rich

most of the stuff they used was stock------header was a true small adder catback was an adder,you change gears of course that will help its an article in JP magazine for november.Guys read it before you just go off with oh thats wrong my cousins brothers sister said it will work. i gave an answer from poeple who get too test this stuff day and day out and who have acess too stuff we dream about . common sence used too go along ways i guess maybe it got shorter,

Programbo

OK..Show me where in this article it specifically talks about them testing swapping out a new style intake manifold onto a pre-1999 4.0 and I shall be more than happy to admit I`m an idiot who has no common sense...BTW I would think the engineers at Jeep who redesigned the intake manifold in 1999 to replace the power lost by all the emissions control requirements might know a bit more than the guys at JP magazine.

VAXJCOUNTRY

Well, I want to agree with you but I'm still on the fence. The point another poster made about this over on another forum was that it was designed as part of a total package. His claim (like everyone else's) isn't backed up with any hard fact but he states the intake is only an upgrade if used in concert with other mods. Specifically a cam I think he said. Because "the engine can only use as much air as the cam allows so giving the runners more volume without changing the cam will not do it any good...might even hurt it due to the loss in port velocity." I come from the world of 4-banger turbo fwd mopar so in my mind a better flowing intake is ALWAYS good. But I suppose that isn't really the case on a tuned EFI naturally aspirated engine.

Is JP mag a good magazine? I don't read 4x4 rags ever because they just make me angry with all the money they spend on baller stuff I can't afford. I don't like how they do not explain any of their testing info in the article...they just say "we've done this for years, trust us." Well I want a real before and after dyno test. With the only part being changed being the intake manifold. I think that is the only way we will know for sure what it does or does not do for mostly stock 4.0. Maybe an extra set of runs using a CAI. I was going to do this swap tomorrow...I have yet to be convince it is a good idea.

Does anyone know where "the engineers re-did the intake to make up the horsepower" comes from? Was that a reliable source?

Programbo

I`ll do some Google searching tomorrow and find the info for you as I`ve read many a review of the 1999 Jeep and this was one of the improvements it mentioned over the 1998 model and they all stated the stricter emissions regulations were the cause. I can at least say for myself I noticed an increase in acceleration after I made the swap in my 1994 Cherokee and after a 500 mile "before" and and "after" test covering the exact same route my mpg (HWY) increased by 2.7 mpg. City mpg seems horrible though....But it seems to me your whole skeptism is based on this JP magazine article and it`s mention of "intake" not being worth the upgrade. I`m sure they are just referring to air intakes and not intake manifold swap..After all anyone who runs cars on a 1/4 track can tell you that one of the first things you do to any muscle car is to upgrade the intake manifold to a more high-flo version to increase HP/torque...Or are the guys at Edelbrock full of it too

JeepCoMJ

*sigh* gojeep is the one who's posted the most info about it.

you guys are being a bit edgy about "facts" etc.

rich

*(Programbo)* no ones an idiot each motor is most likly different from the other in certain ways thus make stuff not jive right. But if you want too be an *idiot* who am i too stop you.like i said it was in an article in jp mag page 60 4.o liter myths and legends. Some people just cant get it.all i did was let others know what they wrote.so read before you speak .i quoted and article hoping too save people money before they listened to some half wit with all the answers that are most likly wrong.if you want to just throw parts on go ahead,and this not written just too try and put you down in any way or anyone else for that fact. (remeber jp magazine 4.0 liter myth and legends page 60) not facts from *rich* i quoted a magazine lets read it all before we jump the gun. and a race motor big differance than the 4.0, ive put a eldbrock intake and carb on my 85 dodge p/u 360 new rebuild great differance just remeber ports have too match pretty well for and increase,i think the eldbrock carb sucks though got a recomendtion for a small block 360 mild cam headers ,sick of hollys too over priced.Read Read Read makes you smarter,plus helps you not look like and *idiot*.good luck we all need it just some more than others.

JeepCoMJ

HUH MY CAPS IS STUCK TOO. JP MAGAZINE DOESN'T KNOW HALF OF WHAT THEY'RE TALKING ABOUT imho....THE OTHER HALF IS GOOD INTEL. UNFORTUNATELY IT SEEMS YOU'RE TAKING THE BAD HALF.

LET'S SEE....INCREASE AIR FLOW VOLUME IN INTAKE TWOFOLD....of course you will see increase.

putting a 2001 manifold on your 4.0 is no guarantee that you will see increased mpg...but it's not all about mpg. it adds power and torque through a superior volume of air capable of getting to the engine, and much better air flow through the superior smooth flowing design of the 2000+ manifold.

I can personally attest to the fact that my mpg stayed roughly the same (about .5 to 1mpg better) after this swap. that said, I also did a complete 95 H.O. conversion to my 87 MJ at the same time...

now, H.O.'s are notorious for getting worse mpg than a renix, and seeing as I was getting 17 with my renix and I'm now getting 17.5-18mpg local (and yes, I calibrated my speedo PERFECTLY). I'd have to deduce from that fact that I actually increased the H.O. motor's economy by at least 2.5mpg.

as for power...I cannot attest to the difference in power by adding the 2001 manifold to H.O....as I did not drive the truck with the H.O. in it before I did the conversion. of course, being bored .030 and the fact that it's a brand new (factory bored reman) engine...that makes alot of difference.

BTW, with 35x12.50 mud terrains, on a d30/d44 combo with 4.10 gears, I manage to get around 20-21mpg on the interstate, if I cruise @ 70mph. on a truck with 6.5" lift I'd say that's pretty darn good.

so maybe it's just me, the quality of the parts I built/installed, (or pure dumb luck???...yeah right) but the facts point to the intake swap being a very productive and economical decision.

JeepCoMJ

oh, "too" should have been "to". if you had said "if you want to be an idiot too" then you would have used the word "too".


random fact...in mid 1999 they had to swap to this manifold to meet more strict EPA standards...to meet them, they had to decrease the exhaust port size by roughly 20%...the result was a loss of roughly 15hp. to fix this, they went with coil-on-spark plug coil packs, basically a nice MDI ignition, and they had to increase the volume of air getting in. ironically, they ended up making *more* hp than the H.O. was previously rated at by doing so.

so...using the newer style intake manifold on an older style head with the free-er flowing exhaust ports, it's easy to deduce that you will see an increase in power, torque, and very likely fuel economy.

remember, fuel economy is about power to weight...having the engine be smaller or "stock" doesn't necessarily mean increased mpg. our unibody/uniframe xj's and mj's are light for their class, and adding power to the existing drive train will likely NOT result in loss of mpg. heck, the guys on jeepstrokers.com use this intake manifold with a stroked 4.0 and manage 24-26mpg on their jeeps.

another side note...I have a buick 3800 in one of my comanches and regulary get (got...before It got hit and the motor sucked something into a rod bearing) 24mpg when I'm abusing it. when not abusing it, I get 29mpg or so, and I max out around 32mpg on an interstate-only trip. it puts out quite a bit more hp and torque than a 4.0, but again...power to weight.

VAXJCOUNTRY

Ok lots of info flying around here. Let me clear up rick's crazy posting about the JP article. I went to B&N last night and read page 60. They say basically the 99+ intake on a 98- vehicle is a waste. They don't say how they tested this. They say it lost them some hp "3-5" on their "mile master project" Well I got online and read the mile master project files...all 3 parts. They mention NOTHING about testing this intake as part of the project. So I still don't know how reliable they are. Further I am not basing all my scepticism on JP because I have read other places on-line that it only works when doing other mods. It makes sense to me just thinking about it that it will increase power, but a lot of things that make sense in your head don't work out at the end of the day.

Let me put it to you this way though. My girlfriend is a professional horse trainer. She knows a **** ton about horses and has her opinions on certain things. She regularly reads the most trusted magazines for the horse business and finds tons of things in there that are "wrong." Tons of things that are "how can they say that..." So I look at JP in the same light, I suppose they should be no more trusted then the internet.

rich

yes lets clear it up i used and article for info for someone so sorry ,too try to help seems you two know it all (Jeepcomj and vaxjcountry) the floor is yours, you just let us know what we can and cant do and we will follow the words of the self proclaimed gods of jeeps.sorry to interfear and give the guy and article to read before he maybe spent his hard earned money on something that may or may not work.I wont give info that im not sure of just things to maybe help out someone, thats why i gave the mag the article the page and the month so he could read it and go from there. plus i just gave a quick brake down of what (they) (not me) said. i dont have half the stuff they went over on my xj so i dont really know for sure (there said that again) so sry for trying to help almighty jeep gods. yup stupity is a right to bad some people abuse their rights im done with this post you guys are just to smart(yeah right) all yours now.

Programbo

Yeah overall my mpg stayed the same which is why I stressed the HWY part..It actually seems as if my CITY MPG went down a LOT after the swap but as mentioned, on several long trips which were 90% HWY my MPG went up near 3 MPG..So if your someone who drives a lot of long highway trips (I`ll do 250 miles today) it paid off

VAXJCOUNTRY

Rich,
I'm not trying to say I know more then anyone here about this. I am actually claiming to know the least and wanting to know all I can. I really appreciate you giving me the info I needed to find the article. The problem becomes when you claim to be simply providing the info when actually (rather poorly) attempting to provide an analysis. You just say "They must know what they are talking about, so I would never do an intake" and thats it...I am of course paraphrasing because your posts are hard as **** to read.

ANYWAY. So here we are. Does anyone have any idea why the last poster would see a drop in city MPG? Thats the very last thing I need. my city is already around 11ish and my average 14ish. I drive around town way more then the highway.

Imabodybuilder

Jamie57

I've stopped reading your posts.
They're too hard to read. Try English, grammer, and some punctuation. Oh yeah and some spelling too.

Jamie57

It depends on the header manufacturer.
If you do a search on here there is one where someone explains which ones need modifications and which don't.
Remember search is your friend.