Topjimmyk

so i did a little looking around on the forum and could find anything. but i have a 98 and wanna upgrade the intake, so what year should i use. a 99? or anything newer. b/c ive herd in 2000 they changed the flange thickness so eventaully they start to leak. and also what about the sensors like tps, and cps, both need to be replaced on my jeep, can i use different years or just swap them out with the same year.

Gee oh Dee

I think the early 90s H.O. motors have the better intake manifold, but I could be wrong.

Why do you need to upgrade?

And if possible I'd get new sensors from Advance Auto or Autozone.

Topjimmyk

Just for the sake of an upgrade. I want to purchase a header and some neon ejecters in the future. So any intake 90 and above are the same?

mark's91-XJ

'99-Up Horseshoe Intake
Myth: According to that great wealth of information that is never wrong, the Internet says you'll get a 5-30hp gain thanks to the '99-up 4.0L's swooped, equal length runners and larger plenum volume.
Our Thoughts: While a free-flow intake manifold can deliver more power, it's only going to allow as much air to flow as the cylinder head and camshaft will call for. Upping the intake runner volume too much will cause the intake charge to lose velocity, killing low- and mid-speed power and torque. On a '98-earlier engine running a stock camshaft and unported cylinder head, it's wasted effort.
Claimed Gains: 5-30hp
Actual Gains: 5hp loss on Trasborg's '98 XJ (Project Mileage Master)

Topjimmyk

Well thanks for the info. I might reconsider this. I've herd people say they accualy noticed a big difference. But had horrible city gas mileage. And that explains why.

Irongrave

pull the silencer/restrictor out of the factory box and run a good clean air filter (no K&N) that will get a little more air into the motor. beyond that no real point as the XJs flow well on the intake side.

Topjimmyk

Currently I do have spectra cold air, In a home made box. Well I think I will just go with the neon injectors and leave it at that. Unless those arnt worth the effort

TrekkerJmm

1 hole spray vs 4 hole will give you more low/top end and atomize the fuel better...Tj

Gee oh Dee

As well as smooth idle a bit.

s14unimog

yeah, I don't think you can go wrong with the injector "upgrade", as long as you source the correct ones...

Hoooper

This is why you have to be careful with the "great wealth of information online", alot of it is wrong or incomplete. This manifold has shown good stuff on pre-1996 4.0Ls. If you have a pre-1996 and non-HO, this will be a lot better than on, say, a 1998 like the one tested

N20jeep

im going to need a lot more info than that 1 little paragraph before i give that test any kind of credibility.

el_roy1985

I'd also need some more proof. What if it was something else they did that didn't like the intake. Maybe the computer simply hadn't gotten used to it yet or another one of there parts went bad. I read all I could find on that "project mileage master" (Which I could not find the actual part that talked about the intake, btw) and at several different stages of the project, they had parts go bad. Which caused loss in performance after adding parts they expected to help with mileage.

I'll be doing the 99+ intake in the future, so if I get a chance, I'll dyno it to get more results on whether it helps or not. I might want to do a header at the same time though, depends on how hard it would be to do the header, dyno and then do the intake and dyno again. Not really a fan of pulling things a part more then once.

Topjimmyk

I have a concern to, not claiming that it will increase power. But if the same motor is put in all jeeps 96 and newer. Then how does an intake that's on all 99 models which is designed to be more efficient, negativey effect the motor in a 98. If there the same exact motors. Correct me if I'm wrong B/c I really don't know enough about jeeps to claim that they are but rnt they pretty much the same?

96_xj

it is from JP magazine. they did an entire spread on it. 3 parts.

http://www.jpmagazine.com/techarticl...ies/index.html