Jeep Cherokee Forum

Go Back   Jeep Cherokee Forum > Technical Discussion > Modified Cherokee Tech
Register Forgot Password?
Search

Welcome to Cherokee Forum!
Welcome to Cherokee Forum,

You are currently viewing our forum as a guest, which gives you limited access to view most discussions and access our other features. By joining our community, at no cost, you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is free, fast and simple, so please join our community today!


Reply
 
 
 
submit to reddit
 
Thread Tools Search this Thread Display Modes
Old 07-30-2009, 09:41 PM   #1
Newbie
 
Join Date: Jul 2009
Posts: 2

View novaducks's Photo Album My Photos
Cherokee
Default XJ Performance upgrades

I have a 1993 Jeep Cherokee and I have a question reguarding performance. I have already bought a K&N full Intake, I would like to upgrade to a 72mm high flow throttle body to increase power and fuel milage. is this or will this be a good choice, and if so, would you reccomend chiping it as well, maybe a JET chip
?
Thanks
Novaducks
novaducks is offline   Reply With Quote
Old 07-30-2009, 09:44 PM   #2
CF Veteran
 
BuckB91XJ's Avatar
 
Join Date: Nov 2008
Location: Oak Harbor, WA.
Posts: 6,971

View BuckB91XJ's Photo Album My Photos
1987 Cherokee
Default

Is that a misprint? I've heard of TBs bored out to 62mm. Where did you find one for sale bored to 72mm?
__________________
Brian "Buck" Buchanan, U.S. Navy Chief Petty Officer (RETIRED) - 87 XJ Laredo - 8.5" Rusty's Offroad/Rough Country lift, D30 trussed up and D44 high clearance shock mounts, 4.56's, Aussies and Disc Brakes front and rear, JCR Offroad Belly Skid Plate and Stage 2 Rock Sliders, Off Road Fab Winch Bumper and Quarter panel Guards, Liberal Front Wheel Well trimming and Rear Wheel Well Cut N Fold, 35" Goodyear MTR with Kevlars, Cobra CB and AW4 First Gear Lock Crawl switch, SYE, Stock XJ driveshafts front and rear and Milemarker SEC8000 Winch.

91 XJ Sport (Old Gray Jeep) - Layed to Rest (04-01-13)
87 XJ Laredo (Ole Red) - (My Jeep)
87 XJ Base (The Boys Jeep)
96 XJ Country (The Daughters Jeep)
08 Dodge Charger R/T (The Wifes Ride)
04 Silverado 2500HD Duramax/Allison (tow rig)
BuckB91XJ is offline   Reply With Quote
Old 07-30-2009, 10:01 PM   #3
CF Veteran
 
ol"blue's Avatar
 
Join Date: Mar 2009
Location: Tenn. and Mich.
Posts: 28,056

View ol"blue's Photo Album My Photos
2004 Grand Cherokee
Default

Quote:
Originally Posted by novaducks View Post
I have a 1993 Jeep Cherokee and I have a question reguarding performance. I have already bought a K&N full Intake, I would like to upgrade to a 72mm high flow throttle body to increase power and fuel milage. is this or will this be a good choice, and if so, would you reccomend chiping it as well, maybe a JET chip
?
Thanks
Novaducks
You can't go that big on the TB without getting bigger injectors, and then you won't be getting better mileage. You can't have it both ways, a lot more power and more mileage too. It takes more fuel to make more power.
__________________
Dan
'04 Grand Cherokee SE: 4.7L V8 w/235 HP, 4X4
'04 Saturn Vue: 3.5L V6 w/250 HP, AWD

"...Never Use Post Count as A Knowledge Gauge." Willys55

CBW Member#97

If no answer, ask here>
www.CHEROKEETECH.com


RIP Carroll Shelby
http://www.carrollshelbyfoundation.org/
http://carrollshelbyfoundation.com/



If you're not breaking parts you're not making enough power!!!
"I NEED MORE TRACTION, NOT MORE BOOST"

ol"blue is offline   Reply With Quote
Old 07-30-2009, 11:03 PM   #4
Senior Member
 
broncofire75's Avatar
 
Join Date: Aug 2008
Posts: 621

View broncofire75's Photo Album My Photos
1998 Cherokee
Default

Only way to add noticable power to the 4.0 is through forced induction. ie turbo


I have an AFE intake, bored TB(60mm), and a Magnaflow muffler. Im sure it helped a little but nothing to crazy.

Dont waste your money on a TB spacer plz.
__________________
'00 XJ Sport 4.7L Stroker
broncofire75 is offline   Reply With Quote
Old 07-31-2009, 12:07 AM   #5
Newbie
 
Join Date: Jul 2009
Posts: 2

View novaducks's Photo Album My Photos
Cherokee
Default

Quote:
Originally Posted by BuckB91XJ View Post
Is that a misprint? I've heard of TBs bored out to 62mm. Where did you find one for sale bored to 72mm?
misprint 62mm`
novaducks is offline   Reply With Quote
Old 07-31-2009, 08:00 AM   #6
Member
 
LongHornCherokeeMan's Avatar
 
Join Date: Mar 2009
Location: Oakland Maine
Posts: 170

View LongHornCherokeeMan's Photo Album My Photos
1999 Cherokee
Send a message via AIM to LongHornCherokeeMan
Default

www.strokedjeep.com 63mm tb probably going to be one jeep purchase away for me need a control arm drop first
__________________
Mainers rule

Last edited by LongHornCherokeeMan; 08-05-2009 at 12:10 PM. Reason: cant spell cant read
LongHornCherokeeMan is offline   Reply With Quote
Old 07-31-2009, 09:11 AM   #7
Senior Member
 
miglia-spyder's Avatar
 
Join Date: Mar 2009
Location: Grand Rapids, Michigan
Posts: 554

View miglia-spyder's Photo Album My Photos
2000 Cherokee
Default

Quote:
Originally Posted by LongHornCherokeeMan View Post
www.strokejeep.com 63mm tb probably going to be one jeep purchase away for me need a control arm drop first
www.strokedjeep.com

Fixed your link...
__________________
VW guy turned Jeep guy

2000' XJ....RC 4.5" w/ full packs, RC Adj. X-FLEX LCA's and UCA's, AA SYE, SS brake lines, Canyon wheels, 32" KM2's, C02 oba, IMO steering, Always in Progress!!!

Build Thread: http://www.cherokeeforum.com/f46/200...tockify-14926/
miglia-spyder is offline   Reply With Quote
Old 07-31-2009, 09:37 AM   #8
Senior Member
 
01LimitedXJ's Avatar
 
Join Date: Sep 2008
Location: Nashville, TN
Posts: 686

View 01LimitedXJ's Photo Album My Photos
2000 Cherokee
Default

ive got a 63mm tb, with a thinner butterfly valve, and smaller flush mounted screws for increased flow. Cant go any further than that as there is just not enough material to bore out.
__________________
i drive a 3/4 ton cherokee
01LimitedXJ is offline   Reply With Quote
Old 07-31-2009, 09:47 AM   #9
Senior Member
 
Mike1998XJ's Avatar
 
Join Date: Apr 2009
Location: Grand Haven, Michigan
Posts: 922

View Mike1998XJ's Photo Album My Photos
1998, 1999 Cherokee
Default Maybe this will help... Off naxja.org

Basic Modification tips for the XJ 4.0 I6
Gleaned from a post on the Click the image to open in full size. Modifications Tech Forum by Ed A Stevens.
Edited by Jeff Veach


Think about what is already good about the 4.0L engine, and then try to improve what needs help.

The engine already has a tube header. Even the early log style tube header flows way better than an iron manifold. The problem is they crack at the #6 cylinder (poor design) so a header replacement is a good choice (but not from a performance standpoint -- only ~3 hp maximum). The HO header is better, than the RENIX header, but not as good as a long tube aftermarket header.

As with any pump, the engine efficiency improves about 1% for every 1 psi drop in the exhaust stream. The stock exhaust from the cat-back restricts about 6 psi (up to 6-10 hp) compared to a 2.5 inch pipe system and a good muffler. The talk about loosing low rpm power is not valid as long as the head pipe from the collector to the cat is still 2.25 (it determines the resonate rpm and flow velocity). A 2.5 inch head pipe only moves the collected resonant rpm from ~900 to ~1400 rpm, so it really does not change much. The best is to get the benefit of the cat back without loosing the resonant flow scavenging at low rpm (your choice).

The intake, head ports and valves flow well. The HO high ports really do not offer an advantage until 4500+ rpm (well beyond most users). Large valves and porting only help if you are reaching past this rpm. It's a wast of money unless you want to move the rpm power range higher. Chamber polishing and piston top polishing helps prevent detonation. Talking to your machinist about 0.045 quench clearance, and decking the block to match with the right head gasket, will help the compression a little without promoting detonation. The 96 & later 4.0L-HO graphite skirt pistons run quieter (and fit all 4.0L's).

The intake of the stock system sucks (from a performance standpoint). It was designed for emissions and noise control and is restrictive. The same style rule of thumb applies, that a 1% increase in power is possible for every 1 inch of water gage reduction in restriction. A K&N style flat filter helps ~2%. An open element cone style air filter will do way more for power than the header (about the same as the cat back exhaust). Save the stock box and system for emissions testing.

The factory RENIX throttle body flows ~325 cfm (the HO ~350 cfm). Both will flow well past 5000 rpm, at the mild volumetric efficiency of a near stock build up. Unless you reach higher in rpm or go big cubes with a stroker the return is not that great for the expense of a large TB (~3%).

The ignition on the 4.0L is very good. The system can be improved with a high altitude CPS to allow advanced timing. The RENIX system has the advantage of the knock sensor so going too far and promoting ping is not an issue. Good plug wires and cap/rotor help, and the stock E-coil is better than most factory systems up to 96. An MSD-5 or 6 will help a tired motor, and areas with poor fuel (rual Mexico), but is not needed for most users.

If you want to know about cams, The Mopar stage 1,2,& 3 cams are very mild. I run an Isky cam listed on Greg's spreadsheet on the strokers list (near identical to a stage 3 Mopar cam). It is locomotive like in building low rpm torque. Greg also runs this same cam in his stroker MJ, and agrees it is a torque monster, but not too powerful past 4500 rpm. The power is still better than stock past 4500 rpm, and it will rum to 6000 or more, but it drops off quickly compared to the punch you feel from idle to 4000. The HO cam (IMO) offers nothing over the regular 4.0L cam in a RENIX engine. Crane, Competition Cams, Isky & others all make 258 cams that will work well with the 4.0L MPI.

The cam problems start when you make choices to improve the rpm past 5500, where the low rpm vacuum suffers. This high rpm range is where the injection system really needs to be matched with large injectors, high flow throttle body work, and port/valve work (and throwing on a 38/38 Weber or 4V carb is much easier to tune). The MPI also cannot resolve poor intake vacuum readings at low rpm (big lumpy idle cams). I don't think this is where your going, but it is worth understanding.

You may also enhance the injection some with a switchable 1000 ohm resister in the temp sensor wiring (to throw it into rich warm up mode) or add an adjustable pot MAP bias bridge (to bias the A/F ratio for more power in both open and closed loop modes -- works good with the other mods, but is not much good on it's own). These MPI modifications are simple but not really needed unless you want every little bit of power (and have a G-Tech or other performance measuring tool to tune the gains).

Happy Trails!

Ed A Stevens
Mike1998XJ is offline   Reply With Quote
Old 07-31-2009, 10:00 AM   #10
Seasoned Member
 
strikechords's Avatar
 
Join Date: Jul 2009
Location: Racine, Wisconsin
Posts: 277

View strikechords's Photo Album My Photos
1996 Cherokee
Default

so strokedjeep.com sounds pretty awesome, i think i wanna get one from there, who else has one of his tb's? i wanna know what his work is like, it sounds cool tho.
strikechords is offline   Reply With Quote
Old 07-31-2009, 10:05 AM   #11
Seasoned Member
 
strikechords's Avatar
 
Join Date: Jul 2009
Location: Racine, Wisconsin
Posts: 277

View strikechords's Photo Album My Photos
1996 Cherokee
Default

btw, awesome info mike! thanks.
strikechords is offline   Reply With Quote
Old 06-15-2011, 08:29 PM   #12
Senior Member
 
chrisquested's Avatar
 
Join Date: Mar 2011
Location: San Antonio, TX
Posts: 634

View chrisquested's Photo Album My Photos
2001 Cherokee
Default

Just pull your motor out and drop in a small block chevy motor.


just kidding this straight six has alot more power than people relize. ( i found this out when i raced my jeep at the mud drags in stock class.)

Last edited by chrisquested; 06-15-2011 at 08:36 PM.
chrisquested is offline   Reply With Quote
Old 06-15-2011, 11:27 PM   #13
CF Veteran
 
xj wheeler's Avatar
 
Join Date: Jun 2011
Location: S.E. Tx
Posts: 1,845

View xj wheeler's Photo Album My Photos
1992 Cherokee
Default

Don't know if this will help but I've got a Poweraid throttle body spacer, Performance Distributors ignition kit, and a custom catback w/magnaflow muffler. The one that made the most difference was the spacer. Can you get a chip for a '93 and if so will it work on my '92?
xj wheeler is offline   Reply With Quote
Old 06-16-2011, 01:04 PM   #14
Seasoned Member
 
waltermitty's Avatar
 
Join Date: Feb 2011
Location: Memphis,TN area
Posts: 424

View waltermitty's Photo Album My Photos
1998 Cherokee
Default

[QUOTE=chrisquested;1043641]Just pull your motor out and drop in a small block chevy motor.


waltermitty is offline   Reply With Quote
Old 06-20-2011, 01:29 PM   #15
Seasoned Member
 
Screwd up 6's Avatar
 
Join Date: Nov 2010
Location: Spring, TX
Posts: 469

View Screwd up 6's Photo Album My Photos
1994 Cherokee
Default

Quote:
Originally Posted by xj wheeler View Post
Don't know if this will help but I've got a Poweraid throttle body spacer, Performance Distributors ignition kit, and a custom catback w/magnaflow muffler. The one that made the most difference was the spacer. Can you get a chip for a '93 and if so will it work on my '92?
I would think the catback exhaust had more postive performance results than a throttle body spacer. To my knowledge, experience and research on TB spacers, they are about as useful for horsepower as a K&N sticker
Screwd up 6 is offline   Reply With Quote
Old 06-20-2011, 01:29 PM
 
 
 
submit to reddit
Reply

Similar Threads
Thread Thread Starter Forum Replies Last Post
newbie needs help with performance upgrades tom9193 OEM Cherokee Tech 8 07-21-2009 02:18 PM
'84 4cyl. upgrades? johnnynegaunee OEM Cherokee Tech 10 02-03-2009 09:53 PM
Did some upgrades this weekend JeepDriver OEM Cherokee Tech 29 08-19-2008 10:10 AM
'89, 4.0L, 6 Cyl, upgrades? Funky Fresh OEM Cherokee Tech 10 02-08-2008 08:20 AM

Go Back   Jeep Cherokee Forum > Technical Discussion > Modified Cherokee Tech



Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -5. The time now is 03:11 AM.


This site is in no way affiliated with Jeep or Chrysler.

Emails Backup