'90 4.0 how to increase Horsepower?

[lookin4fun_inca]

Well long story short, I picked up a 90 XJ with the 4.0 and has a bad engine. I bought the autozone stock type long block with the rollor timing chain set to replace the engine.

Well now what else Within reason can be done to increase the HP reliably? A few thoughts I had were....

*Keeping it More consistantly cool with a high flow WP and t-stat

*Cam, but how much honestly will this add and is it worth the lower vacuum?

*Electric fan

*Air filter tube, how helpful though is this?

*exhaust kit from manifold/header back, any experiences here?

Any insight is welcome an appreciated.

Thanks

[Jay5.9L]

I had a 90 XJ with the 4.0L. I put on a rusty's intake. jacobs omni pack and wires, and a borla cat back.

The intake helped a little but I realy could not tell a big difference

The jacbos stuff did jack sh*t.

The cat back did help some and did sound a lot better.

I have heard that headers will help.

[webjeep]

Probably want to move this to newb.

On the topic... None of the things that you listed are going to give you any noticeable power increase. Compression, fuel/intake modification, head work, stroke/bore and exhaust modification all together will get you some noticeable power, but there is really no such thing as cheap, easy, bolt on power.

If your 4.0 doesn't have enough power for you then look for an 8 or stroke your 4.0, but either way it aint gonna be cheap or easy.

Oh yeah, and hang on, cause this is probably going to get ugly soon...

[lookin4fun_inca]

Originally Posted by webjeep

Probably want to move this to newb.

On the topic... None of the things that you listed are going to give you any noticeable power increase. Compression, fuel/intake modification, head work, stroke/bore and exhaust modification all together will get you some noticeable power, but there is really no such thing as cheap, easy, bolt on power.

If your 4.0 doesn't have enough power for you then look for an 8 or stroke your 4.0, but either way it aint gonna be cheap or easy.

Oh yeah, and hang on, cause this is probably going to get ugly soon...

Well I didnt say not enough power, its just that a HO has what, like 20-30 more HP? so I was thinking that without doing the Intk, and TB as well as new Inj and fuel pump that if I could add small crapola on to it for that 20 or so HP then cool.

As for cheap easy, well there sure is on my SRT, the 69 'bird and most any other veh I ever owned. Mostly just opening in the Intake and exhaust seems to yield 20hp on most anything. So, thats what I was hoping to get an answer for. Hell for under 1K I yeilded over 120HP and close to 200lb/ft tq on the SRT...

As for ugly.. hell life is ugly for so many right now that I can take a little / lot of flamin for a while...

[crawlinyjeep]

how cheap do you want to go?? for a "cold air intake" you can go to kragen get some exhaust tube drill some holes for your computer junk then put on a cone filter the hole thing will cost about 40 bucks. and the real ones are suposed to give you 15 hp i think so you should be able to get like 10 hp i would think.
note i have never done this to cheap for me but i have seen it done

[YXwhenUcanFAB?]

Swap in a 440

[lookin4fun_inca]

Originally Posted by YXwhenUcanFAB?

Swap in a 440

That has got to be the WORST HP to wieght engine EVER produced! Expecially if you compare it to anything in the same cubie range. Hell my 2.4 4cyl makes more torque to the wheels even, then any street driven 440 I have ever personally seen.

but hey thanks for the thought

[Rattlecan]

The cold air intake, header, and cat back will give you power where you don't need it - top end ... I am guessing you have the auto tranny (most common in an xj)

if you want to notice the power on the trail - swap in some 4.88s or better and maybe a cam that is geared for more low end grunt.

Intakes and cat backs are great for imports - bad for Jeeps.

[lookin4fun_inca]

yes auto.. 34" tires and 4.10's with atlas 3.8. So gear ratio should be about perfect, or so currie and AA says.

I am more concerned with hill driving and not totally killing the highway speeds. so that combo should yield good compromise of both.

The exhaust I am thinking as well as maybe a port match for the int and exh will be the way I go. Maybe a cam, but like the thought of the 3yr engine warranty. so may not go with a cam.

I am guessing that theres no "secret" power gain method to this motor and to just run it and be happy...

[lookin4fun_inca]

WTF?? hy the hell was this moved to a General 4x4 forum when this is a JEEP specific question??

So next time someone ask about a JEEP tranny is getting moved here also? How gay.....

[ChaseYJ]

It was moved to newbie, and yep I'd guess it would in that case too.

To answer your question anyways just get a 4.0 head and exhaust manifold from a 92up YJ and call it a day. You'll see at least the 20hp you're looking for.