Dodge 12V diesel upgrades. [Archive] - NAXJA Forums -::- North American XJ Association

View Full Version : Dodge 12V diesel upgrades.

JohnX

October 24th, 2006, 17:24

Just wondering what you have done to your 12 valve cummins, and whether or not you were satisfied. I just bought a 98 with an auto trans, so I'm not looking for major upgrades that the tranny cant handle, but I was thinking about the fuel plates that offer around 60-70 hp for about $100.

Anything else you would reccommend or not?

Thanks,

JohnX

October 30th, 2006, 12:09

Nobody reads this forum!

serialphreak

November 11th, 2006, 09:20

edge performance programers/chips work good. i work on dodge diesels all day long and that seems to be the most popular performance mod where i live.

JohnX

November 12th, 2006, 09:55

Thanks, But mine is a 98 12 Valve motor...No programming to change, it is still mechanical injection.

vetteboy

November 12th, 2006, 10:39

I've done the full Banks kit...the BigHead wastegate, both turbo halves, and the fuel plate. Also 4" Dynomax exhaust all the way back and a better air filter. Turbo spools up to about 35 psi now and sounds wicked.

Haven't gotten to tow anything with it yet, but just driving the truck around the EGT barely gets above 300-400, which means I'm not even getting close to putting a load on it. The fact that it's in a Bronco w/total weight of 5600 lbs probably helps this...the truck the motor came from weighed nearly twice that. :)

serialphreak

November 12th, 2006, 15:02

Thanks, But mine is a 98 12 Valve motor...No programming to change, it is still mechanical injection.
my bad i shoulda paid attention to ur first post lol with ur year of truck :)

JohnX

November 12th, 2006, 19:26

AzRick

November 12th, 2006, 19:43

I've got a 97 12v, auto trans. Bought it stock with 124,000 miles.

Slid the stock plate forward and moved the starwheel forward as well. Within a few months the tranny was slipping bad.

Got a full tranny rebuild from DTT, #5 plate, 3k GSK, timing at 16.5, Afe intake, blocked the wastegate, and gutted the cat and removed the muffler. The truck is now fun to drive and pulls my junk with ease.

I ended up spending about $4500 for all the mods.

If you want to go cheap, I'd recommend a 3k GSK no matter what plate you go with. This will allow you to drive the truck at 2-3k rpm, which builds line pressure that your tranny desperately needs.

Rick

Appalachianxj

November 12th, 2006, 20:30

I got 215 HP and 527 torque on the dyno with a banks 10 plate and cranked down on the governer springs. Got the plate for free but if you look on TDR and DTR you can make your own fuel plate.

I would sat make/buy a feul plate, and governer spring kit is a good place to start.

May want to think about some 215 injectors, Valve body/flex plate for your tranny.

Dont spend the money on a aftermarket airfilter just pick up a BHAF.

This isin't a power upgrade but I would reccoment tst product's KDP kit. Its for a dowel pin(Killer Dowel Pin) in the back of the timing chain. It can walk out and fall into the timing case or into the oil pan. Did mine, the pin had walked out 1/8''.

vetteboy

November 13th, 2006, 06:34

This isin't a power upgrade but I would reccoment tst product's KDP kit. Its for a dowel pin(Killer Dowel Pin) in the back of the timing chain. It can walk out and fall into the timing case or into the oil pan. Did mine, the pin had walked out 1/8''.

Yeah, that lil guy is a bitch. I don't know anything about the kit though...I just pulled the timing cover off, tapped the pin back in (mine had walked out about 1/16"), and there's a small bolt right next to the pin. I just cut out a piece of 16-ga sheet metal, drilled a hole in it, and bolted it over the dowel pin. Definitely an issue worth taking care of though as it'll blow up the whole timing assembly on the motor if it comes out.

Thats where I'm headed, but without the turbo halves. Which plate did you use 6, 8, 10?

Well, we didn't intend to go with the full turbo originally. We just did the exhaust half and the wastegate first, but then the intake side sucked in a little metal shaving that was in the air tube and killed the impeller. An OEM turbo was rediculously expensive so we figured might as well upgrade while we're in there...

Not sure which plate it was. The original package we got was the plate, exhaust turbo half, and the wastegate. The front turbo half blew up before the truck was even off the jackstands so I can't tell you what the performance difference would have been.

Here's a video of the truck in action for the first test run...it's since gotten a different front end, different wheels (wider stance), etc.
http://www.tcnj.edu/~macock2/stuff/broncocummins.wmv

http://www.phatserver.net/~chris/XJbuild/110206/bronco1.JPG

http://www.phatserver.net/~chris/XJbuild/110206/bronco2.JPG

We're also running a 5-speed though, so YMMV.

JohnX

November 15th, 2006, 22:16

Okay...Starting with a 4 inch exhaust and helping out the intake a little.

Whats the deal with the 3k springs? What exactly do they change...redline?

vetteboy

November 15th, 2006, 23:36

Whats the deal with the 3k springs? What exactly do they change...redline?

I'd like to know about this too. As far as I know, from the factory gauge cluster the redline was at 3k for the Cummins 12V motor. We didn't change any of the springs in the one we built, so I'm curious as to what this upgrade does and what years it applies to.

AzRick

November 19th, 2006, 20:19

The governor spring kit allows the pump to add fuel to a much higher rpm. If you've driven a stock 12V, I'm sure you've noticed the truck sort of "hit the wall" about 2100 rpm. With the 3K GSK, the truck will keep pulling up to about 3000 rpm. I've actually had mine to about 3500 rpm, which is a bit unnerving. A 4K GSK is also used by some guys, but that seems a bit scary to me.

A stock auto tranny needs line pressure to stay alive, and being able to drive it above 2000 rpm really helps.

Rick

JohnX

November 19th, 2006, 21:21

Maybe I'll look into that....it does seem to fall off after 2k.