Went to the strip! Kind of... ok not really. WJ vs XJ!

[PurpleCherokee]

My buddy just got his WJ put back together after rebuilding the motor and getting it broken in.

It's a 4.7 non-HO. He's got a CAI on it and he also updated his valve seals to boost compression (apparently there was somewhat of a problem with the original seals on those motors that contributed to some compression loss).

My jeep is a 2000 4.0 of course with intake, bored TB, map adjuster, 160 t-stat, headers and exhaust.

So we lined up last night just for shits and giggles. For those of you that don't know, that particular WJ is good for a fairly easy 15.5 stock, or at least with a new motor with a little more compression and a CAI. Holy shit I've never seen a closer race. From 0-90 there was never more than a fender's difference between us and when we stopped at 90 we were dead even. I was pretty shocked and happy. I've always wondered/hoped that my jeep was in the 15's, so I was VERY pleased to know that there's a good chance that I'm deep into the 15's

I pulled on him the most from about 55-75... not normal for a 4.0 :firedevil. I attribute about 80% of my performance to the headers and exhaust. Obviously I felt more of a power increase when I got the headers and exhaust because all the other mods were already done so they complemented the system and I gained more than I would've from just adding the headers and exhaust to a stock motor. I've got a LOT of flack for my exhaust set up from a bunch of dream crushers and tree hugers (oops, I'm not really anti-earth, I just think that a lot of it is hype and sensationalism). But for those of you that dont' know, it's a DUAL outlet shorty Clifford header with 2.25" DUAL pipes with a set of straight through resonators and a straight through x-pipe cased muffler and NO CATS.

 

[kcjeep6]

Put the Cats back on, I have to breathe!

 

[GrimmJeeper]

me too! and... dual exhaust exiting on the same side of the jeep... :roflmao:

 

[j99xj]

Well my WJ racing story doesn't have a happy ending like yours.

A few years ago when I raced my brothers 4.7 HO, he killed me, and he had 4 people in his Jeep! I was alone driving my XJ with the same mods as you.

He took me by at least 4 Jeep lengths.

I guess the 4.7 HO is really that much better than the regular 4.7.

 

[PurpleCherokee]

The HO is only +30hp and +30 ft.lbs. Which is a lot, but not four jeep lengths lol.

 

[j99xj]

Well he was 4 Jeep lengths ahead.

It might be more than just the extra power. I think the GJ Overland models had a 5 speed transmission (auto).

Supposedly they had a lower than normal 1st gear and "super second" that was designed specifically for power.

 

[Hellbent]

i've driven both the h.o. and non, the 4.7 h.o. is a BEAST. pulling the grades going out the 8 to ocotillo, it passes people like a land rocket. she's bone stock and i can't keep up with it with my xj: fipk, bored tb, header, jet chip/180 stat/runs on super, catback, etc.

 

[JJacobs]

My buddy just got his WJ put back together after rebuilding the motor and getting it broken in.

It's a 4.7 non-HO. He's got a CAI on it and he also updated his valve seals to boost compression (apparently there was somewhat of a problem with the original seals on those motors that contributed to some compression loss).

Valve seals have nothing to do with compression-

 

[GSequoia]

Valve seals have nothing to do with compression-

Whatever.

Hater.

He totally knows what he's talking about!

His XJ does, like, 15's!!!!!!!

All becuase he has none of those stupid cats.

I mean it's not like he could possibly run them and get the exact same results.

:looser:

 

[wolfpackjeeper]

Valve seals have nothing to do with compression-

I was wondering when that would get picked up

 

[j99xj]

Valves with carbon deposits or severe pitting can leak compression. But I find it hard to believe that a modern engine like the 4.7 would have a problem like that from the factory.

A good 3 angle valve job helps flow but doesn't do anything for compression.

 

[wolfpackjeeper]

Valves with carbon deposits or severe pitting can leak compression. But I find it hard to believe that a modern engine like the 4.7 would have a problem like that from the factory.

A good 3 angle valve job helps flow but doesn't do anything for compression.

he said valve seals though. Those are the little rubber caps that go around the valves and keep oil out. They will not do anything for compression.

 

[JJacobs]

Valves with carbon deposits or severe pitting can leak compression. But I find it hard to believe that a modern engine like the 4.7 would have a problem like that from the factory.

A good 3 angle valve job helps flow but doesn't do anything for compression.

Valve seats directly affect compression. Seals are on the other end of the valve and don't affect it.

 

[toplessxj89]

i didnt know wj's ran in the 15's lol was it a 4x4? my grand prix gtp ran 15.4 in the quarter and theres no way a wj will hold a candle to it

 

[wolfpackjeeper]

the 4.7ho's are as quick or quicker than your gtp. that is a great motor/application match up

 

[PurpleCherokee]

i didnt know wj's ran in the 15's lol was it a 4x4? my grand prix gtp ran 15.4 in the quarter and theres no way a wj will hold a candle to it

Not exactly.

Those numbers a pretty damn quick for a stock SUV.

The old valve seals most definately did leak compression. You could hear it pretty easily. But my point wasn't that fixing leaky valve seals would net a lot of horsepower, or any. Just that the motor should've been running strong, so that with CAI and someone who knows how to drive, it should be running a strong ~15.5 or so.

And you probably could run a 15.5 with just intake and exhaust and still keep your cats. Probably... maybe... I dunno, I haven't seen it yet. But the cat delete was really just a small part of my exhaust design. So you guys can hate all you want I don't really care, I just posted this to those of you who don't get off on criticizing everybody else's junk. But you can't argue, my set up... works.

 

[GSequoia]

The old valve seals most definately did leak compression.

That would make perfect sense if the valve seals actually sealed compression. They don't. The valve seats seal compression, not the valve seals. Somebody has been bullshitting you.

...I just posted this to those of you who don't get off on criticizing everybody else's junk. But you can't argue, my set up... works.

Don't post up if you can't handle being criticized for mods that are not well through out let alone, if I recall, federal crime.

 

[Talyn]

The old valve seals most definately did leak compression. You could hear it pretty easily. But my point wasn't that fixing leaky valve seals would net a lot of horsepower, or any. Just that the motor should've been running strong, so that with CAI and someone who knows how to drive, it should be running a strong ~15.5 or so.

The compression is all in the cylinder, not past it into the valve pocket, nor the guide. While the valve seals may have been leaking (maybe exhaust gas??), it wasn't from the compression in the cylinder. Usually when a valve seal leaks it causes burn oil to be put out the exhaust.

 

[Talyn]

So you guys can hate all you want I don't really care, I just posted this to those of you who don't get off on criticizing everybody else's junk. But you can't argue, my set up... works.

1) put your cat back on
2) Your exhaust and header will not have let you pull on a 4.7L. His engine obviously had problems to begin with.

 

[PurpleCherokee]

1) put your cat back on
2) Your exhaust and header will not have let you pull on a 4.7L. His engine obviously had problems to begin with.

Lol, the motor was JUST rebuilt and broken in. It was running as well as a stock 4.7 ever will. I also raced another 4.7 before I got my new fuel pump and lost by about half a length to about ~50.

All I know is the mods that my jeep has and the mods that his jeep has and that we were dead even. Be in denial if you want, I don't care. I don't mean that to sound mean, I just honestly don't care. I just thought I'd let y'all know to add to the general knowledge base on the forum cause to my knowledge, noone has used an exhaust set up like mine.