i was thinking about doing a 5.9 swap to get more power out of the old 98 dodge but i think im gonna stick with the 5.2 for now because it was recently rebuilt, and i dont think i'd see much gain powerwise (correct me if im wrong). i have been doing a lot of reading and i found some ideas and wanted you guys opinion. its stock except for a rancho leveling kit, flowmaster muffler, and cold air intake with spacer and K&N. so for you guys who have done power mods to your 5.2 motors, what do you think of this.....right now its very gutless off idle until about 3000 rpms and then the power kicks on but is nothing special. checked the plenum and deffinetly have a blown plenum gasket, its black and oily in there, so that according to my reading is a huge power loss right? so if i fix it with the hughes plenum fix, do a high flow cat, and a new O2 sensor that should take care of that. next some 1.7 roller rockers, read they give about 15-20 hp to the engine, and a fastman 50mm throttle body. and finally a sc 3815 (is 3815 right?). after all this my truck should be noticeably faster right? and be able to pull a small enclosed trailer with quads no problem? all this stuff will be expensive im assuming so ill try to do the plenum fix on my own. what should i expect? this is a 1998 4x4 1500 5.2 extra cab if tat makes a difference

 

very interesting posting,
but what the hell is a plenum, blown plenum or plenum gasket ??
Is it a part of the air intake system and where is it located?
...or did you mean the cylinder head gasket ?
( i can´t translate it - i ám german, sorry. )

Someone told me, that i have a possible blown plenum because my engine is knocking after use of the 3815 tuner.
I have used the search function and found this thread here.

Thank you for help.

 

First you need to search a little farther as this just got posted.

The plenum is the area under the intake manifold. Because of the design of the dodge magnum intake manifold there is an opening on the bottom of the intake. This opening is sealed with a gasket and steel plate. This was a very poor design and this gasket fails often unless it is properly fixed. To fix this a) buy a hughes or ATS kit or b) get an aftermarket intake manifold such as the Mopar M-1 or the Hughes airgap.

To determine if you have a blown plenum take off the air cleaner. Then with the truck off open the throttle blades and look inside with a flashlight. If the plenum is blown there will be carbon and oil buildup inside the intake.

 

@Gerehead8: thank you for the explanation.
I will take a look into the intake manifold.

 

we should have a banner on the main page for the 2nd gen that says "check your plenum" lol.

 

"If you look on your truck,and its says Dodge anywhere, you have plenum leak."

 

joking about me ? .... nice,.. most helpful ?!
:-X



@Gerehead8:
I got it.
If i ám right, a APS kit looks like this:

Intake Manifold Plenum Plates



right ??
.. but it is "only" a steel plate.
:-o

 

I have a Hughes but yeah it looks like that. It is actually 1/4 aluminum. Since the intake and plate would now be aluminum it eliminates the shear force with different expansion rates. It also is much more rigid than the cheap OEM steel plate.

The replacement plates are simple and very effective.

 

so back to my thread, any thoughts?

 

Sorry for the Hijack. Fix the plenum first. It will be the biggest power gain.