motor beef up

[xjrugger]

Im looking to do a cone air filter, bored throttle body, throttle body spacer and map sensor if need be. I want more power without getting in too deep. Has anyone done these together and what can u tell me? Big difference? Better off buying as a kit? and from who? How does it run with these mods? I did the header, hollowed the cat and did exhaust but it needs more. Also is the new map sensor neccessary and is it for correct air/fuel mix purposes? Does a 5.0 fuel injector setup help a lot, or will i have to do something else to compensate for that? Who should i call for all these parts? I have an 88 4.0

 

[Dr. Dyno]

I've done them all and went beyond simple bolt-ons by home porting the head as well. Now I'm building a 4.6 stroker because I still want more power even though I have plenty already.
Since you've done the exhaust by all means add a cone filter (I suggest you look at my homebrew FIPK), bored Renix TB, and custom made TB spacer. You won't need a MAP adjuster at this stage but I suggest that you get a set of '91-'95 4.0 HO injectors to supply more fuel than your existing units.
Take a look around my performance website for some more ideas, tips, and tricks.
________________________________________________________________
- 1992 4.0 XJ Laredo UpCountry with modifications - 173k miles - AX15, NP231, D35c, D30
Estimated 240hp@5250rpm/280lbft@3500-4000rpm, 1/[email protected], race weight 3465lb
- Future mods -
4.6L stroker (under construction)
- Websites -
Jeep 4.0 performance, 4.6L stroker build-up
- Tech Webpages -
CTS resistor trick, Dual electric fans, IAT sensor relocation, Intake manifold heatshield, MAP adjuster, Oil temp. gauge install
- Info Pages -
Automotive formulae, Jeep 4.0 cam specs, Jeep engine dyno graphs

 

[scottsxj]

well me being young im full of some crazy ideas, but is the airtude absolutley nessecary or is it possible to put the filter right onto the throttle body, or would that even have an effect on performance

 

[scottsxj]

and sorry about that i know its a little off topic

 

[Dr. Dyno]

well me being young im full of some crazy ideas, but is the airtude absolutley nessecary or is it possible to put the filter right onto the throttle body, or would that even have an effect on performance

It's not a good idea to bolt the filter straight onto the TB for two reasons. Firstly, it'll inhale hot underhood air and that's not good for performance. Secondly, the engine will produce less torque than if you have an airtube and the longer the airtube, the better as long as there aren't any sharp bends in it.
The heatshield is also desirable to isolate the filter from hot underhood air so that it only breathes cooler air from outside.
My FIPK may not be a paragon of beauty but there's a lot of engineering excellence in the design.

 

[woody431]

I want to change my air tube to the TJ style that goes over the valve cover and runs by the dipstick. I want to add a 2nd battery maybe so I'll have plenty of room if I get rid of the air box.

(just thought everyone would like to know.)

 

[xjrugger]

Good tips Dr. Dyno. ?'s = is your heat shield fire retardant enough? Where do u suggest i buy these parts from? What do u think my hp gain will be by doing the filter, tb and spacer and injectors? Can i use a newer 4.0 tb? Will it have the same results? b/c i see that the newer factory ones are 60mm and aftermarket are 62mm, correct? Whats the difference in power? Can i do the injectors w/o going beyond bolt on hardware? Will the fuel injections be fine with all these upgrades? Oh and I have a ? that i have never been given the correct answer to and it seems you def. would know. In cold weather, especially with minimal weekly usage, when i start the jeep she sometimes goes instantly to 2500-3000 rpm and sticks and even climbs higher. If i tap the throttle it just sticks higher. It has been doing this for years and has driven me f'n crazy! Also has this caused any premature wear on the engine, which has 134000 on it? btw, where r those pictures taken? Sorry to overwhelm with ?'s but i finally have began a new spending spree after a year at idle since i got the 35's. Just did rear discs for the d44 and now my new point of improvement is on the motor, then a cage, and then maybe 37's and then, and then, and then.....

 

[Dr. Dyno]

I haven't tried setting fire to my heatshield yet but the aluminium foil lining should retard flames a bit. I made my own out of double-ply cardboard but you could use plastic and cut it to shape.
The combination of cone filter, 60mm HO TB, HO TB spacer, and HO injectors should add at least 10hp and possibly as much as 15. You can use the HO TB but you'll need to drill and tap new holes in the intake manifold and you'll also need to adapt your Renix TPS to fit. A 62mm TB will only produce minimal gain over the 60mm.
Your high revs at idle problem could be caused by a sticking IAC motor. Take it out of the TB, give it a good cleaning, and clean the inside of the barrel in which it rests. After you've reassembled it, disconnect the negative battery terminal for at least 10 seconds to reset the PCM and your problem should be cured.

 

[xjrugger]

very very good, so do u think i should just buy the kit that rock it parts(i think it is) makes, b/c w/ my new job im at a loss of time these days for tinkering. Also are these parts what woud be used if i decide to stroker it later on? Again, thanks

 

[Dr. Dyno]

All the performance mods that you apply to the 4.0 will also work on a stroker. The only difference is that a stroker will need more fuel and that'll have to come from bigger injectors e.g. Ford 24lb'ers.
The Turbo City Rock-It intake kit doesn't have a heatshield. You could get Rusty's intake instead and build a heatshield around the filter.