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99+intake

9

98xjlimited4.0

NAXJA Forum User
Location
illinois
Ok..I have read lots of info on this swap...everywhere from it loses power...no difference...to big difference.. I put a 2002 intake on my 98...WOW!! What a difference...I used stock injectors from the 98...power is smoother and it seems less throttle is required for acceleration. I do have a cone style air filter mounted above valve cover with a cowl induction hood...but I had that with the stock manifold so its not a factor in what I noticed..now I have a 6.5 lift with 33's, winch bumper, winch and 4.10's...which also was on there before the swap..I feel acceleration is at least the same or a touch quicker than stock weight and tire size..also stock form I was getting 20mpg avg... with all the mods except manifold it was getting 15mpg avg...and now getting 17mpg avg with the swap completed...I got the manifold for $40, so I figured on taking a chance...glad I did...maybe the people doing the swap that say it lost power just screwed something up or something... I don't knoow...it was well worth it to me
 
how did you determine the gain in fuel economy?

im going to play devils advocate here, but not because i dont want your claims to be true. i have a ported '99 intake i plan to put on my '97 along with a 60mm throttle body (stock is 58mm, i just milled off the "step" strait through to the bottom) and hope to see gains myself. but it sounds like your using the "butt dyno". when someone installs a new part, they swear it made a difference.

do you have any real number figures to back up your claims? explain where you got your numbers from.

:wave:
 
ok... driving in the same conditions? all highway driving or mixed with city? same path/destination and weather conditions (head winds are horrible with our brick of a vehicle)?

there are a lot of variables... i could get 300 miles with a tank, i could get 100 miles with a tank.
 
VAhasnoWAVES said:
ok... driving in the same conditions? all highway driving or mixed with city? same path/destination and weather conditions (head winds are horrible with our brick of a vehicle)?

there are a lot of variables... i could get 300 miles with a tank, i could get 100 miles with a tank.
Click to expand...

did you travel in the exact same lane? was it the same time, like rush hour vs. 2am?

C'mon, think about the actual reason there is a different manifold in a 99 vs. a 98... Jeep had to raise the HP back up to 190 because it was lowered due to EPA changes for that year (at least that's what I remember the article saying), so of course the part to raise the HP back up will benefit the vehicle that wasn't crippled in the first place... at least that's my theory.

I really want to do this mod myself, and I'm glad you did and reported back. My jeep is pretty much stock, so when I do, I'll try to do some before and after testing to confirm... or affirm I'm an idiot.
 
did this swap on my 98 and noticed zero diffrence, its also got bored tb and catback
 
ROBZ95Xj said:
did this swap on my 98 and noticed zero diffrence, its also got bored tb and catback
Click to expand...
see, there are too many conflicting stories to not be skeptical.

like i said, i have mine sitting in the garage at home. if i can get some dyno time, id like to get a before and after shot to get hard numbers. also, more HP means more fuel and power, it does not directly translate to better mileage.

again, to the OP... NOT BASHING. just being conservative.
 
Yes I travel the same all the time...same roads same lane...since they are only 2 lane streets...also I live where the roads are mostly flat....I only spent $40 on this manifold...so my but dyno doesn't HAVE to tell me it made a difference...it was kind of a slug before I changed it...not peppy at all...for some who say it helped you none....well...I guess...that sucks maybe something else is messed up on yours...I don't know..mpg was miles divided by gallons...numerous times...I am a mpg freek...as in I moniter it on all my vehicles religously...I have absolutely no reason to bulls#%@ anyone here...this is my experiance with the swap.. Remember I stated I was skeptical before I started the swap...I really was expecting nothing...but had to see for myself since online reprorts seem to be 50/50...to be honest...if it made no difference I would have wrote about that too..
 
98xjlimited4.0 said:
Yes I travel the same all the time...same roads same lane...since they are only 2 lane streets...also I live where the roads are mostly flat....I only spent $40 on this manifold...so my but dyno doesn't HAVE to tell me it made a difference...it was kind of a slug before I changed it...not peppy at all...for some who say it helped you none....well...I guess...that sucks maybe something else is messed up on yours...I don't know..mpg was miles divided by gallons...numerous times...I am a mpg freek...as in I moniter it on all my vehicles religously...I have absolutely no reason to bulls#%@ anyone here...this is my experiance with the swap.. Remember I stated I was skeptical before I started the swap...I really was expecting nothing...but had to see for myself since online reprorts seem to be 50/50...to be honest...if it made no difference I would have wrote about that too..
Click to expand...
:thumbup: power to you man.

curious... how many miles do you get off of a full tank with 4.10s and 33s? do you have a new speedo gear or is it all done by GPS?
 
The speedo matches the readings on the gps. The speedo gears for stock tires and 3.55's is the same for 33's and 4.10,s. I reset the trip everytime I fill up and divide that by the gallons I use
 
I've also done this swap with an APN header and it works well if you have the supporting mods to go along with it (enlarged TB, cai, catback/highflow cat).
 
Well I have been working on engines for the past 20 years...camaros and firebirds,atvs and motorcycles...I have had my fare share of buying something that didn't seem to do anything when there were claims that it was supposed to. All I know is this mod DID to MY jeep. I don't have stock in 99 and up manifolds, so I have nothing to gain with my claim here. There is definately a difference in the response and smoothness. Maybe not all jeeps are created equal...who knos...I say if you get one cheap enough give it a shot..only took 2.5hrs to change and $50 with gaskets..just don't expect to lift the front wheels when leaving a green light...LOL
 
My 99 classic is quite a bit slower than my 91 briarwood was. Think about how an engine works. The intake might be helping a little, but it won't make a big difference in how you feel in the driver's seat. Certainly not 2 MPG. But that is just my opinion.

Ben
 
chpmnsws6 said:
Your full tank and my full tank could be several gallons different.
Click to expand...


Good statement. Some people will overfill their tank and run the XJ until the low fuel light come on for a full tank. Others will fill until the pump stops and refill when the guage reads 1/4 full. That's their idea of a full tank. The differrence in the amount used per fill up could be as much as 5 gallons.

I too have 99+ intake that I plan to install when I return to the US along with a new exhaust header to replace the leaking one that is there now. Maybe I will see some gains via the butt dyno,...maybe the gains will be all in my head because that will be what I want... :dunno: . The manifold cost me about $10.00. The only additional cost to me will be a gasket and a few hours of my time if I descide to go back to the pre '99 manifold.
 
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