in mind that it only matters at wide open throttle as it is a "closed loop" system.

That being said, I have a dumb question - what would you fill the plenum with? The beater is getting a "makeover" (I can't leave anything alone), and I want to experiment with it.
 

·
Registered
Joined
·
815 Posts
I assume what do you put in the hole left by the sensor. Get an appropriate sized plug or bolt and put it in there (coat the threads with teflon goop or silicone to prevent leaks).

That said I should clear up what racer_X said about the IAT. I try not to mention this too much, but I'm one of those evil people who has an in cab IAT adjuster - easy to make - it just uses a couple of resistors and a 2k pot. You can get fancy and throw a switch and light on it but I did the KISS version and just have a knob on the dash.

Anyhoo, I was at a light last winter and it was like 75 million degrees below zero and all of a sudden Stinker started idling rough. Way way rough. Backfires through the TB (didn't even know that was possible on a FI). I thought for sure I blew the motor. Then I realized that I had left the IAT adjuster all the way lean. I turned it back rich and bingo bango smooth idle once more. All of this happened at idle not WOT. The IAT exists in two loops. One is at everything below WOT where the combo of the TPS, IAT, MAS and the O2 sensors are used to determine the mixture and advance. The 4 of them together are also used by the OBDII system to make sure that everything is okie-dokie in the engine. At WOT the MAS and TPS become useless (remember our MAS uses vacuum instead of air flow - why they use that getto idea is beyond me) so the IAT becomes closed loop by itself at that point. The idea is to break into the part throttle data stream and tell the ECU that the air temps are cold so it will stay in the rich/big advance mode which gains more ponies. The problem with the adjuster (if you're inclined to go this route) is that with the adjuster at full "cold", it throws the OBDII into fits and triggers the check engine light because you've put the drive loop into a condition that it can't deal. Even with a custom burn in the ECU like I have, the OBDII is a system that can't really be changed to accept the changes. Some years of OBDII can take the out of norm readings and some can't. Mine can't, but the ponies are worth the light being on.

More information is in my OBDII article here: http://www.kitcar.dynip.com/obd2andyou.htm
 

·
Registered
Joined
·
18 Posts
Instead of thinking how you are going to plug that hole, add a second sensor, especially if you live in colder climates. It's also a good idea if you just not in the mood to burn a lot of excess gas.

Modifying the v6 tb is a great alternative to using a v8 tb. Here are several reasons-
1. You don't have to replace the throttle cable
2. Anything larger than 47.5 mm is a waste, because that is the size of your manifold
3. It's much cheaper than buying a fastman or f&b
4. You get to use your imagination and be different.

 
1 - 10 of 10 Posts
Status
Not open for further replies.
Top