Diggerbob Posted August 9, 2006 Share Posted August 9, 2006 I just rebuilt my 4.0 litre in my 88 comanche and it runs great! I'm wondering if there are any options for performance upgrades to this engine aside from a wipple blower. Does anybody have any suggestions? Dual exhaust? header? can't find a cold air intake kit or chip for this vehicle. Any suggestions would be much appreciated. Thank you. Diggerbob rob_tharp@comcast.net :cheers: Link to comment Share on other sites More sharing options...
cmcolfax Posted August 9, 2006 Share Posted August 9, 2006 I quality intake setup like a K&N FIPK will add a little. Mated to a quality header and exhaust system will add a little more. But if you wanna make a 4.0L go fast... http://www.jeep4.0performance.4mg.com/ http://www.angelfire.com/my/fan/ http://www.angelfire.com/my/fan/stroker.html :D -cmc- Link to comment Share on other sites More sharing options...
Bounty Hunter Posted August 9, 2006 Share Posted August 9, 2006 A HO head will make a great improvement over stock, as well as a performance camshaft. Then there's the FirePower ignition kit from Performance Distributors. Link to comment Share on other sites More sharing options...
BIGHEEP Posted August 9, 2006 Share Posted August 9, 2006 I heard that Rustys now makes a throtle body spacer for the Renix 4.0L. Link to comment Share on other sites More sharing options...
DirtyComanche Posted August 10, 2006 Share Posted August 10, 2006 I heard that Rustys now makes a throtle body spacer for the Renix 4.0L. Which, doesn't do anything. As is the nature of TB spacers. Renix performance is somewhat elusive. I mean, you can run a aftermarket header, no exhaust, and a HO head and the newer manifold (2000+ IIRC), and you'll still only be a little over 200 Crank HP. Not wheel HP. That's about 140 to the ground. But, if you really want to spend the dough and make it scream, yeah, it's possible. Link to comment Share on other sites More sharing options...
randimal Posted August 10, 2006 Share Posted August 10, 2006 Ya'll forgot fuel injectors. Mine are from a Mustang (I got a box of 8 for 10 bucks on E-bay). Supposedly they work better. I didn't put mine in until the stock ones were leaking all over. By then the engine was fairly worn out so I couldn't tell you how well they work. BUT... they don't leak. Aside from that, K&N is easiest. Keeping it tuned up is good for HP. Headers are also supposed to work well. I have a Borland or something like that that I never got around to installing. Maybe it will go on my MJ when I find one. Link to comment Share on other sites More sharing options...
DirtyComanche Posted August 10, 2006 Share Posted August 10, 2006 Larger injectors without really modifying the engine is a waste. It's similar to over-carbing an engine. Everything suffers. But the ford injectors do have a better spray pattern. Link to comment Share on other sites More sharing options...
feerocknok Posted August 10, 2006 Share Posted August 10, 2006 Heresay, but apparently HO injectors are an upgrade. :dunno: One day I'll learn about these... four litres... Link to comment Share on other sites More sharing options...
DirtyComanche Posted August 10, 2006 Share Posted August 10, 2006 They flow a little more, but the 5.0 ford injectors are better. Link to comment Share on other sites More sharing options...
Oizarod115 Posted August 10, 2006 Share Posted August 10, 2006 i got the 5-0 injectors from five-o motorsports online... theyre damn nice. mine were sprayin fuel all over the place. ugh. also have the k&n 6x9 cone filter. and my jeep runs pretty fast. fast enough for me. Link to comment Share on other sites More sharing options...
pingpong Posted August 11, 2006 Share Posted August 11, 2006 Here is my take on the whole Upgrades for the renix 4.0. Most are not worth the trouble cause you can not "tune" the engine to take advantage of it. Larger injectors just equal less fuel economy :eek: AS for the headers.. most of the aftermarket headers out there for the 4.0 only use slightly larger tubes... by no means do the improve flow, unless you get a 2 into one setup... I think Doug Thorley is the name with that style, but expect to pay big bucks. IMHO.. the best bang for the buck performance upgrade for the 4.0 is proper gearing Link to comment Share on other sites More sharing options...
ORCA Posted August 11, 2006 Share Posted August 11, 2006 Here is my take on the whole Upgrades for the renix 4.0. Most are not worth the trouble cause you can not "tune" the engine to take advantage of it. Larger injectors just equal less fuel economy :eek: AS for the headers.. most of the aftermarket headers out there for the 4.0 only use slightly larger tubes... by no means do the improve flow, unless you get a 2 into one setup... I think Doug Thorley is the name with that style, but expect to pay big bucks. IMHO.. the best bang for the buck performance upgrade for the 4.0 is proper gearing I've run the same borla header on both a 95 4.0 HO and now an 88 4.0, and on both engines i've noticed a large improvement. Although moving 35's requires alot of power and by no means is my truck a street racer because of the head, it simply has more low end power noticable on hill climbs and accelerating from a dead stop. Which in my opinion made the header worth the money. Plus mine was cracked in the first place. :yes: Only problem with the borla is that there is no factory dent in it so my front ds mashes into it and is slowly denting it in (which in the name of clearence, is a good thing :roll: ) just my 2 cents EDIT: Oh and yea I agree with pingpong - gearing is key. :bowdown: Link to comment Share on other sites More sharing options...
Oizarod115 Posted August 12, 2006 Share Posted August 12, 2006 5-0 injectors don't spray more fuel than 4.0 ones do. theyre the same lb/hr rate. and 4/6=.666 5/8=.625 so the 5-0 injectors spray a tad less. Link to comment Share on other sites More sharing options...
DirtyComanche Posted August 12, 2006 Share Posted August 12, 2006 5-0 injectors don't spray more fuel than 4.0 ones do. theyre the same lb/hr rate. and 4/6=.666 5/8=.625 so the 5-0 injectors spray a tad less. Normally, you don't use the stock 5.o injects. They are however better because of the spray pattern. Link to comment Share on other sites More sharing options...
randimal Posted August 12, 2006 Share Posted August 12, 2006 The Mustang injectors are supposed to have a better spray pattern which supposedly causes more a efficient burn. Should actually improve economy and performance if that is true. But the amount of fuel they use is about the same. Link to comment Share on other sites More sharing options...
pingpong Posted August 12, 2006 Share Posted August 12, 2006 Southlake, The key to your statement was a 95 HO xj. You can "tune" the later 4.0's, but it is almost impossible to tune the early renix style comps. You might have noticed a small amount of lowend torque, but more then likely what you thought was more power was just your foot going into the throttle more :brows: Link to comment Share on other sites More sharing options...
ORCA Posted August 12, 2006 Share Posted August 12, 2006 pingping - That could possibly be. Infact, on the 88 4.0, I replaced the blow OEM motor mounts with poly ones, which also makes an engine feel more powerful (because it's more stable). But I still believe the borla has added some extra ponies. Granted it's probably not worth the 500-600 bones it'll cost you (unless of course your current manifold is cracked) Link to comment Share on other sites More sharing options...
Oizarod115 Posted August 13, 2006 Share Posted August 13, 2006 pingping - But I still believe the borla has added some extra ponies. Granted it's probably not worth the 500-600 bones it'll cost you (unless of course your current manifold is cracked) thas what i bought a 500$ welder for :D Link to comment Share on other sites More sharing options...
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