Metlic53

Alright, i have a 1997 XJ with 150k miles. Friend has a 2001 XJ with 80k miles. My xj had on it originally 31 bfg tires with aluminum wheels and 3 inch lift. went to a jeep jamboree in Louisiana so i put 31.11.50 tsl super swampers on heavy 10 inch STEEL cragers. He has a 4.5 inch lift with 32.10.50 Michelin street tires on aluminum wheels. Everything on both motors was stock except for CAI. My XJ was loaded down way more than his and i still smoked him in a race from a dead-stop and from a roll on the highway. both had same gears 3.55's. Now his XJ has the bigger intake in it (which supposedly puts out more HP) so why did i beat his XJ?

Moparboy01

Well first off, you put this post in the wrong section. As for uprading you intake what do you mean? Do you want to upgrade your air intake or your exhaust manifold. I honestly would stay away from doing that cuz JP magazine put out an article, I believe last month's issue, it was called 4.0L myths. They talked about the whole swap and said that they actually lost horsepower. I did that whole swap on my 98 ZJ with a 4.0L and actually noticed a lose in hp as well, that is why I am planning on putting the stock one back on and leaving it. If you would like to beat your friend, dont do the whole swap and add a cold air intake, headers, exhaust and a high flow cat. But last time I checked, Cherokees are meant to go offroad not street race but thats just me.

VAXJCOUNTRY

JP mag is a joke. That article is contradictory in certain places to other articles they have put out so I call them BS. They say TBs are a no gain then in another article in an older mag talk up a TB. Its all about money. From what I have read and seen the manifold is best upgraded as part of a total package including exhaust and intake system (filter and pipe) As to why you beat him in a drag race? You got a better draw on the light? His engine needs a tune up? All kinds of things...the intake is not the only variable.

Also, @ MoparBoy...how do you "notice" a drop in HP? ButtDyno does not count. Did you strap it to rollers?

XJSETH

jeeps+street racing=

Moparboy01

Vaxjcountry, when you are an ASE certified mechanic for Jeep and worked on 4.0Ls for about 8 yrs now, you notice those types of things without going to the dyno machine.

VAXJCOUNTRY

Lol wut? You must think you are the only technician on this forum? Maybe the only one with magical SAE ninja butt dyno Maybe you earn your magic powers at 8 years? 5 might not be enough... Anyway, the only real FACT in this thread is that no one knows anything for sure. No one has ever booked a Dyno and tested just the 99+ intake on a 98 or older engine with NO other mods. If someone has those dyno sheets I want to see them. Local place said they would let me on their rollers for $100 for 4 runs to do 2 baseline and 2 after installing the intake on my stock 97. I'm to cheap for that. So until someone has the loot or the time to do it the right way everything anyone says (including that rag JP) is just opinion and speculation.

milmat1

No two engines are the same........

You beat him because your motor was breathing correctly WHY mess with that?

You do not create a fast car by adding Performance parts and money to it, You build a fast car by focusing on whatever is limiting it's performance. Sure a different intake might make improvements IF that was the Limiting factor in your motor. But I doubt that is true.
Focus on what is holding it back ! Thats how ya build a fast motor !

VAXJCOUNTRY

+1