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Renix top end on 97 block.

T

Tedmon1967

NAXJA Forum User
Location
Libertyville IL
Hey all! I'm new here so thanks for the add! My 90 xj started smoking out the tail pipe so it's time to get some interior engine work done. My buddy has a 97 4.0 that he will give me to, but I know swapping all of that over can be a hassle. But I had a thought. Could I take the 97's short block and bolt up my top end renix system to it? I'm trying to figure out my quickest option to getting my jeep back on the road because it's my daily. Any info or advice is greatly appreciated! Thanks!!
 
If you can keep the head + I would, many of us have done renix to ho top ends. Going the other way you're losing flow.
Issues you'll have to adapt to are, fuel rail (I switched to AN fittings) TPS adapter (couple nylon washers and screws with a little dremel action) and you'll need a newer throttle cable.

I'm running a 7120 head, 99+ intake, 91+ header, 91+ TB, early 90's block, everything else renix.

The renix head is crap and the tb is crap.
 
And your head may be the problem in the first place and you may need to fix it regardless. No point in pulling the block if the head's the problem anyway, right?
 
Well it just reached 405k when the blue/white smoke started coming out. I thought it may have been valve seals, so I did that and cleaned up the head and there was smoke still. I assumed it was piston rings or something. I just don't really have the time to deal with going to a machine shop and redoing the short block. I assumed that I could just take the block from the 97 and throw my renix top end on it. I'm not worried about getting tons of power and stuff like that, it's just my daily. If I need power I will just drive my Duster lol
 
It isn't the perfect solution but it will work fine and everything will mate up, the HO cam isn't optimum for an Renix system.

I've had a Renix head and manifolds mated to 1996 block in the red Jeep for the past nine years.
 
Just hang onto the 97 parts and prep them to swap at your leisure.
 
Tedmon1967 said:
Hey all! I'm new here so thanks for the add! My 90 xj started smoking out the tail pipe so it's time to get some interior engine work done. My buddy has a 97 4.0 that he will give me to, but I know swapping all of that over can be a hassle. But I had a thought. Could I take the 97's short block and bolt up my top end renix system to it? I'm trying to figure out my quickest option to getting my jeep back on the road because it's my daily. Any info or advice is greatly appreciated! Thanks!!
Click to expand...

It's NOT a hassle. super easy.

http://cruiser54.com/?p=100
 
AIbandit said:
If you can keep the head + I would, many of us have done renix to ho top ends. Going the other way you're losing flow.
Issues you'll have to adapt to are, fuel rail (I switched to AN fittings) TPS adapter (couple nylon washers and screws with a little dremel action) and you'll need a newer throttle cable.

I'm running a 7120 head, 99+ intake, 91+ header, 91+ TB, early 90's block, everything else renix.

The renix head is crap and the tb is crap.
Click to expand...

Nah.....

HO myth buster


Renix in 90 made 182 HP. HO in 91 made 190 HP. That's 8 HP difference.

HO only made more HP than Renix at higher RPMs and not a bit more torque. HO had a 58 mm throttle body versus a 52 mm throttle body on a Renix. That’s 20% more air available through the HO throttle body. The HO also had a better design header. See where I'm going with this?

It’s only a 4% horsepower increase…..

The whole 8HP was not mostly from the head, but from the bigger TB and better exhaust manifold.

Put a 60mm TB from www.strokedjeep.com on your present manifold using the Renix head, eliminate the "crush" in your headpipe with proper re-routing, and go for it.

HO stands for Highly Overrated.
__________________
 
IIRC, there is a difference in the matchup of the early head to the late model block. I seem to remember a hole in the back of the head that didn't go through on one of the heads/blocks and that a gasket had to be modified or some such thing. That was some years ago, so do some searching on old threads.

My understanding about the different horsepower was mainly related to a different cam. They moved the power band up to a higher rpm which isn't necessarily the best for crawling.
 
The only difference as far as head match up goes ... Is later heads (0331s so not an issue here) had dowels for alignment. But just the holes were block side, pins were in the head. I have a 93 head on a 2000 XJ HO block (so it's a 98 casting) and a 92 head on an 88 Renix block. Very little changed over the years on the block, headgaskets were the same for both swaps, box stated compatible from. 87-06 4.0s (Felpro).
The last gen 4.0 did have several changes but they were never dropped in an XJ (1999+ castings only went in the WJ and TJ).


Sent from my SGH-I337M using Tapatalk
 
cruiser54 said:
Nah.....

HO myth buster


Renix in 90 made 182 HP. HO in 91 made 190 HP. That's 8 HP difference.

HO only made more HP than Renix at higher RPMs and not a bit more torque. HO had a 58 mm throttle body versus a 52 mm throttle body on a Renix. That’s 20% more air available through the HO throttle body. The HO also had a better design header. See where I'm going with this?

It’s only a 4% horsepower increase…..

The whole 8HP was not mostly from the head, but from the bigger TB and better exhaust manifold.

Put a 60mm TB from www.strokedjeep.com on your present manifold using the Renix head, eliminate the "crush" in your headpipe with proper re-routing, and go for it.

HO stands for Highly Overrated.
__________________
Click to expand...
8 hp is pretty relevant to me, my motor is also a 4.6 I'll take all of the flow I can get.
 
I would just port the head and intake runners myself if I wanted the extra flow. And if I did the math and got a good cam for it, I can make up the 8 HP. But again, I'm not worried about power. I got my 340 Duster so I'm doing fine on the speed thing lol. I really appreciate all the help everyone!! If there is any other little things that may be odd during the swap, just keep me posted. I will probably be on here to ask more questions as well!
 
Hey guys! I'm in the home stretch. Is there a reason why my belt won't fit? I went to text for everything and my belt is too large for the set up. I got a belt for a 97, which is shorter, but still too big. Any advice?
 
Tedmon1967 said:
Hey guys! I'm in the home stretch. Is there a reason why my belt won't fit? I went to text for everything and my belt is too large for the set up. I got a belt for a 97, which is shorter, but still too big. Any advice?
Click to expand...

Did you use the alternator mount from the '90 or the '97? I think they changed it a bit which may be your issue. It is pretty easy to move the mounts over between the two.
 
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