Engine Swap 4.7 Stroker vs 4.0 Replacement!

[chrs93]

Ive got a 90' Non HO 4.0, automatic tranny w/205,000 on it. I'm going to go ahead and replace motor w a rebuilt motor. My question really is simple should I replace my stock 4.0 w/ a rebuilt motor of the same size or should I opt for 4.7 stroker. Just looking for pros vs cons, opinions,etc.

[Pookapotamus]

that's a tough question Chris, how big is your jeep? what tires are you running? what is its main purpose?

I personally love my stroker, even though it has not made it over 5000 kms on every rebuild! (don't ask, lets just say I have had issues!)

A relatively cheap 4.6 stroker will liven up a heavy lifted jeep, mine weighs 5000lbs and runs 33" tires with 410 gearing, its no sports car but I can at least pass on the highway and not have to drop down to 80 or 60 to climb a hill. off road its an absolute blast!!! Gas mileage is not super horrible but you will definitely notice it!

if your are stock and just need a new motor the 4.0L has lots of power, but if you want to roast the tires off your stocker, or are planning on going big soon, the stroker is a great option.

reading your post it says you don't have the high output, even getting a newer high output to put in would be a nice upgrade if you are stock.

I know this does not really answer your question, give us more info and we can advise further.

Pook

[chrs93]

Currently I'm only running 31" tires. I will be upgrading to at least 33 when I wear these out. 90% of the time this is a daily driver. I only drive about 20 miles a day. So gas mileage isnt a huge concern. I need this jeep to be a DD and a toy. I just feel like my 4.0 is under powering the jeep. Now that might be because its got over 205,000 on it. I could drive this engine to the end if necessary, but I figure if I'm going to swap. I might as well consider more power. I was unsure if a 4.7 was a direct swap with 90' 4.0 or not. From what I've seen a lot changed 91 and newer. Just dont want to get into something that is not going to reliable or more of a headache that the extra power is worth.

[4.3LXJ]

Chris, 205K is not that high a milage on these engines. I think a couple of things you can do to liven it up that you could reuse on a stroker is the HO head and the 00/01 intake. That alone will add at least 30 hp and probably more. That combo is analogous adding good heads and intake to a Chevy V8

[chrs93]

I agree w your assessment. I guess I was under the impression that 91" and newer intakes and HO head wasnt a direct swap on the Renix non HO motors.

The only reason I'm even looking at swapping motors, other that power issues is I have a pretty good oil blow by issue thru the CCV system into stock airbox. I have already pulled, cleaned and did a mod on valve cover as well as replaced all CCV grommets and lines and I'm still having this issue. I havent done a compression test as of yet, but I'm under the assumption that I have excessive piston/ring gap and thats my problem. So in short, If I've got to rebuld might as well swap.


.....Thoughts

[4.3LXJ]

Do your compression check and make sure the rear line from the valve cover to the air box is completely clear. As far as strokers go, one thing to take into consideration is passing smog. Lots of guys have done strokers in CA and cannot license their rigs because the strokers wont pass. The Jeep ECM doesn't seem to be too bright

[chrs93]

I definitely will. Thanks for all the input. One last question or two. Now youve got me thinking maybe a 4.0 with a newer intake an HO head might be the way to go to. Do you recommend a head off of any particular year of 4.0? I know you mention 00' & 01' on the intake man.

[4.3LXJ]

I can't remember which head is considered the best. Seems like 96-7. But better confirm that. Matching the 00/01 intake up requires a little porting on the head since it flows so much better. You just have to match the ports to the gasket

[chrs93]

Doesn't the newer intake support larger TB or does it use the smaller one thats on mine? Hmmmm?

[Pookapotamus]

the best head is the 7120, cant remember what year they came on, but there are lots out there, the newer intake comes with the 58mm throttle body, the small one, but can take a larger one.

if I remember right, the renix put out something like 140 hp and the high output was 190 hp, definitely a bump up, and probably a great choice for a daily, cant remember if you need to swap in the wiring for the high out put vs the renix though.... anyone know??

Pook

[4.3LXJ]

What I would do on that is transfer all sensors to the new intake. If you have to drill and tap, do it. Then you will not have to change anything else. Also, I would use the original throttle body with sensors and IAC, only bore it, or get one already bored. With all that stuff you should be hitting at least 210 hp

[XJ Wheeler]

Not sure you could put a renix tb on a ho intake. Very different mounting points. Plus the renix tb is much smaller. The renix engines were rated at 177hp.

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