Tips for top end?

[Greasemunky13]

I have a '89 xj 4.0 that I'm looking to get more top end out of. I'm new to the Jeep family and don't have a ton of knowledge about them. I've been searching around but can't seem to find anything that has any solid solutions. I have headers, a k&n filter (not an intake system), and four hole injectors. Is there more things I could do to get some more power on the top side?! Anything I can swap from '91-'01s?! Thanks in advance.

 

[cruiser54]

Get rid of the "crush" in the exhaust downpipe, bigger throttle body (www.strokedjeep.com), make sure your distributor is indexed correctly.

 

[GregGA]

I put the Leigh 60mm throttle body(strokedjeep) on my 87. Along with the opened up exhaust, it is night and day difference. You will love it!

 

[Greasemunky13]

I am running open exhaust too. Definitely a difference. And I forgot to mention I also have a 1" throttle body spacer

 

[Dr. Dyno]

I have a '89 xj 4.0 that I'm looking to get more top end out of. I'm new to the Jeep family and don't have a ton of knowledge about them. I've been searching around but can't seem to find anything that has any solid solutions. I have headers, a k&n filter (not an intake system), and four hole injectors. Is there more things I could do to get some more power on the top side?! Anything I can swap from '91-'01s?! Thanks in advance.

Aftermarket CAI (preferably one that has a heatshield for the filter)
Bored 62mm HO throttle body
'99+ curved runner HO intake manifold
'91-'99 HO head (porting it will add even more HP)
Performance camshaft

Then if you're still not happy, add more displacement and build a 4.6L stroker.

 

[Greasemunky13]

The 99+ manifold will fit? Didn't know that. Nor did I know about the head. How much more do I need to do to replace both? And do you ha e a link to get a cam? I can't seem to find a good place....

 

[Greasemunky13]

P. S. Stroker kit is a future project. Found a 4.9 that I wanna get.

 

[PacificEd]

For the head, which it more desirable to swap onto a Renix, the 7120 or 0630?

Can you use a HO throttle body with a Renix system?

 

[cruiser54]

You can use an HO throttle body, but you have to fab up a TPS mount and all that crap to gain 2mms.

Renix head is fine. Port match the manifold you intend to use with the head and use the intake gasket for the manifold you use.

 

[GregGA]

I am running open exhaust too. Definitely a difference. And I forgot to mention I also have a 1" throttle body spacer

Ditch the spacer and get a bigger throttle body.

 

[cruiser54]

Ditch the spacer and get a bigger throttle body.

Yup........

 

[GregGA]

You can use an HO throttle body, but you have to fab up a TPS mount and all that crap to gain 2mms.

Go to www.stokedjeep.com and he has a picture showing the size comparison between his bored Renix and a stock TB. Agree with Cruiser, you don't need to mess with HO for 2mm.

 

[cruiser54]

I've got comparison photos but I can't post them here.

52mm stock to 60mm bored is a lot. The hole in the intake manifold is 60mm by the way....

Stock HO is 58mm throttle body.

 

[Johnnie Walker]

These guys have it covered.
When I get some time to measure parts, I am going to attempt to draw up an adapter plate in CAD for 99+ intake to Renix TB. And hopefully find someone to make it. Will make a late model intake swap much easier.

 

[Dr. Dyno]

For the head, which it more desirable to swap onto a Renix, the 7120 or 0630?

Can you use a HO throttle body with a Renix system?

Either head will do fine and both will comfortably outflow a Renix head.
You can use the HO TB with the Renix system by adapting the Renix TPS to fit. The hole in the HO intake manifold is 62mm so use a 62mm TB to get the best result.
The '99+ curved runner manifold has a smaller differential in airflow across all six runners than the Renix and early-HO manifolds so there's the potential for better gas mileage and emissions as well as a little more midrange torque. You won't need a TB spacer with this manifold.

 

[Greasemunky13]

Completely off topic, but is there a difference in buying a brake light switch with out cruise control vice with? Besides the obvious. The price doubles without it.

 

[GregGA]

Completely off topic, but is there a difference in buying a brake light switch with out cruise control vice with? Besides the obvious. The price doubles without it.

You'll never get it answered this way. Please start a new thread in OEM if you can't find the answer by searching.

 

[Greasemunky13]

Thanks

 

[REVROK]

For the money is no object crowd a hesco aluminum head is good for some 20 hp

 

[cal]

how do you figure that?