Power increase on 4.0 (yes i check forum)

[bullitt85]

So I have an 03 rubicon I want to get some more power out of this is what I want to do and I need to know if it will work ...

62mm TB and Spacer
Upgraded injectors
Performance head and cam
Programmer
Full exhaust with a punched out cat

What I need to know is where will I get a custom tune for this?
If I do the exhaust first will it throw codes the entire time for the O2 sensors? is there a bypass for them? or a deletion?
if I do TB and Exhuast will the programer work without throwing codes all the time?

I am hoping I can get around 100hp out of that 4.0 with these.

Thanks all. Any advice or past experience will be an asset in this engine mod.

[dac]

punched out cat

If I do the exhaust first will it throw codes the entire time for the O2 sensors? is there a bypass for them? or a deletion?

unless they changed things significantly between 02 and 03 there are 3 cats.  you could punch out the one just before the muffler but you probably won't notice a difference and it won't throw codes.

http://www.rockcrawler.com/techreports/edge_trailjammer_tj/index.asp

[Moezer]

Lol u won't get 100 HP from those kinda mods dude, those mods plus a turbo or a super charger then sure u can. That way u have more of a ground to stand on tuning wise crap if u can get 100 HP with only those mods then every one can do it. Another thing is the 4.0 has 190 HP so for u to jump to 290 sort of speak is impossible with only small mods like that crap better just swap a him I in there

[JackstandJohnny]

Throttle body spacer a flow master exhaust and k&n air intake will push your jeep to 300 hp easy.  Make sure you put the stickers on the rear window or full horse power won't be achieved







Simple question. If these things would give you a reliable 100 hp, why didnt they do it at the factory?  Start collecting dollars for a real striker build

[morerpmfred]

With a performance head it could be possable but doubt it. Aluminium head you can bump up the compression a full point and a half and if you run premium up to 3 points compression increase. A full port, polish, align flow on the butterfly intake , roller rockers, lots of cam and custom tune. Maybe close ?
Yj and corey from Gp has a couple of builds on pirate. Will have to look at the recipe on what he did. Think Brian here has one of his turbo moters and think it dynod at 440.

[hps4evr]

If you want to start easy try an air intake, cat back exhaust, electric fan, throttle body. These will give you a nice seat of the pants gain in throttle response and hp/torque. The edge programmer for tjs is supposed to help a little too. After these a cam, head, roller rockers  would be the next step, going that deep in the engine puts you one step from a stroker. After all that just add boost. 9 psi makes a huge difference. Adding a turbo from the start makes a huge difference too.
Are you prepared to dump 5-10G into your engine? Painless performance has a stand alone kit for the 4.0L with cam and 68mm TB.
You do have options, just depends on how much and who is installing.

[frenchy]

5.3l swap would get you an extra 100 + HP, maintaining stock component reliability.

[Bnine]

So I have an 03 rubicon I want to get some more power out of this is what I want to do and I need to know if it will work ...

62mm TB and Spacer
Upgraded injectors
Performance head and cam
Programmer
Full exhaust with a punched out cat

What I need to know is where will I get a custom tune for this?
If I do the exhaust first will it throw codes the entire time for the O2 sensors? is there a bypass for them? or a deletion?
if I do TB and Exhuast will the programer work without throwing codes all the time?

I am hoping I can get around 100hp out of that 4.0 with these.

Thanks all. Any advice or past experience will be an asset in this engine mod.

You wont get quite 100, but you will get 70-80 and dramatically change your torque profile. Talk to Bennie at Hesco. He will get you set up. Let him know you are in a non emission testing area.

Get the milled head that adds another compression point. I run 11:1 in my stroker, but I do run premium fuel. You can tune timing back with certain programers, but with the right injectors and good fuel, you dont need to.

Im pushing just over 300hp out of a 4.5L stroker that yj and corey out of gp helped me put together. But, the biggest difference is the torque. Where I used to stall on 35's when climbing on the trail, I can now launch and brake loose 38's with no effort at all.

Difference is day and night.

I was also running and 03, and the problem with them is that the head is so restricted, and the cam profile is so tuned down for emissions, you leave a ton of power on the table just waiting to be opened up.

Lastly, the second most effective thing you can do for power is keep your rig lightweight. Dont bolt a bunch of steel on it that doesnt need to be there.

[Bnine]

Oh, and if you look around, Robert J Yates on JU and Jeepforum did a complete ground up build and study with a build like yours. Im pretty sure his results was 60hp at the wheels after a bunch of tuning.

But, few things to consider in roberts built. First, Robert was working with a 97 or 98. Those motors are snappier then the 03's, so you would see more gains there. Also, he is in california, so he had to tune with emissions in mind, meaning for you, there would be a little more power to be had there as well.

So like I said, you should have no problem getting to 70-80 with a head, cam, throttle body, injectors, and exhaust.

And just ditch your 3rd cat. It isnt sensored anyways. Leave the two pre cats alone, they arent hurting anything.

For a header that fits nice, I went with edlebrock. I tried a pace setter but it didnt work.

Good luck